Making Sense of Rhodium Catalysis: Three Core Engines—Rh(I), Rh(II), and Cp*Rh(III)—plus a Quick Selection Guide to Representative Product Tables A–G

You often see the words “Rh catalysis” in the literature, but in the lab it usually refers to a whole variable system: the rhodium input form (salt/oxide/supported material/complex), counteranions and ligands, solvent, and additives together determine what the true active species is in the reaction. That, in turn, explains why activity and selectivity can “jump” when you change what looks like a minor detail.

This article uses a practical framework—Rh source → precatalyst → active species—to make rhodium catalysis intuitive and actionable. The companion Tables A–G at the end help you start from the task and quickly locate: which “engine” to choose, which table to begin with, and which variables are most likely to cause run-to-run drift.

What does “rhodium catalyst” actually mean?

Why can the same element (Rh) behave so differently when you change the precursor/anion/ligand? Start by separating three concepts:

1. Rhodium source (Rh source): the starting material that supplies rhodium, such as RhCl₃·xH₂O, rhodium nitrate, Rh(acac)₃, Rh₂O₃, rhodium black, Rh/C, Rh/Al₂O₃, etc. These are not necessarily the real “active species” in the reaction, but they constrain which activation pathways are accessible later.
2. Precatalyst: a well-defined, weighable, storable convertible form that becomes the active species under the reaction conditions. Examples include [RhCl(COD)]₂, [Rh(COD)₂]BF₄, [Cp*RhCl₂]₂, Rh₂(OAc)₄, and so on.
3. Active species: the transient species that actually performs key steps during catalysis (e.g., H₂ activation, insertion, reductive elimination, carbene transfer, C–H metalation). In solution it may exist as a dynamic equilibrium of multiple forms, strongly influenced by ligands, anions, solvent, and trace impurities.

Note: These are functional roles, not strict chemical categories; the same reagent can play different roles in different systems.

Why rhodium is often seen as “expensive but worth it”: four classic strengths

Rhodium catalysis is repeatedly used in organic synthesis and in materials/process chemistry mainly because it excels at four things:

1. High selectivity and mild conditions in homogeneous hydrogenation/addition: Rh systems exemplified by Wilkinson’s catalyst are milestones in the history of homogeneous hydrogenation. Early work already demonstrated pathways where Rh complexes participate in hydrogenation via metal–hydride intermediates.
2. Industrial impact of asymmetric hydrogenation: Work exemplified by Knowles established chiral Rh-catalyzed asymmetric hydrogenation as a major pillar of modern enantioselective synthesis.
3. Two modern “engines”: Rh(II) carbene transfer + Rh(III) C–H activation: Dirhodium “paddlewheel” catalysts are highly efficient and classic in carbene chemistry, while Cp*Rh(III) occupies a central position in directed C–H functionalization.
4. Hydroformylation/carbonylation (syngas: CO/H₂) as an industrial backbone: Under CO/H₂, Rh(I) readily enters working states such as Rh–H / Rh–CO, enabling olefin hydroformylation (to aldehydes) and related carbonylation reactions under relatively mild conditions. Importantly, linear/branched selectivity (n/iso), rate, and side reactions can often be engineered by tuning phosphine/phosphite ligand electronics and sterics and by adjusting CO partial pressure—making this a mature large-scale Rh platform.

The three most common “rhodium active centers”: Rh(I) / Rh(II) / Rh(III)

Engine (common oxidation state)	“Tags” you often see in product names	Typical precatalysts/precursors (examples)	Common activation modes	Signature reactions / capability boundaries	Selection tips
Rh(I) (the main homogeneous workhorse; often enters Rh(I)/Rh(III) cycles)	COD, NBD, MeCN, PPh₃; also BF₄⁻/PF₆⁻/OTf⁻/SbF₆⁻/BArF₄⁻ (often in cationic systems)	Chloride-bridged dimers such as [RhCl(COD)]₂; cationic [Rh(diene)₂]⁺X⁻; classic platforms such as RhCl(PPh₃)₃	Ligand exchange / creation of coordination vacancies; cationic systems are more strongly affected by ion pairing, anion weak-coordination, and solubility	Hydrogenation, additions, isomerization, (some) carbonyl-related platforms; asymmetric hydrogenation often uses chiral bisphosphine–Rh(I)	For rapid screening: start from general Rh(I) precursors and build a ligand library (Table B). For ee: go directly to pre-formed chiral Rh(I) catalysts (Table C).
Rh(II) dirhodium (paddlewheel)	“Dirhodium(II)”, “Rh₂(OOCR)₄”, “paddlewheel”; various carboxylate/ chiral ligand names	Rh₂(OAc)₄, Rh₂(TFA)₄, chiral Rh₂(DOSP)₄, BTPCP, PTAD, etc.	Reaction with carbene precursors to form metal–carbene; axial sites/additives/solvent may also modulate	Cyclopropanation, C–H insertion, X–H insertion (carbene transfer); chiral dirhodium controls enantioselectivity	First make it work: achiral dirhodium (Table D). For ee: chiral dirhodium (Table E).
Rh(III) (especially Cp*Rh(III))	CpRh, [CpRhCl₂]₂; often described together with “silver salt / halide abstraction” conditions	[Cp*RhCl₂]₂; halide-free or weakly coordinating anion CpRh(III) precursors	Commonly: halide abstraction → more reactive Rh(III) (silver salts are common, but silver-free routes exist)	Directed C–H activation/cyclization/coupling; sensitive to additive package and substrate directing groups	For C–H activation, start with Table F. If you need “cleaner activation,” compare with halide-free/weakly coordinating precursors.

Homogeneous vs heterogeneous: selection is not only about separation, but also “site controllability + process pathway”

Dimension	Homogeneous Rh catalysis	Heterogeneous/supported Rh catalysis (Rh/C, Rh/Al₂O₃, rhodium black, etc.)	Practical, actionable tip
What is the active site?	Molecular, often structurally definable Rh complexes/intermediates; sites are more “describable”	Surface atoms/edges/defects/metal–support interfaces; sites may change dynamically; identification and counting are harder	For mechanistic clarity and predictable optimization: homogeneous is usually easier; heterogeneous relies more on experience plus characterization/controls
What can be tuned (selectivity tools)?	Fine control via ligand electronics/sterics/chirality—especially good for ee and site selectivity	Mainly via support, dispersion, particle size, metal–support interactions, additives, and conditions; fewer “chiral tools” (unless special strategies)	If you need ee/high stereoselectivity → prioritize homogeneous
Activity/selectivity (typical trend)	Often easier to reach both high activity and high selectivity; more predictable	Selectivity may be influenced by support and mass transfer; modern heterogeneous systems can also be very strong (not inherently worse)	—
Separation/recycling/continuous operation	Separation is often harder; recycling may require extraction, immobilization, biphasic systems, membranes, etc.	Filtration/fixed beds are natural; often better for scale-up and continuous production	If the goal is scale-up, recycling, continuous processing: heterogeneous often has an edge
Sensitivity to impurities/handling	Often more sensitive to water/oxygen/halides/strongly coordinating impurities; reproducibility depends on operational discipline	Also sensitive to some impurities, but problems often stem from mass transfer, bed/stirring, deactivation (sintering/poisoning)	For homogeneous: lock down “cleanliness/order/ligands.” For heterogeneous: lock down “stirring/H₂ pressure/filtration/reuse.”
Key reminders	Control metal residues; workup losses; active species may not match the input structure (confirm by controls)	Leaching/redeposition can make a system “look heterogeneous” while homogeneous species participates; sites are hard to define	Do a “hot filtration test” (does it keep reacting after filtration?) and measure metal residues (e.g., ICP)

From precatalyst → active species: common activation pathways in Rh catalysis

Activation pathway	Common precursors / “name clues”	What typically happens	Most sensitive variables (often cause “jumps”)
A. Ligand dissociation / dimer cleavage → coordination vacancy	Rh(I)–COD/NBD/MeCN/PPh₃; chloride-bridged dimers such as [Rh(μ-Cl)(COD)]₂; cationic [Rh(COD)₂]BF₄	“Occupying ligands stabilize first, then vacate under reaction conditions”; dimers are split into mononuclear species that can enter the catalytic cycle	Ligand addition order and equivalents; solvent donor strength; presence of halides/strongly coordinating impurities
B. Halide abstraction/activation (common in Rh(III) C–H)	[Cp*RhCl₂]₂ + AgX / AgOAc etc.	“Remove Cl⁻ to make Rh more ‘open’ and reactive,” facilitating species that can undergo C–H metalation (note: Ag salts can do more than just halide abstraction)	Ag salt identity and loading; anion (SbF₆⁻/BF₄⁻/OTf⁻, etc.); presence of acetate/base (affects CMD)
C. Formation of key intermediates (Rh–H / Rh–carbene / Rh–metalated)	Hydrogenation: Rh(I) precursors; carbene: Rh₂(OOCR)₄; C–H: Cp*Rh(III)	Hydrogenation: Rh(I) oxidative addition → Rh(III) dihydride, then insertion and reductive elimination; carbene: Rh–carbene generation and transfer (often from diazo compounds); C–H: Rh–C bond formation (CMD, etc.)	Dryness/inert atmosphere; additives (base/acid/halide scavengers); substrate coordination interference
D. Redox / reductive activation (often overlooked but critical)	Rh(III) salts or higher-oxidation precursors; in some cases metal Rh(0)/nanoparticles form	First “reduce into a catalytically competent state” (Rh(I) or Rh–H); reductants may come from H₂, phosphines, substrate, or additives	Whether a reductant exists; induction period; impurities (O₂/H₂O/halides)

Reading product names: quickly tell “which engine it is” and “what it’s for”

When you see in the name…	Usually which “engine/family”	Go to which table first	Use-case hint
COD / NBD / MeCN / PPh₃ (especially with Rh(I))	Mostly Rh(I) homogeneous precursors/platforms	Table B (general Rh(I)) / Table C (chiral Rh(I))	“Stabilize first, then activate/ligand exchange”; good for library screening and literature benchmarking
Rh₂(… )₄ / dirhodium(II) / paddlewheel	Rh(II) dirhodium (carbene transfer)	Table D (achiral) / Table E (chiral)	Cyclopropanation, C–H/X–H insertion; for ee, go straight to chiral dirhodium
CpRh / [CpRhCl₂]₂	Typical Rh(III) C–H activation platform	Table F	Directed C–H activation/cyclization/coupling; often paired with halide abstraction/activation additives
Rh/C, Rh/Al₂O₃, rhodium black, Rh powder	Heterogeneous/material-side Rh	Table A	Easier separation/recycling and scale-up; watch mass transfer, support/dispersion, and reproducibility

The three most common “sensitivity points” in Rh catalysis

Sensitivity point	What it usually causes	Common symptoms	Quick response
Trace water/oxygen	Affects activation, changes oxidation state/intermediate equilibria → induction periods and reproducibility drift	“Sometimes fast, sometimes dead” under nominally identical conditions; large day-to-day differences with the same catalyst batch	Dry solvents/glassware; inert atmosphere; standardize addition order and pre-activation time
Halides/strongly coordinating impurities (Cl⁻/Br⁻; strongly coordinating S/N compounds, etc.)	Can passivate cationic Rh(I) or alter Rh(III) activation pathways	Reaction “suppressed,” clear activity drop; suddenly improves after adding Ag salt or switching anion	Control halide sources; run halide scavenging/abstraction controls when needed; avoid strongly coordinating impurities
Ion pairing & solubility (anion effects)	Changes how “naked” a cationic Rh(I) is, ion-pair tightness, and solubility → rate/selectivity shifts	Results “jump” when switching BF₄⁻/OTf⁻/SbF₆⁻/BArF₄⁻	Treat the anion as a tunable knob; run a small matrix (anion × solvent × ligand) and record solubility/turbidity

Notes:

1. 5For heterogeneous systems, additionally watch mass transfer/stirring/H₂ pressure and catalyst wetting/dispersion; otherwise what looks like a catalyst issue is often a mass-transfer issue.
2. Strongly coordinating sulfur/amine species and the site-blocking effect of CO: many Rh(I) systems are easily “captured” and passivated by such ligands—especially when using more “naked” cationic Rh(I). This often looks like catalyst failure, but is actually coordination inhibition.

Aladdin Rhodium Catalyst R&D Selection & Application Navigation: Representative Product Subtables (Tables A–G; Rh sources / homogeneous Rh(I) / chiral Rh(I) / Rh₂(II) / Cp*Rh(III) / clusters)

Navigation for Rhodium Catalyst Product Tables

Your goal/task	Start with which table	What this table mainly contains	Typical use scenarios	Quick in-table screening keywords
Need a metal Rh source/salt/solution, or want to make supported catalysts/electroplating/material precursors	Table A	Rh(III) inorganic salts/solutions, Rh oxides, supported Rh/C, etc.	Preparing supported Rh catalysts (impregnation → reduction), making Rh solutions, materials/electrochemistry/surface treatment, process-scale “feedstock side”	“rhodium nitrate / rhodium chloride / rhodium bromide / rhodium sulfate solution / rhodium oxide / Rh on carbon”
Want to quickly build a general homogeneous Rh(I) system and screen ligands yourself	Table B (precursor section)	Rh(I) precursors with exchangeable ligands (COD/NBD/olefin/acac/MeCN, etc.), cationic [Rh(diene)₂]⁺	Homogeneous hydrogenation/isomerization/addition/coupling: precursor + candidate ligand library for fast condition scouting	“(COD)₂Rh⁺, NBD, acac, MeCN, chloride-bridged dimer, BF4/OTf/PF6/SbF6/BArF4”
Don’t want to formulate ligands yourself; want plug-and-play Rh(I) platforms for quick validation/benchmarking	Table B (mature platforms section)	Pre-ligated platforms with PPh₃/CO/H etc. (Wilkinson-type, Rh–H, Rh–CO, etc.)	Literature benchmarking, teaching demos, quick “can this route run?”, mechanistic controls (Rh–H/Rh–CO)	“PPh₃, Wilkinson, hydride, carbonyl, Rh–CO, Rh–H”
Need asymmetric hydrogenation/asymmetric addition with ready-made chiral Rh(I) catalysts	Table C	Pre-formed chiral Rh(I) catalysts based on commercial chiral ligands (DUPHOS, BPE, NORPHOS, BINAP, phane, ferrocene, etc.)	ee is the goal: start from mature chiral families, then fine-tune ligand family, anion (BF4/OTf, etc.), solvent, additives	“DUPHOS, BPE, NORPHOS, BINAP, phane, ferrocene, catASium, BF4/OTf”
Doing carbene transfer (cyclopropanation, C–H insertion, X–H insertion) without emphasizing chirality	Table D	Achiral Rh(II) dirhodium with varied carboxylate/ligand environments (OAc, TFA, perfluorocarboxylates, bulky carboxylates, lactamates, etc.)	First make the reaction work; tune activity/selectivity/solubility by changing carboxylate environment	“Rh2, dirhodium, acetate/TFA/pivalate/perfluoro, caprolactamate”
Doing enantioselective carbene transfer (ee-focused cyclopropanation/insertion)	Table E	Chiral Rh(II) dirhodium (DOSP, BTPCP, PTAD, amino-acid-derived families, etc.)	ee is the core metric: start from mature chiral dirhodium families, then match substrates and fine-tune conditions	“Rh2(DOSP), BTPCP, PTAD, Leu/Phe-derived, HPLC grade”
Doing C–H activation / directed cyclization / coupling (Cp*Rh(III) systems) or cyclometalated Rh(III) chemistry	Table F	CpRh(III)Cl₂ dimer, halide-free cationic CpRh(III), cyclometalated Rh(III) dimers, etc.	Reproducing Cp*Rh(III) literature systems; comparing “cleaner activation” using halide-free/weakly coordinating anion precursors	“Cp*Rh, pentamethylcyclopentadienyl, SbF6, cyclometalated (2-phenylpyridine)”
Doing mechanistic/clusters/CO chemistry, or want cluster precursors	Table G	Rh carbonyl clusters, hydride clusters, etc. (more mechanism/model oriented)	Mechanistic models, cluster/nanoparticle precursor exploration, CO coordination and cluster chemistry	“Rh4(CO)12, Rh6(CO)16, μ-hydride cluster”

Table A | Engineering/Materials-Facing Rh Sources (Rh(III) Salts/Solutions/Oxides + Supported Catalysts)

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Rh(III) nitrate (hydrated) precursor	R431254	Rhodium(III) nitrate hydrate	10139-58-9	~36% Rh	Aqueous Rh(III) metal source; commonly used to prepare Rh salt solutions, synthesize complexes, or impregnate supports to make supported Rh catalysts
Rh(III) nitrate (assay specified)	T1373807	Same as above (adduct; N content specified)	154090-43-4	Elemental analysis: N 3.30–4.50%	Suitable when “batch-consistent / assay-specified” charging is required for controlled dosing and comparative studies
Supported Rh/C (heterogeneous)	R485647	Rhodium on activated carbon	—	Water-wet; 5% Rh (on dry basis)	Classic heterogeneous hydrogenation/reduction catalyst; water-wet form improves handling safety and weighing/transfer
Supported Rh/C (heterogeneous, with stabilizer)	R111023	Rhodium on carbon catalyst	7440-16-6	5% Rh; contains 55–60% water stabilizer	Widely used for heterogeneous hydrogenation/reduction; water stabilizer improves storage/handling safety and is helpful for scale-up evaluation
Metallic Rh (powder/black) for heterogeneous catalysis/materials	R109241	Rhodium black	7440-16-6	≥99.9% metals basis	High-surface-area metallic Rh; often used for heterogeneous hydrogenation/reduction, materials/electrochemical benchmarks, and as a metal source for preparing supported Rh
Supported Rh/Al₂O₃ (heterogeneous)	R383782	Rhodium on alumina	7440-16-6	5 wt.% loading labeling, matrix alumina support	Classic supported catalyst (Rh/Al₂O₃) for hydrogenation/hydrogenation under gas-phase or scale-up conditions; support affects dispersion and selectivity (useful comparison to Rh/C)
Rh(III) chloride (hydrated) precursor	R109233	Rhodium(III) chloride hydrate	20765-98-4	Rh 38.5–42.5%	Classic Rh(III) metal source for Rh complex synthesis, catalyst precursors, and supported Rh preparation
Rh(III) chloride (trihydrate) precursor	R190691	Rhodium(III) chloride trihydrate	13569-65-8	≥98%	RhCl₃·xH₂O-type precursor; suitable for routine Rh complex synthesis and catalyst system setup
Rh(III) chloride (anhydrous/low-water) precursor	R132432	Rhodium chloride	10049-07-7	≥98%	RhCl₃-type metal source; more compatible with moisture-sensitive systems; often used for complex synthesis and for making Rh⁰ by supported/reductive routes
Rh(III) bromide (hydrated) precursor	R665349	Rhodium(III) bromide hydrate	123333-87-9	Rh 23.6%	Rh(III) halide source; useful for halide-effect controls or specific Rh(III) complex synthesis
Rh(III) bromide (dihydrate) precursor	R282830	Rhodium(III) bromide dihydrate	15608-29-4	≥97%	Rh(III) bromide source; commonly used for Rh complex/precatalyst preparation and condition benchmarking
Rh(III) iodide precursor	R117876	Rhodium(III) iodide	15492-38-3	Rh 21.3%	Rh(III) iodide metal source; suitable for halide exchange and coordination-strength comparison studies
Rh oxide / materials precursor	R322316	Rhodium(III) oxide pentahydrate	39373-27-8	≥99.95% metals basis	High-purity hydrated Rh(III) oxide precursor; used for demanding coordination/material precursor work and catalytic controls
Rh(III) nitrate (dihydrate) precursor	R339896	Rhodium(III) nitrate dihydrate	13465-43-5	≥95%	Rh(III) nitrate metal source for solution preparation and impregnation–reduction routes to Rh/C or Rh/oxide supports
Rh(III) sulfate solution precursor	R346721	Rhodium sulfate solution	10489-46-0	≥99.95% metals basis	Aqueous Rh solution metal source; commonly used for electroplating/surface treatment or impregnation-based preparation of supported Rh
Rh(III) carboxylate precursor	H124011	Rhodium(III) acetate	42204-14-8	Rh ≥38%	Rh(III) carboxylate metal source; used for complex synthesis and selected homogeneous catalyst-precursor routes
Rh(III) β-diketonate complex (high purity)	R118540	Rhodium(III) acetylacetonate (Rh(acac)₃)	14284-92-5	PrimorTrace™, ≥99.99% metals basis	High-purity Rh(acac)₃; common in coordination/material precursor studies and catalytic benchmarks
Rh oxide (materials/heterogeneous precursor)	R113303	Anhydrous rhodium oxide	12036-35-0	≥99.8% metals basis, Rh ≥80.6%	Used in materials/electrochemistry/heterogeneous studies; can also serve as a precursor for reduction to Rh⁰ or supported Rh preparation

Table B | General Homogeneous Rh(I) (Mostly Achiral): Ligand-Exchangeable Precursors + Mature PPh₃/CO/H Platforms

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Rh(I) chloro-bridged COD dimer precursor	C113573	Chloro(1,5-cyclooctadiene)rhodium(I) dimer	12092-47-6	Rh 41.7%	One of the most commonly used Rh(I) starting materials; readily undergoes ligand exchange / halide abstraction to generate active Rh(I) species (hydrogenation/addition/isomerization, etc.)
Rh(I) chloro-bridged NBD dimer precursor	B293967	Chloro(norbornadiene)rhodium dimer	12257-42-0	≥99.95% metals basis	“Workhorse” precursor similar to COD; NBD is easily displaced—useful for rapid construction of ligated Rh(I) catalysts
Rh(I) chloro-bridged olefin dimer precursor	C118535	(Bicyclooctene)chloro-rhodium dimer	12279-09-3	≥98%	Olefin ligand is exchangeable; used to rapidly generate ligated Rh(I) catalysts and screen conditions
Rh(I) chloro-bridged diene dimer precursor	C118545	Chloro(1,5-hexadiene)rhodium(I) dimer	32965-49-4	≥98%	More “readily activatable” olefin precursor; often used in ligand screening and mechanistic benchmarking
Rh(I) chloro-bridged vinyl dimer precursor	D118537	Chloro-di(vinyl)rhodium(I) dimer	12081-16-2	≥98%	Vinyl/olefin-type precursor; used to build Rh(I) active centers via ligand exchange or for related mechanistic studies
Rh(I) COD–acac neutral precursor	A284018	(1,5-Cyclooctadiene)(2,4-pentanedionato)rhodium(I)	12245-39-5	≥99.95% metals basis	Neutral and soluble; suitable for ligand substitution and building a homogeneous Rh(I) library (screening reaction window/solvent/additives)
Rh(I) NBD–acac neutral precursor	A118525	(Norbornadiene)(acetylacetonato)rhodium	32354-50-0	≥97%	Neutral Rh(I) precursor; commonly used for rapid installation of phosphine/N ligands to build catalytic systems
Rh(I) olefin–acac neutral precursor	A282799	Acetylacetonato bis(cyclooctene)rhodium(I)	34767-55-0	≥97%	Neutral; olefin is readily exchangeable—useful for ligand screening and generating active Rh(I) species
Rh(I) acac–olefin neutral precursor	A118538	Acetylacetonato bis(ethylene)rhodium(I)	12082-47-2	≥95%	Neutral Rh(I) platform; used to construct ligated Rh(I) catalysts and for mechanistic comparisons
Rh(I) COD–(8-quinolinato) chelate	C469098	(1,5-Cyclooctadiene)(8-quinolinolato)rhodium(I)	33409-86-8	≥97%	Neutral N,O-chelated Rh(I); suitable for coordination/activation-pathway studies and as a precursor in specific systems
Rh(I) alkoxy–COD dimer	M138106	Methoxy(1,5-cyclooctadiene)rhodium(I) dimer	12148-72-0	≥98%	Rh–OMe reactive precursor; useful for building Rh(I) systems under halide-free/low-salt conditions or as a base-related control
Rh(I) hydroxy–COD dimer	H467391	Hydroxy(1,5-cyclooctadiene)rhodium(I) dimer	73468-85-6	≥95%	Rh–OH reactive precursor; facilitates generation of ligated Rh(I) active centers; useful for activation/mechanistic controls
Rh(I) cation “stabilized adduct”	C282825	(1,5-Cyclooctadiene)(hydroquinone)rhodium(I) tetrafluoroborate	120967-70-6	≥95%	Stabilized source of cationic Rh(I); safer/more reliable for weighing and storage, releases active Rh(I) in situ
Rh(I) cation [Rh(COD)₂]⁺ (BF₄⁻)	B140876	Bis(1,5-cyclooctadiene)rhodium tetrafluoroborate	35138-22-8	Rh 24.8%	Common cationic precursor; convenient for introducing ligands (including chiral ligands) to build homogeneous catalysts
Rh(I) cation [Rh(COD)₂]⁺ (OTf⁻)	B284034	Bis(1,5-cyclooctadiene)rhodium triflate	99326-34-8	≥99.95% metals basis	Weakly coordinating anion often promotes activation; used to build high-activity Rh(I) systems and for rapid ligand exchange
Rh(I) cation [Rh(NBD)₂]⁺ (BF₄⁻)	B284043	Bis(norbornadiene)rhodium(I) tetrafluoroborate	36620-11-8	≥99.95% metals basis	NBD dissociates/is replaced readily; suitable for fast generation of active Rh(I) centers (hydrogenation/addition, etc.)
Rh(I) cation [Rh(COD)₂]⁺ (hydrated BF₄⁻)	B168465	Bis(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate hydrate	207124-65-0	≥97%	Hydrated form as listed; still a common cationic precursor for ligand introduction and condition screening
Rh(I) cation [Rh(COD)₂]⁺ (PF₆⁻)	B589714	Bis(1,5-cyclooctadiene)rhodium hexafluorophosphate	62793-31-1	≥98%	Common cationic precursor; PF₆⁻ can help with solubility/ion-pairing controls—useful for achiral and asymmetric library building
Rh(I) MeCN “activated-site” precursor (BF₄⁻)	B169584	Di(acetonitrile)(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate	32679-02-0	≥98%	MeCN is labile → easier activation; suitable for quickly generating ligated Rh(I) active centers
Rh(I) cation [Rh(COD)₂]⁺ (SbF₆⁻)	B468674	Bis(1,5-cyclooctadiene)rhodium(I) hexafluoroantimonate	130296-28-5	≥97%	Extremely weakly coordinating anion; often chosen for highly active cationic Rh(I) systems (“cleaner” activation)
Rh(I) cation [Rh(NBD)₂]⁺ (OTf⁻)	B468858	Bis(norbornadiene)rhodium(I) triflate	178397-71-2	≥97%	OTf⁻ is weakly coordinating; helps form more reactive Rh(I) centers—good for ligand exchange/activity benchmarking
Rh(I) MeCN/COD mixed cation (BF₄⁻)	B282800	Bis(acetonitrile)(1,5-cyclooctadiene)rhodium(I) tetrafluoroborate	46360-78-5	≥97%	Combines COD stabilization with MeCN lability; suitable for “quick-start” homogeneous screening
Rh(I) ultra-weakly coordinating anion (BArF₄⁻)	B432697	Bis(1,5-cyclooctadiene)rhodium(I) tetrakis[bis(3,5-trifluoromethyl)phenyl]borate	404573-66-6	—	BArF₄⁻ is extremely weakly coordinating; used to access highly “naked” cationic Rh(I) for high-activity exploration
Rh(I) PPh₃ platform (Wilkinson-type)	W347495	Rhodium(I) chloride tris(triphenylphosphine) (NSC 124140)	14694-95-2	≥99.95% metals basis	Classic homogeneous hydrogenation platform; well-defined ligation, good reproducibility—useful for teaching/screening/benchmarking
Rh(I) PPh₃ platform (halide variant)	B580700	Rhodium(I) bromide tris(triphenylphosphine)	14973-89-8	≥99.95% metals basis	Same family as the chloride; used for halide-effect/activation comparisons and condition optimization
Rh(I) hydride (PPh₃)	H597603	Tetrakis(triphenylphosphine)rhodium(I) hydride	18284-36-1	Rh 8.4% min	Common precursor for homogeneous hydrogenation; relates directly to Rh–H active forms—useful for hydrogenation/isomerization, etc.
Rh(I) carbonyl hydride (PPh₃)	C117877	Carbonylhydridotris(triphenylphosphine)rhodium(I)	17185-29-4	≥97%	Rh–H/CO platform; often used for hydroformylation/carbonylation-related mechanistic and catalytic benchmarking
Rh(I) carbonyl chloride (PPh₃)	B113668	Chlorocarbonylbis(triphenylphosphine)rhodium(I)	13938-94-8	Rh ≥14.90%	Rh–CO platform; suitable for carbonylation, ligand exchange, and mechanistic controls
Rh(I) carbonyl–β-diketonate–PPh₃ platform	C124012	Carbonylacetylacetonato(triphenylphosphine)rhodium(I)	25470-96-6	Rh 21%	Contains CO/β-diketonate/PPh₃ simultaneously; used for carbonylation-related screening and ligand-exchange routes
Rh(I) dicarbonyl–β-diketonate platform	A293954	Dicarbonyl(acetylacetonato)rhodium	14874-82-9	≥99.95% metals basis	(CO)₂ platform that readily undergoes ligand substitution; useful as a carbonylation/activation precursor and benchmark
Rh(I) carbonyl chloro-bridged dimer	D118541	Di-μ-chloro-tetracarbonyldirhodium	14523-22-9	≥97%	Rh–CO/Cl-bridged platform; used for carbonylation mechanism studies or to build Rh–CO active species
Rh(I) special “scorpionate” ligand platform (Tp type)	T282823	[Hydridotris(3,5-dimethyl-1H-pyrazolyl)borato]bis(triphenylphosphine)rhodium(I) toluene adduct	341483-76-9	≥99%	Tp-type platform stabilizes Rh(I); used for small-molecule activation, mechanism, and coordination-chemistry benchmarking
Rh(I) bisphosphine cationic platform (dppb type)	B775166	Rhodium(I) 1,4-bis(diphenylphosphino)butane tetrafluoroborate (contains CH₂Cl₂)	79255-71-3	≥98%	General bisphosphine–Rh(I) platform for homogeneous hydrogenation/addition/isomerization system setup
Rh(I) NBD + bisphosphine platform	B139300	(Bicyclo[2.2.1]hepta-2,5-diene)[1,4-bis(diphenylphosphino)butane]rhodium(I) tetrafluoroborate	82499-43-2	≥95%	NBD is easily replaced; suitable for quickly generating bisphosphine–Rh(I) active centers and benchmarking conditions
Rh(I) ferrocene bisphosphine platform	B282815	1,1′-Bis(diisopropylphosphino)ferrocene (1,5-cyclooctadiene)rhodium(I)	157772-65-1	≥98%	Ferrocene-based bisphosphine–Rh(I) platform; used for ligand-effect studies and building homogeneous catalytic systems
Rh(I) specialty phosphine/aminophosphine platform	D282812	3-Diisopropylphosphino-2-(N,N-dimethylamino)-1H-indene (1,5-cyclooctadiene)rhodium(I)	540492-55-5	≥95%	Specialty tunable electronic/steric ligand–Rh(I); useful for “difficult substrate” screening and activation-pathway exploration
Polymer-supported Rh(I) (recyclable)	T487001	Triphenylphosphine(norbornadiene)rhodium(I) tetrafluoroborate, polymer-bound Fibre-cat®	305367-01-5	—	Facilitates separation/recycling and reuse; suitable for scale-up/flow chemistry or for lowering metal residues

Table C | Chiral Rh(I) (Asymmetric Hydrogenation/Additions, etc.): Pre-formed Chiral Ligand–Rh(I) Platforms

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Chiral Rh(I)–DUPHOS (BF₄⁻)	B282816	(R,R)-i-Pr-DUPHOS-Rh(COD)BF₄	569650-64-2	≥98%	Pre-formed chiral bisphosphine–Rh(I); commonly used for asymmetric hydrogenation (fast to deploy; convenient for substrate screening)
Chiral Rh(I)–DUPHOS (BF₄⁻)	B359399	(S,S)-i-Pr-DUPHOS-Rh(COD)BF₄	—	≥98%	Enantiomer of i-Pr-DUPHOS version; used for ee benchmarking and condition optimization
Chiral Rh(I)–DUPHOS (OTf⁻)	B282803	(R,R)-Et-DUPHOS-Rh(COD)OTf	136705-77-6	≥98%	OTf⁻ is weakly coordinating and often favors activation; used for asymmetric hydrogenation/addition screening
Chiral Rh(I)–DUPHOS (BF₄⁻)	B282801	(R,R)-Et-DUPHOS-Rh(COD)BF₄	228121-39-9	≥98%	BF₄⁻ version useful for anion-effect comparisons (activity/solubility/selectivity)
Chiral Rh(I)–DUPHOS (OTf⁻)	B282807	(S,S)-Me-DUPHOS-Rh(COD)OTf	136705-75-4	≥98%	Me-DUPHOS platform; used to build steric/electronic gradients in asymmetric hydrogenation
Chiral Rh(I)–BPE (BF₄⁻)	B282814	(S,S)-Ph-BPE-Rh(COD)BF₄	849950-53-4	≥98%	BPE family often delivers high ee in asymmetric hydrogenation; suitable for screening acrylic acid/amides and related substrates
Chiral Rh(I)–BPE (BF₄⁻)	B282809	(S,S)-Me-BPE-Rh(COD)BF₄	213343-65-8	≥98%	Substituent changes tune sterics/electronics; used to optimize ee and activity
Chiral Rh(I)–phospholane	B282802	Rh(I)(COD) BF₄ complex of 1,2-bis[(2S,5S)-diethylphospholanyl]benzene	213343-64-7	≥98%	Phospholane ligands often give strong stereocontrol; used for quick library building in asymmetric hydrogenation/addition
Pre-formed chiral bisphosphine cationic Rh(I)	B472689	(+)-1-Benzyl-[(3R,4R)-bis(diphenylphosphino)]pyrrolidine (1,5-cyclooctadiene)rhodium(I) tetrafluoroborate	99143-48-3	≥98%	Rigid chiral scaffold bisphosphine–Rh(I); used for asymmetric hydrogenation and stereochemical induction studies
Chiral Rh(I)–phosphacycle (DuPhos-style)	B282813	(−)-1,2-bis((2R,5R)-2,5-diphenylphospholane)ethane (1,5-cyclooctadiene)rhodium(I) tetrafluoroborate	528565-84-6	≥98%	One classic asymmetric hydrogenation platform; suitable for substrate-window screening and ee optimization
Chiral Rh(I)–phosphacycle (iPr version)	B590611	1,2-bis((2R,5R)-2,5-diisopropylphospholane)ethane (cyclooctadiene)rhodium(I) tetrafluoroborate	895541-38-5	≥98%	More sterically demanding version; used to adjust/improve ee and activity (substrate matching dependent)
Chiral Rh(I) bisphosphine (name truncated as provided)	B282808	1,2-bis[(2R,5R)-2,5-(dimethylphos…)]ethane (cyclooctadiene) rhodium(I) tetrafluoroborate	305818-67-1	≥98%	Chiral bisphosphine–Rh(I) platform for asymmetric hydrogenation/addition screening (name kept as in source)
Chiral Rh(I) bisphosphine (OTf⁻)	B282806	1,2-bis[(2R,5R)-2,5-dimethylphosph…]benzene (cyclooctadiene) rhodium(I) triflate	187682-63-9	≥98%	OTf⁻ weakly coordinating; used to build more readily activated chiral Rh(I) systems
Chiral Rh(I) bisphosphine (OTf⁻)	B359397	1,2-bis[(2S,5S)-2,5-diethylphospholanyl]benzene (1,5-cyclooctadiene) rhodium(I) triflate	142184-30-3	≥98%	Uses configuration/alkyl differences for ee/rate comparisons and optimization
Chiral Rh(I) bisphosphine (BF₄⁻)	B282805	1,2-bis[(2S,5S)-2,5-dimethylphosph…]benzene (cyclooctadiene) rhodium(I) tetrafluoroborate	205064-10-4	≥98%	BF₄⁻ version; convenient for anion-effect controls and process condition optimization
Chiral Rh(I) bisphosphine (BF₄⁻)	B282804	(−)-1,2-bis((2R,5R)-2,5-dimethylphospholane)benzene (cyclooctadiene)rhodium(I) tetrafluoroborate	210057-23-1	≥95%	Chiral bisphosphine platform; common for benchmarking/optimization in asymmetric hydrogenation
Chiral Rh(I) arylphosphine platform	R118527	(R,R)-(−)-1,2-bis[(o-methoxyphenyl)(phenyl)phosphino]ethane (1,5-cyclooctadiene)rhodium(I) tetrafluoroborate	56977-92-5	≥95%	Aryl substitution can strongly affect ee; suitable for electronic/steric ligand-effect screening
Chiral Rh(I)–NORPHOS	R282810	(R,R)-NORPHOS-Rh(COD)BF₄	521272-85-5	≥97%	NORPHOS chiral bisphosphine–Rh(I) platform; commonly used to build asymmetric hydrogenation systems
Chiral Rh(I)–NORPHOS	S282811	(S,S)-NORPHOS-Rh(COD)BF₄	78355-59-6	≥97%	Enantiomer control; used to assess ee and condition sensitivity
Chiral Rh(I)–BINAP-type	S282821	(S,S)-BINAP-type (o-methoxyphenyl/phenylphosphine) Rh(I)(COD) BF₄	71423-54-6	≥95%	Classic BINAP-family platform; applicable to asymmetric hydrogenation/addition, convenient for literature benchmarking
Chiral Rh(I) [2.2]paracyclophane bisphosphine (R)	R282822	(R)-[2.2]paracyclophane (COD)BF₄–Rh(I)	1038932-67-0	≥97%	Rigid scaffold supports stereocontrol; used for high-selectivity asymmetric hydrogenation/addition exploration
Chiral Rh(I) phane bisphosphine (R)	R282817	(R)-[2.2]paracyclophane (phane) bisphosphine (COD)BF₄–Rh(I)	619334-93-9	≥97%	Rigid “phane” bisphosphine platform; used for high-ee asymmetric hydrogenation/addition screening
Chiral Rh(I) paracyclophane bisphosphine (R)	R282819	(R)-[2.2]paracyclophane bisphosphine (COD)BF₄–Rh(I)	849950-56-7	≥97%	Rigid paracyclophane framework; useful for optimizing “stereochemical environment → ee response”
Chiral Rh(I) phane bisphosphine (S)	S282818	(S)-[2.2]paracyclophane phane bisphosphine (COD)BF₄–Rh(I)	1174218-30-4	≥97%	Enantiomer version; used for enantioselectivity comparisons
Chiral Rh(I) paracyclophane bisphosphine (S)	S282820	(S)-[2.2]paracyclophane bisphosphine (COD)Rh(I)	200808-73-7	≥97%	Same series (S) enantiomer; used for ee/activity comparison and optimization
Chiral Rh(I) “bipyridine/bisphosphine” (R)	R282838	(R)-Bipyridine/bisphosphine-type (COD)BF₄–Rh(I)	573718-56-6	≥97%	Hybrid-ligand platform; useful for library screening and structure–selectivity relationship studies
Chiral Rh(I) “bipyridine/bisphosphine” (S)	S282839	(S)-Bipyridine/bisphosphine-type (COD)BF₄–Rh(I)	1174131-02-2	≥97%	Enantiomer control; used for ee/substrate-window optimization
Chiral Rh(I) ferrocene bisphosphine (R,R)	B282842	1,1′-Bis((2R,5R)-2,5-diethylphosphino)ferrocene (COD) rhodium(I) tetrafluoroborate	162412-90-0	≥95%	Ferrocene-based chiral platform; widely used for stereocontrol in asymmetric hydrogenation/addition
Chiral Rh(I) ferrocene bisphosphine (R,R)	B282824	1,1′-Bis((2R,5R)-2,5-diisopropylphosph… )ferrocene (COD) rhodium(I) tetrafluoroborate	849773-96-2	≥95%	Bulkier version; used to enhance stereocontrol or improve substrate matching
Chiral Rh(I) ferrocene bisphosphine (R,R)	B282849	1,1′-Bis((2R,5R)-2,5-dimethylphosphino)ferrocene (COD) rhodium(I) tetrafluoroborate	854275-87-9	≥95%	Less bulky version; useful for steric-gradient building to optimize ee/activity
Chiral Rh(I) ferrocene bisphosphine (S,S)	B282843	1,1′-Bis((2S,5S)-2,5-diethylphosphino)ferrocene (COD) rhodium(I) tetrafluoroborate	290347-88-5	≥95%	Enantiomer control; used for ee benchmarking and optimization
Chiral Rh(I) ferrocene bisphosphine (S,S)	B282846	1,1′-Bis((2S,5S)-2,5-diisopropylphosph… )ferrocene (COD) rhodium(I) tetrafluoroborate	854920-94-8	≥95%	Bulkier enantiomer; used for optimization and controls
Chiral Rh(I) ferrocene bisphosphine (S,S)	B282850	1,1′-Bis((2S,5S)-2,5-dimethylphosphino)ferrocene (COD) rhodium(I) tetrafluoroborate	854920-90-4	≥95%	Less bulky enantiomer; used to build steric gradients
Chiral Rh(I) bisphosphine (BF₄⁻)	B282841	1,2-bis((2R,5R)-2,5-diethylphosphino)ethane (COD) rhodium(I) tetrafluoroborate	136705-70-9	≥95%	Chiral bisphosphine–Rh(I) platform for asymmetric hydrogenation substrate screening and ee optimization
Chiral Rh(I) bisphosphine (BF₄⁻)	B282844	1,2-bis((2R,5R)-2,5-diisopropylphosph… )ethane (COD) rhodium(I) tetrafluoroborate	136705-72-1	≥95%	Version differing in sterics/electronics; used to tune ee/activity and substrate fit
Chiral Rh(I) bisphosphine (BF₄⁻)	B282845	1,2-bis((2S,5S)-2,5-diisopropylphosph… )ethane (COD) rhodium(I) tetrafluoroborate	213343-67-0	≥95%	Enantiomer version; used for controls and optimization
Commercial pre-formed chiral Rh(I) (catASium®)	B282827	catASium® MNN(R)Rh(COD)BF₄	908128-78-9	≥95%	“Plug-and-play” pre-formed system; suitable for rapid feasibility checks in asymmetric hydrogenation/addition
Chiral Rh complex (BOX/related)	B405175	Bis(acetato)[(S,S)-4,6-bis(4-isopropyl-2-oxazolin-2-yl)-m-xylene]rhodium	929896-28-6	—	Chiral oxazoline-ligand Rh platform; used for screening in asymmetric addition/cyclization (reaction-dependent)
Chiral Rh(I) bisphosphine–diene platform	B120916	(S,S)-1,2-bis[(tert-butyl)methylphosphino]ethane [η-(2,5-bicycloheptadiene)] rhodium(I) tetrafluoroborate	203000-59-3	—	Chiral bisphosphine + diene cationic Rh(I) platform; used to explore ligand effects in asymmetric hydrogenation/addition

Table D | Rh(II) Dirhodium (Achiral): General Systems for Carbene Transfer/Insertion

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Rh(II) dirhodium carboxylate (OAc)	R102671	Dirhodium(II) tetraacetate	15956-28-2	Rh 43.0%–46.6%	Classic dirhodium carbene-transfer catalyst; widely used for cyclopropanation, C–H insertion, X–H insertion, etc.
Rh(II) dirhodium carboxylate (TFA)	R118543	Dirhodium(II) tetratrifluoroacetate	31126-95-1	Rh 27.5–35.0%	More electron-withdrawing variant; often used for higher activity or altered selectivity in carbene transfer
Rh(II) dirhodium carboxylate (octanoate)	R113304	Dirhodium(II) octanoate	73482-96-9	Rh ≥25.0%	More hydrophobic and often more soluble in organic media; suitable for carbene transfer in organic-solvent systems
Rh(II) dirhodium carboxylate (pivalate)	R465789	Dirhodium(II) pivalate (dimer)	62728-88-5	≥99.9% metals basis	Bulkier carboxylate; often used to tune selectivity in carbene transfer reactions
Rh(II) dirhodium carboxylate (TPA)	R167247	Dirhodium(II) tetrakis(triphenylacetate) (Rh₂(TPA)₄)	142214-04-8	≥99%	Aromatic bulky carboxylate; used to modulate selectivity and substrate matching in carbene transfer
Rh(II) dirhodium perfluorocarboxylate	R338680	Dirhodium(II) heptafluorobutyrate (dimer)	73755-28-9	≥97%	Strongly electron-withdrawing perfluorocarboxylate; used to explore more reactive/strongly driven carbene-transfer systems
Rh(II) dirhodium aromatic carboxylate	T299618	Tetrakis(triphenylacetato)dirhodium	68803-79-2	≥97%	Aromatic bulky carboxylate; used for selectivity optimization and mechanistic comparisons in carbene transfer
Rh(II) dirhodium (lactam ligand)	B301149	Dirhodium(II) tetracaprolactamate	138984-26-6	≥95%	Classic Rh₂(caprolactamate)₄; often used for robust, reproducible carbene transfer
Dinuclear Rh carboxylate complex	B152255	Bis[(α,α,α′,α′-tetramethyl-1,3-benzenedipropionate)rhodium]	819050-89-0	≥96% (HPLC)	Dinuclear carboxylate platform; used for reactivity/selectivity benchmarking and exploratory catalysis studies

Table E | Chiral Rh(II) Dirhodium: Asymmetric Carbene Transfer (Cyclopropanation / C–H & X–H Insertion, etc.)

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Chiral Rh(II) dirhodium (amino-acid-derived)	T406155	Tetrakis[N-tetrafluorophthalimido-(R)-tert-leucinate]dirhodium, bis(ethyl acetate) adduct	—	≥98% (HPLC)	Common in asymmetric carbene transfer; used for enantioselective cyclopropanation and insertion reactions
Chiral Rh(II) dirhodium (amino-acid-derived)	T406154	Same as above (S-tert-leucine) adduct	—	≥98% (HPLC)	Enantiomer control; used for ee optimization and substrate matching
Chiral Rh(II) dirhodium (halogenated aroyl tuning)	T405008	Tetrakis[N-tetrachlorophthalimido-(R)-tert-leucinate]dirhodium adduct	2001054-66-4	≥98% (HPLC)	Halogenated aroyl group tunes electronics/sterics; used for selectivity optimization in asymmetric carbene transfer
Chiral Rh(II) dirhodium (homologous control)	T121192	Same as above (R-tert-leucine) adduct	—	≥98%	Chiral dirhodium platform; used for benchmarking and scale-up verification in asymmetric carbene transfer
Chiral Rh(II) dirhodium (S series)	T121194	Tetrakis[N-tetrafluorophthalimido-(S)-tert-leucinate]dirhodium adduct	564450-56-2	≥98%	S-configuration platform; used for enantioselectivity comparisons and ee optimization
Chiral Rh(II) dirhodium (S series)	T121191	Same as above (S-tert-leucine) adduct	515876-71-8	≥98%	S-series chiral dirhodium; suitable for building “enantiomer–conditions–selectivity” comparison matrices
Chiral Rh(II) dirhodium (tetrachloroaroyl, S)	T406153	Tetrakis[N-tetrachlorophthalimido-(S)-tert-leucinate]dirhodium adduct	—	≥95% (HPLC)	Adds an electronics/sterics gradient; used for optimizing asymmetric carbene transfer
Chiral Rh(II) dirhodium (Phe-derived)	T121173	Tetrakis[N-phthalimido-(S)-phenylalaninate]dirhodium, ethyl acetate adduct	131219-55-1	—	Amino-acid-derived chiral dirhodium; used for screening asymmetric carbene transfer reactions
Chiral Rh(II) dirhodium (DOSP series)	T282836	Rh₂(R-DOSP)₄	178879-60-2	≥95%	Widely used in asymmetric carbene transfer; for high-ee cyclopropanation/insertion
Chiral Rh(II) dirhodium (BTPCP series)	T282834	[Rh₂(R-BTPCP)₄]	1345974-62-0	≥95%	BTPCP family; suitable when seeking stronger stereocontrol in carbene transfer
Chiral Rh(II) dirhodium (PTAD series)	T282832	[Rh₂(R-PTAD)₄]	909393-65-3	≥95%	PTAD family; used for enantioselective cyclopropanation and C–H insertion
Chiral Rh(II) dirhodium (BTPCP, specific ligand form)	T282835	Tetrakis[[S]-(+)-[(1S)-1-(4-bromophenyl)-2,2-diphenylcyclopropanecarboxylate]]dirhodium(II) [Rh₂(S-BTPCP)₄]	1345974-63-1	≥95%	Specific BTPCP variant; for fine-tuning selectivity and substrate scope
Chiral Rh(II) dirhodium (PTAD, specific ligand form)	T282833	Tetrakis[[S]-(+)-(1-adamantyl)-(N-phthalimido)acetate]]dirhodium(II) [Rh₂(S-PTAD)₄]	909389-99-7	≥95%	Specific PTAD variant; used to fine-tune enantioselectivity and activity
Chiral Rh(II) dirhodium (DOSP, specific ligand form)	T282837	Tetrakis[[S]-(−)-N-(p-dodecylphenylsulfonyl)prolinate]dirhodium(II) Rh₂(S-DOSP)₄	179162-34-6	≥95%	Specific DOSP variant; long-chain substitution may affect solubility/microenvironment and thus selectivity

Table F | Cp*/C–H Activation and Cyclometalated Rh Platforms

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Cp*Rh(III)Cl₂ dimer precursor	P284028	Dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer	12354-85-7	≥99.95% metals basis	Cp*Rh(III) C–H activation “workhorse”; used for directed C–H activation/cyclization/coupling, etc.
Cp*Rh(III) halide-free cationic precursor	T282840	Tris(acetonitrile)(pentamethylcyclopentadienyl)rhodium(III) hexafluoroantimonate	125357-42-8	≥98%	Halide-free with weakly coordinating anion; used for “cleaner” Cp*Rh(III) activation and mechanistic benchmarking
Substituted Cp–Rh(III)Cl₂ dimer	B405459	[1,3-Bis(ethoxycarbonyl)-2,4,5-trimethylcyclopentadien-1-yl]rhodium(III) dichloride dimer	1352745-18-6	≥95% (T)	Cp substitution tunes electronics/sterics; used to modulate reactivity and selectivity in C–H activation systems
Cp*Rh(I)(CO)₂ precursor	D282826	Dicarbonyl(pentamethylcyclopentadienyl)rhodium(I)	32627-01-3	≥99%	Cp*Rh platform interconversion precursor; suitable for organometallic/mechanistic and ligand-exchange studies
Cyclometalated Rh(III) dimer (C^N)	C472408	Chloro-bis(2-phenylpyridine)rhodium(III) dimer	33915-80-9	≥98%	Typical C^N cyclometalated Rh(III) platform; used for cyclometalated complex studies/materials and related catalytic exploration

Table G | Clusters / CO Clusters and Hydride Clusters (Mechanistic Models / Cluster Precursors)

Category	Aladdin Cat. No.	Product name	CAS No.	Spec./Purity	Key features / typical uses
Rh carbonyl cluster (Rh₆)	H485521	Hexarhodium hexadecacarbonyl (Rh₆(CO)₁₆)	28407-51-4	Rh 57–60%	Representative carbonyl cluster; used as a cluster/nano-Rh precursor and for CO coordination and mechanistic studies
Rh carbonyl cluster (Rh₄)	T132698	Tetrarhodium dodecacarbonyl (Rh₄(CO)₁₂)	19584-30-6	≥98%	Classic Rh₄(CO)₁₂; used in carbonyl cluster chemistry, mechanistic models, and precursor exploration
Rh hydride cluster (Rh₄–H)	T282831	Tetrakis(1,5-cyclooctadiene) tetra-μ-hydrido tetrarhodium	82660-97-7	≥98%	Hydride-cluster model; used for hydrogen transfer/hydrogenation mechanism studies and exploratory reaction platforms

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