Rhodium carbonyl chloride

Updated: 2026-07-22

Overview

Carbonylrhodium chloride (CClORh) is an organometallic compound featuring rhodium coordinated to both carbonyl and chloride ligands. As a Rh(I) complex, it serves as a versatile catalyst precursor in homogeneous catalysis, particularly for carbonylation and hydroformylation reactions. Its industrial significance stems from rhodium's unique ability to facilitate selective bond formation under mild conditions. First synthesized in the mid-20th century, this compound gained prominence with the development of Monsanto's acetic acid process. Today, it remains critical for producing fine chemicals and pharmaceutical intermediates, with annual demand closely tied to specialty chemical manufacturing.

Physical and Chemical Properties

The compound typically appears as orange-red crystals that degrade upon exposure to air or moisture. Its molecular structure consists of a square-planar rhodium center bound to one chloride and two carbonyl ligands (dimeric form exists in solid state). Decomposition occurs at elevated temperatures (>150°C) without distinct melting. Key reactivity includes ligand exchange reactions and oxidative addition processes. In solution, it demonstrates high catalytic activity for C-C bond formation. The CO stretching frequencies in IR spectroscopy (≈2000 cm⁻¹) serve as diagnostic markers for quality control. Solubility is optimal in polar aprotic solvents like THF or DMF, but aqueous solubility is negligible.

Main Applications

Primary use involves catalytic cycles for carbonylation reactions, notably in acetic acid production via methanol carbonylation (alternative to Monsanto process). Pharmaceutical manufacturers employ it for synthesizing chiral intermediates through asymmetric hydroformylation. In fine chemicals, it facilitates aldehyde synthesis from olefins. Emerging applications include polymer synthesis and renewable fuel research, where its selectivity outperforms cobalt catalysts. The compound's value derives from enabling reactions at lower temperatures/pressures than alternative catalysts, reducing energy costs in continuous flow systems.

Safety and Storage

As an air-sensitive compound, storage requires argon/vacuum-sealed containers with desiccants. Decomposition products may include toxic rhodium oxides and CO gas. Always handle in fume hoods with nitrile gloves and protective eyewear. Spills should be quenched with inert absorbents (vermiculite) and disposed as hazardous waste. Firefighting requires dry chemical suppressants – water reacts with decomposition products. Regulatory classifications typically include GHS05 (corrosion) and GHS08 (health hazard). SDS documentation must accompany commercial shipments due to transport restrictions under IATA/ADR regulations.

B2B Procurement Guide

Industrial buyers should prioritize suppliers offering batch-tested certificates of analysis (COA) with quantified Rh content (≥98% purity). Ampoule packaging (1–5g units) minimizes decomposition versus bulk containers. Consider vendors providing stabilized formulations with phosphine ligands for enhanced shelf life. Pricing fluctuates with rhodium spot markets (≈$15,000/oz in 2023). For pilot plants, consider leasing catalyst recovery services to offset costs. Lead times often exceed 4 weeks for custom specifications. Verify supplier compliance with REACH/TPED regulations, especially for EU imports. Alternative catalysts like [Rh(acac)(CO)₂] may offer cost advantages for specific applications.