Rhodium carbonyl chloride

This has a folded structure (Figure 2.27) similar to that of rhodium carbonyl chloride (Figure 2.18) with ethene acting as a two-electron donor, but ethene is more weakly held and readily displaced by CO and certain alkenes (e.g. cycloocta-1,5-diene). 

Remarkably, Claver et al. showed that in a square planar rhodium carbonyl chloride complex, two bulky phosphite ligands (65) were able to coordinate in a trans orientation.214 Diphosphite ligands having a high selectivity for linear aldehyde were introduced by Bryant and co-workers. Typical examples are (67)-(70).215,216... 

Recently, it has been discovered that catalysis by rhodium compounds is more effective than by the older cobalt catalyst when tris(triphenylphosphine)rhodium chloride is treated with carbon monoxide, the catalyst bis(triphenylphosphine)rhodium carbonyl chloride is formed. This catalyst is very effective under very mild conditions (49-51). It is believed that the tr-ir rearrangement is also important with this catalyst and operates in a manner analogous to that in the cobalt-catalyzed process, since stablization of the cr complex has been shown to lead to olefin isomerization and lower linear selectivity (52). 

Two reactions differing from the customary ones are observed in the presence of rhodium carbonyl chloride (Eqs. 146 and 147). 37,838... 

Representative Chemicals Rhodium chloride (RhCls) Rhodium carbonyl chloride... 

Chloro(carbonyl)bis(triphenylphosphine)rhodium(I), [Bis(triphenylphosphine)-rhodium carbonyl chloride], [(C6H5)3P]2Rh(CO)Cl. Mol. wt. 690.96, air stable. Suppliers Alfa, ROC/RIC. 

Rhodium carbonyl chloride Dirhodium tetracarbonyl dichloride C4Cl204Rh2 14623-22-9 388.768 red-oran cry 124 S OS... 

When the reaction is complete (3-S hX the apparatus is withdrawn from the oil bath. When the apparatus has been cooled, the orange-red crystals can be scraped from the reaction vessel and the last traces of compound washed out with dry benzene or hexane. The yield is 8.3 g (96%). The rhodium carbonyl chloride so obtained is pure enough for most purposes, but it may be recrystallized from hexane or sublimed at 80° at a pressure of 0.1 mmHg. 

KiJi, J., S. Yoshikawa, and J. Furukawa Carbonylation of Phenylacetylene by Rhodium Carbonyl Chloride. Bull. Chem. Soc. Japan 47, 490 (1974). 

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