Three‐Coordinate Rhodium Complexes in Low Oxidation States

Abstract

The isolation of simultaneously low-coordinate and low-valent compounds is a timeless challenge for preparative chemists. We showcase here the preparation and full characterization of tri-coordinate rhodium(-I) and rhodium(0) complexes and a rare rhodium(I) complex. Reduction of [{Rh(μ-Cl)(IPr)(dvtms)} 2 ] ( 1 , IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazolyl-2-ylidene; dvtms = divinyltetramethyldisiloxane) with KC 8 gave the trigonal complexes K[Rh(IPr)(dvtms)] and [Rh(IPr)(dvtms)], whereas the cation [Rh(IPr)(dvtms)] + results from their oxidation or by abstraction of chloride from 1 with silver salts. The paramagnetic Rh(0) complex is a unique fully metal centered radical with the unpaired electron in the d z2 orbital. The Rh(-I) complex is an electrophile that reacts with PPh 3 with replacement of the NHC ligand, and a nucleophile, which upon reaction with [AuCl(PPh 3 )] generates the trigonal pyramidal complex [(IPr)(dvtms)Rh-Au(PPh 3 )] with a metal-metal bond between two d 10 metal centers.