Three‐Coordinate Rhodium Complexes in Low Oxidation States
Víctor Varela‐Izquierdo, José A. López, Bas de Bruin, Cristina Tejel, Miguel A. Ciriano
Abstract
Abstract The isolation of simultaneously low‐coordinate and low‐valent compounds is a timeless challenge for preparative chemists. This work showcases the preparation and full characterization of tri‐coordinate rhodium(‐I) and rhodium(0) complexes as well as 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 reacts with PPh 3 with replacement of the NHC ligand, and behaves as 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.