Synthesis and characterization of bissilyl cobalt and iron hydrides bearing disilazane ligands via Si-H bond activation

Abstract

Abstract The reaction between 2-pyridinetetramethyldisilazane 1 and CoMe(PMe3)4 led to the formation of the novel bissilyl cobalt(III) hydride CoH((C5H4N)-N(SiMe2)2)(PMe3)3 (2) via the cleavage of two Si-H bonds with the elimination of methane. The reaction of phenyltetramethyldisilazane 3 with CoMe(PMe3)4 could directly provide the hydrido cobalt(III) complex CoH((C6H5)-N(SiMe2)2)(PMe3)3 4. Complex 4 is an analogue to complex 2. This result indicates that a pre-coordination of the nitrogen atom in pyridine to the cobalt center before Si-H bond activation can be excluded in the formation mechanism of 2. This exclusion is further supported by the in situ 1H NMR spectra of the reaction mixtures between 2-pyridinetetramethyldisilazane 1 with CoMe(PMe3)4 in C6D6 in different reaction times. A new bissilyl iron hydride FeH((C5H4N)-N(SiMe2)2)(PMe3)3 (5) was obtained through the reaction of Fe(PMe3)4 with 1. Complexes 2, 4 and 5 with two metal-Si bonds are very stable and did not react with MeI, EtBr, acetylacetone, CO or CO2. The molecular structures of complexes 2, 4 and 5 were determined by single crystal X-ray diffraction.