Disilicon Dicarbonyl Complex: Synthesis and Protonation of CO with O-H Bond

Reaction of solid NHB-stabilized disilyne (NHB)SiSi(NHB) (1, NHB = [ArN(CMe)2NAr]B, Ar = 2,6-iPr2C6H3) with 1 atm of carbon monoxide yielded the first 1,2-disilicon dicarbonyl complex (NHB)(OC)SiSi(CO)(NHB) (2). Hydrolysis and methanolysis of 2led to the C-C coupling and protonation of two CO oxygen atoms giving disilacyclobutene derivatives 3 and 4. In contrast, reaction of 2 with iodomethane resulted in the oxidative addition to the silicon atoms with the formation of 1,2-diiodo-disilane 5 with the liberation of CO molecules. Single-crystal X-ray diffraction analysis of 2 disclosed the coordination of CO to the two silicon atoms with a unique 1,2-dicarbonyl-disilane skeleton, in which the pronounced backbonding from the lone pairs of silicon p orbitals to CO pi* orbitals was elucidated by DFT calculations.