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

Reaction of solid NHB-stabilized disilyne (NHB)Si≡Si(NHB) ( 1 , NHB = [ArN(CMe) 2 NAr]B, Ar = 2,6- i Pr 2 C 6 H 3 ) with 1 atm of carbon monoxide yielded the first 1,2-disilicon dicarbonyl complex (NHB)(OC)SiSi(CO)(NHB) ( 2 ). Hydrolysis and methanolysis of 2 led 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 π* orbitals was elucidated by DFT calculations.