From As-Zincoarsasilene (LZn-As=SiL') to Arsaethynolato (As≡C-O) and Arsaketenylido (O=C=As) Zinc Complexes.

Abstract

The reactivity of the As-zincosilaarsene LZn-As=SiL' A (L=[CH(CMeNDipp)2 ]- , Dipp=2,6-i Pr2 C6 H3 , L'=[{C(H)N(2,6-i Pr2 -C6 H3 )}2 ]2- ) towards small molecules was investigated. Due to the pronounced zwitterionic character of the Si=As bond of A, it undergoes addition reactions with H2 O and NH3 , forming LZnAs(H)SiOH(L') 1 and LZnAs(H)SiNH2 (L') 2. Oxygenation of A with N2 O at -60 °C furnishes the deep blue 1,2-disiloxydiarsene, [LZnOSi(L')As]2 4, presumably via dimerization of the arsinidene intermediate LZnOSi(L')As 3. Oxygenation of A with CO2 leads to the monomeric arsaethynolato siloxido zinc complex LZnOSi(L')(OC≡As) 5, essentially trapping the intermediary arsinidene 3 with liberated CO following initial oxidation of the Si=As bond. DFT calculations confirm the ambident coordination mode of the anionic [AsCO] ligand in solution, with the O-arsaethynolato [As≡C-O].- in 5, and the As-arsaketenylido ligand mode [O=C=As]- present in LZnO-Si(L')(-As=C=O) 5' akin to the analogous phosphorus system, [PCO]- .