Synthesis and Characterization of 5‐Coordinate Tungsten Hydride Anions: [(tBu3SiNH)(tBu3SiN=)2HWR]M

Treatment of (tBu3SiNH)(tBu3SiN=)2WH (1-H) with small alkyl anions (RM) afforded tungsten alkyl hydride anions [(tBu3SiNH)(tBu3SiN=)2HWR)]M (3-(R)M: R=CH3, M=Li; R=nBu, M=Li; R=neoPe, M=Li; R=CH2Ph (Bn), M=K (two isomers); R=CCH, M=Na; R=CH=CH2 (Vy), M=Li). The saturated alkyl anions 3-(R)M (3-(R)M: R=CH3, M=Li; R=nBu, M=Li; R=neoPe, M=Li; R=CH2Ph (Bn), M=K) degraded via apparent 1,2-RH-elimination to produce the known [(tBu3SiN=)3WH]M (2-HM), but the acetylide (3-(C2H)Na) and vinyl (3-(Vy)Li) anions converted to their hydrogenated isomers, [(tBu3SiN=)3WVy]Na (2-VyNa) and [(tBu3SiN=)3WEt]Li (2-EtLi), respectively. The structure of 3-(nBu)Li is reported, and a discussion of tungsten-hydride coupling constants in tBu3SiX-ligated (X=O, NH, N) systems is given.