Manganese Silylene Hydride Complexes: Synthesis and Reactivity with Ethylene to Afford Silene Hydride Complexes.

Reaction of the ethylene hydride complex trans-[(dmpe)2 MnH(C2 H4 )] (1) with Et2 SiH2 at 20?°C afforded the silylene hydride [(dmpe)2 MnH(=SiEt2 )] (2?a) as the trans-isomer. By contrast, reaction of 1 with Ph2 SiH2 at 60?°C afforded [(dmpe)2 MnH(=SiPh2 )] (2?b) as a mixture of the cis (major) and trans (minor) isomers, featuring a Mn-H-Si interaction in the former. The reaction to form 2?b also yielded [(dmpe)2 MnH2 (SiHPh2 )] (3?b); [(dmpe)2 MnH2 (SiHR2 )] (R=Et (3?a) and Ph (3?b)) were accessed cleanly by reaction of 2?a and 2?b with H2 , and the analogous reactions with D2 afforded [(dmpe)2 MnD2 (SiHR2 )] exclusively. Both 2?a and 2?b engaged in unique reactivity with ethylene, generating the silene hydride complexes cis-[(dmpe)2 MnH(R2 Si=CHMe)] (R=Et (4?a), Ph (4?b)). Compounds trans-2?a, cis-2?b, 3?b, and 4?b were crystallographically characterized, and bonding in 2?a, 2?b, 4?a, and 4?b was probed computationally.