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

Reaction of the ethylene hydride complex trans ‐[(dmpe) 2 MnH(C 2 H 4 )] ( 1 ) with Et 2 SiH 2 at 20 °C afforded the silylene hydride [(dmpe) 2 MnH(=SiEt 2 )] ( 2 a ) as the trans ‐isomer. By contrast, reaction of 1 with Ph 2 SiH 2 at 60 °C afforded [(dmpe) 2 MnH(=SiPh 2 )] ( 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 MnH 2 (SiHPh 2 )] ( 3 b ); [(dmpe) 2 MnH 2 (SiHR 2 )] (R=Et ( 3 a ) and Ph ( 3 b )) were accessed cleanly by reaction of 2 a and 2 b with H 2 , and the analogous reactions with D 2 afforded [(dmpe) 2 MnD 2 (SiHR 2 )] exclusively. Both 2 a and 2 b engaged in unique reactivity with ethylene, generating the silene hydride complexes cis ‐[(dmpe) 2 MnH(R 2 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.