Reactions of [(dmpe) 2 MnH(C 2 H 4 )] with hydrogermanes to form germylene, germyl, hydrogermane, and germanide complexes.

Reactions of the ethylene hydride complex trans -[(dmpe) 2 MnH(C 2 H 4 )] (1) with secondary hydrogermanes H 2 GeR 2 at 55-60 °C afforded the base-free terminal germylene hydride complexes trans -[(dmpe) 2 MnH(GeR 2 )] (R = Ph; 2a, R = Et; 2b). Room temperature reactions of 2a or 2b with an excess of the primary hydrogermanes H 3 GeR' (R' = Ph or n Bu) afforded trans -[(dmpe) 2 MnH(GeHR')] (R' = Ph; 3a, R' = n Bu; 3b) in rapid equilibrium with small amounts of 2a/b, as well as the digermyl hydride complex mer -[(dmpe) 2 MnH(GeH 2 R') 2 ] {R' = Ph (4a) or n Bu (4b)} and the trans -hydrogermane germyl complex trans -[(dmpe) 2 Mn(GeH 2 R')(HGeH 2 R')] {R' = Ph (5a) or n Bu (5b)}. Pure 3b was isolated from the reaction of 2b with H 3 Ge n Bu, whereas 3a decomposed readily in solution in the absence of free H 3 GePh, and a pure bulk sample was not obtained. Reactions of 1 with H 3 GeR' (R' = Ph or n Bu) also proceeded at 55-60 °C to afford mixtures of 3a/b, 4a/b and 5a/b, accompanied by remaining 1. However, upon continued heating to consume 1, various unidentified manganese-containing intermediates were formed, ultimately affording the germanide complex [{(dmpe) 2 MnH} 2 (μ-Ge)] (6) in 17-49% spectroscopic yield. Pure trans , trans -6 was isolated in 27% yield from the reaction of 1 with H 3 Ge n Bu, and it is notable that this reaction involves stripping of all four substituents from the hydrogermane. Complexes 2a, 3a, and 6 were crystallographically characterized, and the nature of the MnGe bonding in these species (as well as in 2b and 3b) was probed computationally.