Silylamide Complexes of Chromium(II), Manganese(II), and Cobalt(II) Bearing the Ligands N(SiHMe2)2 and N(SiPhMe2)2

Bis­(dimethylsilyl)­amide and bis­(dimethylphenylsilyl)­amide complexes of the divalent transition metals chromium, manganese, and cobalt were synthesized. Dimeric, donor-free {Mn­[N­(SiHMe2)2]2}2 could be obtained via two different pathways, a salt metathesis route (utilizing MnCl2(thf)1.5 and LiN­(SiHMe2)2) and a transsilylamination protocol (utilizing Mn­[N­(SiMe3)2]2(thf) and HN­(SiHMe2)2). Addition of 1,1,3,3-tetramethylethylendiamine (tmeda) to {Mn­[N­(SiHMe2)2]2}2 yielded the monomeric adduct Mn­[N­(SiHMe2)2]2(tmeda). The syntheses of Cr­[N­(SiHMe2)2]2(tmeda), Co­[N­(SiMe3)2]­[N­(SiHMe2)2]­(tmeda), and Co­[N­(SiHMe2)2]2(tmeda) were achieved by transsilylamination from Cr­[N­(SiMe3)2]2(tmeda) and {Co­[N­(SiMe3)2]2}2(μ-tmeda), respectively. Bis­(dimethylphenylsilyl)­amide complexes Mn­[N­(SiMe2Ph)2]2, Cr­[N­(SiMe2Ph)2]2, and Co­[N­(SiMe2Ph)2]2(thf) were obtained via salt metathesis employing MCl2(thf)x (M = Cr, Mn, Co) with equimolar amounts of LiN­(SiMe2Ph)2 in n-hexane. Treatment of CrCl2 with LiN­(SiMe2Ph)2 in thf gave Cr­[N­(SiMe2Ph)2]2(thf)2, featuring an almost square planar trans-coordination. All complexes were examined by elemental analyses, DRIFT and UV–vis spectroscopy, as well as X-ray structure analysis, paying particular attention to secondary M---SiH β-agostic and M---π­(arene) interactions. Magnetic moments were determined by Evans’ method.