We report here a series of heavier alkaline earth metal complexes with a phosphinoselenoic amide ligand using two synthetic routes. In the first route, the heavier alkaline earth metal bis(trimethylsilyl)amides [M{N(SiMe3)2}2(THF)n] (M = Ca, Sr, Ba) were treated with phosphinoselenoic amine [Ph2P(Se)NH(CHPh2)] (3), prepared by the treatment of bulky phosphinamines [Ph2PNH(CHPh2)] (1) with elemental selenium in THF, and afforded homoleptic alkaline earth metal complexes of composition [M(THF)2{Ph2P(Se)N(CHPh2)}2] (M = Ca (7), Sr (8), Ba (9)). The metal complexes 7–9 can also be obtained via salt metathesis route where the alkali metal phosphinoselenoic amides of composition [{(THF)2M′Ph2P(Se)N(CHPh2)}2] (M′ = Na (5) and K (6)) were reacted with respective metal diiodides in THF at ambient temperature. The solid state structures of the alkali metal complexes 5–6 and alkaline earth metal complexes 7–9 were established by single crystal X-ray diffraction analysis. In the solid state, alkali metal complexes 5 and 6 are dimeric and form a poly-metallacyclic structural motif. In contrast, complexes 7–9 are monomeric and a direct metal–selenium bond is observed in each case.

International audienceWe report the N−H/H−Si cross-dehydrogenative coupling (CDC) of hydrosilanes and amines with high conversion (>90 %) and chemoselectivity for the production of silazanes, using group 1 metal hexamethyldisilazides [MN(SiMe3)2] (M=Li, Na, K) as precatalysts under mild conditions. [KN(SiMe3)2] showed higher activity than the congeneric lithium and sodium salts. The catalyzed CDC reaction displays a broad substrate scope. Phenylsilane and diphenylsilane react with a number of amines under ambient conditions; more elevated temperature is required for triphenylsilane to undergo CDC reactions. The intermediate lithium complex [(THF)2Li-{N(SiHPh2)(Dipp)}] (1) has been isolated and characterized in an attempt to identify the operative reaction mechanism

N–H/H–B cross-dehydrogenative coupling (CDC) of boranes and amines with high conversion (>90%) and chemo-selectivity using group-1 metal salts as pre-catalysts, and under ambient conditions is presented.

No abstract

The N-benzhydrylamido-1,1-diphenylphosphine−borane ligand [Ph 2 P(BH 3 )NH(CHPh 2 )] (1-H) has been prepared via the reaction of an equimolar ratio of the phosphine amine [Ph 2 PNH(CHPh 2 )] and the borane adduct [BH 3 •SMe 2 ] at an ambient temperature. The reaction of 1-H with ((trimethylsilyl)methyl)lithium (neosilyllithium), [LiCH 2 SiMe 3 ], afforded a three-membered lithium amidophosphine−borane complex with the composition ([η 2 -Ph 2 CHNP(BH 3 )Ph 2 )Li(THF) 2 ] (2). Analogous reactions with sodium and potassium bis(trimethylsilyl)amides at ambient temperature yielded the respective alkali-metal amidophosphine−borane complexes [{(Ph 2 CHNP(BH 3 )Ph 2 )Na(THF) 2 } 2 ] (3) and [{(Ph 2 CHNP(BH 3 )Ph 2 )K(THF) 2 } 2 ] (4), with the loss of hexamethyldisilazane, [(Me 3 Si) 2 NH]. The corresponding heavier alkaline-earth-metal complexes [M-(THF) 2 {Ph 2 P(BH 3 )N(CHPh 2 )} 2 ] (M = Ca ( 5), Sr (6), Ba ( 7)) can be obtained via the reaction of [M{N(SiMe 3 ) 2 } 2 (THF) n ] (M = Ca, Sr, Ba) and 1-H. The metal complexes 5−7 can also be prepared via a salt metathesis route, where the alkali-metal salts 3 and 4 were reacted with the respective metal diiodides in THF at ambient temperature. The molecular structures of 1-H and 2−7 have been established by X-ray diffraction analyses, and from the solid-state structures of 3−7, it was confirmed that, in all of the compounds, the metal ions are chelated through the nitrogen atom and the hydrogen atoms of the borane group of ligand 1-H.