Pnictides as symmetrically bridging ligands in novel neutral complexes

Abstract

The reaction of [LWCl] (3) [L=N(CH2CH2NiPr)3] with LiE/SiMe3)2 (E=P, As, Sb) yields the novel, neutral pnictido-bridged complexes [LW=E=WL] (5–7). By following the reaction, which starts from the LiP/SiMe3)2 derivative, by 31P NMR spectroscopy, the formation of an intermediate with a terminal pnictido ligand can be ruled out. The paramagnetic complexes 5–7 are comprehensively spectroscopically characterised. The X-ray structure analysis of the heterocumulenes 5–7 reveals a linear structure in which the two W-“tren” units bind to the central pnictido atom in a staggered conformation [“tren”=tren-based ligand; tren=tris(2-aminoethyl)amine. When N2 is used as the inert gas in the synthesis of the starting material [{N(CH2CH2NNp)3}WCl] [Np=CH2C(CH3)3], the complex [{[N(CH2CH2NNp)3]W}2(μ,η1:η1-N2)] (4) is formed as a side product. Complex 4 possesses a hydrazido(4−) (N24−) ligand connected by two tungsten-“tren” moieties.