Novel Copper(I) Clusters with 2-(Diphenylphosphanyl)anilide Ligands. Synthesis and Crystal Structures of [Cu6X2(NHR)4] (X= Cl, Br, I;R= C6H4-2-PPh2)

Multinuclear Cu(I) Clusters Featuring a New Triply Bridging Coordination Mode of Phosphaamidinate Ligands

Phosphabenzamidine [mes-NH-C(Ph)═P-mes) (1) and phosphaformamidine (mes-NH-CH═P-mes) (4) ligands have been synthesized and characterized. The conjugate bases of 1 and 4 coordinate by each bridging three Cu(I) ions, forming hexa- and tetranuclear clusters Cu₆[mes-N═C(Ph)-P-mes]₃Cl₄Li(THF)₂ (3) and Cu₄[mes-N═CH-P-mes]₄ (5), respectively. Both clusters have been fully characterized using ¹H NMR, ³¹P NMR, and X-ray crystallography. Complexes 3 and 5 exhibit a previously unknown coordination mode of phosphaamidinates, which are far less studied than their well-known amidinate counterparts.