The Reactivity of Phosphanylphosphinidene Complexes of Transition Metals Toward Terminal Dihaloalkanes

Abstract

The reactivities of phosphanylphosphinidene complexes [(DippN)2W(Cl)(η2-P-PtBu2)]- (1), [(pTol3P)2Pt(η2-P-PtBu2)] (2), and [(dppe)Pt(η2-P-PtBu2)] (3) toward dihaloalkanes and methyl iodide were investigated. The reactions of the anionic tungsten complex (1) with stochiometric Br(CH2)nBr (n = 3, 4, 6) led to the formation of neutral complexes with a tBu2PP(CH2)3Br ligand or neutral dinuclear complexes with unusual tetradentate tBu2PP(CH2)nPPtBu2 ligands (n = 4, 6). The methylation of platinum complexes 2 and 3 with MeI yielded neutral or cationic complexes bearing side-on coordinated tBu2P-P-Me moieties. The reaction of 2 with I(CH2)2I gave a platinum complex with a tBu2P - P - I ligand. When the same dihaloalkane was reacted with 3, the P - P bond in the phosphanylphosphinidene ligand was cleaved to yield tBu2PI, phosphorus polymers, [(dppe)PtI2] and C2H4. Furthermore, the reaction of 3 with Br(CH2)2Br yielded dinuclear complex bearing a tetraphosphorus tBu2PPPPtBu2 ligand in the coordination sphere of the platinum. The molecular structures of the isolated products were established in the solid state and in solution by single-crystal X-ray diffraction and NMR spectroscopy. DFT studies indicated that the polyphosphorus ligands in the obtained complexes possess structures similar to free phosphenium cations tBu2P+-P-R (R = Me, I) or (tBu2P+-P)2