The Reactivity of Phosphanylphosphinidene Complexes of Transition Metals Toward Terminal Dihaloalkanes

Abstract

The reactivities of phosphanylphosphinidene complexes [(DippN) 2 W(Cl)(η 2 -P–P t Bu 2 )] − ( 1 ), [( p Tol 3 P) 2 Pt(η 2 -P=P t Bu 2 )] ( 2 ), and [(dppe)Pt(η 2 -P=P t Bu 2 )] ( 3 ) toward dihaloalkanes and methyl iodide were investigated. The reactions of the anionic tungsten complex ( 1 ) with stochiometric Br(CH 2 ) n Br ( n = 3, 4, 6) led to the formation of neutral complexes with a t Bu 2 PP(CH 2 ) 3 Br ligand or neutral dinuclear complexes with unusual tetradentate t Bu 2 PP(CH 2 ) n PP t Bu 2 ligands ( n = 4, 6). The methylation of platinum complexes 2 and 3 with MeI yielded neutral or cationic complexes bearing side-on coordinated t Bu 2 P–P-Me moieties. The reaction of 2 with I(CH 2 ) 2 I gave a platinum complex with a t Bu 2 P—P—I ligand. When the same dihaloalkane was reacted with 3 , the P—P bond in the phosphanylphosphinidene ligand was cleaved to yield t Bu 2 PI, phosphorus polymers, [(dppe)PtI 2 ] and C 2 H 4 . Furthermore, the reaction of 3 with Br(CH 2 ) 2 Br yielded dinuclear complex bearing a tetraphosphorus t Bu 2 PPPP t Bu 2 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 t Bu 2 P + =P−R (R = Me, I) or ( t Bu 2 P + =P) 2 .

Addition of a Phosphinoboronate Ester to Borole and Borafluorene

“…Phosphinoboranes 1 2 3 (R 2 P–BR 2 ) feature trivalent and tricoordinate P and B atoms linked covalently and are valence isoelectronic with aminoboranes (R 2 N–BR 2 ; Scheme 1a ). 1 3 4 In species with alkyl or aryl substituents on boron, dimerization typically occurs; 1 5 6 7 however, if there is sufficient steric bulk or the boron atom is disubstituted with alkoxy groups, dimerization is precluded. These monomers can be viewed as frustrated Lewis pairs.…”

“…Within these, Modes A and C , in which the boron atom acts as a Lewis acid, have been widely explored, 7 , 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 whereas reports on the phosphorus atom acting as a Lewis base (Mode B ) are scarce. 6,21,37…”