Phosphinidene-bridged binuclear complexes

Abstract

This article contains a comprehensive review of the work carried out within the last three decades on the synthesis, structural studies and reactivity of the binuclear complexes of transition and lanthanide elements bearing bridging phosphinidene (PR) ligands. The latter are grouped into three different classes according to their geometry and electronic distribution: pyramidal, symmetric planar trigonal and asymmetric planar trigonal. Different reactivity patterns can be then outlined for each of these classes of metal complexes, which differ in many ways from those characterizing the extensively studied chemical behaviour of mononuclear phosphinidene complexes.

Titanocene Pnictinidene Complexes

“…[9][10][11][12] Nucleophilic phosphinidene complexes are preferred when the spectator ligands L are strong -donors, while strong π-accepting ligands render the phosphinidene unit more electrophilic. 13 In contrast to the rich chemistry of phosphinidene-bridged dinuclear complexes, 14 terminal phosphinidene complexes are rare and Mindiola et al bond lengths were found and result in pseudo-triply bonded systems. 15,16 Attempts to synthesize a base-free titanocene phoshinidene complex using phospha-Wittig reagent 2c with a sterically more demanding Dip Ter group did only result in decomposition of 1 at higher temperatures.…”

A Bridging Carbonyl of Unlikely Geometry: On the True Nature of the Technetium Complex [Tc2(μ-CO)2(CO)6(NC5H5)2]

“…We have been working for many years on the synthesis, structure and reactivity of binuclear transition-metal carbonyl complexes, particularly those involving elements of groups 6 to 8, and displaying metal-metal or metal-phosphorus bonds. [1][2][3] While looking for binuclear species connected by long intermetallic bonds at the Cambridge Crystallographic Data Centre (CCDC) data base, we came across the structure of a simple, but rare ditechnetium complex having two bridging carbonyls, formulated as [Tc2(-CO)2(CO)6(NC5H5)2] (1). This complex was reported by Zuhayra et al as the main product of the reaction of [Tc2(CO)10] with pyridine at room temperature, using the reagent itself as solvent.…”

Transition metal complexes of the naked pnictide elements

“…Binuclear phosphinidene compounds have recently been reviewed. 3 The M-E distances are strongly affected by the steric bulk of the MLn fragment. The variety of MLn fragments observed in these complexes has expanded, however, with examples being observed for M(CO)4, M(CO)5, CpM(CO)x (X = 0 -3), Cp2M and cyclic carbene ligands.…”

“…The structures of (A) [Bi{Cr(CO)5}4]3and (B) [Bi{Co(CO)4}4] -.2.1.2 E(MLn)3 and E(MLn)4 Compounds with One or Two M-M BondsStructures III -V can be derived from E(MLn)3 and E(MLn)4 with the introduction of one or two M-M bonds (Table 3;Figures 6-8), the hemi-spirocyclic species IV(Table 4) and the spirocyclic compounds V (Table 5)(Figures 11-14, Schemes 1-4). For metal carbonyls, loss of CO may lead to M-M bond formation, but these structures may also be obtained without observation of intermediate open structures as in the cases of the Sb-and Bi-clusters with osmium or rhenium as seen in…”