Syntheses, Crystal Structures and Reactivity of Organometallic Tantalum(IV) Phosphinidene Complexes: trans-[{Cp*TaCl(μ-PR)}2] (Cp* = C5Me5, R = Cy, tBu, Ph), cis- and trans-[{Cp*TaCl(μ-PMes)}2] (Mes = 2,4,6-Me3C6H2) and cis-[{Cp′TaCl(μ-PMes)}2] (Cp′ = C5H4Me)

Phosphinidene-bridged binuclear complexes

“…A final example of this approach was reported by Hey-Hawkins and co-workers, who prepared several ditantalum bis(phosphinidene) complexes in high yield (73- [30]. We note that the role of the lithium reagent in these reactions is multiple, since it acts as reducing agent, base and substitution reagent.…”

“…The reaction of the ditantalum complex 22c with an excess (50-fold) of wet acetone gives the trinuclear oxo complex 162 in very low yield (Scheme 79) [30]. The presence of the phosphinidene-derived phenylphosphinate group in the latter compound was confirmed through a single-crystal X-ray diffraction analysis, although no signals were detected in the 31 P NMR spectrum to confirm the presence of the PH proton.…”

“…All these complexes have Sc-P bond lengths in the range 2. 41 Significant structural data are also available for an extensive family of dinuclear tantalum complexes reported by the groups of Hey-Hawkins [30,44] and Fryzuk [46]. All these complexes display trigonal planar geometry around the P atoms, with relatively short Ta-P lengths (av.…”

Lewis base character of the phosphorus atom in phosphanido-niobocene complexes. Synthesis of new early–early homo- and heterobimetallic entities

“…4 More recently, Nikonov et al 5 used an imido-phosphanido niobocene for the construction of Nb/Rh heterobimetallic complexes that have proven to be active precatalysts for the hydrosilylation of ketones and aldehydes. In addition, Hey-Hawkins et al 6 have prepared a series of dimeric phosphinidene-bridged Ta V complexes, a rare example of homobimetallic group 5 species containing bridged-phosphanido or related moieties. In the last decade we have developed a series of studies focused on the reactivity of phosphanido-containing niobocene complexes; thus, the insertion reaction of carbon disulfide into the Nb-P bond gave a series of new niobocene complexes that contained the anionic phosphanylthioformato ligand R 2 PCS 2 -.…”

Reactions of the Phosphinidene-Bridged Complexes [Fe2(η5-C5H5)2(μ-PR)(μ-CO)(CO)2] (R = Cy, Ph, 2,4,6-C6H2tBu3) with Diazoalkanes. Formation and Rearrangements of Phosphadiazadiene-Bridged Derivatives

“…Most of the work in this active area has been carried out so far on the bent-terminal complexes, these having a nonbonding electron pair at a low-coordination phosphorus atom and a metal−phosphorus bond that can be described as essentially single or double, depending on the metal environment ( A and B in Chart ), all of which makes these complexes highly reactive toward a great variety of unsaturated organic molecules, then making them useful in the synthesis of numerous organophosphorus compounds . In contrast, the chemistry of binuclear complexes having phosphinidene bridges has remained comparatively little explored until recently, even though the presence of multiple M−P bonds or lone pairs at phosphorus in their different coordination modes ( C to E in Chart ) should make these complexes quite reactive toward unsaturated organic molecules or other metal complexes. , Recent work from our lab , and the group of Carty ,, has shown that this is indeed the case for several complexes exhibiting trigonal-phosphinidene bridges of the types C and D , but apparently the reactivity of binuclear complexes having bent (or pyramidal) phosphinidene bridges ( E in Chart ) toward organic molecules has not been explored to date, with the exception of the transient species [Fe 2 {μ-P(N i Pr 2 )} 2 (CO) 6 ] . Recently we developed a high-yield route to the diiron compounds [Fe 2 Cp 2 (μ-PR)(μ-CO)(CO) 2 ] (Cp = η 5 -C 5 H 5 ; R = Cy ( 1a ), Ph ( 1b ), Chart ), these exhibiting a quite nucleophilic bent-bridging phosphinidene ligand .…”