A Novel Synthetic Approach to Highly Reactive Intermediates Containing a Metal-Phosphorus Triple Bond

Abstract

A new synthetic route providing access to the highly reactive intermediate [Cp*(CO)2W≡P→W(CO)5] with a tungsten–phosphorus triple bond is presented (see scheme). The intermediate is formed by thermolysis of [Cp*P{W(CO)5}2] by Cp* migration from the phosphorus to give η5 coordination at the transition metal. Addition of other reactive molecules to solutions conatining the intermediate provides a simple approach to novel W/P‐containing ligands.

Insertion Reactions of Nitriles into the P−C Bond of [(η1-C5Me5)P{W(CO)5}2]—A Novel Approach to Phosphorus-Containing Heterocycles

“…[1] The chemistry of this highly reactive intermediate A offers promising synthetic routes to a large variety of new phosphametallaheterocycles. Thus, the trapping reaction of A with phosphaalkynes [1] and alkynes [2] proceeds by formal [22] cycloaddition reactions to form novel main group element transition metal cage compounds. In continuation of these reactivity studies we attempted to employ nitriles for trapping reactions of intermediate A.…”

Different Transformation Pathways in the Photolysis of [Cp*P{W(CO)5}2]

“…[1] We recently found a synthetic approach to generate complexes B directly as highly reactive intermediates. [4] In contrast to the sterically demanding complexes of type A, they reveal a high ''side-on'' reactivity. The principle of their generation is based on the migration of a σ-bound Cp* substituent at the phosphorus atom to an η 5 -coordination at the transition metal (Scheme 1).…”

“…The molecular structure of 4 ( Figure 1) shows a slightly distorted W 2 P 2 tetrahedron containing a Cp*(CO) 2 W and a W(CO) 4 unit. Both of the phosphorus atoms coordinate to W(CO) 5 groups.…”

“…The bond length P(1)ϪP(2) of 2.166(6) Å is shorter than a single bond length found, for example, in the structure of β-P 4 at Ϫ185°C [2.190Ϫ2.212 Å ]. [9] Since the PϪP bond length in 4 is longer than in the nonsubstituted tetrahedral P 2 W 2 complex [{CpW(CO) 2 } 2 (µ,η 2 -P 2 )] [2.104(4) Å ], [7] and also longer than in the monosubstituted complex [Cp*W(CO) 2 } 2 (µ,η 2 :η 1 -P 2 ){W(CO) 5 }] [2.092(4) Å ], [4] one can conclude that the coordination of the phosphorus lone pairs in 4 lengthens the PϪP bond. Furthermore, each of the P atoms of 4 is more closely bound to a different W atom of the tetrahedral P 2 W 2 moiety.…”

“…Thus, the bond lengths P(1)ϪW(1) and P(2)ϪW(2) are 2.492(4) Å and 2.510(4) Å , respectively, in comparison to the other P(1)ϪW(2) and P(2)ϪW(1) bond lengths of 2.540(4) Å and 2.554(4) Å , respectively. The W(1)ϪW(2) bond length [3.1417(9) Å ] in 4 is slightly longer than the WϪW bond length in other W 2 P 2 tetrahedral complexes: [{Cp*(CO) 2 W} 2 {µ,η 2 :η 1 -P 2 W(CO) 5 }] [3.0920(7) Å ] [4] and [{Cp(CO) 2 W} 2 (µ,η 2 -P 2 )] [3.0026(11) Å ]. [7] The formation of 4 from the photolysis of [Cp* P{W(CO) 5 } 2 ] (1) can be regarded as a dimerisation of two reactive intermediates (Scheme 2): the triple bond intermediate D, formed by Cp* migration as described in Scheme 1, and a second intermediate E created by elimination of the Cp* ligand.…”