850794-22-8Relevant articles and documents
Addition of primary and secondary phosphines to dinuclear tantalum hydrides: Synthesis of phosphides and phosphinidenes via P-H bond activation
Shaver, Michael P.,Fryzuk, Michael D.
, p. 1419 - 1427 (2008/10/09)
The dinuclear complex (Rph[NPN]Ta)2(μ-H) 4 (where Rph[NPN] = [RP(CH2SiMe 2NPh)2] and R = Ph, Cy) shows remarkable reactivity with molecular nitrogen, producing the side-on end-on bound dinitrogen complex ( Rph[NPN]Ta)2(μ-η1:η2- N2)(μ-H)2. This tantalum tetrahydride also promotes other small molecule activation. Addition of secondary phosphines HPR′2 (R′ = Ph, Cy) to (Rph[NPN]Ta) 2(μ-H)4 accesses trihydride phosphide systems ( Rph[NPN]Ta)2(μ-H)3(μ- PR″2). Addition of primary phosphines H2PR″ (R″ = Cy, Ad) gives bridging phosphinidene tantalum complexes ( Rph[NPN]Ta)2(μ-H)2(μ-PR″). Molecular structures as determined by X-ray crystallography for the complexes (PhPh[NPN]Ta)2(μ-H)3(μ-PCy2) and (CyPh[NPN]-Ta)2(μ-H)2(μ-PAd) are presented. Isotopic labeling studies offer mechanistic insights into the reactivity of this tetrahydride system. Reaction of Cy2PH with ( CyPh[NPN]Ta)2(μ-D)4, for instance, gives solely the monohydride dideuteride complex (CyPh[NPN]Ta) 2(μ-H)(M-D)2(μPCy2). This labeling study indicates that D2 loss forms the reactive species, ( CyPh[NPN]Ta)2-(μ-D)2, which promotes small molecule activation. Addition of CyPH2 to (CyPh[NPN]Ta) 2(μ-D)4 gives a series of isotopomers, with an average composition of 0.67 H and 1.33 D, supporting a 1,2-H2 elimination step to form the tantalum phosphinidenes. These results are tied into the general reactivity of (Rph[NPN]Ta)2(μ-H)4.
