Journal of the American Chemical Society, Vol.138, No.50, 16220-16223, 2016
Phosphinidene Reactivity of a Transient Vanadium P N Complex
Toward the preparation of a coordination complex of the heterodiatomic molecule PN, P N-V(N[Bu-t]Ar)(3) (1, Ar = 3,5-Me2C6H3), we report the use of ClPA (A = C14H10, anthracene) as a formal source of phosphorus(I) in its reaction with Na[NV(N[Bu-t]Ar)(3)](Na[4]) to yield trimeric cyclo-triphosphane [PNV(N[Bu-t]Ar)(3)](3) (3) with a core composed exclusively of phosphorus and nitrogen. In the presence of NapS(2) (peri-1,8-naphthalene disulfide), NapS(2)P-NV(N[Bu-t]Ar)(3) (6) is instead generated in 80% yield, suggesting trapping of transient 1. Upon mild heating, 3 readily fragments into dimeric [PNV(N[Bu-t]Ar)(3)](2) (2), while in the presence of bis(trimethylsilyl)acetylene or cis-4-octene, the respective phosphirene (Ar[Bu-t]N)(3)VN-PC2(SiMe3)(2) (7) or phosphirane (Ar[Bu-t]N)(3)VN-P(C8H16) (8) compounds are generated. Kinetic data were found to be consistent with unimolecular decay of 3, and [2+1]-cycloaddition with radical clocks ruled out a triplet intermediate, consistent with intermediate 1 reacting as a singlet phosphinidene. In addition, both 7 and 8 were shown to reversibly exchange cis-4-octene and bis(trimethylsilyl)acetylene, serving as formal sources of 1, a reactivity manifold traditionally reserved for transition metals.