Bis(trichlorophosphine)iminium salts, [Cl₃P=N=PCl₃]⁺, with transition metal halide counter-ions

Abstract

The structures of four bis(trichlorophosphine)iminium [[Cl(3)P=N=PCl(3)](+); systematic name: trichloro[(trichlorophosphoranylidene)iminio]phosphorus(V)] salts, namely bis(trichlorophosphine)iminium hexachloroniobate, (Cl(6)NP(2))[NbCl(6)], (I), bis(trichlorophosphine)iminium hexachlorotantalate, (Cl(6)NP(2))[TaCl(6)], (II), bis(trichlorophosphine)iminium tri-micro-chloro-bis[trichlorotitanium(IV)], (Cl(6)NP(2))[Ti(2)Cl(9)], (III), and bis[bis(trichlorophosphine)iminium] di-micro-chloro-bis[tetrachlorozirconium(IV)], (Cl(6)NP(2))(2)[Zr(2)Cl(10)], (IV), have been determined. The P=N distances in the discrete [Cl(3)P=N=PCl(3)](+) moieties in structures (I), (II) and (IV) range from 1.5460 (14) to 1.5554 (16) A, and the P=N=P angles range from 136.8 (3) to 143.4 (4) degrees. The [Cl(3)P=N=PCl(3)](+) cation in (III) is disordered and the calculated geometries for the cation are therefore less reliable. Compounds (I) and (II) are isostructural and the metal anions have slightly distorted octahedral geometries. The anion in compound (III) consists of two distorted octahedral Ti centres linked by three micro (2)-Cl atoms, while in compound (IV), the dianion is derived from two distorted edge-shared ZrCl(6) octahedra.

Synthesis of Linear and Cyclic Carbophosphazenes via an Oxidative Chlorination Strategy

“…An X-ray diffraction study of the t Bu-terminated carbophosphazene, ClPh 2 PNC(Ph)N t Bu ( 5 ), revealed that this species exists as a monomer in the solid state (Figure ) with a significantly shorter P−N distance of 1.5417(12) Å when compared to that of the phosphorus(III)-containing PNCN chain 1 . Furthermore, the observed P−N bond length within 5 is similar to those found within the bis(trichlorophosphine)iminium cation [Cl 3 PNPCl 3 ] + (1.5−1.6 Å) and suggests the presence of significant multiple bond character. A localized bonding arrangement is present within the adjacent C−N bonds of the chain, with an internal (imine) C−N bond length [C(1)−N(2)] of 1.4005(18) Å and a shortened terminal C−N distance [C(1)−N(1)] of 1.2788(19) Å.…”

“…For comparison, the remaining C−N single bond involving the quaternary carbon atom of the t Bu group [C(8)−N(1)] was 1.4829(18) Å. The P−Cl bond length within 5 was 2.0801(5) Å and is typical for a phosphorus(V)−chlorine bond …”