Synthesis and crystal structure of 1,3-di-tert-butyl-2-chloro-4,4-diphenyl-1,3,2λ(3),4-di­aza­phospha­siletidine

The chemical reaction of di­lithium N,N′-di((t)but­yl)-Si,Si-di­phenyl­silanedi­amide and PCl(3) yielded an off-white solid. Sublimation of the crude product under reduced pressure at elevated temperature gave colourless prismatic crystals of the title compound, C(20)H(28)ClN(2)PSi, which crystallizes in the non-centrosymmetric monoclinic space group Cc. The asymmetric unit of the crystal structure contains one mol­ecule and it is dominated by the central SiN(2)P four-membered ring, which is almost planar with a mean deviation of the atoms from the best plane of 0.014 Å. The angles between the plane defined by the silicon atom and the two nitro­gen atoms and the best planes of the Si-phenyl groups are 85.1 (2) and 77.4 (2)°, with the tilt of the phenyl rings in the opposite direction. Both tert-butyl groups suffer from a two-position rotational disorder with site occupancies of 0.752 (6)/0.248 (6) and 0.878 (9)/0.122 (9). The P—Cl bond [2.2078 (17) Å] is remarkably elongated compared to the P—Cl distance in PCl(3) [2.034 Å; Galy & Enjalbert (1982). J. Solid State Chem. 44, 1–23].