Crystal structure of, and solution adduct equilibria involving, tetraphenylarsonium tetrachloro-oxochromate(V)
Abstract
Crystals of the title complex are tetragonal, space group P4/n, with a= 12.590(7), c= 7.840(5)Å, and Z= 2. The crystal structure has been solved by the heavy-atom method and refined by full-matrix least-squares calculations to R 0.059 over 860 statistically signrfrcant reflections from diffractometer measurements (Cu-Kα radiation). The square-pyramidal [CrCl4O]– anion has crystallographic 4mm(C4v) symmetry with Cr–O 1.519(12) and Cr–Cl 2.240(3)Å, and O–Cr–Cl 104.5(1)°. The [AsPh4]+ cation has crystallographic (S4) symmetry [As–C 1.906(6)Å C–As–C 105.3(3) and 111.5(3)°]. E.s r. spectroscopy has been used to estimate the equilibrium constants for the reaction [CrCl4O]–+ L [graphic omitted] [CrCl4OL]n– in CH2Cl2solution {n= 1 when L = PPh3O (K= 3 ± 2), P(NMe2)3O (K= 463 ± 130), thf (K < 1), or py (K= 160); n= 2 when L = Cl–(K= 43 ± 10 with [AsPh4]Cl and 250 ± 33 dm3 mol–1 with [NEt4]Cl)}.