5,5-diethyl-2,2,2-triphenylbenz[c]oxaphospholane, synthesis and structure

5,5-Diethyl-2,2,2-triphenylbenz[ c ]-1,2-oxaphospholane (1) was obtained in 82 % yield by interaction of ethylmagnesium bromide with 5-oxo-2,2,2-triphenylbenz[ c ]-1,2-oxaphospholane in ether, followed by hydrolysis of the reaction mixture, removal of the solvent, and recrystallization of the target product from the benzene-octane mixture (3: 1 vol.). Structure 1 was determined by X-ray diffraction analysis. X-ray diffraction analysis of the complex was performed on a Bruker D8 Quest automatic four-circle diffractometer (Мо Кα radiation, λ = 0.71073 Å, graphite monochromator) at 293 K. Colorless crystal С29Н29OP, crystal size 0.57×0.33×0.32 mm, P -1, a = 10.262(5), b = 12.194(6), c = 19.478 (14) Å, a = 83.03(3), β = 81.67(3), g = 79.504(16) degrees, V = 2360(2) Å3, Z = 2, rcalc = 1.195 g/cm3, µ = 0.135 mm-1, F (000) 904.0. The parameters of the cell and the intensity of 114431 reflections, of which 13180 were observed with I ³ 3 s , were measured at 20 °С. The final values of the divergence factors are: R 1 = 0.0426, wR 2 = 0.1003 (CCDC 1982346). In crystal 1 there are two types (A and B) of crystallographically independent molecules. The coordination polyhedron of phosphorus atoms is a trigonal bipyramide with an oxygen atom and a phenyl ligand in axial positions (the axial CPO angles are 174.05 (7)° and 170.82 (8)°, and one of the ethyl groups in molecule B is disordered in two positions, the Р-О and Р-С distances are 1.7783(15), 1.7750(17) Å and 1.8296(19), 1.929 (2) Å). The lengths of the equatorial bonds vary in the range 1.823(2)-1.867(2) Å, the О-С distances are 1.428(3), 1.419(4) Å. The sums of the equatorial СРС angles are 359.34° (132.17(9)°, 114.40(9)°, 112.77(9)°) and 359.47° (135.57(10)°, 112.44(9)°, 111.46(10)°), which are close to the ideal value of 360°. The phosphorus atoms in molecules A and B protrude from the equatorial plane to the axial phenyl substituent at 0.086 and 0.077 Å, respectively.