ARYL-SUBSTITUTED PHOSPHONITRILIC FLUORIDES .4. CRYSTAL AND MOLECULAR STRUCTURE OF 1,1-DIPHENYLPHOSPHONITRILIC FLUORIDE TRIMER

The crystal structure of the 1,1-diphenylphosphonitrilic fluoride trimer, 1,1-N3P3F4/C6H52, has been determined by symbolic addition and Fourier techniques. The results have been refined to a conventional R factor of 0.059 by a full-matrix leastsquares treatment employing anisotropic temperature factors on 2442 reflections measured by counter methods. The crystals belong to the orthorhombic system, with a = 14.803 (4), b = 12.571 (5), c = 16.732 (8) Å; the space group is Pnma, and there are eight molecules in the unit cell (pmeasd = 1.54 g cm-3, pca1cd = 1.56 g cm-3). The asymmetric unit contains two independent molecules each of which has C8 crystallographic symmetry. The phosphorus-nitrogen ring has five atoms approximately coplanar, with the phenyl-substituted phosphorus atom 0.20 Å out of this plane. There are three different sets of phosphorus-nitrogen bonds with mean lengths 1.618 (5), 1.558 (4), and 1.539 (5) Å. The exocyclic bond angles are: C-P-C, 107.9 (3)°; F-P-F, 96.9 (2)°. The endocyclic angles are: N-P-N, 115.5 (3)°; 120.6(3)°; P-N-P, 120.5 (2)°. © 1969, American Chemical Society. All rights reserved.