Preparation of 1,1,5,5-tetraphenyl-3,7-diaryl-1,5-diphosphatetrazocines and 1,1,3,3,5-pentaphenyldiphosphatriazine and the x-ray structure of 1,5-Ph4P2N4C2(C6H4CH3-4)2

The reactions of Li[PhC(NSiMe3)2] or ArCN2(SiMe3)3 (Ar = C6H4CH(3)-4, C6H4CF(3)-4) with Ph2PCl3 produce 1,5-Ph4P2N4C2Ar2 (Ar = C6H5 (4a), 4-CH3C6H4 (4c)) and, as a minor product, the six-membered ring Ph4P2N3CPh (1b). Compound 1b is also obtained from the reaction of PhC[N(SiMe3)2](NPPh2) with 2 molar equiv of benzeneselenenyl chloride in CH2Cl2. Compounds 1b and 4a-c exhibit high thermal stability with no indication of polymer formation below 250-degrees-C. An X-ray structural determination of 4b showed that it consists of an eight-membered ring in a distorted boat-boat conformation with the phosphorus atoms out of and on the same side of the plane and the carbon atoms on the other side of the plane. One of the nitrogen atoms also deviates significantly from the best plane. The crystals of 4b are monoclinic, space group P2(1)/c, with a = 17.236 (3) angstrom, b = 19.558 (1) angstrom, c = 20.694 (3) angstrom, beta = 107.66 (1)-degrees, V = 6647 (2) angstrom 3, and Z = 8. Two crystallographically independent molecules of 4b are present in the asymmetric unit. The final R and R(w) values were 0.059 and 0.039, respectively. The average P-N and C-N bond lengths are ca. 1.60 and 1.31 angstrom, respectively, and the endocyclic bond angles at phosphorus are ca. 126-degrees. There are two distinct bond angles at nitrogen for both molecules with values of ca. 127 and 139-degrees.