CRYSTAL AND MOLECULAR-STRUCTURES OF -DIPHENYL-N-METHYL-SELENOPHOSPHINYL-THIOFORMAMIDE, CYCLOHEXYL-N-METHYL-SELENOPHOSPHINYL-THIOFORMAMIDE AND CYCLOHEXYL-N-PHENYL-SELENOPHOSPHINYL-THIOFORMAMIDE

The crystal structures of three compounds of the general formula R(2)P (Se)C(S)N(H)R' have been determined at room temperature. The green cry stals of [Ph(2)P(Se)C(S)N(H)Me], C14H14NPSSe, are triclinic, space gro up <P(1)over bar> with unit cell dimensions a = 12.511(3) Angstrom, b = 13.298(3) Angstrom, c = 10.178(3) Angstrom, alpha = 109.28(2)degrees , beta = 103.25(2)degrees, gamma = 66.94(2)degrees, Z = 4 and D-x = 1. 538 Mg m(-3). The yellow crystals of [(c)Hex(2)P(Se)C(S)N(H)Me], C14H2 6NPSSe, are orthorhombic, space group Pnma with unit cell dimensions a = 10.299(2) Angstrom, b = 15.384(2) Angstrom, c = 10.344(2) Angstrom, Z = 4 and D-x = 1.420 Mg m(-3). The yellow crystals of [(c)Hex(2)P(Se )C(S)N(H)Ph], C19H28NPSSe, are triclinic, space group <P(1)over bar> w ith unit cell dimensions a = 9.738(2) Angstrom, b = 11.248(2) Angstrom , c = 9.406(1) Angstrom, alpha = 100.72(1)degrees, beta = 104.84(1)deg rees, gamma = 83.58(1)degrees, Z = 2 and D-x = 1.403 Mg m(-3). The str uctures were solved by direct methods and refined by a full-matrix lea st-squares procedure to final R = 0.038 using 2097 reflections for [Ph (2)P(Se)C(S)N(H)Me], R = 0.034 using 1180 reflections for [(c)Hex(2)P( Se)C(S)N(H)Me], and R = 0.033 using 2508 reflections for [(c)Hex(2)P(S e).. C(S)N(H)Ph]. The conformation about the C(1)-N(1) bond in all thr ee structures is Z. Differences in the P(1)-C(1) and C(1)-N(1) bond di stances in a series of R(2)P(Y)C(S)N(H)R', Y = 0, O, S, or Se, R = Ph or (c)Hex and R' = Ph or Me, compounds are correlated with the nature of the phosphorus- and nitrogen-bound substituents, respectively.