NEW CLASSES OF SKELETALLY STABILIZED TRIPHOSPHAZANES AND TETRAPHOSPHAZANES

Reactions of 1,2,4,5-(NH2)4C6H2 with (Et2N)3P and 1,2,3-(NH2)3C6H3 with (Me2N)3P yield the new bis(triphosphazane) C6H2{N2[P(NEt2)2]2PNEt2}2 (4) and tetraphosphazane C6H3N3[P(NMe2)2]2(PNMe2)2 (6), respectively. 4 with sulfur is oxidized at the exo phosphorus atoms to a tetrasulfide C6H2{N2[P(S)(NEt2)2]2PNEt2}2 (5). 6 reacts with elemental selenium to form stepwise diselenide C6H3N3[P(Se)(NMe2)2]2(PNMe2)2 (7) and tetraselenide C6H3N3[P(Se)(NMe2)2]2[P(Se)NMe2]2 (8). 6 with elemental sulfur yields directly the tetrasulfide C6H3N3[P(S)(NMe2)2]2[P(S)NMe2]2 (10). 7 reacts smoothly with anhydrous HCl to yield the dichloride C6H3N3[P(Se)(NMe2)2]2(PCl)2 (9); in contrast, 4-6 with HCl undergo extensive cleavage with skeletal unit destruction. 4-10 have been characterized by spectral (H-1 and P-31 NMR, MS, and IR) data. 4, 8, and 10 have also been characterized in the solid by single-crystal X-ray diffraction. Crystal data for 4: monoclinic, P2(1)/c, a = 12.573 (3) angstrom, b = 16.976 (3) angstrom, c = 15.455 (3) angstrom, beta = 111.55 (2)-degrees, V = 3068(5) angstrom-3, Z = 2, d(calc) = 1.12 g cm-3, R = 0.055, and R(w) = 0.085. Crystal data for 8: orthorhombic, Pbca, a = 14.858 (3) angstrom, b = 21.626 (6) angstrom, c = 22.327 (7) angstrom, V = 7174 (3) angstrom-3, Z = 8, d(calc) = 1.68 g cm-3, R = 0.060, and R(w) = 0.076. Crystal data for 10: orthorhombic, Pbca, a = 14.706 (3) angstrom, b = 21.610 (5) angstrom, c = 22.000 (5) angstrom, V = 6991 (3) angstrom-3, Z = 8, d(calc) = 1.20 g cm-3, R = 0.049, and R(w) = 0.050. 6 contains the longest linear extension of a P(III) phosphazane system so far achieved, the result of skeletal stabilization of the phosphazane system. 4 contains a near-planar P2N4C6 atom core with two 1,3,2-diazaphosphole rings incorporated at the 1,2- and 4,5-positions of a benzene ring. 8 and 10 contain a planar P2N3C6 atom core consisting of two fused 1,3,2-diazaphosphole rings attached at the 1,2,3-positions of a benzene ring. Structural features of 4 and 5 and the 6-10 series are compared and discussed.