Inorganic Chemistry, Vol.34, No.5, 1180-1186, 1995
S,S’-Diorgano Derivatives of the 1,5-pH(4)P(2)N(4)S(2) Ring - Lithium Halide Adducts, Conformational Isomerism, and N-Methylation
The reaction of the lithium reagents [Li(Ph(4)P(2)N(4)S(2)R)THF](2) (R = Me, t(B)u, Ph) with organic iodides R’I (R’ = Me, allyl) at 23 degrees C in THF produces lithium iodide adducts of the type [Ph(4)P(2)N(4)(SR)(SR’)LiI(THF)], which were characterized by H-1, Li-7, C-13 and P-31 NMR spectroscopy. The dissolution of these adducts in CH2Cl2 or toluene results in the precipitation of LiI and the concomitant formation of eight-membered rings Ph(4)P(2)N(4)(SR)(SR’) in the form of boat (6B), R = R’ = Me) or twisted boat (10B, R = (t)Bu, R’ = allyl) conformers with sulfur atoms in the prow and stern positions. The boat conformers (delta(P-31) = 14-17 ppm) are converted quantitatively to the corresponding chair conformers (delta(P-31) = 27-29 ppm) upon mild heating (35-40 degrees C) in CH2Cl2 or CH3CN for 12 h. The reaction of Na-2[Ph(4)P(2)N(4)S(2)] with 2 molar equiv of allyl iodide produces Ph(4)P(2)N(4)(Sallyl)(2) (11B) in which the P2N4S2 ring adopts a boat conformation with nitrogen atoms as the prow and stem. The treatment of Ph(4)P(2)N(4)(SPh)(2) with methyl triflate yields the N-methylated adduct [Ph(4)P(2)N(3)(NMe)(SPh)(2)][SO3CF3] (12). N-methylation results in elongation of the P-N and S-N bonds involving the methylated nitrogen atom by 0.074 and 0.078 Angstrom, respectively. Crystal data : 6B, monoclinic, space group C2/c, a = 34.886(12) Angstrom, b = 11.870(3) Angstrom, c = 12.827(8) Angstrom, beta = 105.97(4)degrees, V = 5106(3) Angstrom(3), Z = 8, R = 0.042, R(w) = 0.040; 10B, triclinic, space group P ($) over bar 1, a = 10.253(3) Angstrom, b = 15.875(4) Angstrom, c = 9.582(1) Angstrom, alpha = 93.97(2)degrees, beta = 100.75(2)degrees, gamma = 84.57(2)degrees, V = 1523.3(6) Angstrom(3), Z = 2, R = 0.051, R(w) = 0.028; 11B, monoclinic, space group C2/c, a = 20.519(2) Angstrom, b = 16.190(3) Angstrom, c = 17.581(3) Angstrom, beta = 96.10(1)degrees, V = 5807(1) Angstrom(3), Z = 8, R = 0.051, R(w) = 0.054; 12, monoclinic, space group Cc, a = 9.949(1) Angstrom, b = 20.377(4) Angstrom c = 19.376(4) Angstrom, beta = 100.16(1)degrees, V = 3866(1) Angstrom(3), Z = 4, R = 0.058, R(w) = 0.032.