COMPLEXES OF AN AZINE DIPHOSPHINE WITH GROUP-6 METAL-CARBONYLS - CRYSTAL-STRUCTURES OF Z,Z-PPH2CH2C(BU(T))=N-N=C(BU(T)CH2PPH2 AND [MO(CO)3(E,Z-PPH2CH2C(BU(T))=N-N=(BU(T))CCH2PPH2)]

Treatment of the azine MeC(Bu(t))=NN=C(Bu(t))Me with 2 equivalents of LiBu(n), followed by 2 equivalents of PPh2Cl, gives the azine diphosphine Z,Z-PPh2CH2C(Bu(t))=N-N=(Bu(t))CCH2PPh2 1. This new diphosphine was treated with H2O2 to give the corresponding diphosphine dioxide 2a and with monoclinic sulfur to give the diphosphine disulfide 2b. Treatment of [M(CO)3(eta-6-cht)] (cht = cyclo-hepta-2, 4,6-triene)with 1 gave the metal tricarbonylfac-[M(CO)3{PPh2CH2C(Bu(t))=NN=(Bu(t))CCH2PPh2}] (M = Mo, 3a; W, 3b; or Cr, 3c) in which the azine diphosphine is bonded in the EZ configuration. Complexes 3a and 3b were also made by treating the corresponding metal hexacarbonyls with the azine diphosphine 1. Treatment of [M(CO)4(nbd)] (M = Mo, W, or Cr; nbd = norbornadiene) with 1 gave the tetracarbonyl complexes [M(CO)4{PPh2CH2C(Bu(t))=NN=(Bu(t))CCH2PPh2}] 4 with the EZ-azine diphosphine acting as a bidentate ligand. On heating, these tetracarbonyl complexes 4 were converted into the tricarbonyl complexes 3. Treatment of either 3a or 4a with 1 mol equivalent of bromine gave the neutral molybdenum(II) complex [MoBr2(CO)2{PPh2CH2C(Bu(t))=NN=(Bu(t))CCH2PPh2}] 5, whereas the tungsten complexes 3b and 4b with bromine gave the cation [WBr(CO)3{PPh2CH2C(Bu(t))=NN=(Bu(t))CCH2PPh2}]+ isolated as its BPh4- salt 6. Proton, C-13-{H-1} and P-31-{H-1} NMR and infrared data are given. Crystals of 1 are monoclinic, space group P2(1)/n, with a = 1667.2(2), b = 572.85(6), c = 1811.0(2)pm, beta = 111.595(8)-degrees and Z = 2; final R factor 0.051 9 for 2049 observed reflections. Crystals of 3a are monoclinic, space group P2(1)/n, with a = 985.7(1), b = 1870.2(2), c = 2220.8(2) pm, beta = 93.71(1)-degrees and Z = 4, final R factor 0.0354 for 5219 observed reflections.