PREPARATION AND 31P DNMR STUDIES OF HOMODINUCLEAR AND cis-MONONUCLEAR COMPLEXES OF Ph2PNSNPPh2: CRYSTAL STRUCTURE OF cis-Cr(CO)4(Ph2PNSNPPh2)*0.5C6H6

Article abstract of DOI:10.1016/0022-328X(87)80398-4

The reaction of K2SN2 with MLn(Ph2PCl) (MLn=Cr(CO)5, Mo(CO)5, MnCp'(CO)2 (Cp'=methylcyclopentadienyl)) yields complexes of the type LnMP(Ph)2NSN(Ph)2PMLn in which the bridging ligand adopts a cis,trans conformation and is coordinated through the phosphorus atoms to the two metal centres.In solution these complexes undergo a cis,trans->trans,cis interconversion, and a 31P DNMR study has provided the activation energies for this process (E_a=10.1 M=Cr), 9.8 (M=Mo) and 13.4 (M=Mn) +/-0.2 kcal mol^-1).The 31P chemical shifts, infrared frequencies (ν_as and ν_s(NSN)) and visible absorption maxima for this series of complexes are discussed in terms of the observed activation energies.The reaction of K2SN2 with cis-MLn(Ph2PCl)2 (MLn=Cr(CO)4 or Mo(CO)4) gives complexes of the type cis-MLn(P(Ph)2NSN(Ph)2P) in which the chelating cis,cis ligand is coordinated to the metal via both phosphorus atoms.The structure of cis-Cr(CO)4P(Ph)2NSN(Ph)2P)*0.5C6H6 has been determined by X-ray crystallography.Crystal data: triclinic, space group P1<*>, a 9.878(1), b 12.240(1), c 12.610(2) Angstroem, α 87.795(9), β 77.018(10), γ 81.027(9) deg, V 1467.6(6) Angstroem³, Z=2.The structure was solved by direct methods and refined by least-squares techniques to give a final R=0.034 and R_w=0.036.The geometry around the chromium atom is approximately octahedral, but the planar, chelating PNSNP ligand is tilted at an angle of 126.7 deg with respect to the plane containing the C2CrP2 unit.The P-N bond distances are both 1.727(2) Angstroem; the S-N distances are 1.525(2) and 1.523(2) Angstroem; the angles at the nitrogen atoms are 129.4(1) and 128.8(1) deg and the angle at sulphur is 123.0(1) deg.