NEW SYNTHESES OF [ET(4)N][(C5H10NCS2)M(CO)(4)](M=CR, MO AND W) - INSERTION REACTION OF CARBON-DISULFIDE INTO THE METAL-NITROGEN BOND

The complex (pip)(2)M(CO)(4) (pip=C5H10NH; M=Cr, Mo or W) reacted with (n)BuLi and CS2 in the presence of Et(4)NBr to give [Et(4)N][(C5H10NC S2)M(CO)(4)](M = Cr (1), Mo (2), W (3)) in high yield. The reaction is initiated by the abstraction of the NH proton of the piperidine ligan d by (n)BuLi, followed by insertion of CS2 into the M-N bond to give t he dithiocarbamate metal complexes. The complex [Et(4)N][(C4H8NCS2)W(C O)(4)] (4) was similarly prepared. Complexes 1-4 were characterized by elemental analysis and IR, mass and NMR spectroscopy. In addition, th e molecular structures of 3 and 4 were determined by single-crystal X- ray diffraction analysis, which confirmed the dihapticity of the dithi ocarbamte ligands in 3 and 4. Compound 3 is monoclinic, space group P2 (1), with a=9.963(2> Angstrom, b=12.724(1) Angstrom, c=10.268(3) Angst rom, beta=117.12(2)degrees and Z=2. Compound 4 is orthorhombic, space group Pna2(1), with a=31.424(5) Angstrom, b=8.281(1) Angstrom, c=17.13 7(2) Angstrom and Z=8. The structure was refined to the final conventi onal R of 0.029 and R(w) of 0.020. The HMBC (H-1-detected heteronuclea r multiple bond correlation) technique was used to assign the C-13 che mical shift of the CS2 group of the dithiocarbamate ligand.