SYNTHESIS OF ALKYLIDYNE COMPLEXES OF BR(CO)2(TMEDA)MCC6H4ME (M=CR, MO W) - CRYSTAL-STRUCTURE OF BR(CO)2(TMEDA)CRCC6H4ME

Abstract

The reaction of (CO5)M=C(OMe)Tol (M=Cr, Mo, W and Tol=P-C6H4Me) and BBr3 followed by treatment with tetramethylethylenediamine (TMEDA) yields a mixture of two diastereomers, trans, cis-Br(CO)2(tmeda)M=CTol [M =Cr(1a), Mo(2a), W(3a)] and cis, trans-Br(CO)2(tmeda)M=CTol [M=Cr(1b), Mo(2b), W(3b)], respectively. These compounds have been isolated as crystalline solids and characterized by spectroscopic (infrared, mass, H-1 and C-13-NMR) data. The trans, cis-Br(CO)2(tmeda)Cr=CTol (1a), has been examine via a single crystal X-ray diffraction study: BrCrO2N2C16H23, Mr=407.27, triclinic, P1BAR, a=12.792(2), b=13.400(5), c=11.645(4) angstrom, alpha=101.26(2)-degrees, beta=103.04(2)-degrees, gamma=91.88(2)-degrees, V=1907(l) angstrom3, Z=2, rho(calcd)=1.418 gcm-3, lambda(MoKalpha)=0.71069 angstrom, mu=26.25 cm-1, F(000)=831.97, T=295 K, R=0.0977 for 1332 significant reflections [F(o)>5sigma(F(o))]. There are two essentially equivalent molecules in the crystallographic asymmetric unit. Each molecule is octahedral with the bromide ligand trans to the alkylidyne carbon, the two cis-carbonyl ligands, and the bidentate TMEDA ligand.