Unsymmetrisch substituierte Alkinkomplexe von Wolfram(IV). Die Kristallstruktur von PPh4*CH2Cl2

Article abstract of DOI:10.1016/0022-328X(88)80117-7

The alkynes Me3SiCCH and PhCCH react with tungsten hexachloride in CCl4 and CH2Cl2, respectively, to form the alkyne complexes 2 (1) and 2 (2).Their IR spectra indicate that they are dimerised via chloro bridges.Complexes 1 and 2 are soluble in dichloromethane, when donor solvents like diethyl ether or acetonitrile are added.The 1H and 13C NMR spectra of the ether adduct of 2 are consistent with alkyne ligand-like bonding which is best described as one of the metallocyclopropene type.Reaction of 2 with tetraphenylphosphonium chloride in CH2Cl2 forms the complex PPh4*CH2Cl2 (3), which is soluble in CH2Cl2.Its structure was determined from X-ray diffraction studies: Space group P2₁/c, Z=4, R=0.072 for 5769 observed, independent reflexins.The lattice constants at 90 K are: a 751.3, b 1620.9, c 2752.6 pm; β 94.47 deg.The crystal lattice of compound 3 consists of PPh4⁺ and ^- ions, and includes CH2Cl2 molecules.In the anion the alkyne ligand is coordinated side-on to the metal; the bonding features correspond to the metallocyclopropene type with W-C bond lengths of 200 and 203 pm, respectively, and C-C bond length of 125 pm.