Alkynylcarbyne complexes containing various tri- and bidentate ligands such as cyclopentadienide, tris(pyrazolyl)borate, bis(pyrazolyl)acetate and tmeda: synthesis and spectroscopic properties
作者:Birgit Schwenzer、Joachim Schleu、Nicolai Burzlaff、Christoph Karl、Helmut Fischer
DOI:10.1016/s0022-328x(01)01310-9
日期:2002.1
The (alkynylcarbyne) tungsten complexes [L-3(CO)(2)WdropC-CdropC-R] (3a,b-6a,b) [L-3 = hydro[tris(3,5-dimethylpyrazol-1-yl)]borato (Tp', 3), hydro[tris(pyrazol-1-yl)]borato (Tp, 4), cyclopentadienyl (Cp, 5), bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza, 6); R = SiMe3 (a), Ph (b)] were prepared in a stepwise fashion from [W(CO)(6)] and Li[CdropCR], (CF3CO)(2)O and M[L-3] (M = Na, K). The formation of 6a,b was highly selective, only complexes with a trans arrangement of the carboxylate group of bdmpza and the alkynylcarbyne ligand were detected. The reaction of [W(CO)(6)] with Li[CdropCR], C2O2Cl2 and tmeda afforded trans[Cl(CO)(2)(tmeda)WdropC-CdropC-R] (7a,b). The electron-donating potential of the different tripodal ligands L-3 was studied by IR- and C-13-NMR spectroscopy and compared to that of the ligand combination Cl/tmeda. The IR data suggest that in these complexes bdmpza is a weaker electron donor than Tp' and Tp but displays stronger electron-donating abilities than Cp. The structures of 6b and 7b were established by X-ray structural analyses. (C) 2002 Elsevier Science B.V. All rights reserved.