title: Cycloheptatrienyl zirconium sandwich complexes with lewis basic phospholyl ligands (phosphatrozircenes): synthesis, structure, bonding and coordination chemistry.
abstract: The transmetalation reaction between [(η(7) -C(7) H(7) )ZrCl(tmeda)] (1; tmeda=N,N,N',N'-tetramethylethylenediamine) and various phospholide anions leads to a new class of mixed sandwich complexes: [(η(7)-C(7)H(7))Zr(η(5)-C(4)PMe(4))] (2), [(η(7)-C(7)H(7))Zr(η(5)-C(4)PH(2)Me(2))] (3) and [(η(7)-C(7)H(7))Zr(η(5)-C(4)PPhHMe(2))] (4). The presence of Lewis basic phosphorus atoms and Lewis acidic zirconium atoms allows ambiphilic behaviour to be observed, and X-ray diffraction analysis reveals dimeric arrangements for 2 and 3 with long intermolecular Zr-P bonds, whereas 4 remains monomeric in the solid state. DFT calculations indicate that the metal-phosphorus interaction is weak, and accordingly, complexes 2-4 act as monodentate ligands upon reaction with [W(CO)(5)(thf)]. The resulting complexes [W(CO)(5)(L)] 5-7 (L=2-4) were studied by IR spectroscopy and compared with the [W(CO)(5) ] complex 9, containing the phosphane-functionalised trozircene [(η(7)-C(7)H(7))Zr(η(5)-C(5)H(4)PPh(2))] (8). They all show a close resemblance to simple phosphanes, such as PMe(3) , although molecular orbital analysis of 2 reveals that the free electron pair in the phosphatrozircenes is not the HOMO. Four equivalents of 2 can replace 1,4-cyclooctadiene (COD) in [Ni(cod)(2)] to form the homoleptic, distorted tetrahedral complex [Ni{2}(4)] (10).
authors.affiliation: Institut für Anorganische und Analytische Chemie, Technische Universität Carolo-Wilhelmina zu Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Glöckner
authors.forename: Thomas
authors.initials: T
authors.lastname: Bannenberg
authors.forename: Susanne
authors.initials: S
authors.lastname: Büschel
authors.forename: Constantin G
authors.initials: CG
authors.lastname: Daniliuc
authors.forename: Peter G
authors.initials: PG
authors.lastname: Jones
authors.forename: Matthias
authors.initials: M
authors.lastname: Tamm