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Zirconium-91 chemical shifts and line widths as indicators of coordination geometry distortions in zirconocene complexes

Zirconium-91 chemical shifts and line widths as indicators of coordination geometry distortions in zirconocene complexes

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BÜHL, Michael, Gudrun HOPP, Wolfgang VON PHILIPSBORN, Stefan BECK, Marc-Heinrich PROSENC, Ursula RIEF, Hans-Herbert BRINTZINGER, 1996. Zirconium-91 chemical shifts and line widths as indicators of coordination geometry distortions in zirconocene complexes. In: Organometallics. 15(2), pp. 778-785. ISSN 0276-7333. eISSN 1520-6041

@article{Buhl1996Zirco-23761, title={Zirconium-91 chemical shifts and line widths as indicators of coordination geometry distortions in zirconocene complexes}, year={1996}, doi={10.1021/om950757c}, number={2}, volume={15}, issn={0276-7333}, journal={Organometallics}, pages={778--785}, author={Bühl, Michael and Hopp, Gudrun and von Philipsborn, Wolfgang and Beck, Stefan and Prosenc, Marc-Heinrich and Rief, Ursula and Brintzinger, Hans-Herbert} }

eng 2013-06-24T16:48:04Z Hopp, Gudrun Rief, Ursula Brintzinger, Hans-Herbert Organometallics ; 15 (1996), 2. - S. 778-785 Brintzinger, Hans-Herbert von Philipsborn, Wolfgang Prosenc, Marc-Heinrich <sup>91</sup>Zr NMR chemical shifts and line widths (Δν<sub>1/2</sub>) are reported for a number of ring-bridged and ring-substituted zirconocene dichloride, dibromide, and dimethyl complexes. Ab initio computations at the SCF level employing basis sets of moderate size suggest that the magnitude of the electric field gradient (EFG) at the Zr atom dominates Δν<sub>1/2</sub> when the substituents X at Zr are varied (X = Br, Cl, Me). Substituents at the cyclopentadiene (Cp) rings affect the computed EFGs much less; in these cases, the line widths Δν<sub>1/2</sub> are governed by the molecular correlation times τc, which were obtained for several zirconocene dichlorides from T1(<sup>13</sup>C) measurements. Experimental trends in δ(<sup>91</sup>Zr) of zirconocenes are well reproduced computationally with the IGLO (individual gauge for localized orbitals) or GIAO (gauge including atomic orbitals) SCF methods employing large basis sets. Model calculations suggest that δ(<sup>91</sup>Zr), as well as the EFG, are quite sensitive to the inclination and twist angles of the Cp rings and, to a lesser extent, to the CpZrCp' angle. A substantial deshielding, δ(<sup>91</sup>Zr) ca. 700 ppm, is predicted for (C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>ZrMe<sup>+</sup>, presumably the active olefin-polymerizing catalyst. Zirconium-91 chemical shifts and line widths as indicators of coordination geometry distortions in zirconocene complexes Bühl, Michael Bühl, Michael deposit-license Prosenc, Marc-Heinrich Rief, Ursula Hopp, Gudrun Beck, Stefan 2013-06-24T16:48:04Z Beck, Stefan von Philipsborn, Wolfgang 1996

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