Matsuzaki Kazutaka, Kawaguchi Hiroyuki, Voth Peter, Noda Kyoko, Itoh Sumitaka, Takagi Hideo D, Kashiwabara Kazuo, Tatsumi Kazuyuki
Research Center for Materials Science and Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.
Inorg Chem. 2003 Aug 25;42(17):5320-9. doi: 10.1021/ic034353l.
Reactions of Cp(2)TiCl(2) (Cp = eta(5)-cyclopentadienide) with 2 or 1 equiv of hybrid P-S ligands (L), (CH(3))(2)P(CH(2))(n)()S(-) (n = 2, dmpet; n = 3, dmppt), produced new dicyclopentadienyltitanium(IV) complexes with L, Cp(2)Ti(L-kappaS)(2) (1, L = dmpet; 2, L = dmppt) and [Cp(2)Ti(L-kappa(2)S,P)]BPh(4) (3, L = dmpet; 4, L = dmppt). The Ti(III) complexes, Cp(2)Ti(L-kappa(2)S,P) (5, L = dmpet; 6, L = dmppt), were prepared by the reaction of Cp(2)Ti(eta(3)-C(3)H(5)) with 1 equiv of L. The structures of complexes 1-6 were confirmed by X-ray diffraction analyses. It was found that complexes 3 and 5 were isostructural around Ti(IV) and Ti(III) centers: the Ti(IV)-S bond length in 3 (2.3498(9) A) is shorter by 0.14 A than Ti(III)-S in 5 (2.4877(7) A), while Ti(IV)-P (2.534(1) A) was merely 0.05 A shorter than Ti(III)-P (2.5844(7) A). The redox potential between 3 and 5 in acetonitrile was -1.14 V vs the ferricinium/ferrocene couple. A heterobimetallic complex that has the frame of complex 1, [Cp(2)Ti(dmpet)(2)Cu]PF(6) (7), was also isolated and structurally characterized: the Ti-Cu distance (2.95(1) A) was shorter than that in [Cp(2)Ti(SC(2)H(4)PPh(2))(2)Cu]BF(4), previously reported by White and Stephan. Structural characterization was also carried out for CpTi(dmpet-kappaS)(2)(dmpet-kappa(2)S,P) (8) and CpTiCl(2)(dmppt-kappa(2)S,P) (9), which were obtained by the reactions of Cp(or Cp)TiCl(3) (Cp = eta(5)-C(5)Me(5)(-)) with n equiv (n = 1-3) of L. The mutual site-exchange reaction between phosphorus atoms on a coordinated dmpet in the kappa(2)S,P mode and on two other coordinated dmpet's in the kappaS mode within complex 8 was analyzed by the variable-temperature (31)P[(1)H] dynamic NMR method. The kinetic parameters for this process, k(ex)(298) = 1.9 x 10(5) s(-)(1), DeltaH = 48 kJ mol(-)(1), and DeltaS = 17 J mol(-)(1) K(-)(1), as well as the rather long Ti(IV)-P distance (2.652(1) A), indicate the fluxional nature of the coordination geometry in complex 8.
二茂钛二氯（Cp = η⁵-环戊二烯基）与2当量或1当量的混合P-S配体（L），即(CH₃)₂P(CH₂)ₙS⁻（n = 2，dmpet；n = 3，dmppt）反应，生成了新的含L的二茂钛（IV）配合物Cp₂Ti(L-κS)₂（1，L = dmpet；2，L = dmppt）和[Cp₂Ti(L-κ²S,P)]BPh₄（3，L = dmpet；4，L = dmppt）。二茂钛（III）配合物Cp₂Ti(L-κ²S,P)（5，L = dmpet；6，L = dmppt）通过Cp₂Ti(η³-C₃H₅)与1当量的L反应制备。配合物1 - 6的结构通过X射线衍射分析得以确认。发现配合物3和5在Ti(IV)和Ti(III)中心周围具有同构结构：3中Ti(IV)-S键长（2.3498(9) Å）比5中Ti(III)-S键长短0.14 Å（2.4877(7) Å），而Ti(IV)-P（2.534(1) Å）仅比Ti(III)-P（2.5844(7) Å）短0.05 Å。在乙腈中，3和5之间的氧化还原电位相对于二茂铁鎓/二茂铁电对为 -1.14 V。还分离并对具有配合物1结构框架的异双核配合物[Cp₂Ti(dmpet)₂Cu]PF₆（7）进行了结构表征：Ti-Cu距离（2.95(1) Å）比White和Stephan先前报道的[Cp₂Ti(SC₂H₄PPh₂)₂Cu]BF₄中的短。还对通过Cp(或Cp)TiCl₃（Cp = η⁵-C₅Me₅⁻）与n当量（n = 1 - 3）的L反应得到的CpTi(dmpet-κS)₂(dmpet-κ²S,P)（8）和CpTiCl₂(dmppt-κ²S,P)（9）进行了结构表征。通过变温³¹P[(¹H)]动态核磁共振方法分析了配合物8中以κ²S,P模式配位的dmpet上的磷原子与以κS模式配位在另外两个dmpet上的磷原子之间的相互位点交换反应。该过程的动力学参数，k(ex)(298) = 1.9×10⁵ s⁻¹，ΔH = 48 kJ mol⁻¹以及ΔS = 17 J mol⁻¹ K⁻¹，以及相当长的Ti(IV)-P距离（2.652(1) Å），表明配合物8中配位几何结构具有动态性质。
