Lyon Jonathan T, Andrews Lester
Department of Chemistry, University of Virginia, P.O Box 400319, Charlottesville, Virginia 22904-4319, USA.
Inorg Chem. 2006 Nov 27;45(24):9858-63. doi: 10.1021/ic0610379.
Laser-ablated titanium atoms react with CX4 (X = F and Cl) to produce triplet state XC/TiX3 complexes trapped in an argon matrix. Products are identified by their infrared spectra and comparison to theoretically predicted vibrations. Density functional theory calculations converge to C(3v) symmetry structures for these lowest-energy products. The two unpaired electrons in the carbon 2p orbitals are shared with empty titanium d orbitals leading to degenerate singly occupied pi molecular orbitals and an electron-deficient triple bond between the carbon and titanium centers, on the basis of DFT bonding analysis and spin density calculations. The carbon-titanium distances are near typical C=Ti double bond lengths, and the C-X bonds in the resulting products are shorter than in the CX4 precursors. It appears that X lone-pair conjugation contributes to the C-X bond strength and somewhat to the C-Ti bond, and Cl does better in this regard than F.
激光烧蚀的钛原子与CX4（X = F和Cl）反应，生成捕获在氩气基质中的三重态XC/TiX3配合物。通过红外光谱并与理论预测的振动进行比较来鉴定产物。密度泛函理论计算得出这些最低能量产物的C(3v)对称结构。基于密度泛函理论的键合分析和自旋密度计算，碳2p轨道中的两个未配对电子与空的钛d轨道共享，导致简并的单占据π分子轨道以及碳和钛中心之间的缺电子三键。碳-钛距离接近典型的C=Ti双键长度，并且所得产物中的C-X键比CX4前体中的短。似乎X孤对共轭有助于C-X键强度，对C-Ti键也有一定贡献，在这方面Cl比F表现更好。
