...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >From two-electron via four-electron to six-electron donor carbonyl groups in trinuclear derivatives of the oxophilic metal niobium
【24h】

From two-electron via four-electron to six-electron donor carbonyl groups in trinuclear derivatives of the oxophilic metal niobium

机译：嗜氧金属铌的三核衍生物中从二电子到四电子的供体羰基

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Trinuclear cyclopentadienylniobium carbonyls are of interest since Cp3Nb3(CO)(7) (Cp = eta(5)-C5H5) is a stable molecule having a unique face-bridging carbonyl group formally donating six electrons to the Nb-3 triangle through one Nb-C sigma-bond and two orthogonal pi-bonds. In this connection, the molecules Cp3Nb3(CO)(n) (n = 9, 8, 7, 6) have been examined by density functional theory. The saturated derivative Cp3Nb3(CO)(9) is predicted to have a structure with all terminal carbonyl groups and a singly bonded Nb-3 triangle with 3.361 angstrom edges. The singly bonded Nb-3 triangle is retained in the lowest energy structure for Cp3Nb3(CO)(8), which has a four-electron donor edge-bridging carbonyl group in addition to seven terminal carbonyl groups. An alternative structure for Cp3Nb3(CO)(8) at similar to 8 kcal mol(-1) above this global minimum has an unusual four-electron donor carbonyl group bridging all three niobium atoms. The two lowest energy structures found for Cp3Nb3(CO)(7) are a pair of stereoisomers within similar to 1 kcal mol(-1) of energy, having a six-electron donor carbonyl group bridging all three niobium atoms, in addition to six terminal carbonyl groups. The structure and n(CO) frequencies of one of these stereoisomers, including the unusually low n(CO) frequency of similar to 1330 cm(-1) for the six electron donor carbonyl group, are in close agreement with experiment. In contrast to Cp3Nb3(CO)(8) and Cp3Nb3(CO)(7), the lowest energy structure for the even more unsaturated Cp3Nb3(CO)(6) has only two-electron donor carbonyl groups, three of which are edge-bridging and three of which are terminal. However, in this Cp3Nb3(CO)(6) structure, two of the Nb=Nb distances in the Nb-3 triangle are shortened to similar to 2.8 angstrom, suggesting a formal bond order of at least two.
机译：三核环戊二烯基铌羰基很受关注，因为Cp3Nb3（CO）（7）（Cp = eta（5）-C5H5）是一种稳定的分子，具有独特的桥联羰基，通过一个Nb-向6个Nb-3三角形式正式提供电子。 Cσ键和两个正交pi键。关于这一点，已经通过密度泛函理论研究了分子Cp3Nb3（CO）（n）（n = 9、8、7、6）。预计饱和衍生物Cp3Nb3（CO）（9）具有所有末端羰基的结构和具有3.361埃边的单键Nb-3三角形。单键结合的Nb-3三角形保留在Cp3Nb3（CO）（8）的最低能级结构中，Cp3Nb3（CO）（8）除七个末端羰基外还具有一个四电子供体边缘桥连的羰基。 Cp3Nb3（CO）（8）的另一种结构类似于该全局最小值之上的8 kcal mol（-1），具有一个桥接所有三个铌原子的不寻常的四电子供体羰基。 Cp3Nb3（CO）（7）的两个最低能级结构是一对类似于1 kcal mol（-1）能量的立体异构体，除了六个外，还具有一个桥接所有三个铌原子的六电子供体羰基末端羰基。这些立体异构体之一的结构和n（CO）频率，包括六个电子供体羰基的异常低的n（CO）频率，类似于1330 cm（-1），与实验非常吻合。与Cp3Nb3（CO）（8）和Cp3Nb3（CO）（7）相比，甚至更不饱和的Cp3Nb3（CO）（6）的最低能级结构只有两个电子供体羰基，其中三个是边缘-桥接，其中三个是终端。但是，在此Cp3Nb3（CO）（6）结构中，Nb-3三角形中的两个Nb = Nb距离缩短到2.8埃，表明形式上的键合顺序至少为2。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号