7-COORDINATION - MOLECULAR-ORBITAL EXPLORATION OF STRUCTURE, STEREOCHEMISTRY, AND REACTION DYNAMICS
7-COORDINATION - MOLECULAR-ORBITAL EXPLORATION OF STRUCTURE, STEREOCHEMISTRY, AND REACTION DYNAMICS
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DOI：
10.1021/ic50169a002
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发表时间：
1977-01-01
影响因子：
4.6
通讯作者：
ROSSI, AR
中科院分区：
文献类型：
--
作者：
HOFFMANN, R;BEIER, BF;ROSSI, AR
本文对七配位分子进行了系统的分子轨道分析，重点讨论了其基本电子结构、取代基位的选择以及不同构型间相互转化的途径。详细研究的构象包括五角双金字塔(PB)、封顶八面体(CO)和封顶三棱柱(CTP)。关于电负性效应，得到了以下结论：pB赤道(Eq)、CO封端(C)、CTP边(E)是d4配合物中较好的给体取代的最佳位置。对于效果，推导出由接受者取代的d4体系和由施主取代的d4体系的下列偏好：PB ax>；eq，eq‘|>；eq_；CO(cf=封顶面，uf=无封顶面，c=封顶位置)cf>；c>；uf，cfx>；cfj，uf±>；uf’；ctp(qf=四边形面，e=边，c=封顶位置)qf~e>；c，qfx>；qfj，e±>；对于d4给体取代基情况，这些偏好是相反的。与结构研究提供的信息的一致性是好的，尽管从严谨的论证中往往会得出相同的结论。所有七配位的多态重排途径都是低能量的。
A systematic molecular orbital analysis of seven-coordinate molecules is presented, with an emphasis on the basic electronic structure, substituent site preferences, and pathways for interconversion of variousgeometries. Conformations studied in detail include the pentagonal bipyramid (PB), capped octahedron (CO), and capped trigonal prism (CTP). With respect to or electronegativity effects the following conclusions are reached for the optimum site of substitution in a d4 complex by a better donor: PB equatorial (eq), CO capping site (c), CTP edge (e). For effects the following preferences are deduced for d4 systems substituted by an acceptor and d by a donor (> means preferred): PB ax> eq, eq¡|> eq_; CO (cf= capped face, uf= uncapped face, c= capping site) cf> c> uf, cfx> cfj, uf±> uf¡; CTP (qf= quadrilateral face, e= edge, c= capping site) qf~ e> c, qfx> qfj, e±> eg, cy> cx. These preferences are reversed for the d4 donor substituent case. The agreement with information available from structural studies is good, though often the same conclusions would be reached from steric arguments. All pathways of polytopal rearrangement in seven-coordination are of low energy.