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5 coordinate complex as a model for the reaction of the square planar complex

5坐标配合物作为方形平面配合物的反应模型

基本信息

批准号：
11640567
负责人：
OKEYA Seichi
金额：
$ 2.3万
依托单位：
Wakayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640567/
关键词：
5 coordinate complex trans effect cis effect carbonyl carbon nucleophilic addition C-H activation platinum(II) complex Schiff base complex ハライドイオンシッフ塩基求核付加中間体置換反応反応機構シック塩基錯体

项目摘要

The 5-coordinate complex, [PtX(hfac)_2]^- (X = Cl, Br or I, hfac = hexafluoroacetyl acetonate), has a distorted square pyramidal structure and exchanges the coordination sites quickly in solution. From the temperature-variable NMR, two independent paths were supposed ; an apical O-donor assaults an X-cis position or an X-trans position. The cis and trans effects of halide ligand were obtained by comparing the each rate data. Ab initio calculations of these intra molecular site exchange process were performed. The transition state energies of possible paths show that the order of the cis effect of halide ligand as, Cl > Br > I, and the trans effect as, I > Br > Cl, which is in accordance with the experimental results. The attempt to prepare similar 5-coordinate complexes with C-, N-, or O-donor resulted in producing the adducts complex anion on a carbonyl carbon in [Pt(hfac)_2]. An NHR adduct complex is a good model of the intermediate of the imine formation reaction between the carbonyl compound and the primary amine. This adduct actually produced a Schiff base complex. But in another reaction conditions, NHR dissociates and assaults Pt(II) to give the substituted products. The NHR adduct activates the C-H or O-H bond in solvent molecule to form the C-donor or O-donor adduct. The newly formed C-C bond is very weak since the C-donor adduct easily liberates the solvent molecule. Also the C-donor exchanges with the OMe in MeOH. Such a weak C-C bond is very novel.

五坐标配合物[PtX(hfac)_2]^- （X = Cl， Br或I， hfac =六氟乙酰丙酮）具有扭曲的方锥体结构，在溶液中能快速交换配位位。从温度变化的核磁共振，假设两个独立的路径；顶端o供体攻击x顺位或x反位。通过对各速率数据的比较，得到了卤化物配体的顺式和反式效应。对这些分子内位点交换过程进行了从头计算。可能路径的跃迁态能量表明，卤化物配体的顺式效应顺序为Cl > Br > I，反式效应顺序为I > Br > Cl，与实验结果一致。在[Pt(hfac)_2]中，用C-、N-或o -供体制备类似的5配位配合物，在羰基碳上产生了配合阴离子的加合物。NHR加合物是羰基化合物与伯胺之间亚胺生成反应的良好中间体模型。这个加合物实际上产生了一个席夫碱配合物。但在另一种反应条件下，NHR解离并攻击Pt（II）生成取代产物。NHR加合物激活溶剂分子中的C-H或O-H键，形成c -供体或o -供体加合物。新形成的C-C键非常弱，因为c给体加合物很容易使溶剂分子解放。c -供体也和MeOH中的OMe交换。这种弱碳碳键是很新奇的。