过渡金属五卤苯基有机化合物的研究(Ⅱ)——五氯苯基镍化合物亲核取代反应动力学

Study on the Organometallic Compounds of Transition Metals Containing Pentahaloaryl Ligands(Ⅱ)——The Kinetics and Mechanisms of Nucleophilic Substitution Reactions of Bis(diphenylalkylphosphine)pentachlo-RophenvInickeK(Ⅱ)Halides

本文用分光光度法研究了双(二苯基烷基膦)合(五氯苯基)卤化镍(MX)与NO_(2)-和CNS-在MeOH、EtOH和DMF溶剂中的亲核取代反应动力学.实验表明,反应遵循两项速率定律,即γ=(k_(1)+k_(2)[L])[MX].实验分别测定了不同温度下的速率常数k1、k2值及对应的活化参数△H≠和△S≠值.讨论了反应机理、溶剂效应,以及化合物中的不同烷基膦配体、不同离去基团和不同进入基团对反应速率的影响.

The kinetics of nuclcophilic substitution reactions of bis(diphenyl-alkylphosphine)pentachlorophenylnickel(Ⅱ)halides with NO_(2)-and SCN-in MeOH EtOH and DMF was studied by spectrophotometric method.The results indicated that the reactions followed a two-term reaction rate law,that is,r=(k_(1)+k_(2)[L])[complex],k1,and k2 values were determined at different temperatures and the corresponding activated thermodynamic parameters△H≠and△S≠were evalualed.Reaction mechanisms have been proposed and factors influencing the reaction rate such as solvent effect,nature of the leaving and entering groups,different alkyl groups in the phosphine ligand,etc,have been discussed.