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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Reactivity of Pt- and Pd-bound nitriles towards nitrile oxides and nitrones: substitution vs. cycloaddition
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Reactivity of Pt- and Pd-bound nitriles towards nitrile oxides and nitrones: substitution vs. cycloaddition

机译：Pt和Pd结合的腈对腈氧化物和硝酮的反应性：取代与环加成

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摘要

Reactions of the nitrone CH3CH=N(CH3)O and the nitrile oxide CH3C= NO with the nitrile complexes trans-[MCl2(N= CCH3)(2)] (M= Pt, 1; Pd, 2) were investigated by theoretical methods at B3LYP and, for some processes, CCSD(T) levels of theory. The mechanisms of substitutions and cycloadditions were studied in detail. The former occur via a concerted asynchronous mechanism of dissociative type. The calculations of the metal-ligand bond energies in the starting complexes and substitution products and the analysis of structural features of the transition states indicate that the M-N bond dissociation (rather than M-O bond formation) is the step, which controls the reactivity of 1 and 2 in substitutions. The different chemical behaviours of the Pt and Pd complexes towards the 1,3-dipoles were investigated. The exclusive isolation of cycloaddition rather than substitution products in any solvents in the case of 1 is both kinetically and thermodynamically controlled. The switch of the reaction mode from cycloaddition to substitution for 2 in CH2Cl2 solution is caused by the significantly lower Pd-N bond energy in comparison with the Pt-N bond energy, consistent with the higher lability of the Pd complexes. The different chemical behaviour of 2 in CH3CN and CH2Cl2 solvents is accounted for by the great excess of acetonitrile in the CH3CN solution rather than a different solvation character. The relative variation of Wiberg bond indices along the reaction path is proposed as a quantitative criterion for the classi. cation of the reaction mechanism.
机译：通过理论研究了硝酮CH3CH = N（CH3）O和一氧化二氮CH3C = NO与腈配合物trans- [MCl2（N = CCH3）（2）]（M = Pt，1; Pd，2）的反应B3LYP中的方法，以及某些过程中的CCSD（T）理论水平。详细研究了取代和环加成的机理。前者通过分离类型的协调异步机制发生。起始配合物和取代产物中金属-配体键能的计算以及过渡态的结构特征分析表明，MN键离解（而非MO键形成）是控制1和2的反应性的步骤。 2换人。研究了Pt和Pd配合物对1,3-偶极的不同化学行为。动力学控制和热力学控制在1的情况下在任何溶剂中环加成而不是取代产物的唯一分离。 CH2Cl2溶液中反应模式从环加成转换为取代2的原因是，与Pt-N键能量相比，Pd-N键能量明显较低，这与Pd络合物的较高稳定性有关。在CH3CN和CH2Cl2溶剂中2的化学行为不同是由于CH3CN溶液中乙腈的过量过多，而不是溶剂化特性不同。 Wiberg键指数沿反应路径的相对变化被提出作为分类的定量标准。阳离子的反应机理。

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