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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Computational study of the spin-forbidden H_2 oxidative addition to 16-electron Fe(0) complexes
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Computational study of the spin-forbidden H_2 oxidative addition to 16-electron Fe(0) complexes

机译：16电子Fe（0）配合物的自旋禁止H_2氧化加成的计算研究

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摘要

The spin-forbidden oxidative addition of H_2 to Fe(CO)_4, Fe(PH_3)_4, Fe(dpe)_2 and Fe(dmpe)_2 [dpe = H_2PCH_2CH_2PH_2, dmpe = (CH_3)_2PCH_2CH_2P(CH_3)_2] has been investigated by density functional theory using a modified B3PW91 functional. All 16-electron fragments are found to adopt a spin triple ground state. The H_2 addition involves a spin crossover in the reagents region of configurational space, at a significantly higher energy relative to the triplet dissociation asymptote and, for the case of Fe(CO)_4·H_2, even higher than the singlet dissociation asymptote. After crossing to the singlet surface, the addition proceeds directly to the classical cis-dihydride product. Only for the Fe(CO)_4 was it possible to locate a stable energy minimum for the non-classical tautomer (dihydrogen complex), but the energy difference between this minimum and the tautomerisation transition state inverts when taking into account the zero-point energy correction. The geometries at the crossing points indicate a "side-on" approach of the H_2 molecule to the metal for the Fe(CO)_4, Fe(CO)_2(PH_3)_2 and Fe(PH_3)_4 systems. These geometries are more reactants-like for the Fe(CO)_4 system and more product-like for the Fe(PH_3)_4 system. the crossing point geometry for the Fe(dpe)_2 system, on the other hand, is nearly C_2-symmetric. The presence of an energy barrier on going from ~3FeL_4 + H_2 to the crossing point is in agreement with the slow observed rates for addition of H_2 to these unsaturated organometallic fragments.
机译：H_2向Fe（CO）_4，Fe（PH_3）_4，Fe（dpe）_2和Fe（dmpe）_2 [dpe = H_2PCH_2CH_2PH_2PH_2，dmpe =（CH_3）_2PCH_2CH_2P（CH_3）_2]的自旋禁止氧化加成通过密度泛函理论使用改进的B3PW91泛函进行了研究。发现所有16电子碎片都具有自旋三基态。 H_2的添加涉及结构空间的试剂区域中的自旋交叉，其相对于三重解离渐近线具有明显更高的能量，并且对于Fe（CO）_4·H_2而言，甚至高于单重解离渐近线。穿过单线态表面后，加成直接进行到经典的顺式二酐产物。仅对于Fe（CO）_4，才可以找到非经典互变异构体（二氢配合物）的稳定能量最小值，但是当考虑零点能量时，该最小值与互变异构过渡态之间的能量差会反转更正。对于Fe（CO）_4，Fe（CO）_2（PH_3）_2和Fe（PH_3）_4系统，交叉点处的几何形状指示H_2分子与金属的“侧向”方法。对于Fe（CO）_4系统，这些几何形状更像反应物，对于Fe（PH_3）_4系统，这些几何形状更像产物。另一方面，Fe（dpe）_2系统的交点几何几乎是C_2对称的。从〜3FeL_4 + H_2到交叉点的能量垒的存在与向这些不饱和有机金属碎片中添加H_2的观察到的缓慢速率一致。

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