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用密度泛函理论在B3LYP/LANL2DZ基组水平上对(η~x-C_6H_6)Cr(CO)_n(x=1-6;n=1-5)复合物体系的可能构型进行了自由优化及相互作用能的计算,研究了不同羰基数对复合物稳定性、苯和羰基铬相互作用的影响,并对苯和羰基铬相互作用进行了NBO分析。得到以下结论:(1)当n≤3时,苯与Cr(CO)_n以η~6配位;当n≥4时,苯与Cr(CO)_n以η~2配位;(2)最稳定复合物中随羰基数的增加Cr-C_(benzene)平均键长增长,最大二面角H-C-C-H偏离碳环的角度随复合物对称性降低而逐渐增大;(3)当n为奇数时,复合物相互作用主要表现为苯C-C键的π轨道和Cr-CO键的σ反键轨道;当n为偶数时,复合物相互作用主要表现为苯C-C键的π轨道或π~*轨道与Cr的孤对电子轨道;(4)复合物羰基数越多,最稳定复合物的相互作用能数值越大,稳定性越小。
The possible configurations of (η ~ x-C_6H_6) Cr (CO) _n (x = 1-6; n = 1-5) complexes were optimized at the B3LYP / LANL2DZ basis by density functional theory And the calculation of the interaction energies, the influence of different carbonyl numbers on the stability of the complex and the interaction between benzene and carbonyl carbonyl was studied. The NBO analysis of the interaction between benzene and carbonyl chromium was also carried out. The main conclusions are as follows: (1) When n≤3, benzene and Cr (CO) _n coordinate to η ~ 6; when n≥4, benzene and Cr (CO) With the increase of carbonyl number, the average bond length of Cr-Benzene increases with the increase of carbonyl number in the most stable complex, and the angle of maximum dihedral angle HCCH deviates from the carbocyclic ring increases with decreasing the symmetry of the complex. (3) When n is odd , The complex interactions mainly show the π orbital of the benzene CC bond and the σ antibonding orbital of the Cr-CO bond. When n is even, the interaction of the complexes mainly shows the π or π ~ * orbital of the benzene CC bond Cr solitary electron orbitals; (4) the more carbonyl carbonyl complex, the most stable complex interaction energy value greater, the smaller the stability.