配合物[M(CO)3(PPh2py)2](M=Fe,Ru)异构体的理论研究

对PPh2py配合物[M(CO)3(PPh2py)2](M=Fe, Ru)的三种构型的异构体1-6进行了研究. 其中PPh2py以两个P原子与M配位形成HH构型1(Fe)和4(Ru), 以一个P和一个N原子与M配位形成HT构型2(Fe)和5(Ru), 以两个N原子与M配位形成HH’构型3(Fe)和6(Ru). 结果表明, (1) PPh2py中P原子对HOMO轨道的贡献最大, PPh2py作为电子给体时易以P原子与金属原子结合. (2)从分子能量和相互作用能数据表明, 配合物中HH构型最稳定, HH'构型最不稳定, 这与合成产物为HH构型的结果一致. (3) 键长和Wiberg键级均表明P—M键比N—M键结合力强. P、M原子间存在σ键, 而N、Fe原子间仅存在nN→n*M或nN→σ*M-P的电荷转移作用. (4) HH构型中M对HOMO的贡献最大, PPh2py向M的电荷转移最强, 使M的负电荷最大, 故HH构型最易作为电子给体以M原子与第二个金属配位形成双核配合物.

Theoretical Study on the Isomers of [M(CO)3(PPh2py)2] (M=Fe,Ru) Complex

Three conformations of [M(CO)3(PPh2py)2] (M=Fe, Ru), HH conformation representing that both P atoms on the PPh2py coordinated to M, HT conformation representing that P and N atoms on two different PPh2py coordinated to M, and HH’ representing that two N atoms coordinated to M, were calculated by means of density functional theory (DFT) PBE0 method. The conclusions were drawn as follows: (1) The largest contribution of P atom in PPh2py to HOMO orbital indicated that P atomin PPh2py was easier to coordinate to metal atom as an electron donor thanNatom. (2) The HHconformation was the most stable one, while HH’ was the most unstable according to molecular energies and interaction energies. This conclusion consisted with the result of synthesis experiment, in which the HH conformation products had always been gotten. (3) P—Mbonds were stronger thanN—Mbonds by a comparison of their bond lengths and bond indices. There was a σ bond between P and Matoms, while in the case of interaction between N andMatoms, there was only a weak charge transfer between them (nN→n*M or nN→σ*M-P ). (4) The largest negative charge and contribution of metal atom in the HH conformation to HOMO orbital indicated that the HH conformation was the easiest to coordinate to a second metal atom and forma binuclear complex withMas the electron donor.