In order to study the Fe-Cu interactions and their effects on 31p NMR, the structures of mononuclear complex Fe(CO)3fPhzPpy)a 1 and binuclear complexes Fe(CO)3(PhEPpy)z(CuXn) (2: Xn = Cl2^2-, 3: Xn = Cl-, ...In order to study the Fe-Cu interactions and their effects on 31p NMR, the structures of mononuclear complex Fe(CO)3fPhzPpy)a 1 and binuclear complexes Fe(CO)3(PhEPpy)z(CuXn) (2: Xn = Cl2^2-, 3: Xn = Cl-, 4: Xn = Br-) are calculated by density functional theory (DFT) PBE0 method. For complexes 1, 3 and 4, the 31p NMR chemical shifts calculated by PBE0-GIAO method are in good agreement with experimental results. The 31p chemical shift is 82.10 ppm in the designed complex 2. The Fe-Cu interactions (including Fe→Cu and Fe←Cu charge transfer) mainly exhibit the indirect interactions. Moreover, the Fe-Cu(I) interactions (mostly acting as σFe-p→4Scu and aFe-C→4Scu charge transfer) in complexes 3 and 4 are stronger than Fe-Cu(Ⅱ) interactions (mostly acting as σFe-p→4Scu and σFe-p←4Sc,) in complex 2. In complex 2, the stronger Fe←Cu interac- tions, acting as σFe-p←44SCu charge transfer, increase the electron density on P nucleus, which causes the upfield 31p chemical shift compared with mononuclear complex 1. For 3 and 4, although a little deshielding for P nucleus is derived from the delocalization of σFe-p→4Scu due to the Fe→Cu interactions, the stronger σFe-c→np charge-transfer finally increases the electron density on P nucleus. As a result, an upfield 31p chemical shift is observed compared with 1. The stability follows the order of 2〉3=4, indicating that Fe(CO)3(PhzPpy)2(CuCl2) is stable and could be synthesized experimentally. The N-Cu(Ⅱ) interaction plays an important role in the stability of 2. Because the delocalization of σFe-p→4SCu and σFe-c→πc-o weakens the a bonds of Fe-C and ~r bonds of CO, it is favorable for increasing the catalytic activity of binuclear complexes. Complexes 3 and 4 are expected to show higher catalytic activity compared to 2.展开更多
基金Supported by the Natural Science Foundation of Guangdong Province (No. 5005938)
文摘In order to study the Fe-Cu interactions and their effects on 31p NMR, the structures of mononuclear complex Fe(CO)3fPhzPpy)a 1 and binuclear complexes Fe(CO)3(PhEPpy)z(CuXn) (2: Xn = Cl2^2-, 3: Xn = Cl-, 4: Xn = Br-) are calculated by density functional theory (DFT) PBE0 method. For complexes 1, 3 and 4, the 31p NMR chemical shifts calculated by PBE0-GIAO method are in good agreement with experimental results. The 31p chemical shift is 82.10 ppm in the designed complex 2. The Fe-Cu interactions (including Fe→Cu and Fe←Cu charge transfer) mainly exhibit the indirect interactions. Moreover, the Fe-Cu(I) interactions (mostly acting as σFe-p→4Scu and aFe-C→4Scu charge transfer) in complexes 3 and 4 are stronger than Fe-Cu(Ⅱ) interactions (mostly acting as σFe-p→4Scu and σFe-p←4Sc,) in complex 2. In complex 2, the stronger Fe←Cu interac- tions, acting as σFe-p←44SCu charge transfer, increase the electron density on P nucleus, which causes the upfield 31p chemical shift compared with mononuclear complex 1. For 3 and 4, although a little deshielding for P nucleus is derived from the delocalization of σFe-p→4Scu due to the Fe→Cu interactions, the stronger σFe-c→np charge-transfer finally increases the electron density on P nucleus. As a result, an upfield 31p chemical shift is observed compared with 1. The stability follows the order of 2〉3=4, indicating that Fe(CO)3(PhzPpy)2(CuCl2) is stable and could be synthesized experimentally. The N-Cu(Ⅱ) interaction plays an important role in the stability of 2. Because the delocalization of σFe-p→4SCu and σFe-c→πc-o weakens the a bonds of Fe-C and ~r bonds of CO, it is favorable for increasing the catalytic activity of binuclear complexes. Complexes 3 and 4 are expected to show higher catalytic activity compared to 2.