Quantum Chemistry Studies on the Fe-Cu Interactions and 31p NMR in Fe（CO）3（Ph2Ppy）2（CuXn） （Xn = Cl2^2-, Cl-, Br-）

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.

Quantum Chemistry Studies on the Fe-Cu Interactions and 31P NMR in Fe(CO)3(Ph2Ppy)2(CuXn) (Xn = Cl22-, Cl-, Br-)

In order to study the Fe-Cu interactions and their effects on 31P NMR, the structures of mononuclear complex Fe(CO)3(Ph2Ppy)2 1 and binuclear complexes Fe(CO)3(Ph2Ppy)2(CuXn) (2: Xn = Cl22-, 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 σFe-C→4sCu charge transfer) in complexes 3 and 4 are stronger than Fe-Cu(II) interactions (mostly acting as σ*Fe-C←4sCu and σ*Fe-P←4sCu) in complex 2. In complex 2, the stronger Fe←Cu interac- tions, acting as σ*Fe-P←4sCu 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(Ph2Ppy)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-C→4sCu and σFe-C→π*C-O weakens the σ bonds of Fe-C and π 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.