Rhodium Complexes with Pincer Diphosphite Ligands. Unusual Olefin in-Plane Coordination in Square-Planar Compounds
作者:Miguel Rubio、Andrés Suárez、Diego del Río、Agustín Galindo、Eleuterio Álvarez、Antonio Pizzano
DOI:10.1021/om800830w
日期:2009.1.26
A family of rhodium complexes bearing pincer diphosphite (PCP) and neutral L (L = PPh3, CO, CNXy, C2H4) ligands has been prepared and characterized. Reactions between Rh(Cl)(PPh3)3 and the diphosphites 2 lead to the chloro hydrides Rh(H)(Cl)(PCP)(PPh3) (4), which can be deprotonated to yield the complexes Rh(PCP)(PPh3) (5). In the latter, the PPh3 ligand is labile and can be exchanged by CO, CNXy,
制备并表征了带有二磷酸钳(PCP)和中性L(L = PPh 3,CO,CNXy,C 2 H 4)配体的铑配合物家族。Rh(Cl)(PPh 3)3与二亚磷酸酯2之间的反应生成氯氢化物Rh(H)(Cl)(PCP)(PPh 3)(4),可以将其去质子化以生成配合物Rh(PCP) (PPh 3)(5)。在后者中,所述PPH 3配体是不稳定的,并且可以通过CO,CNXy,和C被交换2 ħ 4,得到衍生物6 - 8。最值得注意的是,乙烯络合物8a,b在固态下显示出显着的面内(ip)构象。这些配合物的溶液NMR研究表明,烯烃在所有温度范围内均能快速旋转,而溶液和固态13 C 1 H} NMR实验给出了几乎可叠加的光谱,这也表明了溶液中ip构象异构体的普遍性。使用化合物模型进行的补充详细DFT计算8表明烯烃构象偏爱是由于空间效应的双重结合,这是由于夹钳配体螯合和亚磷酸酯取代基的性质引起的P-Rh-P角从180°减小引起的,t