Determination of 1J( 59Co– 59Co) scalar coupling constants in the tetrahedral mixed-metal cluster HFeCo 3(CO) 10(PCyH 2)(PPh 2[CH 2C(O)Ph]) using COSY-type NMR experiments

Abstract

Two-dimensional 59Co correlation spectroscopy (COSY) and double-quantum-filtered (DQF) COSY NMR experiments are reported for the tetrahedral mixed-metal cluster HFeCo 3(CO) 10(PCyH 2)(PPh 2[CH 2C(O)Ph]), which consists from the point of view of 59Co NMR spectroscopy, of an AMX system of three-spin S = 7/2. Both 2D NMR spectra prove the existence of a J scalar coupling constant between non-equivalent 59Co nuclei. By contrast to what happens with the conventional 2D 59Co COSY NMR spectrum, it was possible to simulate the 2D 59Co DQF-COSY NMR spectrum by density matrix calculations in order to extract the values of the 1J( 59Co– 59Co) coupling constants. The comparison between experimental and theoretical 2D NMR spectra gives spin-couplings constants of several hundreds Hertz for this cluster.