SYNTHESIS AND FEATURES OF THE MOLECULAR AND CRYSTAL STRUCTURE OF THE Cp4Ru4(µ3-CO)4 CLUSTER

Abstract

When preparing the ruthenium dimer [Ru(CO)2Cp]2 in the thermal reaction of cyclopentadiene with Ru3(CO)12, the tetranuclear cluster [Ru(μ3-CO)Cp]4 (I) was obtained as a minor product. Spectral (13C and 1H NMR, IR) and structural studies were carried out for cluster I. By crystallization under different conditions, two types of dark cherry crystals were obtained, cluster I itself (crystal 1) and its tetrahydrate (crystal 2), the structure of which was determined by X-ray diffraction. Structural data for 1 and 2 have been deposited in the Cambridge Structural Data Center (CCDC nos. 2241197 and 2241199, respectively; deposit@ccdc.cam.ac.uk; http://www.ccdc.cam.ac.uk). Based on a comparative analysis of cluster geometry, it is shown that the distortion of the Ru4(CO)4 framework in I from ideal Td symmetry in the structure of a pure compound is determined by the anisotropy of intermolecular contacts in the crystal. Features of chemical bonding in the [Ru(μ3-CO)Cp]4 cluster and its iron-containing analogue were studied using DFT calculations using topological analysis of electron density to compare energy characteristics and effective force constant bonding interactions. The necessity of using criteria for elastic deformations of interatomic interactions (force constants) for the correct description of structural and chemical phenomena, for example, such as the structural non-rigidity of the framework of transition metal clusters, has been demonstrated.