STERIC EFFECT OF THE TERT-BUTYL SUBSTITUENT IN THE CRYSTALSTRUCTURE OF THE BINUCLEAR COMPLEX (tBuСр)2Мo2(СО)6 (tBuСp = tert-C4H9C5H4)

Abstract: The features of the crystal structure of bis(tert-butylcyclopentadienyltricarbonyl)molybdenum(I)) (tBuСр)2Мo2(СО)6 (1) have been established. Molecule (1), like the molecule of the unsubstituted complex Cp2Mo2(CO)6 (2)(Cp – C5H5), is in the trans-form. Both complexes (1) and (2) are sterically strained. However, the steric strain of molecule (1) is more pronounced, which is due to the steric interaction of the tert-butyl substituent with the trans-carbonyl (C12O3) group. Comparative analysis of structural parameters of complexes (1) and (2) made it possible to show that this interaction is reflected in changes in most structural parameters of complex (1). First of all, it is reflected in an increase in the Ct–Mo–C12 angle (Ct – is the centroid of the C5-ring), in a decrease in the Moi–Mo–C12 and C12–Mo–C11 angles, as well as in the rotation of the tBuСр ring around the Ct–Mo axis, away from the trans-С12О3 group. The rise of the cis-C11O2 group relative to the middle plane of the C5-ring is also accompanied by a reduction in non-valent contacts between cis-carbonyl ligands bonded to different Mo atoms ((С11О2)С…С(С10iО1i), ((С10О1)С…С(С11iО2i) (2.771 Å). The appearance of shorter non-valent contacts between the two halves (tBuCpMo(CO)3) of molecule (1) is not reflected in the length of the Mo–Mo bond (CIF file CCDC № 2243119).