[Er2Al2(OiPr)12(HOiPr)2], a novel heterobimetallic alkoxide

A new heterobimetallic tetranuclear alkoxide of the Er-Al system, [Al2Er2(C3H7O)(12)(C3H8O)(2)], has been synthesized and characterized by single-crystal X-ray diffraction and LR spectroscopy. Hexakis(mu(2)-isopropoxo)hexakis(isopropoxo)bis(2-propanol)dialuminiumdierbium has the linear composition [((OPr)-Pr-i)(2)Al]-(mu(2)- (OPr)-Pr-i)(2)-[(HOPr)-Pr-i)Er((OPr)-Pr-i)]-(mu(2)-(OPr)-Pr-i)(2)-[((OPr)-Pr-i)Er((HOPr)-Pr-i)]-(mu(2)-(OPr)-Pr-i)(2)-[Al((OPr)-Pr-i)(2)]. The inner pair of Er atoms are each sixfold coordinated and the outer Al atoms are each fourfold coordinated by O atoms. Two intramolecular hydrogen bonds exist between the 2-propanol group at the Er atom and the monodentate isopropoxo ligand at the adjacent Al atom. The adopted chain geometry of four alkoxo-bridged metal atoms is a rather unusual structural feature for heterobimetallic (M2M'(2)) alkoxides.