Two novel mononuclear neodymium alkoxides [Nd{OC(C14H11S2)}3(thf)3]·thf (9) and [Nd{OC(C16H13S)}3(thf)3]·thf (10) have been prepared by the reaction between Nd[N(SiMe3)2]3 and the tertiary alcohols HO-C(C14H11S2) (3) and HO-C(C16H13S) (4). The geometry around the neodymium metal is almost octahedral with a facial ligand arrangement similar to [Nd{OC(C8H5S2)3}3(thf)3]·4thf (5), [Nd{OC(C4H3S)3}3(thf)3]·thf (7) and Er[OC(C4H3S)3]3(thf)3 (8) (X-ray diffraction on single crystals). The cyclic voltammograms of a series of neodymium and erbium alkoxides indicate that the electrochemical properties are essentially dominated by the organic ligands. In comparison to the carbinols HO-C(C8H5S2)3 (1), HO-C(C4H3S)3 (2), HO-C(C14H11S2) (3) or HO-C(C16H13S) (4), the oxidation peak potentials of the thienyl units for the neodymium alkoxides [Nd{OC(C8H5S2)3}3(thf)3]·4thf (5), [Nd{OC(C4H3S)3}3(thf)3]·thf (7), [Nd{OC(C14H11S2)}3(thf)3]·thf (9) and [Nd{OC(C16H13S)}3(thf)3]·thf (10) are marginally shifted towards higher values by 0.03-0.10 V, whereas for Er[OC(C8H5S2)3]3(thf) (6) and Er[OC(C4H3S)3]3(thf)3 (8) a decrease of these potentials is noticed. Repetitive cyclic voltammetry does not generate polymeric films for 7-10, as found for the free organic ligands 2-4. Contrarily, the mononuclear precursors [Nd{OC(C8H5S2)3}3(thf)3]·4thf (5) and Er[OC(C8H5S2)3]3(thf) (6) are electro-oxidized and electro-active polymer films are obtained and characterized. To investigate the positions of the excited states of the ligands, emission spectra of the carbinols 1-4 have been recorded. The luminescence studies of the neodymium alkoxides reveal an energy transfer from the ligand to the metal centre with a remarkable Nd emission efficiency upon ligand excitation in the case of 5.
European Journal of Inorganic Chemistry , 2010, 2010 879-889.