Lanthanum alkoxides. Crystal structure of [La6(μ6-Cl)(μ3-OPr i )2(μ-OPr i )9(OPr i )6

Abstract

La(OR)3 (R = Me, Et, Pri, or C2H4OMe) has been synthesized via direct and electrochemical dissolution of metallic lanthanum in alcohols (in the presence of I2 or a HgCl2/HgI2/Hg(OAc)2 mixture catalysts or Bu4NBr or Et3BzNCl electrochemical additives, respectively). Lanthanum methoxide, ethoxide, and n-buthoxide have been synthesized via etherification of La(OPri)3 and were characterized by IR spectroscopy and mass spectroscopy. The composition and physicochemical characteristics of lanthanum isopropoxide can vary over broad ranges depending on a method of its synthesis. The electrochemical dissolution of lanthanum in isopropanol or in the presence of I2 catalytic amounts yields an insoluble polymeric product, and the synthesis of “La(OPri)3” in the presence of a HgCl2/HgI2/Hg(OAc)2 mixture results in the crystallization of La6Cl(OPri)17, whose composition and structure have been established by X-ray diffraction. In a La6(μ6-Cl)(μ3-OPri)2(μ-OPri)9(OPri)6 molecule, lanthanum atoms form a trigonal prism centered by a chlorine atom (La–Cl, 3.14–3.15 A), and isopropyl groups are μ3-bridging, μ2-bridging or terminal (La–O, 2.537, 2.435, and 2.152 A, respectively).