Synthesis and Spectroscopic Characterization of Two Different Types of Heterobimetallic Glycolate Complexes of Niobium(V)

An entirely new class of heterobimetallic homoleptic glycolate complexes of the type Nb(OGO)3{Ta(OGO)2} [where G=CMe2CH2CH2CMe2 (G1) (3); CMe2CH2 CHMe(G2) (4); CHMeCHMe (G3) (5); CH2CMe2CH2 (G4) (6); CMe2CMe2(G5) (7); CH2CHMeCH2 (G6) (8); CH2CEt2CH2 (G7) (9); CH2CMe(Prn)CH2 (G8) (10)] have been prepared by the reactions of Nb(OGO)2(OGOH) [G=G1(1a); G2(1b); G3(1c); G4(1d); G5(1e); G6(1f); G7(1g); G8(1h)] with Ta(OGO)2 (OPri) (G=G1(2a); G2(2b); G3(2c); G4(2d); G5(2e) G6(2f); G7(2g); G8(2h). In addition to the novel derivatives (2)–(10), our earlier investigations on heterobimetallic glycolate-alkoxide derivatives have been extended to derivatives of the type Nb(OGO)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$_{3} \{\hbox{M}(\hbox{OPr}^i)_{n-1}\}$$ \end{document} [where M=A1 n=3, G=G3(11);G4(12); G6(13) G7(14); Gs(15); G9=CH2CH2CH2(16) and M=Ti (n=4, G=G4) (17), Zr(n=4,G=G4) (18)], which are conveniently prepared by the reactions of metalloligands Nb(OGO)2(OGOH) [G=G3(1c); G4(1d); G6(1f); G7(1g); G8(1h); G9(1i)] with different metal alkoxides. All of these new complexes have been characterized by elemental analyses, molecular weight determinations, and spectroscopic (I.r. and 1H, 27Al-n.m.r.) studies. Structural features of the new derivatives have been elucidated on the basis of molecular weight and spectroscopic data.