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

n entirely new class of heterobimetallic homoleptic glycolate complexes of the type Nb(OGO) 3 Ta(OGO) 2 [where G=CMe 2 CH 2 CH 2 CMe 2 (G 1 ) (3) ; CMe 2 CH 2 CHMe(G 2 ) (4) ; CHMeCHMe (G 3 ) (5) ; CH 2 CMe 2 CH 2 (G 4 ) (6) ; CMe 2 CMe 2 (G 5 ) (7) ; CH 2 CHMeCH 2 (G 6 ) (8) ; CH 2 CEt 2 CH 2 (G 7 ) (9) ; CH 2 CMe(Pr n )CH 2 (G 8 ) (10) ] have been prepared by the reactions of Nb(OGO) 2 (OGOH) [G=G 1 (1a) ; G 2 (1b) ; G 3 (1c) ; G 4 (1d) ; G 5 (1e) ; G 6 (1f) ; G 7 (1g) ; G 8 (1h) ] with Ta(OGO) 2 (OPr i ) (G=G 1 (2a) ; G 2 (2b) ; G 3 (2c) ; G 4 (2d) ; G 5 (2e) G 6 (2f) ; G 7 (2g) ; G 8 (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) _3{M(OPr^i)_n-1} [where M=A1 n =3, G=G 3 (11) ;G 4 (12) ; G 6 (13) G 7 (14) ; G s (15) ; G 9 =CH 2 CH 2 CH 2 (16) and M=Ti ( n =4, G=G 4 ) (17) , Zr( n =4,G=G 4 ) (18) ], which are conveniently prepared by the reactions of metalloligands Nb(OGO) 2 (OGOH) [G=G 3 (1c) ; G 4 (1d) ; G 6 (1f) ; G 7 (1g) ; G 8 (1h) ; G 9 (1i) ] with different metal alkoxides. All of these new complexes have been characterized by elemental analyses, molecular weight determinations, and spectroscopic (I.r. and 1 H, 27 Al-n.m.r.) studies. Structural features of the new derivatives have been elucidated on the basis of molecular weight and spectroscopic data.