Ge(IV)–citrate complex formation: synthesis and structural characterisation of GeCl4(bipy) and GeCl(bipy)(Hcit) (bipy=2,2′-bipyridine, H4cit=citric acid)

✍ Scribed by Gerald R. Willey; Usha Somasunderam; Damian R. Aris; William Errington

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 103 KB
• Volume: 315
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(01)00358-9

✦ Synopsis

The adduct [GeCl 4 (bipy)] (I), obtained by direct treatment of the parent halide with 2,2%-bipyridine (bipy), reacts with citric acid (H 4 cit) in acetonitrile solution to provide the chelate derivative [GeCl(bipy)(Hcit)] (II). The structures of compounds I and II have been determined by single crystal X-ray diffraction. For I the central germanium shows octahedral geometry with two mutually cis-chlorine atoms, Ge Cl (mean) 2.244(1) A , , and the bidentate ligand, Ge N (mean) 2.065(4) A , occupying equatorial positions and two mutually trans-chlorine atoms, Ge Cl (mean) 2.267(1) A , in axial locations. For II the citrate ligand is terdentate and bound to the central germanium via its hydroxyl, a-carboxylate and one of the b-carboxylate groups in a fac-octahedral arrangement. Ge O hydroxyl 1.800(3) A , , Ge O carboxylate (mean) 1.904(3) A , , Ge Cl 2.209(1) A , , Ge N (mean) 2.012(3) A , . The uncoordinated b-carboxylate group remains intact as a 'dangling arm'. The structure also contains poorly defined and disordered acetonitrile (solvent) molecules trapped in the lattice.