The reactions of GeCl4, GeBr4, and MeGeCl3 with O-trimethylsilyl derivatives of N,N-disubstituted amides of 2-hydroxycarboxylic acids afforded pentacoordinate and hexacoordinate neutral (O,O)-mono- and (O,O)-bischelates. The reactions of glycolic acid derivatives with GeX4 produced bischelates X2Ge[OCH 2C(O)NR2R3]2 7a,c,d (X = Cl, R 2 = R3 = Me (a), (CH2)5 (c), (CH2CH2)2O (d)) and 8a (X = Br). By contrast, the reactions of lactic and mandelic acid derivatives with GeCl4 and MeGeCl3 gave monochelates Cl3Ge[OCH(R1)C(O) NR2R3] (S)-9a-c (R1 = Me) and Cl 2MeGe[OCH(R1)C(O)NR2R3] 10a (R 1 = H), (S)-11a,b (R1 = Me), and (S)-12a (R1 = Ph) (R2R3 = (CH2)4 (b)), respectively. According to the X-ray diffraction data, the Ge atom in bischelates 7c,d and 8a has a coordination number 6, and its coordination polyhedron can be described as a slightly distorted octahedron. In monochelates (S)-9a-c, 10a, (S)-11a,b, and (S)-12a, the Ge atom has a coordination number 5, and its coordination polyhedron can be described as a trigonal bipyramid with two halogen atoms or one halogen atom and one ethereal oxygen atom in equatorial positions and the halogen atom and the amide oxygen atom in the axial positions. The bonds in the axial positions are somewhat longer than the corresponding bonds in tetracoordinate Ge compounds.
- penta- and hexacoordinate germanium compounds
- X-ray diffraction study
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