PHTHALENEDIOLATO(2-)](PYRROLIDINIOMETHYL)GERMANATE TETRATOACETONITRILE, THE 1ST ZWITTERIONIC LAMBDA-5-GERMANATE - SYNTHESIS AND CRYSTAL-STRUCTURE ANALYSIS

The zwitterionic spirocyclic lambda5-germanate htha-lenediolato(2-)](p yrrolidiniomethyl)germanate (8) was synthesized and the crystal struct ure of its tetartoacetonitrile solvate 8 . 1/4 CH3CN studied by single -crystal X-ray diffraction. Compound 8 was prepared by reaction of (Me O)3-GeCH2NC4H8 (11; NC4H8 = pyrrolidino) with two equivalents of 2,3-n aphthalenediol (isolated as 8 . 1/4 CH3CN; yield 92%). The coordinatio n polyhedron around the pentacoordinate germanium atom of 8 . 1/4 CH3C N can be described as a strongly distorted trigonal bipyramid (the str ucture is displaced by 38.9% from the ideal trigonal bipyramid towards the ideal square pyramid), the carbon atom occupying an equatorial po sition. In the crystal lattice of 8 . 1/4 CH3CN, the zwitterions form intermolecular N-H...0 hydrogen bonds leading to the formation of dime rs. H-1- and C-13-NMR studies revealed that 8 also exists in solution ([D6]DMSO).