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The crystal structure of K2VO2F3 has been determined by a three-dimensional single-crystal X-ray diffractometer study. The crystals are orthorhombic, space group Pnma, with a = 7.379 (4), b = 5-640 (2), c= 11.413 (7). For Z=4, De= 3.05 g.cm-3, in agreement with the measured density, Din= 3.05 g.cm-a. The structure was refined by full-matrix least squares to a weighted R' (the conventional R factor was 0-0258) value of 0.0198 for 668 observed reflections. Octahedrally coordinated vanadium atoms are

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The mass spectra of eight pairs of cis and trans isomers of PtL2X2 (L = NH3, pyridine P(C2H5)3, or P(C2H5)3; X = Cl, Br, or I) are presented and discussed. Two chelates, Pt(bipy)Cl2 and Pt(dpm)Cl2 (dpm = di-apyridylmethane), are also included. The most significant results are: (1) parent ions can be observed for almost all these relatively involatile coordination compounds; (2) most ligand fragmentations and rearrangements occur with ligand-metal bonds intact; (3) some rearrangements appear to involve the metal; (4) cis and trans isomers of phosphine complexes give different fragmentation patterns; (5) spectra of chelates differ considerably from the spectra of analogous nonchelates; (6) in Pt(NH3)2Cl2 and Pt(py)2Cl2, little or no difference is observed in the spectra of cis and trans isomers after electron impact. Therefore, excitation to a tetrahedral state may take place.There have been a limited number of applications of mass spectrometry to relatively involatile coordination compounds5-8 including a few studies of platinumill) compounds.9-11 There are several important questions that have been addressed in the research reported in this paper. Is the excitation imparted to tetragonal planar platinum(II) complexes on electron impact sufficient to cause cis-trans isomerization?12•13 Can mass spectrometry be used to identify platinum(II) complexes and distinguish cis and trans isomers? Can parent peaks be used to obtain molecular weights and thereby assist in structure proofs ? What contrasts are there between chelated and nonchelated compounds?14 In fragmentation, how readily do coordinate bonds break compared to covalent bonds in the ligands ? Results

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