X-ray crystal structure of salts

P Fluonnation always strongly stabilizes carbamons both by induction and by negative (anionic) hyperconjugaQon, 7 The latter "no-bond resonance has been controversial, but its importance is now well established both theoretically [133, 134] and expenmentally [67] The X-ray crystal structures of salts 8 [fi5] and 9 [136] provide cogent evidence for negative hyperconjugation... 

A mechanistic study by Haynes et al. demonstrated that the same basic reaction cycle operates for rhodium-catalysed methanol carbonylation in both homogeneous and supported systems [59]. The catalytically active complex [Rh(CO)2l2] was supported on an ion exchange resin based on poly(4-vinylpyridine-co-styrene-co-divinylbenzene) in which the pendant pyridyl groups had been quaternised by reaction with Mel. Heterogenisation of the Rh(I) complex was achieved by reaction of the quaternised polymer with the dimer, [Rh(CO)2l]2 (Scheme 11). Infrared spectroscopy revealed i (CO) bands for the supported [Rh(CO)2l2] anions at frequencies very similar to those observed in solution spectra. The structure of the supported complex was confirmed by EXAFS measurements, which revealed a square planar geometry comparable to that found in solution and the solid state. The first X-ray crystal structures of salts of [Rh(CO)2l2]" were also reported in this study. 

Fig. 2 X-ray crystal structure of salt 39 prior to (left) and following (right) photolysis in the solid state...

Slovokhotov, Yu.L. and Struchkov, Yu.T (1984) X-ray crystal structure of a distorted tetrahedral cluster in the salt [(Ph P)4Au4N] BF4 . Geometrical indication of stable electronic configurations in post-transition metal complexes and the magic number 18-e in centred gold clusters. Journal of Organometallic Chemistry, 177, 143-146. 

The X-ray crystal structure of the hexafluoroantimonate salt of 1,4-diithin radical cation stabilized by bicyclo[2.2.2]octane annelation revealed a planar ring and was in agreement with theoretical calculations. Tertiary aminium radical cations underwent facile 5-exo-cyclization to give distonic 2-substituted pyrrolidinium radical cations. 

Figure 1 shows the X-ray crystal structure of the (R)-(+)-l-phenylethyl-amine salt of keto-acid 37a prior to reaction and following 70% conversion to the corresponding cyclobutanol 38b. The structure of the mixed crystal is... 

The X-ray crystal structure of K[RuO ] shows the salt to have the scheelite (CaWO ) structure with a slightly flattened tetrahedral anion (mean Ru=(0) 1.79 A) [451], A single crystal X-ray structure of TRAP shows this to contain the expected tetrahedral anion [472],... 

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