Sodium-meso-tartrate

Mixed dinuclear complexes of tartrates and 2,2 -bipyridyl or 1,10-phenanthroline and chromium(III) have been prepared 934,935 the typical structure is illustrated below (213). Stereochemical correlations have been carried out by oxidatively cleaving the tartrate bridge (214,215).936 The crystal structure of sodium hydrogen bis(//-meso-tartrato)bis(2,2 -bipyridyl)dichromate(III) heptahydrate has been reported.937... 

An early report of the stereospecific reaction between (/ )(-f )-tartaric or (l )(- -)-malic acid and [Co(C03)(phen)2]Cl at ambient temperature has been refuted and both A- and A-[Co (i )L (phen)2] ions (233) are formed. The distribution ratio A(J )/A(/ ) = 0.38 for the (i )-tartrate complex. Using [Co(Cl)2(phen)2]Cl at 60 °C and Na(- -)-tartrate the ratio is 0.70, but thermodynamic distributions remain unknown. A(Ji) and A(i ) diastereoisomers of both acids have recently been isolated and characterized by CD and 360 MHz H NMR. The reaction of meso-tartaric acid results in four diastereoisomeric possibilities (depending on which asymmetric carbon is in the chelate ring) and all four have been separated (J S)R. M S)R A K)S A R)S = 26 24 27 23). From these results it appears likely that the reported stereospecific reaction of [Co(C03)(en)2]Cl with (5)(—)-tartaric acid resulting in only A-[Co (S)tart (en)2]CP is in error. The reaction of sodium citrate with [Co(Cl)2(trien)]Q also leads to a preference for the five-membered chelate involving the hydroxyl group (234) as has recently been shown by a crystal structure of )3-[Co(cit)(trien)] 5H20. ... 

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