The phenomenon of conglomerate crystallization. Part 54. The crystallization modes of five new complexes [trans-(3,2,3-tet)Co(III)X-2]Y, X=NO2- CN-, NCS-

A few complexes of formula [trans-Co(N-4)X-2]Y, where X=a monodentate ligan d, N-4 = a tetraamine ligand and Y=a halide or oxy anion have been found to crystallize as conglomerates; however, the majority crystallize as racemat es. The complexes are of such variety of composition and packing characteri stics that it is difficult to ascertain why they crystallize in one form or the other. We decided to investigate a series of [trans-Co(N-4)X-2]Y compo unds in which the amine was kept constant in order to limit the variables t hat affect the outcome. Five different compounds of composition [trans-Co(3,2,3-tet)X-2] Y (3,2,3-t et = 1,10-diamino-4,7-diaza-decane, X = NO2-, CN-, SCN-, and Y = BF4-, Cl-, Br-, I-) were prepared and their crystallization behavior examined by dete rmining their crystal structures. In all cases, when crystallized from deio nized water at 21 degreesC, these substances are racemates. Suggestions reg arding this crystallization mode are offered in the discussion.