THE CRYSTALLIZATION BEHAVIOR OF O-TRANS-ME-(N-ME-ETHYLENEDIAMINE)2-TRANS-(NO2)2]CL AND OF NS-ME-(N-ME-ETHYLENEDIAMINE)2-TRANS-(NO2)2]CL.2H2O

A pair of geometrical isomers, -trans-Me-(N-Me-ethylenediamine)2-trans -(NO2)2]Cl, I and s-Me-(N-Me-ethylenediamine)2-trans-(NO2)2]Cl.2H2O, I I, were prepared which differ only by the chirality at one quaternary nitrogen. Their crystal structures were determined in order to establi sh the amount of intracationic and packing rearrangements caused by su ch substituent exchange. I, CoClO4N6C6H20, crystallizes as a racemate in space group Pccn (No. 56), with lattice constants: a = 9.907(3), b = 10.615(2) and c = 12.655(4) angstrom; V = 1330.83 angstrom3 and d (c alc; M.W. = 334.65, Z = 4) = 1.670 g/cm3. A total of 32% data were col lected over the range of 4-degrees less-than-or-equal-to 2theta less-t han-or-equal-to 70-degrees; of these, 1916 (independent and with I gre ater-than-or-equal-to 3sigma(I)) were used in the structural analysis. Data were corrected for absorption(mu = 15.052 cm-1) and the relative transmission coefficients ranged from 0.7236 to 0.9897. Refinement co nverged to R(F) and R(w)(F) of 0.0298 and 0.0522. II, CoClO6N6C6H24, c rystallizes as a racemate in space group, P2(1)/c (No. 14) with lattic e constants: a = 17.017(7) angstrom, b = 9.661(3), c = 20.316(4) angst rom and beta = 107.11(3)-degrees; V = 3192.19 angstrom3 and d (calc; M .W. = 370.68, Z = 8) = 1.543 g/cm3. A total of 5851 data were collecte d over the range of 4-degrees less-than-or-equal-to 2theta less-than-o r-equal-to 50-degrees; of these, 4089 (independent and with I less-tha n-or-equal-to 3sigma(I)) were used in the structural analysis. Data we re corrected for absorption (mu = 12.710 cm-1) and the relative transm ission coefficients ranged from 0.7770 to 0.9997. Refinement converged to final R(F) and R(w)(F) residuals of 0.0332 and 0.0443. In its high est idealized geometry, the cation of I has an inversion center, which it uses crystallographically. In II, the highest idealized geometry f or its cation is a twofold axis. Such changes in cationic stereochemis try are responsible for concomitant packing changes observed in this s tudy and, appropriately, the existence of such relationships between m olecular point groups and lattice symmetry operations had been noted b y Professor Kitaigorodskii some thirty years ago using, primarily, obs ervations derived from the crystallization behavior of organic compoun ds. Here, we show that in coordination compounds the conclusions he ar rived at hold as well.