CRYSTAL AND MOLECULAR-STRUCTURE OF METHYLPROPYLGLYOXAL BIS(AMIDINOHYDRAZONE) SULFATE MONOHYDRATE

A single-crystal X-ray diffraction study was performed on methylpropyl glyoxal bis(amidinohydrazone) (MPGBG) sulphate monohydrate. The bis(am idinohydrazone) dication was found to exist exclusively in the form of the anti-anti isomer, with an all-trans configuration of the glyoxal bis(amidinohydrazon) chain. just as do the free base, the monocation a nd the dication of glyoxal bis(amidinohydrazone) and the dications of all mono- and dialkylglyoxal bis(amidinohydrazones) so far studied. MP GBG sulphate monohydrate crystallizes in the triclinic space group P ( 1) over bar with unit cell parameters a = 8.860(2), b = 9.195(2), c = 10,788(2) Angstrom, a = 73.71(3), beta = 77.59(3), gamma = 65.28(3)deg rees and with Z = 2. When the structure is compared with that of propy lglyoxal bis(amidinohydrazone) (PGBG) sulphate, an analogous compound that is devoid of the methyl group of MPGBGI a distinct difference can be observed regarding the conformation of the propyl side chain. In t he MPGBG dication, the propyl group is directed away from the glyoxal bis(amidinohydrazone) chain, whilst in the case of the PCBG dication i t is tangled around the glyoxal bis(amidinohydrazone) moiety. Whether this difference results from packing effects and related factors, or w hether it is a result of a more fundamental difference between MPGBG a nd PGBG. remains to be studied. The observed difference may contribute to the biochemical differences between the two compounds.