CRYSTAL STRUCTURES OF THREE GEOMETRICAL ISOMERS OF [RU(OAC)(2MQN)(2)NO] (OAC EQUALS ACETATE, H2MQN EQUALS 2-METHYL-8-QUINOLINOL) AND THEIR THERMAL ISOMERIZATION REACTIONS

摘要

The structures of three geometrical isomers of [Ru(OAc)(2mqn)(2)NO], one trans isomer and two cis isomers (cis-1 and cis-2), were determined by X-ray diffraction. OAc in the cis-1 (1) and cis-2 isomers (2) is cis to NO and the geometries of the ligating N and O atoms in the two quinolinolato ligands are in cis(O,O) and trans(N,N) configurations for 1 and in cis(O,O) and cis(N,N) for 2, In the trans isomer (3), OAc is trans to NO and the geometry is in trans(O,O) and trans(N,N) configurations. The Ru-O(OAc) bond for 3 was shorter than those for 1 and 2, and the Ru-O(2mqn) bond trans to NO was also shorter than that cis to NO due to a trans-strengthening effect of NO. Reversible thermal isomerization between 1 and 2, and the irreversible one from 3 to 1 and 2 were observed in deaerated N,N-dimethylformamide at higher than 353 K. [References: 22]