RUTHENIUM CARBONYL-COMPLEXES OF N-HETEROCYCLIC MOLECULES .3. SYNTHESIS OF RUTHENIUM COMPLEXES OF THE AMBIDENTATE LIGAND 4-AMINO-3,5-BIS(PYRIDIN-2-YL)-1,2,4-TRIAZOLE (APT) - X-RAY CRYSTAL-STRUCTURES OF 2 COORDINATION ISOMERS OF RU(CO)2CL2(APT)

4-Amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (APT), a poly- and ambidentate ligand, forms two bidentate coordination isomers of Ru(CO)2Cl2, Which in one case is coordinated to a pyridyl ring and an adjacent triazole ring (A), and in the other case to a pyridyl ring and the amino nitrogen atom (B). Both isomers of Ru(CO)2Cl2(APT) have been crystallographically characterized: A, orange, orthorhombic, Pbca, a = 15.332(4), b = 17.715(4), c = 13.083(4) angstrom, R(F) = 3.26%; B(MeOH), yellow, triclinic, P1BAR a = 8.712(2), b = 9.492(2), c = 12.142(2) angstrom, alpha = 86.03(2), beta = 82.63(2), gamma = 74.21(2)-degrees, R(F) = 3.49%. The complexes are formed directly from the reaction of [Ru(CO)2Cl2]n with APT in boiling MeOH. In a similar reaction with Re(CO)5Cl, Re(CO)3Cl(APT) is formed. The Br analogue of the Ru complex forms predominantly the yellow isomer (B), while the I analogue crystallizes only as the orange isomer (A). Based on NMR data, the Re complex most likely coordinates via the A mode.