Abstract 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) 2Cl 2, 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) 2Cl 2(APT) have been crystallographically characterized: A, orange, orthorhombic, Pbca, a=15.332(4), b=17.715(4), c=13.083(4) Å, R( F)=3.26%; B(MeOH), yellow, triclinic, P 1 , a=8.712(2), b=9.492(2), c=12.142(2) Å, α=86.03(2), β=82.63(2), γ=74.21(2)°, R( F)=3.49%. The complexes are formed directly from the reaction of [Ru(CO) 2Cl 2] 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.