Synthesis, crystal structures, and characterization of 4,5-diaza-9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-fluorene (L) metal complexes [(TPyA)MII(L)](SbF6)2 (MII = Mn, Fe, Co; TPyA = tris(2-pyridylmethyl)amine)

• Three capped-metal diazafluorene complexes have been synthesized and characterized.
• Comparative lability of the diazafluorene-type ligand was determined.
• Temperature dependent magnetic studies were reported for all new compounds.
• Potential usage of complexes as molecular synthons is commented.

Transition metal complexes incorporating 9′-(4,5-dimethyl-1,3-dithiol-2-ylidene)-4′,5′-diazafluorene (L) have been synthesized and single crystal structures of [(TPyA)MnII(L)](SbF6)2 (1), [(TPyA)FeII(L)](SbF6)2 (2), and [(TPyA)CoII(L)](SbF6)2 (3) (where TPyA = tris(2-pyridylmethyl)amine) have been characterized. In addition, spectroscopic analysis (IR and UV–Vis) and temperature dependent magnetic susceptibility measurements are reported for all new complexes. Compounds 1–3 are isostructural. Solid-state IR and solution UV–Vis spectra in dichloromethane (CH2Cl2) are consistent with other metal complexes with the ligand L bound to the metal. However, when complexes 1–3 are dissolved in acetone and acetonitrile the ligand L is labile enough to result in a complex with C3H6O or MeCN in the coordination sphere, respectively. This suggests L is more substitutionally labile than C3H6O and MeCN. Magnetic analyses of 1–3 revealed weak ferromagnetic interactions for 1 and 3 and weak antiferromagnetic interactions for 2. These new molecular synthons may have further applications in the synthesis of new heterobimetallic dinuclear complexes by removal of the methyl group from the dithiolate-end of the ligand L that is unbound to a metal ion at this point.

Transition metal complexes incorporating the ditopic ligand 9′-(4,5-dimethyl-1,3-dithiol-2-ylidene)-4′,5′-diazafluorene (L) may be utilized as molecular precursors towards the synthesis of new heteropolymetallic complexes. We have successfully synthesized and characterize the complexes [(TPyA)MnII(L)](SbF6)2 (1), [(TPyA)FeII(L)](SbF6)2 (2), and [(TPyA)CoII(L)](SbF6)2 (3) (where TPyA = tris(2-pyridylmethyl)amine).Figure optionsDownload as PowerPoint slide