Ferromagnetic CUII4, COII4, and NiII6 Azido Complexes Derived from Metal-Assisted Methanolysis of Di-2,6-(2-pyridylcarbonyl)pyridine

Reaction of copper(II) perchlorate with di-2,6-(2-pyridylcarbonyl)pyridine (pyCOpyCOpy, dpcp) in the presence of sodium azide yields complex [Cu-4(N-3)(2){pyC(OMe)(O)pyC(OMe)(O)py}(2)(MeOH)(2)](ClO4)center dot 2MeOH (1 center dot 2MeOH), which crystallizes in the monoclinic P2(1)/c space group. Similar reaction of cobalt(II) nitrate yields complex [Co-4(N-3)(2)(NO3)(2){pyC(OMe)(O)pyC(OMe)(O)py}(2)]center dot 0.5MeOH (2 center dot 0.5MeOH) which crystallizes in the monoclinic 12/m space group. Reaction of nickel(II) perchlorate yields complex [Ni-6(CO3)(N-3)(6){pyCOpyC(O)(OMe)py}(3)(MeOH)(2)(H2O)][Ni-6(CO3)(N-3)(6){pyCOpyC(O)(OMe)py}(3) (MeOH)(3)](ClO4)(2)center dot 1.8MeOH (3 center dot 1.8MeOH), which crystallizes in the triclinic P (1) over bar space group, as a mixed salt of two similar Ni-6(II) cations, differing only in one terminally coordinated solvate molecule. The cation of 1 consists of four Cull ions in a rhombic topology, while complex 2 consists of four Coll ions in a defective double cubane topology. Each of the two cations in 3 contains six Ni-II ions in a cyclic topology, adopting a chair conformation. In 1 and 2 the ligand has undergone complete methanolysis and full deprotonation, yielding its dianionic bis-gem-diol form. In 3 it has undergone only partial methanolysis. All complexes exhibit ferromagnetic intramolecular interactions. Ferromagnetism in 1 is caused by the structural constraints imposed by the {pyC(OMe)(O)pyC(OMe)(O)py}(2-) ligand on the Cu-II ions, while in the case of 2 and 3 it is the result of the combined effect of the end-on azido and alkoxo bridges of dpcp, which form M-N-azido-M and M-O-alkoxo-M angles between 90-105 degrees. The magnetic susceptibility data of 1 and 3 were analyzed with appropriate spin Hamiltonian models ((H) over cap = - 2J(ij)(S) over cap (i)(S) over cap (j) formalism). For 1, a solution considering J = +26.8 cm(-1) along the periphery of the rhombus was found. In 3 it was found that alternating exchange couplings of J = +6.1 cm(-1) and J = +27 cm(-1) were operative along the periphery of the ring.