Donor atom set and spin state of iron(II). Bis(ligand)iron(II) and bis(ligand)nickel(II) complexes of 2,2 '-bipyridine-6-carbothioamide and 2,2 '-bipyridine-6-carboxamide

摘要

2,2'-Bipyridine-6-carbothioamide (bpytm) and 2,2'-bipyridine-6-carboxamide (bpyam) are NNS and NNO donors, respectively, in their cationic bis(ligand)iron(II) and bis(ligand)nickel(II) complexes. The former ligand provides the stronger field and salts of [Fe(bpytm)(2)](2+) have a singlet ground state, while those of [Fe(bpyam)2]2+ have a quintet ground state. The magnetism and the electronic and Mossbauer spectra of salts of these cations have been measured. The low-temperature Mossbauer spectra of iron(II) complex salts of the carboxamide indicate, for the perchlorate and triflate salts, but not for the fluoroborate salt, a partial transition to singlet-state species. The mode of coordination of the ligands is indicated by infrared spectral data and has been confirmed by determination of the structures of [Ni(bpytm)(2)] Cl-2 . 4H(2)O, [Ni(bpyam)(2)][BF4](2) . H2O and [Fe(bpyam)(2)][BF4](2). In addition, the structures of the free ligands have been determined. Hydrogen bonding is present in the free ligands and their complexes. 2,2'-Bipyridine-6-carbothioamide: monoclinic, space group P2(1)/c, a 8.265(3), b 11.175(2), c 11.114(4) Angstrom, beta 94.47(2)degrees, Z 4. 2,2'-Bipyridine-6-carboxamide: monoclinic, space group P2(1)/c, a 13.581(2), b 9.926(1), c 16.824(3) Angstrom, beta 116.481(7)degrees, Z 8. [Ni(bpytm)(2)]Cl-2.4H2O: triclinic; space group , a 9.291(5), b 12.426(7), c 13.425(7) Angstrom, alpha 113.54(3), beta 95.63(3), gamma 94.43(3)degrees, Z 2. [Ni(bpyam)(2)][BF4](2).H2O: triclinic, space group , a 10.663(5), b 10.861(6), c 12.799(6) Angstrom, a 68.70(4), beta 77.84(4), gamma 78.47(4)degrees, Z 2. [Fe(bpyam)(2)][BF4](2): orthorhombic, space group P bcn, a 12.317(6), b 12.609(4), c 16.664(8) Angstrom, Z 4. [References: 35]