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 Mössbauer
spectra of salts of these cations have been measured. The low-temperature
Mössbauer 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]
Cl2.4H2O,
[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
P21/c,
a 8·265(3), b
11·175(2), c 11·114(4) Å, β
94·47(2)°, Z 4.
2,2′-Bipyridine-6-carboxamide: monoclinic, space group
P21/c,
a 13·581(2), b
9·926(1), c 16·824(3) Å, β
116·481(7)°, Z 8.
[Ni(bpytm)2]
Cl2.4H2O: triclinic, space group
P-1, a
9·291(5), b 12·426(7),
c 13·425(7) Å, α 113·54(3),
β 95·63(3), γ 94·43(3)°, Z 2.
[Ni(bpyam)2][BF4]2.H2O:
triclinic, space group P-1,
a 10·663(5), b
10·861(6), c 12·799(6) Å, α
68·70(4), β 77·84(4), γ 78·47(4)°,
Z 2. [Fe(bpyam)2]
[BF4]2: orthorhombic,
space group P bcn, a
12¡317(6), B 12¡609(4),
c 16·644(8) Å, Z 4.
Determination Of Interactions Of Ferrihydrite-Humic Acid-Pb(II) System
