TY - JOUR
T1 - Iron(II) tris-[N4-substituted-3,5-di(2-pyridyl)-1,2,4-triazole] complexes
T2 - Structural, Magnetic, NMR, and Density Functional Theory Studies
AU - Kitchen, Jonathan A.
AU - White, Nicholas G.
AU - Boyd, Maruta
AU - Moubaraki, Boujemaa
AU - Murray, Keith S.
AU - Boyd, Peter D.W.
AU - Brooker, Sally
PY - 2009/7/20
Y1 - 2009/7/20
N2 - Eight mononuclear iron(II) complexes of N4-3,5-di(2-pyrldyl)-1, 2,4-trlazole (Rdpt) ligands have been prepared and characterized. In all cases the iron(II)/ligand ratio used is 1:3, giving red complexes of the general formula [FeII(Rdpt)3](BF4)2 ̇ solvents, in 55-89% yield. The ligands differ only in the nature of the N 4-substituent (amino, pyrrolyl, iso-butyl, methyl, phenyl, para-tolyl, 3,5-dichlorophenyl, and 4-pyrldyl; for ligands adpt, pldpt, lbdpt, medpt, phdpt, ptdpt, Cldpt, and pydpt, respectively) allowing substituent effects on the properties of the resulting iron(ll) complexes to be probed. The low temperature crystal structures of seven of the complexes reveal low spin iron(II) environments. Packing analyses reveal anion- π and acetonltrile-jr interactions involving the tetrafluoroborate counteranions and Interstitial acetonltrile molecules, respectively. Both "π-pockets" and "π-sandwlches" are observed. Solid state magnetic susceptibility measurements (4-300 K) indicate the iron(II) Is low spin (LS) in all complexes at all temperatures studied, except for [FeII(pldpt) 3](BF4)2 · 1 1/2 H2O which has the beginnings of spin crossover (SCO) at elevated temperatures. Downfield shifts and peak broadening observed in the variable temperature 1H NMR studies indicate that in d3-nltromethane solution the LS [Fe II(Rdpt)3]2+ complexes are in equilibrium with a trace of a high spin (HS) species. 15N NMR spectra (measured and calculated) of the ligands reveal that altering the N4-substituent changes the chemical shift of the N1 triazole and pyridine nitrogen atoms, allowing probing of the relationship between ligand substituent and the nature of the coordinating nitrogen atoms.
AB - Eight mononuclear iron(II) complexes of N4-3,5-di(2-pyrldyl)-1, 2,4-trlazole (Rdpt) ligands have been prepared and characterized. In all cases the iron(II)/ligand ratio used is 1:3, giving red complexes of the general formula [FeII(Rdpt)3](BF4)2 ̇ solvents, in 55-89% yield. The ligands differ only in the nature of the N 4-substituent (amino, pyrrolyl, iso-butyl, methyl, phenyl, para-tolyl, 3,5-dichlorophenyl, and 4-pyrldyl; for ligands adpt, pldpt, lbdpt, medpt, phdpt, ptdpt, Cldpt, and pydpt, respectively) allowing substituent effects on the properties of the resulting iron(ll) complexes to be probed. The low temperature crystal structures of seven of the complexes reveal low spin iron(II) environments. Packing analyses reveal anion- π and acetonltrile-jr interactions involving the tetrafluoroborate counteranions and Interstitial acetonltrile molecules, respectively. Both "π-pockets" and "π-sandwlches" are observed. Solid state magnetic susceptibility measurements (4-300 K) indicate the iron(II) Is low spin (LS) in all complexes at all temperatures studied, except for [FeII(pldpt) 3](BF4)2 · 1 1/2 H2O which has the beginnings of spin crossover (SCO) at elevated temperatures. Downfield shifts and peak broadening observed in the variable temperature 1H NMR studies indicate that in d3-nltromethane solution the LS [Fe II(Rdpt)3]2+ complexes are in equilibrium with a trace of a high spin (HS) species. 15N NMR spectra (measured and calculated) of the ligands reveal that altering the N4-substituent changes the chemical shift of the N1 triazole and pyridine nitrogen atoms, allowing probing of the relationship between ligand substituent and the nature of the coordinating nitrogen atoms.
UR - http://www.scopus.com/inward/record.url?scp=67650424377&partnerID=8YFLogxK
U2 - 10.1021/ic900634t
DO - 10.1021/ic900634t
M3 - Article
SN - 0020-1669
VL - 48
SP - 6670
EP - 6679
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 14
ER -