TY - JOUR
T1 - 1D magnetic interactions in Cuii oxovanadium phosphates (VPO), magnetic susceptibility, DFT, and single-crystal EPR
AU - Venegas-Yazigi, Diego
AU - Spodine, Evgenia
AU - Saldias, Marianela
AU - Vega, Andrés
AU - Paredes-García, Verónica
AU - Calvo, Rafael
AU - Santana, Ricardo Costa De
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/4/20
Y1 - 2015/4/20
N2 - We report the crystal face indexing and molecular spatial orientation, magnetic properties, electron paramagnetic resonance (EPR) spectra, and density functional theory (DFT) calculations of two previously reported oxovanadium phosphates functionalized with CuII complexes, namely, [Cu(bipy)(VO2)(PO4)]n (1) and [{Cu(phen)}2(VO2(H2O)2)(H2PO4)2 (PO4)]n (2), where bipy = 2,2′-bipyridine and phen = 1,10-phenanthroline, obtained by a new synthetic route allowing the growth of single crystals appropriate for the EPR measurements. Compounds 1 and 2 crystallize in the triclinic group P1¯and in the orthorhombic Pccn group, respectively, containing dinuclear copper units connected by two -O-P-O- bridges in 1 and by a single -O-P-O- bridge in 2, further connected through -O-P-O-V-O- bridges. We emphasize in our work the structural aspects related to the chemical paths that determine the magnetic properties. Magnetic susceptibility data indicate bulk antiferromagnetism for both compounds, allowing to calculate J = -43.0 cm-1 (dCu-Cu = 5.07 Å; J defined as Hex(i,j) = -J Si·Sj), considering dinuclear units for 1, and J = -1.44 cm-1 (dCu-Cu = 3.47 Å) using the molecular field approximation for 2. The single-crystal EPR study allows evaluation of the g matrices, which provide a better understanding of the electronic structure. The absence of structure of the EPR spectra arising from the dinuclear character of the compounds allows estimation of weak additional exchange couplings |J′| > 0.3 cm-1 for 1 (dCu-Cu = 5.54 Å) and a smaller value of |J′| 0.15 cm-1 for 2 (dCu-Cu = 6.59 Å). DFT calculations allow evaluating two different exchange couplings for each compound, specifically, J = -36.60 cm-1 (dCu-Cu = 5.07 Å) and J′ = 0.20 cm-1 (dCu-Cu =5.54 Å) for 1 and J = -1.10 cm-1 (dCu-Cu =3.47 Å) and J′ = 0.01 cm-1 (dCu-Cu = 6.59 Å) for 2, this last value being in the range of the uncertainties of the calculations. Thus, these values are in good agreement with those provided by magnetic and single-crystal EPR measurements.
AB - We report the crystal face indexing and molecular spatial orientation, magnetic properties, electron paramagnetic resonance (EPR) spectra, and density functional theory (DFT) calculations of two previously reported oxovanadium phosphates functionalized with CuII complexes, namely, [Cu(bipy)(VO2)(PO4)]n (1) and [{Cu(phen)}2(VO2(H2O)2)(H2PO4)2 (PO4)]n (2), where bipy = 2,2′-bipyridine and phen = 1,10-phenanthroline, obtained by a new synthetic route allowing the growth of single crystals appropriate for the EPR measurements. Compounds 1 and 2 crystallize in the triclinic group P1¯and in the orthorhombic Pccn group, respectively, containing dinuclear copper units connected by two -O-P-O- bridges in 1 and by a single -O-P-O- bridge in 2, further connected through -O-P-O-V-O- bridges. We emphasize in our work the structural aspects related to the chemical paths that determine the magnetic properties. Magnetic susceptibility data indicate bulk antiferromagnetism for both compounds, allowing to calculate J = -43.0 cm-1 (dCu-Cu = 5.07 Å; J defined as Hex(i,j) = -J Si·Sj), considering dinuclear units for 1, and J = -1.44 cm-1 (dCu-Cu = 3.47 Å) using the molecular field approximation for 2. The single-crystal EPR study allows evaluation of the g matrices, which provide a better understanding of the electronic structure. The absence of structure of the EPR spectra arising from the dinuclear character of the compounds allows estimation of weak additional exchange couplings |J′| > 0.3 cm-1 for 1 (dCu-Cu = 5.54 Å) and a smaller value of |J′| 0.15 cm-1 for 2 (dCu-Cu = 6.59 Å). DFT calculations allow evaluating two different exchange couplings for each compound, specifically, J = -36.60 cm-1 (dCu-Cu = 5.07 Å) and J′ = 0.20 cm-1 (dCu-Cu =5.54 Å) for 1 and J = -1.10 cm-1 (dCu-Cu =3.47 Å) and J′ = 0.01 cm-1 (dCu-Cu = 6.59 Å) for 2, this last value being in the range of the uncertainties of the calculations. Thus, these values are in good agreement with those provided by magnetic and single-crystal EPR measurements.
UR - http://www.scopus.com/inward/record.url?scp=84928337629&partnerID=8YFLogxK
U2 - 10.1021/ic503045d
DO - 10.1021/ic503045d
M3 - Article
C2 - 25831075
AN - SCOPUS:84928337629
SN - 0020-1669
VL - 54
SP - 3805
EP - 3814
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 8
ER -