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Abstract: A recently developed experimental and theoretical procedure is used in order to calculate the magnitude and anisotropy of interaction between a lanthanide and a 3d-metal ion. The general formula of the molecular compounds is [Ln(H2O)3(dmf)4(μ-CN)Fe–(CN)5]· nH2O where 1⩽ n ⩽1,5 and dmf= N,N′-dimethylformamide, abbreviated as [LnFe] from now on. The main parts of this procedure are (a) the evaluation of the effective g-parameters of the lanthanide ion with the help of EPR measurements. (b) The use of dual mode EPR spectroscopy to define the anisotropic exchange interactions with the help of an anisotropic Hamiltonian model. (c) Use of the same magnetic model to fit magnetization and susceptibility data in order to verify the EPR findings. It was possible to define some trends concerning the exchange components of the [DyFe] dimer according to which the antiferromagnetic isotropic exchange constant is smaller than 4cm−1 and the anisotropic components are [D exc, E exc]=[⩾6(1),0.0]cm−1. Also for the case of [TmFe] and [YbFe] dimers the antiferromagnetic isotropic exchange constant is smaller than 0.3cm−1 while the anisotropic components are [D exc, E exc]=[⩾12.0,0.0]cm−1 and [D exc, E exc]=[0.4(1),0.0]cm−1, respectively. [Copyright &y& Elsevier]

Abstract: A recently introduced experimental and theoretical procedure is presented in order to calculate the magnitude and anisotropy of interaction between a lanthanide and a 3d-metal ion. The general formula of the hetero-one-dimensional molecular compounds is trans-[M(CN)4(μ-CN)2Ln(H2O)4(bpy)] n ·nH2O·1.5nbpy (M=Fe3+, Cr3+; Ln=Er3+, Yb3+), where bpy=2,2′-bipyridine, abbreviated as [LnM] from now on. The main parts of this procedure are: (a) the evaluation of the effective g-parameters of the lanthanide ion with the help of EPR measurements; (b) the use of dual-mode EPR spectroscopy to define the anisotropic exchange interactions with the help of an anisotropic Hamiltonian model; (c) use of the same magnetic model to fit magnetization and susceptibility data in order to verify the EPR findings. It was possible to define some trends concerning the exchange components of the [ErCr] chain according to which the antiferromagnetic isotropic exchange constant is smaller than 0.7(1)cm−1 and the anisotropic components are [D exc, E exc]=[−0.4(1), 0.0(1)]cm−1. Also for the case of [YbCr] and [YbFe] chains the antiferromagnetic isotropic exchange constant is smaller than 0.1(1)cm−1 and 0.25(1)cm−1, respectively while the anisotropic components are [D exc, E exc]=[−0.3(1), 0.0(1)]cm−1 and [D exc, E exc]=[−0.1(1), 0.0(1)]cm−1, respectively. [Copyright &y& Elsevier]

Abstract: An experimental and theoretical approach for the determination of the anisotropic exchange interaction constants in (Cu2+,Ln3+) pairs where Ln=Tb3+,Dy3+ is presented. According to this approach the same phenomenological anisotropic magnetic model was used to simulate the low temperature magnetic behaviour of the pairs as well as their EPR spectra in parallel and perpendicular mode. For the (Cu,Tb), [L1Cu(O2COMe)Tb(thd)2], (L1 = N,N′-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato; thd–=tetramethylheptanedionato)) and (Cu,Dy) complexes, [L2Cu-(Me2CO)Ln(NO3)3], (L2 = N,N′-2-methyl-1,2-propylenedi(3-methoxysalicylideneiminato)), it has been found that the exchange interaction is ferromagnetic with the J z interaction component larger than the other two terms (J z ≫ J x ∼J y ). In order to determine the zero-field splitting of the high-spin ground state S =4 in two ferromagnetic-coupled (Cu,Gd) pairs, [L1Cu(O2COMe)Gd(thd)2] and [L2Cu(Me2CO)Gd(NO3)3], the EPR spectra in parallel mode were simulated with an appropriate magnetic model. Indeed, one of the most important problems concerning the (Cu,Gd) systems is the complexity of the X-band, perpendicular-mode EPR spectra that renders any simulation procedure difficult. Improvement in analysis of the spectra results from using parallel mode EPR experiments. [Copyright &y& Elsevier]