Iron(II) and Nickel(II) Complexes of N-Alkylimidazoles and 1-Methyl-1H-1, 2, 4-Triazole: X-ray Studies, Magnetic Characterization, and DFT Calculations†

Using the ligands N-methylimidazole (MeIm), N-ethylimidazole (EtIm), N-propylimidazole (PrIm), and 1-methyl-1H-1, 2, 4-triazole (MeTz) three series with a total of 13 iron(II) complexes were isolated. The series comprise of the following complexes: (a) [Fe(MeIm)6](ClO4)2 (1), [Fe(EtIm)6](ClO4)2 (2), [Fe(PrIm)6](ClO4)2(3), [Fe(MeTz)6](ClO4)2 (4), [Fe(MeIm)6](MeSO3)2 (5), [Fe(EtIm)6](MeSO3)2 (6), and [Fe(MeTz)6](BF4)2 (10); (b) [Fe(MeIm)4(MeSO3)2](7), [Fe(EtIm)4(MeSO3)2] (8), and [Fe(PrIm)4(MeSO3)2] (9); (c) [Fe(MeIm)4(NCS)2] (15), [Fe(EtIm)4(NCS)2] (16), and [Fe(MeTz)4(NCS)2] (17). Single crystal X-ray diffraction studies were performed on 7–10 and 15–17. Temperature dependent magnetic susceptibility measurements were performed on selective examples of all series, and confirmed them to be in the HS state over the range 6–300 K. DFT calculations were performed at BP86/def-SV(P) and TPSSh/def2-TZVPP level on all [FeL6]2+ complex cations and the neutral complexes 7–9 and 15–17. Additionally the four homoleptic nickel(II) complexes [NiL6](ClO4)2 (11: L = MeIm; 12: L = EtIm; 13: L = PrIm; 14: L = MeTz) were synthesized and compounds 11–13 structurally characterized. UV/Vis/NIR spectroscopic measurements were carried out on all homoleptic iron(II) and nickel(II) complexes. The 10Dq values were determined to be in the range of 11547–11574 and 10471–10834 cm–1 for the iron(II) and nickel(II) complexes, respectively.

[1]  A. Goeta,et al.  Solid- and solution-state studies of the novel mu-dicyanamide-bridged dinuclear spin-crossover system {[(Fe(bztpen)]2[mu-N(CN)2]}(PF6)3 x n H2O. , 2005, Chemistry.

[2]  O. Roubeau,et al.  Triazoles and tetrazoles: Prime ligands to generate remarkable coordination materials , 2011 .

[3]  Shubin Liu,et al.  Towards understanding performance differences between approximate density functionals for spin states of iron complexes. , 2006, The Journal of chemical physics.

[4]  K. Hagen,et al.  Iron(II) triflate salts as convenient substitutes for perchlorate salts: crystal structures of [Fe(H2O)6](CF3SO3)2 and Fe(MeCN)4(CF3SO3)2. , 2000, Inorganic chemistry.

[5]  Jianmin Tao,et al.  Meta-generalized gradient approximation: explanation of a realistic nonempirical density functional. , 2004, The Journal of chemical physics.

[6]  M. Marchivie,et al.  Structural Aspects of Spin Crossover — Example of the [FeIILn(NCS)2] Complexes , 2005 .

[7]  G. Sheldrick.  A short history of SHELX. , 2008, Acta crystallographica. Section A, Foundations of crystallography.

[8]  S. Riedel,et al.  Is rhodium tetroxide in the formal oxidation state VIII stable? a quantum chemical and matrix isolation investigation of rhodium oxides , 2011 .

[9]  L. Wiehl.  Structures of hexakis(1‐propyltetrazole)iron(II) bis(tetrafluoroborate), [Fe(CHN4C3H7)6](BF4)2, hexakis(1‐methyltetrazole)iron(II) bis(tetrafluoroborate), [Fe(CHN4CH3)6](BF4)2, and the analogous perchlorates. Their relation to spin crossover behaviour and comparison of Debye–Waller factors from stru , 1993 .

[10]  W. Forsling,et al.  The Structure of Hexakis(imidazole)nickel(II) Diperchlorate , 1979 .

[11]  M. Drew,et al.  Geometric control of manganese redox state , 1995 .

[12]  Joel S. Miller,et al.  One- and two-step spin-crossover behavior of [Fe(II)(isoxazole)(6)](2+) and the structure and magnetic properties of triangular [Fe(III)(3)O(OAc)(6)(isoxazole)(3)][ClO(4)]. , 2003, Inorganic chemistry.

[13]  Francesco Aquilante,et al.  Fast noniterative orbital localization for large molecules. , 2006, The Journal of chemical physics.

[14]  R. Lavi,et al.  Sonochemical Synthesis and Characterization of Ni(C4H6N2)6(PF6)2, Fe(C4H6N2)6(BF4)2, and Ni(C4H6N2)6(BF4)2 in 1‐Butyl‐3‐methylimidazole with Hexafluorophosphate and Tetrafluoroborate , 2005 .

[15]  H. Toftlund.  Spin equilibria in iron(II) complexes , 1989 .

[16]  F. Weigend,et al.  Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy. , 2005, Physical chemistry chemical physics : PCCP.

[17]  J. Reedijk.  Pyrazoles and imidazoles as ligands. II. Coordination compounds of N-methyl imidazole with metal perchlorates and tetrafluoroborates , 1969 .

[18]  P. Gütlich,et al.  Spin Crossover— An Overall Perspective , 2005 .

[19]  J. Perdew,et al.  Density-functional approximation for the correlation energy of the inhomogeneous electron gas. , 1986, Physical review. B, Condensed matter.

[20]  G. Scuseria,et al.  Climbing the density functional ladder: nonempirical meta-generalized gradient approximation designed for molecules and solids. , 2003, Physical review letters.

[21]  Kasper P. Jensen,et al.  Accurate computed enthalpies of spin crossover in iron and cobalt complexes. , 2009, The journal of physical chemistry. A.

[22]  TsuchidaRyutaro.  Absorption Spectra of Co-ordination Compounds. I , 1938 .

[23]  K. Yamauchi,et al.  Esters of phosphorus oxy-acids as alkylating agents. Part II. N-Alkylation of imidazole and related heterocyclic compounds with trialkyl phosphates , 1973 .

[24]  Hans W. Horn,et al.  Fully optimized contracted Gaussian basis sets for atoms Li to Kr , 1992 .

[25]  M. Swart.  Accurate Spin-State Energies for Iron Complexes. , 2008, Journal of chemical theory and computation.