Considerable efforts are being devoted to designing enhanced molecular magnetic materials, in particular single molecule magnets (SMMs), that can meet the requirements for future technologies such as quantum computing and spintronics. One of the current trends in the field is to enhance the global anisotropy in metal complexes using single-ion anisotropy. This work is devoted to study the importance of tuning the local coordination environments of metal ions in order to ensure enhanced single ion anisotropy.1 The vanadium (III) ion can give rise to strong ferromagnetic interactions 2 and often exhibits large zero-field splitting |D| up to - 20 cm-1.2This makes it a very promising building block for SMMs.A family of axially distorted mononuclear vanadium (III) compounds of general formula, A[L3VX3] (3-9  ) (X = F, Cl or Br, A+ = Et4N+, nBu4N+ or PPN+ , L3 = Tp or Tp* (Tp = tris(-1-pyrazolyl)borohydride), Tp* = tris(3,5-dimethyl-1-pyrazolyl)borohydride)), were studied (Figure 1). Replacement of the Tp ligand in 3  with the stronger p-donor Tp* results in a near doubling of the magnitude of the axial zero-field splitting parameter Dz (Dz = -16.0 cm-1 in 3  , and -30.0 cm-1 in PPN[Tp*VCl3] 4  )as determined by magnetic measurements. Such findings support the notion that control of the axial crystal field distortion is an excellent way to control single-ion anisotropy. High Field-High Frequency EPR measurements on 4  revealed an even higher D value, -40.0 cm-1. Interestingly, compound 4   exhibits evidence for an out-of-phase signal under a dc applied field indicating the first mononuclear vanadium single molecule magnet.3Zadrozny, J. M.; Xiao, D. J.; Atanasov, M.; Long, G. J.; Grandjean, F.; Neese, F.; Long, J. R. Nat Chem 2013  , advance online publication.a) Tidmarsh, I. S.; Batchelor, L. J.; Scales, E.; Laye, R. H.; Sorace, L.; Caneschi, A.; Schnack, J.; McInnes, E. J. L. Dalton Trans. 2009 , 9402-9409; b) Krzystek, J.; Fiedler, A. T.; Sokol, J. J.; Ozarowski, A.; Zvyagin, S. A.; Brunold, T. C.; Long, J. R.; Brunel, L. C.; Telser, J. Inorg. Chem. 2004 , 43, 5645-5658

Enhancing zero field splitting parameters in mononuclear vanadium complexes

247th National Meeting (2014)

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