Do Metal–Metal Multiply‐Bonded “Ligands” Have a trans Influence? Structural and Magnetic Comparisons of Heterometallic CrCr···Co and MoMo···Co Interactions Academic Article uri icon

abstract

  • Reported here are two new compounds containing either a Cr=Cr⋯Co [1, CrCrCo(dpa)4Cl2, dpa = 2,2′-dipyridylamide] or a Mo=Mo⋯Co [2, MoMoCo(dpa)4Cl2] framework both having a multiply-bonded unit (Cr=Cr in 1, Mo=Mo in 2) in close proximity to the Co2+ ion and trans to a Co-Cl bond. Variable temperature magnetic susceptibility measurements reveal 1 to have a temperature-dependent spin equilibrium between a low-spin (S = 1/2) and high-spin (S = 3/2) state, whereas the Co2+ ion in 2 exists solely in its high-spin state. The crystal structures of 1 and 2 were determined. Variable temperature crystallographic data of 1 at 100 K and at room temperature reveal that the spin-transition affects not only the Co-ligand bond lengths but also the terminal Cr-ligand bond lengths. Whereas the Cr⋯Co distance becomes shorter by 0.13 Å in the low-spin form, the Co-Cl distance becomes longer by 0.2 Å. These observations, along with the crystal structure of 2, suggest that the multiply-bonded M=M group has a trans influence on the Co2+ ion. © Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

author list (cited authors)

  • Nippe, M., Victor, E., & Berry, J. F.

citation count

  • 45

publication date

  • December 2008

publisher