Andreas Sieber, Dolos Foguet-Albiol, Oliver Waldmann, Stefan T. Ochsenbein, Roland Bircher, George Christou, Felix Fernandez-Alonso, Hannu Mutka and Hans U. Güdel
Direct Determination of the Anisotropy and Exchange Splittings in the Dimeric Single-Molecule Magnet [Mn₄O₃Cl₄(O₂CEt)₃(py)₃]₂·8MeCN by Inelastic Neutron Scattering
Inorg. Chem. 44, 6771-6776 (2005)                 

Abstract: Energy splittings resulting from anisotropy and exchange interactions in the dimer of single-molecule magnets [Mn₄O₃Cl₄(O₂CEt)₃(py)₃]₂·8MeCN are determined for both an undeuterated and a partially deuterated sample using inelastic neutron scattering. The antiferromagnetic (AF) exchange coupling between the two Mn₄ subunits strongly depends on their separation. The Cl···Cl distance between the two subunits can be modified either by exchanging the solvent of crystallization or by deuteration of the C-H···Cl hydrogen bonds. The exchange of acetonitrile for n-hexane leads to a five times greater shortening of the Cl···Cl separation than does full deuteration of all the hydrogen bonds. As a result, the AF exchange coupling constants between the subunits are 0.0073(4) and 0.0103(9) meV in the samples with acetonitrile and n-hexane solvent molecules, respectively, in the crystal structure. On the other hand, the effect of C-H···Cl deuteration on the AF exchange coupling is not detectable within the experimental accuracy of INS.