Spin Transfer through Hydrogen Bonding in [CO(NH3)5(OH2)][Cr(CN)6] ?

A polarised-neutron diffraction experiment on [Co(NH (H O)][Cr(CN) ] shows the unexpected features of spin populations on the cobalt ((0.5(2) e) and the "ammine" hydrogen (0.8(1) e in total) atoms. A local density approximation DV-Xα calculation on a unit that models the molecular geometry in the crystal returns features that are broadly in agreement with the experiment. The calculation also reproduces the major features of a charge density experiment on the complex, including the low (±1.6 e) charges on the ions, in place of the formal ±3 e.