A new chain complex is reported, containing ten Cr III and four Ni II paramagnetic centres. The structure is terminated by Ni II ions bound to 1, 4, 7, 10-tetrazacyclododecane (cyclen) with the chain forming through Cr…Ni and Cr…Cr edges bridged by fluoride and pivalate ligands. At the centre of the chain are two Ni II sites bridged by oxalate (ox) giving a chain of formula [Ni (cyclen) 2 Cr 10 Ni 2 (ox) F 14 (O 2 C t Bu) 22. The oxalate appears to have formed in situ from atmospheric CO 2. Magnetic and EPR studies suggest either an S = 1 ground state with significant zero-field splitting or an S = 0 ground state with a low-lying S = 1 excited state. A new anti-ferromagnetically (AF) coupled chain is reported which contains ten Cr (III) and four Ni (II) centers. This is one of the longest finite AF chains known. • The extraordinarily beautiful structure which is one of the longest finite metal chains known. • The formation of oxalate from CO 2 under mild conditions. • The use of advanced magnetic fitting techniques to model the magnetism of this complicated spin system. • Use of EPR spectroscopy to characterise the spin ground state.
Churchill et al. (Fri,) studied this question.