[MIII2MII3] trigonal bipyramidal cages based on diamagnetic and paramagnetic metalloligands.

A family of five [MIII2MII3] trigonal bipyramidal cages (M = Fe, Cr and Al; M = Co, Zn and Pd; = 0 for and = 6 for ) of formulae [FeCoLCl] (), [FeZnLBr] (), [CrZnLBr] (), CrPdL(dppp) () and AlPdL(dppp) () (where HL is 1-(4-pyridyl)butane-1,3-dione and dppp is 1,3-bis(diphenylphosphino)propane) are reported. Neutral cages were synthesised using the tritopic [ML] metalloligand in combination with the salts CoCl and ZnBr, which both act as tetrahedral linkers. The assembly of the -protected [Pd(dppp)(OTf)] with [ML] afforded the anionic cages of general formula MIII2PdII3. The metallic skeleton of all cages describes a trigonal bipyramid with the M ions occupying the two axial sites and the M ions sitting in the three equatorial positions. Direct current (DC) magnetic susceptibility, magnetisation and heat capacity measurements on reveal weak antiferromagnetic exchange between the Fe and Co ions. EPR spectroscopy demonstrates that the distortion imposed on the {MO} coordination sphere of [ML] by complexation in the {MIII2MII3} supramolecules results in a small, but measurable, increase of the zero field splitting at M. Complete active space self-consistent field (CASSCF) calculations on the three unique Co sites of suggest ≈ -14 cm and / ≈ 0.1, consistent with the magnetothermal and spectroscopic data.