Synthesis, structure and magnetism of new single molecule magnets composed of MnII2MnIII2 alkoxo-carboxylate bridged clusters capped by triethanolamine ligandsElectronic supplementary information (ESI) available: Detailed magnetisation discussion, Mn bond valence sums (Table S1), H-bonding details (Table S2). See http://www.rsc.org/suppdata/dt/b3/b312672b/