Effect of the apical ligand on the geometry and magnetic properties of copper(ii)/mesoxalate trinuclear unitsElectronic supplementary information (ESI) available: Experimental details, powder diffraction patterns, figures, structural tables. CCDC 1532625-1532627. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7dt00594f

Three new heterometallic metal-organic frameworks, namely, {(Ph 4 P) 2 [MnCu 3 (Hmesox) 3 Br(H 2 O)]·H 2 O} n ( 1 ), {(Ph 4 P) 2 [CoCu 3 (Hmesox) 3 Br]} n ( 2 ) and {(Ph 4 P) 2 [ZnCu 3 (Hmesox) 3 Br]·2.5H 2 O} n ( 3 ) were prepared and their structure and magnetic properties were investigated (H 4 mesox = mesoxalic acid, Ph 4 P + = tetraphenylphosphonium). The structure of all the compounds consist of two interpenetrating opposite-chirality supramolecular cationic and polymeric anionic 3-D (10,3)- a networks, which results in chiral compounds. The anionic network is formed from the polymerization of [Cu 3 (Hmesox) 3 Br] 4− units, working as three connectors, and M( ii ) cations, working as three-connecting nodes, M = Mn( ii ), Co( ii ) and Zn( ii ). The Ph 4 P + cations build the cationic chiral supramolecular network opposite to the anionic one. Compounds 1 and 2 exhibit long-range magnetic ordering with critical temperatures of 7.2 K and 6.9 K, respectively. However, compound 3 does not display long-range order, but shows ferromagnetic and antiferromagnetic coupling among the Cu( ii ) ions. The magnetic interactions are studied by DFT calculations and compared with related Cu( ii )-mesoxalate compounds previously reported. The Cu X distance and the bridging mode of the apical ligand determine the nature of the magnetic coupling.