Tri- and pentanuclear NCS-bridged [MoIII–CuII] cluster compounds: Crystal structures and magnetic properties

Two heteronuclear NCS-bridged compounds, namely [{Cu(3,3,3-tet)(CH3CN)}2{Mo(NCS)6}][Mo(NCS)6][PPh4]2·6CH3CN (1) and [{Cu(3,3,3-tet)(CH3CN)}4{Mo(NCS)6}][Mo(NCS)6]3[Cu(3,3,3-tet)(CH3CN)]2 (2) (with 3,3,3-tet = N,N-bis(3-aminopropyl)-1,3-propanediamine) have been synthesized and their crystal structures were characterized by single crystal X-ray diffraction studies. For the cationic trinuclear cluster of 1 one hexaisothiocynato Mo(III) unit, [Mo(NCS)6]3−, is linked to two Cu units through two NCS bridging ligands, and the anionic pentanuclear cluster of 2 results from the linkage of the Mo unit to four Cu moieties. In 1 and 2, the coordination of a solvent molecule (i.e. acetonitrile) in one apical position of Cu prevents the extension of the system, while charge neutrality is achieved by co-crystallization of non-bonded Cu and/or Mo complexes. Magnetic studies of 1 and 2 reveal the weak antiferromagnetic interaction between the two spin carriers CuII and MoIII, through the NSC ligand. For 1, modeling the experimental data yields a value of JMoCu = −5.9 cm−1 (H = −J(S1S2 + S2S3)) for the exchange interaction.

Two discrete NCS-bridged heterometallic MoIII–CuII compounds have been obtained from 4d-metallo-ligand [Mo(NCS)6]3− and a [Cu(3,3,3-tet)]2+ units. Reaction conditions allow directing the assembling to either a tri- or a pentanuclear cluster. Structures and magnetic behaviors are reported.Figure optionsDownload as PowerPoint slide