Synthesis, crystal structure and magnetic properties of trithiocyanurate or thiodiacetate polynuclear Ni(II) and Co(II) complexes

• New polynuclear complexes of NiII and CoII.
• First heptanuclear coordination compound with trithiocyanurate bridge: [Ni7(pmdien)6(H2O)2(μ-ttc)3](ClO4)5·3H2O.
• Antiferromagnetic interacting centers indicated by magnetic measurements.
• DFT calculation as a confirmation of the Co(II) trimer composition.
• ttc ligand as a good species for the formation of polynuclear coordination compounds.

Three new polynuclear complexes [Ni2(pmdien)2(H2O)2(μ-tda)](ClO4)2·2H2O (1), [Ni7(pmdien)6(H2O)2(μ-ttc)3](ClO4)5·3H2O (2) and [Co3(pmdien)3(μ-ttc)](ClO4)3 (3) (pmdien = N,N,N′,N″,N″-pentamethyldiethylenetriamine, ttc3− = trithiocyanurate3− anion, tda2− = thiodiacetate2− anion) have been prepared and characterized structurally and magnetically. The X-ray structure of heptanuclear Ni(II) complex revealed three hexa and four pentacoordinated nickel cations connected by trithiocyanuarate bridge, forming a regular NiII7 core. The composition of 3 was determined by ESI-MS spectra and DFT calculation. Magnetic susceptibility data over the 1.8–300 K temperature range along with the magnetization data up to B = 5 T showed antiferromagnetic interactions: J/hc = −0.65 cm−1 for 1; −6.1 and −6.5 cm−1 for 2; −0.001 cm−1 for 3. The magnetic susceptibilities of all antiferromagnetic complexes were fitted by using approximate models.

Dinuclear Ni(II), heptanuclear Ni(II) and trinuclear Co(II) complexes with terminal N,N,N′,N″,N″-pentamethyldiethylenetriamine (pmdien) bridged by trithiocyanurate3− anion (ttc3−) or thiodiacetate2− anion (tda2−) were prepared and thoroughly characterized. The magnetic data of all examined complexes reveal antiferromagnetic exchange coupling among the M(II) centers that is eventually tuned by asymmetric and/or antisymmetric exchange.Figure optionsDownload as PowerPoint slide