Interplay between π-stacking and AFM interaction in the novel triazine based dimeric crystal

We carried out experimental SQUID and EPR studies together with LSDA + U quantum calculations of the electronic spectra and spin density distribution for dimeric crystals [(L)2Cu2Cl2(H2O)], where L=6-phenyl-3-(2-pyridyl)-5-trifluoroacetylmethylidene-4,5-dihydro-1,2,4-triazine. We found experimentally and confirmed numerically that μeff(T), T<52K, and M(B),T=2K, are affected by intradimer spin polarization of the 1,2,4-triazine fragment and interstack exchange interactions. The interplay between π-stacking and Cu1-Cu1# antiferromagnetic coupling causes a structure instability which ends up by spontaneous destruction of the crystal at 2 K under influence of DC and AC magnetic fields.