Weak ferromagnetism in chiral diamond-like neutral networks: Mn(2-pymS) ₂ and Co(2-pymS) ₂ (2-pymSH = 2-mercaptopyrimidine)

The reactions of 2-mercatopyrimidine with MCl ₂ (M = Mn ²⁺ or Co ²⁺) in solvothermal conditions result single crystals of Mn(2-pymS) ₂1 and Co(2-pymS) ₂2. The two complexes both have the diamond-like topology frameworks, which could be traced back to the similar way of pyrimidine rings acting as the asymmetric bridging ligands. Interestingly, although they have similar chemical formulas, structural analysis by single-crystal X-ray diffraction studies reveals that the sulfur atoms play different roles in 1 and 2. For 1, the Mn ion lies in a distorted octahedral environment bonded to four nitrogen atoms and two sulfur atoms, whereas the Co ion in a distorted tetrahedral environment only coordinates to nitrogen atoms of pyrimidine ligands in the case of Co(2-pymS) ₂2. More interestingly, although magnetic measurements for both complex 1 and 2 indicate long range magnetic ordering and spin canting below the critical temperature (20 K for 1 and 42.9 K for 2), a hysteresis loop can be observed even at 40 K, which is just below the T _C for complex 2, which is distinctly harder than 1.