Construction of a robust pillared-layer framework based on the rare paddlewheel subunit [MnII2(μ-O2CR)4L2]: synthesis, crystal structure and magnetic properties

With numerous examples of heavier congeners as well as neighbors, only four paddlewheel compounds, including one coordination architecture, of manganese with the [MnII2(μ-O2CR)4L2] core were reported in the literature. We report here a robust pillared-layer framework with an α-polonium topology comprising such a core as a subunit, {[Mn2(O2CC6H4Si(CH3)2C6H4CO2)2(4,4′-bpy)]}n (1), where 4,4′-bpy = 4,4′-bipyridine, with an Mn⋯Mn distance of 3.005(2) A, which does not vary with temperature. For the first time, the variable temperature magnetic data (2–300 K) and crystal structures at two different temperatures (100 K and 296 K) are combined for the same example to support the fact that there is no metal–metal bond in such compounds like 1. Based on the magnetic measurements, an antiferromagnetic interaction (2J = −12.4 cm−1 with g = 2.014 (H = −2JS1S2)) between two S1 = S2 = 5/2 spin centers exists in 1.