A binuclear MnII complex of the formula [Mn2(H2O)6(bpym)(SO4)2] (bpym = 2,2′-bipyrimidine) has been prepared and its structure and magnetic properties have been determined by X-ray diffraction, ESR and magnetic susceptibility measurements. The structure consists of two MnII ions bridged by bis-bidentate bpym ligands and coordinated by H2O and SO42− groups to make a binuclear neutral [Mn2(H2O)6(bpym)(SO4)2] unit. The coordination geometry around the manganese atom is that of a highly distorted octahedron: The averaged MnIIN distance (2.31 Å) is longer than those of the MnIIO (2.16 Å) of H2OMnII and MnIIO (2.069 Å) of SO42−MnII. The configuration of coordinated SO42− groups has a disorder with a 6:4 rattio. X-band ESR spectra of the complex in water shows an isotropic signal with g = 2.007 and A = 94 G. Cryomagnetic investigations (4–300 K) reveal a weak antiferromagnetic spin exchange with J = −9.96 cm−1 between manganese(II) cations through the bpym bridge.
