A　novel　complex,　[Mn(C6H12N4)(2)(H2O)(4)][Mn(H2O)(6)][SO4](2)center　dot　6H(2)O,　was　synthesized　and　hexagonal　single　crystals　with　centimeter-scale　sizes　were　obtained　by　the　method　of　solvent　evaporation.　It　was　characterized　by　elemental　analysis,　infrared　spectrum,　thermogravimetric　analysis　and　X-ray　single-crystal　diffraction.　The　complex　belongs　to　triclinic　crystal　system,　space　group　P1　with　a　=　9.3390(8),　b　=　13.3520(13),　c　=　16.3207(13)　angstrom,　alpha　=　100.7160(3)degrees,　beta　=　90.1020(10)degrees,　gamma　=　109.9490(5)degrees,　V　=　1874.9(3)　angstrom(3),　Z　=　2,　D-c　=　1.542　g/cm(3),　M-r　=　870.64,　mu=　0.876　mm(-1),　T　=　293(2)　K,　F(000)　=　916　and　S　=　0.990.　The　crystal　structure　determination　displayed　a　distorted　octahedral　geometry　around　the　manganese　atom,　which　is　bound　to　two　nitrogen　atoms　from　hexamethylenetetra-　mine,　acting　as　monodentate　ligands,　and　to　four　aqua　ligands.　Variable-temperature　magnetic　measurements　of　the　complex　indicate　the　presence　of　weak　antiferromagnetic　interaction　between　manganese　centers.