Two modifications of the ${alpha};and;{eta}$ forms of propyl mercaptan nickel(II) cluster, [$Ni_6(SCH_2CH_2CH_3)_{12}$], have been synthesized and their crystal structures have been determined by single-crystal X-ray diffraction. The alkyl groups are away from $Ni_6$ ring in $alpha$ form whereas they are near to the Ni atom in $eta$ form. The distance of Ni-H in $eta$ form [2.576(5) $AA$] is much shorter than that in $alpha$ form [3.101(2) $AA$]. In the crystal lattice of $eta$ form, the whole structure forms a flower shape.