As part of our ongoing studies of metal coordination complexes with multidentate ligands (Tai et al., 2005), the synthesis and structure of the title compound, (I), is reported.
Two O-monodentate ligands and two water molecules are attached to the calcium atom, resulting in a distorted CaO 4 tetrahedron (Fig. 1). The identical S2=O8 [1.437 (3) 5) Å] bonds lengths imply double bond character. The dihedral angle between the two benzene ring mean planes (C7-C12 and C20-C25) is 129.9 (3) °.
Two molecules of water complete the structure of (I) and a network of hydrogen bonds helps to establish the crystal packing.
Experimental 1 mmol of calcium perchlorate was added to a solution of 4-toluenesulfonyl chloride-L-leucine (2 mmol) in 10 ml of CH 3 OH/ H 2 O (v/v 1:1). The mixture was continuously stirred for 4 h at refluxing temperature, evaporating some methanol, then, upon cooling, the solid product was collected by filtration and dried in vacuo (yield 69%). Clear blocks of (I) were obtained by evaporation from a methanol solution after a week.
Refinement
The water H atoms were located in a difference map and refined as riding in their as-found relative positions with U iso (H) = 1.2U eq (O). Other H atoms were placed geometrically (C-H = 0.93-0.97 Å, O-H = 0.82 Å, N-H = 0.86 Å) and refined as riding with U iso (H) = 1.2U eq (C,N) or 1.5U eq (O).