Structural comparison of octahedral MoO 22+ complexes of bidentate and linear tetradentate N,S-donor ligands

Abstract

The structures of MoO 2[NH 2C(CH 3) 2CH 2S] 2 and MoO 2[SC(CH 3) 2CH 2NHCH 2CH 2NHCH 2C(CH 3) 2S] have been determined using X-ray diffraction intensity data collected by counter techniques. MoO 2[NH 2C(CH 3) 2CH 2S] 2 crystallizes in space group Pbca with a = 11.234(3), b = 11.822(3) and c = 20.179(5) Å, V = 2680(2) Å 3 and Z = 8. Its structure is derived from octahedral coordination with cis oxo groups [MoO = 1.705(3) and 1.705(3)], trans thiolate donors cis to the oxo groups [MoS = 2.416(1) and 2.402(1) and N donors trans to oxo [MoN = 2.325(3) and 2.385(4) Å]. MoO 2[SC(CH 3) 2CH 2NHCH 2CH 2NHCH 2C(CH 3) 2S] crystallizes in the space group P2 1/c with a = 10.798(5), b = 6.911(2), c = 20.333(9) Å, β = 95.20°, V = 1511(2) Å 3 and Z = 4. Its structure is very similar to that of MoO 2[NH 2C(CH 3) 2CH 2S] 2 with MoO = 1.714(2) and 1.710(2), MoS = 2.415(1) and 2.404(1) and MoN = 2.316(3) and 2.362(3). The small differences in the geometries of the two compounds are attributed to the constraints of the extra chelate ring in the complex with the tetradentate ligand. The structures in this paper stand in contrast to those reported for complexes of similar ligands wherein steric hindrance produces complexes with a skew trapezoidal bipyramidal structure.