The Effect of Steric Bulk on Coordination Sphere Geometry for BiCl3 Complexes with Bulky Heterocyclic Imidazolethione Ligands


Chemistry and Biochemistry

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The synthesis and characterization of three new complexes, BiCl3(mipit)2 (1), BiCl3(emit)2 (2), and BiCl3(mnpit)2 (3) are reported, where emit = 1-ethyl-3-methyl-2(3H)-imidazolethione; mnpit = 1-methyl-3-(1-propyl)-2(3H)-imidazolethione; mipit = 1-methyl-3-(2-propyl)-2(3H)-imidazolethione. X-ray crystallog. results are reported for 1 and 3, the mipit and mnpit complexes whereas the structure of 2, the emit complex is under restudy because of disorder. BiCl3(mnpit)2 (3) crystallizes in a triclinic space group (P.hivin.1) with lattice parameters; a 9.4223(6), b 10.6275(6), c 12.8860(8) Å, α 108.329(1), β 90.388(1), γ 115.200(1)°, Z = 2. BiCl3(mipit)2 (1) crystallizes in a triclinic space group (P.hivin.1) with a 10.4347(8), b 11.0018(9), c 11.2075(9) Å, α 95.827(1), β 104.890(1), γ 117.064(1)°, Z = 2. Both complexes show the same pattern with two BiL2Cl4 (L = ligand) octahedra sharing a common edge through bridging chlorine atoms and the ligands occupying trans positions perpendicular to the plane made by the two bismuth atoms and six chlorine atoms. No strong evidence for a hemidirected lone pair is obsd. in either of the two complexes.