Structural Diversity of Iso-Maleonitrile Dithiolate d¹⁰s² Metal Complexes of Lead and Bismuth

The synthesis and solid-state structures of four structurally diverse i-mnt-based anionic complexes and coordination polymers are described (i-mnt = iso-maleonitrile dithiolate). (nPr4N)4[Pb2(i-mnt)4] is dimeric, containing a five-coordinate distorted square pyramidal Pb(II) center with a stereochemically active lone pair. The isoelectronic (nPr4N)[Bi(i-mnt)2] is a distorted six-coordinate complex that crystallizes in the polar P21 space group and forms a 2D coordination polymer via intermolecular Bi–N interactions; the d10s2 Bi(III) center also has a hemidirectional coordination sphere with a stereochemically active lone pair. Using the more compact (Me4N)+ cation, (Me4N)2[Pb(i-mnt)2] contains eight-coordinate holodirectional Pb(II) centers that form 1D chains via bridging Pb–S bonding. These anionic complexes could provide the foundation to incorporate stereochemically active lone pairs into heterometallic coordination polymers. As a comparison, (nPr4N)3Cr(i-mnt)3·H2O was also prepared and has a propeller structure with a typical octahedral Cr(III) center.