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

Abstract

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). ( n Pr 4 N) 4 [Pb 2 (i-mnt) 4 ] is dimeric, containing a fivecoordinate distorted square pyramidal Pb(II) center with a stereochemically active lone pair. The isoelectronic ( n Pr 4 N)[Bi(i-mnt) 2 ] is a distorted sixcoordinate complex that crystallizes in the polar P2 1 space group and forms a 2D coordination polymer via intermolecular Bi−N interactions; the d 10 s 2 Bi(III) center also has a hemidirectional coordination sphere with a stereochemically active lone pair. Using the more compact (Me 4 N) + cation, (Me 4 N) 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, ( n Pr 4 N) 3 Cr(i-mnt) 3 •H 2 O was also prepared and has a propeller structure with a typical octahedral Cr(III) center.