Reaction of lead(II) acetate with 1,2-diaminobenzene (DAB) or 4-substituted-1,2-diaminobenzene derivatives in refluxing ethanol results in the formation of lead(II) complexes that incorporate acetate and diaminobenzene in their coordination spheres. Single-crystal X-ray crystallographic analysis reveals that the complexes exhibit extended structures.When DAB is used, a compound with interlinked chains containing four symmetry independent lead(II) ions is obtained: Pb4(DAB)2(OAc)8.  Two of the lead ions have a coordination sphere consisting of one monodentate DAB ligand, two acetate ligands bonded in bidentate fashion and bridging to two adjacent lead ions, and two additional oxygen atoms, each from a different bridging acetate ligand. The other two lead(II) ions each have a coordination sphere composed of a nonbridging, bidentate acetate ligand, a second bidentate acetate ligand that bridges to two different lead ions, and two oxygen atoms from different bridging acetate ligands.The compound obtained with 4-cyano-1,2-diaminobenzene (DABCN) crystallizes with an extended structure involving discrete chains of acetate-bridged lead(II):  Pb(DABCN)(OAc)2. Lead ions are related to each other by a crystallographically imposed center of symmetry.  The lead ion is coordinated to a monodentate DABCN ligand and two bidentate acetate ligands. One of the acetate ligands uses each oxygen atom to bridge to adjacent lead ions.The coordination number of the lead(II) in each of the complexes is formally seven with an open coordination site located opposite of the bridging acetate ligand. The open coordination site is the presumed location of the stereochemically active 6s2 electron pair. The coordination geometry and extended structures of these and similar compounds will be presented.

Structural characterization of novel acetato-bridged (benzene-1,2-diamine-<i>?</i>N)lead(II) complexes

247th National Meeting (2014)

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Structural characterization of novel acetato-bridged (benzene-1,2-diamine-?N)lead(II) complexes