Facile Access of Well-Defined Stable Divalent Lead Compounds with Small Organic Substituents

Abstract

The reaction of 1 equiv of β-diketiminate lithium, LLi·OEt2 {L = HC(CMeNAr)2 (Ar = 2,6-iPr2C6H3), nacnac ligand} with 1 equiv of PbCl2 in THF afforded the β-diketiminate lead(II) chloride (1) as a yellow compound. Treatment of 1 with stoichiometric amounts of methyl lithium, phenyl lithium, lithium phenylacetylide, and silver triflate resulted in the divalent organolead compounds LPb(II)Me (2), LPb(II)Ph (3), LPb(II)CCPh (4), and LPb(II)OTf (5). Compounds 2 and 3 are the first stable, monomeric lead(II) derivatives involving small alkyl and aryl groups Me and Ph, respectively, supported by the β-diketiminate ligand. Compound 4 is the first alkynyl lead(II) derivative. All compounds (2, 3, 4, 5) were characterized by microanalysis, X-ray crystallography, and 1H, 13C, and 207Pb NMR spectroscopy. Single-crystal X-ray structural analyses indicate that compounds 2−4 are monomeric, and the lead center resides in a trigonal-pyramidal environment, whereas 5 has a polymeric structure. The results demonstrate the effectiveness of the β-diketiminate ligand in creating a protected surrounding for the lead atom.