Synthesis and reactions of β-diketiminato heavy group 14 metaludalkoxides and phosphanides

摘要

Some low-valent, three-coordinated β-diketiminato heavy group 14 metal complexesudhave been synthesised and their reactions examined. Initially, our attention is focusedudon several β-diketiminatolead(II) alkoxides. The lead(II) alkoxides show different basicudand nucleophilic reactivities from transition metal analogues. For example, the reactionudbetween the lead(II) tert-butoxide and methyl iodide proceeds only under forcingudconditions to give the lead(II) iodide and methyl tert-butyl ether. However, facileudreversible carbon dioxide insertion into the lead-oxygen bond is observed.ududTo investigate the steric effect of the bulky β-diketiminato ligand, compounds withudvarious aromatic groups attached to nitrogen have been made. When eitherud[(BDIPh)PbCl] (BDIPh = [HC{C(Me)N(C6H5)}2]−) or [(BDIIPP)PbCl] (BDIIPP =ud[HC{C(Me)N(4-iPrC6H4)}2]−) was treated with potassium tert-butoxide, the reactionsudgave the unexpected bis[β-diketiminato]lead(II) complexes. However, treatment ofud[(BDIDMP)PbCl] (BDIDMP = [HC{C(Me)N(2,6-Me2C6H3)}2]−) with AgOTf led to theudexpected β-diketiminatolead(II) triflate. These results suggest that the ortho-substituentudon the N-aryl groups in the β-diketiminato ligand plays an important role in influencingudthe formation of bis[β-diketiminato]lead(II) complexes.ududA series of β-diketiminato heavy group 14 metal phosphanides was synthesised. Theudphosphorus is pyramidally coordinated in the compounds containing diphenyl- oruddicyclohexylphosphanido ligands. In contrast, the geometry at phosphorus is planar inudthe germanium(II) and tin(II) bis(trimethylsilyl)phosphanides. The phosphorus in theudlead(II) bis(trimethylsilyl)phosphanide is pyramidally coordinated. The observedudconformations may be explained by the steric congestion from the β-diketiminato ligand and electronic effects in the phosphanido ligand. Reactions of the phosphanidoudcomplexes with one equivalent of elemental chalcogen give phosphinochalcogenoitoudcomplexes. Further reaction with elemental chalcogen gives phosphinodichalcogenoatoudcomplexes. In contrast, treatment of the germanium(II) dicyclohexylphosphanide withudelemental chalcogen leads to the formation of germanium(IV) chalcogenide. Theudpresence of NMR-active nuclei in these complexes makes possible detailedudspectroscopic analysis.