Synthesis and Structures of Complexes Demonstrating the Coordinative Versatility of the 2,4-Diimino-3-phosphinopentene Anion (γ-Phosphino-β-diketiminate)

The synthesis and characterization of a 2,4-diimino-3-phosphinopentene anion (γ-phosphino-β-diketiminate) is reported
and enables diversification of the β-diketiminate ligand framework, which has been widely employed across the
periodic table. Phosphines are observed to adopt the γ-position of the ligand rather than the N,N‘ chelate. While
aluminum and lithium adopt the familiar N,N‘ chelate arrangement with the new 2,4-diimino-3-phosphinopentene
anion ligand, reactions with AsCl3 or SbCl3 result in substitution at the β-methyl position on the ligand backbone,
realizing novel P→E (E = As or Sb) intramolecular coordination. The chemistry of the 2,4-diimino-3-phosphinopentene
anion can be monitored by the 31P NMR chemical shifts, which are distinctively diagnostic of the coordinative
engagement of the ligand.