Results
Title

Alkali Metal Complexes of a Bis(diphenylphosphino)methane Functionalized Amidinate Ligand: Synthesis and Luminescence.

Authors

Zovko, Christina; Schoo, Christoph; Feuerstein, Thomas J.; Münzfeld, Luca; Knöfel, Nicolai D.; Lebedkin, Sergei; Kappes, Manfred M.; Roesky, Peter W.

Abstract

A novel bis(diphenylphosphino)methane (DPPM) functionalized amidine ligand (DPPM−C(N‐Dipp)2H) (Dipp=2,6‐diisopropylphenyl) was synthesized. Subsequent deprotonation with suitable alkali metal bases resulted in the corresponding complexes [M{DPPM−C(N‐Dipp)2}(Ln)] (M=Li, Na, K, Rb, Cs; L=thf, Et2O). The alkali metal complexes form monomeric species in the solid state, exhibiting intramolecular metal‐π‐interactions. In addition, a caesium derivative [Cs{PPh2CH2‐C(N‐Dipp)2}]6 was obtained by cleavage of a diphenylphosphino moiety, forming an unusual six‐membered ring structure in the solid state. All complexes were fully characterized by single crystal X‐ray diffraction, NMR spectroscopy, IR spectroscopy as well as elemental analysis. Furthermore, the photoluminescent properties of the complexes were thoroughly investigated, revealing differences in emission with regards to the respective alkali metal. Interestingly, the hexanuclear [Cs{PPh2CH2‐C(N‐Dipp)2}]6 metallocycle exhibits a blue emission in the solid state, which is significantly red‐shifted at low temperatures. The bifunctional design of the ligand, featuring orthogonal donor atoms (N vs. P) and a high steric demand, is highly promising for the construction of advanced metal and main group complexes.

Subjects

ALKALI metals; ALKALI metal ions; METHANE; METAL complexes; LIGANDS (Chemistry); ELEMENTAL analysis; METALWORK

Publication

Chemistry - A European Journal, 2021, Vol 27, Issue 61, p15119

ISSN

0947-6539

Publication type

Academic Journal

DOI

10.1002/chem.202102243