Enantiopure Calcium Iminophosphonamide Complexes: Synthesis, Photoluminescence, and Catalysis. Issue 13 (2nd February 2021)

• Record Type: Journal Article
• Authors: Goswami, Bhupendra; Feuerstein, Thomas J.; Yadav, Ravi; Köppe, Ralf; Lebedkin, Sergei; Kappes, Manfred M.; Roesky, Peter W.
• Is Part Of: Chemistry. Volume 27:Issue 13(2021)
• Page Start: 4401
• Page End: 4411
• Publication Date: 2021-02-02
• Subjects: calcium -- homoleptic -- hydroboration -- iminophosphonamide -- photoluminescence; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202004833
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The synthesis of calcium complexes ligated by three different chiral iminophosphonamide ligands, L‐ H (L =[Ph2 P{N( R )CH(CH3 )Ph}2 ]), L′ ‐H (L′ =[Ph2 P{NDipp}{N( R )CH(CH3 )Ph}]), (Dipp=2, 6‐ i Pr2 C6 H3 ), and L′′ ‐H (L′′ =[Ph2 P{N( R )CH(CH3 )naph}2 ]), (naph=naphthyl) is presented. The resulting structures [L 2 Ca], [L′ 2 Ca], and [L′′ 2 Ca] represent the first examples of enantiopure homoleptic calcium complexes based on this type of ligands. The calcium complexes show blue–green photoluminescence (PL) in the solid state, which is especially bright at low temperatures. Whereas the emission of [L′′ 2 Ca] is assigned to the fluorescence of naphthyl groups, the PL of [L 2 Ca] and [L′ 2 Ca] is contributed by long‐lived phosphorescence and thermally activated delayed fluorescence (TADF), with a strong variation of the PL lifetimes over the temperature range of 5–295 K. Furthermore, an excellent catalytic activity was found for these complexes in hydroboration of ketones at room temperature, although no enantioselectivity was achieved. Abstract : Glowing bones : Enantiopure homoleptic iminophosphonamide calcium complexes have been prepared. These show rich photoluminescence properties and catalytic activity in the hydroboration of ketones.