Monoanionic salicylaldimine ligands with (thio)phosphoryl pendant arms: Synthesis and complexing features

Lithium, zinc and scandium complexes of phosphorylated salicylaldimines: synthesis, structure, thermochemical and photophysical properties, and application in OLEDs

“…As well as in the case of the related Re(I), Ni(II), and Pd(II) complexes of 1a, 6 the coordination of a salicylaldimine moiety results in the expected lengthening of the N(1)-C (7) and N(1)-C(8) bonds from 1.412(2) and 1.285(2) Å in free ligand 1a to 1.413(2) and 1.296(2) in lithium complex 2a. In addition to the shortening of the O(2)-C(1) and C(1)-C(2) bonds upon complex formation by 0.059 and 0.14 Å, respectively, this testies the extensive delocalization of electron density in the coordinated anion of salicylaldimine 1a.…”

“…1) indeed appeared to be coordinated to the metal ion in a tridentate monoanionic fashion (via the imine nitrogen and phosphoryl and phenoxy oxygen atoms), forming two-six-membered fused metallocycles, like in the Re(I) and Ni(II) analogs. 6 This dimeric complex lies on an inversion center being situated between two metal atoms. The differences in the lengths of lithium-heteroatom bonds (see Fig.…”

“…2, the corresponding parameters for Zn complex 4b also have the normal values. 6,9 Interestingly, despite the coordination of the phosphoryl group in the case of complex 2a, the length of the P(1)-O(1) bond in 2a (1.489(1) Å) almost does not differ from those in free ligand 1a (1.488(1) Å) and Zn derivative 4b (1.487(2) Å), suggesting the realization of a very week Li/O interaction (cf. with the lengths of the coordinated P]O bond in Re(I) (1.513(2) Å) and Ni(II) (1.503(2) Å) complexes of 1a).…”

“…3 Numerous examples of luminescent complexes based on salicylaldimines are known, 4 and their successful application in fabrication of OLEDs has been reported. 5 Recently, we have shown that P(X)-substituted (X ¼ O, S) salicylaldimines act as versatile ligands for transition metals, 6 including f-elements, 7 showing wide diversity of coordination modes depending on the reaction conditions and nature of both substituent X in the P]X group and metal ion. Herein, we report on the k 2 -O,N-and k 3 -O,N,O Li(I), Zn(II), and Sc(III) complexes of P(O)-functionalized salicylaldimines with the phosphoryl group either directly attached to the central benzene ring or connected with it via an additional methylene unit, which possess high thermal stability and detectable luminescence in THF solution at room temperature and can be used in fabrication of OLEDs.…”

Michael addition of P-nucleophiles to azoalkenes provides simple access to phosphine oxides bearing an alkylhydrazone moiety

“…Well-known examples include fosazepam ( Nicholson and Wright, 1977 ), brigatinib ( Huang et al, 2016 ), and fosenazide ( Zainkonnikova et al, 1980 ) ( Scheme 1 , A). Apart from a biological use, phosphine oxides having additional nitrogen functionality can serve as ligands for transition metal catalysis ( Minghetti et al, 1998 ; Pailloux et al, 2011 ; Zhang et al, 2012 ; Aleksanyan et al, 2013 ; Nyamato et al, 2015 ; Junges et al, 2019 ; Enikeeva et al, 2023 ) and as building blocks for organic synthesis via Wittig and HWE-type reactions ( Palacios et al, 1994 ) ( Scheme 1B ).…”