Cyclometalated Iridium(III) Complexes Featuring Disubstituted Cyanamides

Abstract

The neutral cyclometalated iridium(III) complexes [Ir(ppy) 2 Cl (NCNR 2 )] [ppy = 2-phenylpyridinato-C 2 ,N, R = Me 3 a, Et 3 b, 1 = 2 C 5 H 10 3 c] were prepared via the reaction of the chlorobridged dimer [Ir 2 (ppy) 4 (μ-Cl) 2 ] (1) with corresponding dialkylcyanamides NCNR 2 (2 a-c) and 3 a-c were isolated in 74-85% yields. The cationic cyclometalated iridium(III) complex [Ir (ppy) 2 (NCNMe 2 ) 2 ](OTf) (4) was obtained by replacement of chloride ligands with NCNMe 2 in 1 in the presence of AgOTf. UV/Vis absorption and emission properties of 3 a À c and 4 were studied; these complexes exhibit luminescence in the solid state upon photoexcitation (340 nm, 77 K). The characteristic feature of the X-ray structures of 3 a-c is a deviation of the fragment Ir-N-C from linearity by 13.8(5)-22.8(3)°. Quantum chemical DFT calculations and topological analysis of the electron density distribution within the formalism of Bader's theory (AIM method) performed for 3 a-c demonstrated that the Ir-N-C fragments in the optimized equilibrium structures of [Ir(ppy) 2 Cl(NCNR 2 )] significantly deviate from the linearity (by 19.8-30.7°) and indicated that the Ir-N contacts between the metal centers and dialkylcyanamide ligands are relatively weak (24-30 kcal/mol) and have a closed-shell dative interactions character. The charge decomposition analysis (CDA) shows existence of {M} ! L donation with almost negligible contribution of the {M}!L back-donation in 3 a-c.

Copper(II) Prevents the Saccarine-Dialkylcyanamide Coupling by Forming Mononuclear (Saccharinate)(Dialkylcyanamide)copper(II) Complexes

“…In contrast, the structures of 1 and 1•2H 2 O demonstrate ∠Cu-N-C (171.6(3) and 146.8(5) • , respectively), which differently deviate from the linearity because of a noticeable contribution of the heterocumulene mesomeric form N (-) =C=N (+) R 2 . The strong deviation from the linearity of the M-N-C fragment of the coordinated NCNR 2 was observed by us for iridium(III) [28], copper(I) [20], and zinc(II) [29] complexes featuring disubstituted cyanamides. This strong deviation from linearity of the M-N-C fragment distinguishes NCNR 2 ligands from NCR.…”

Combined σ- and π-Hole Donor Properties of Perfluorinated Iodo(or bromo)benzenes: Halogen Bonding and π-Hole Interactions in Cocrystals Including Cu4I4 Clusters

“…In view of our interest in the chemistry of dialkylcyanamides − and also in crystal engineering involving coinage metal complexes, − we attempted to crystallize CuI with the dialkylcyanamides NCNR 2 (R 2 = Me 2 , Et 2 , C 4 H 8 , C 5 H 10 , C 4 H 8 O) in the presence of such mixed σ-/π-hole donors as 1,4-FIB or 1,4-FBrB. Despite our repeated attempts, only experiments with the system CuI/NCNMe 2 /halo­(perfluoro)­arenes in MeCN gave cocrystals 1 ·1,4-FIB, 2 ·1,4-FIB, and 1 ·1,4-FBrB; they all were studied by XRD.…”

Rational design of efficient photosensitizers based on cyclometalated iridium(iii) complexes with 2-arylbenzimidazole and aromatic 1,3-diketone ligands

“…Complexes 10–12 were synthesized by refluxing of the dimers with 4,4′-dicarboxy-2,2′-bipyridine (L 3 ) in the presence of a slight excess of silver triflate. 48 The resulting complexes were characterized by 1 H and 13 C ( 7–9 ) NMR spectroscopy and HRMS.…”