TY - JOUR

T1 - Cyclometalated Iridium(III) Complexes Featuring Disubstituted Cyanamides

AU - Kinzhalov, Mikhail A.

AU - Parfenova, Suzanna N.

AU - Novikov, Alexander S.

AU - Katlenok, Evgeniy A.

AU - Puzyk, Mikhail V.

AU - Avdontceva, Margarita S.

AU - Bokach, Nadezhda A.

PY - 2018/11/13

Y1 - 2018/11/13

N2 - The neutral cyclometalated iridium(III) complexes [Ir(ppy)2Cl(NCNR2)] [ppy=2-phenylpyridinato-C2,N, R=Me 3 a, Et 3 b, 1/2C5H10 3 c] were prepared via the reaction of the chloro-bridged dimer [Ir2(ppy)4(μ-Cl)2] (1) with corresponding dialkylcyanamides NCNR2 (2 a–c) and 3 a–c were isolated in 74–85% yields. The cationic cyclometalated iridium(III) complex [Ir(ppy)2(NCNMe2)2](OTf) (4) was obtained by replacement of chloride ligands with NCNMe2 in 1 in the presence of AgOTf. UV/Vis absorption and emission properties of 3 a−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)2Cl(NCNR2)] 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.

AB - The neutral cyclometalated iridium(III) complexes [Ir(ppy)2Cl(NCNR2)] [ppy=2-phenylpyridinato-C2,N, R=Me 3 a, Et 3 b, 1/2C5H10 3 c] were prepared via the reaction of the chloro-bridged dimer [Ir2(ppy)4(μ-Cl)2] (1) with corresponding dialkylcyanamides NCNR2 (2 a–c) and 3 a–c were isolated in 74–85% yields. The cationic cyclometalated iridium(III) complex [Ir(ppy)2(NCNMe2)2](OTf) (4) was obtained by replacement of chloride ligands with NCNMe2 in 1 in the presence of AgOTf. UV/Vis absorption and emission properties of 3 a−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)2Cl(NCNR2)] 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.

KW - cyanamides

KW - DFT calculations

KW - Iridium(III) complexes

KW - luminescence

KW - QTAIM, CDA

UR - http://www.scopus.com/inward/record.url?scp=85056784429&partnerID=8YFLogxK

U2 - 10.1002/slct.201802900

DO - 10.1002/slct.201802900

M3 - Article

AN - SCOPUS:85056784429

VL - 3

SP - 11875

EP - 11880

JO - ChemistrySelect

JF - ChemistrySelect

SN - 2365-6549

IS - 42

ER -