Synthesis, Structures, and Catalytic Properties of Dinuclear Iridium(I) Complexes with a Hexadentate Macrocyclic Diamine‐Tetracarbene Ligand

Abstract

Two dinuclear macrocyclic Ir I NHC complexes, [Ir 2 (L 1 )(COD) 2 ](PF 6 ) 2 (1, COD = 1,5-cyclooctadiene) and [Ir 2 Cl(L 1 )(COD)]Cl (2), were prepared by the reaction between [{IrCl(COD)} 2 ] and macrocyclic N-heterocyclic carbene (NHC) ligand precursor (H 4 L 1 )(PF 6 ) 4 containing four benzimidazolium and two secondary amino groups. Furthermore, 1 and 2 were carbonylated to give [Ir 2 (L 1 )(CO) 4 ](PF 6 ) 2 (3) and [Ir 2 Cl(L 1 )(CO) 2 ]Cl (4), respectively. Notably, 1 can capture the chloride ion to turn itself into 2 with accompanying transformation from cis to trans [a]

Luminescent Mechanochromic Dinuclear Cu(I) Complexes with Macrocyclic Diamine-Tetracarbene Ligands

“…All other solvents and chemicals are commercially available and were used as received without further purification. The macrocyclic benzimidazolium salts [H 4 L 1 ]­[PF 6 ] 4 and [H 4 L 2 ]­[PF 6 ] 4 were prepared according to the literature procedures . NMR spectra were recorded on a Bruker Avance 400 MHz ( 1 H, 400 MHz; 13 C, 100 MHz) spectrometer at 298 K. Elemental analyses (C, H, and N) were carried out on a PerkinElmer 240C analytic instrument.…”

“…Recently, our groups have designed two tetra-NHC macrocyclic precursors [H 4 L 1 ]­[PF 6 ] 4 and [H 4 L 2 ]­[PF 6 ] 4 (Scheme ) containing four benzimidazoliums and two secondary amines with different length of bridging alkylene groups (ethylene and propylene) between benzimidazolium units. These precursors have been employed to prepare Ag­(I), Au­(I), Ni­(II), Pd­(II), and Ir­(I) complexes . It is reasoned that the macrocyclic NHCs L 1 and L 2 could be used as dinucleating ligands to construct dinuclear Cu­(I) complexes, which allow us to study luminescent properties of Cu­(I) complexes supported by the flexible macrocyclic framework.…”

Toward a Porphyrin-Style NHC: A 16-Atom Ringed Dianionic Tetra-NHC Macrocycle and Its Fe(II) and Fe(III) Complexes

“…Macrocyclic N-heterocyclic carbenes (NHCs) have gained considerable attention in organometallic chemistry for a wide variety of applications, ranging from catalysis to fluorescence. − Since their structure inherently resembles naturally occurring porphyrins, a main emphasis for research has been on their heme-analogue Fe complexes. ,,, Indeed, several of those Fe-NHC complexes are more effective catalysts than heme analogues for oxidation reactions like aziridination and epoxidation. − Combining those traits with other known advantages of iron, such as very low toxicity, natural abundance, and low cost, the current effort put into the investigation of this type of organometallic systems is highly rational …”

1,4‐Conjugate Addition of Aryl boronic Acids on Cyclohexenone as Catalyzed by Rhodium(I) Complexes of C2‐Symmetric Bioxazoline Fused N‐heterocyclic Carbenes

“…Though the 1,4‐conjugate addition of nucleophiles like organocopper and organozinc to the α,β ‐unsaturated carbonyl compounds is a powerful approach for the construction of C‐C bonds in organic synthesis, their larger applicability is however curtailed by their air and moisture sensitivities, and against this backdrop, the air and moisture stable organoboron nucleophiles became relevant. The transition metal catalysed 1,4‐conjugate addition of nucleophiles to the α,β ‐unsaturated carbonyl compounds have been reported for various transition metals like copper, palladium, gold, rhodium and iridium based catalysts including its asymmetric versions . In this regard, we became interested in extending the scope of N‐heterocyclic carbene based transition metal complexes for the 1,4‐conjugate addition reaction.…”