Construction of Rhodium(I) and Gold(I) Macrocycles by Transferring a Phosphine-Functionalized 4,5-Diazafluorenide Ligand from Its Copper(I) N-Heterocyclic Carbene Complex

Abstract

We report the synthesis and characterization of a phosphine-functionalized 4,5-diazafluorene ligand, 9-(2-(diphenylphosphino)ethyl)-4,5-diazafluorene (L p H), and its Cu(IPr) complex (IPr = N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) [Cu(IPr)L p ] (2a), which exhibits a monomeric structure in solution but dimerizes in the solid state. Compound 2a reacts with Rh(PPh 3 ) 3 Cl, [Rh(COD)-Cl] 2 , Au(SMe 2 )Cl, and Au(IPr)Cl to form the macrocyclic complexes [Rh(PPh 3 )L p ] 2 (2b), [Rh(COD)L p ] 2 (2c), and [AuL p ] 2 (2d) and the mononuclear complex [Au(IPr)L p ] (2f), respectively, via ligand transfer. Although 2b−d,f could also be synthesized from the deprotonated ligand L p − and the corresponding metal starting materials directly, the reactions require longer time and give lower yields. The reaction between L p H and Au(SMe 2 )Cl gives Au(L p H) 2 Cl (2e) exclusively.

Selective one-pot syntheses of PtII–CuI heterobimetallic complexes of 4,5-diazafluorenide derivatives

“…We tentatively assign the peak at −13.6 ppm at 298 K to the monomer, because the 31 P NMR signal observed for the monomeric 1a was at −14.2 ppm. 15,17 Analogous to 1a, complex 1b is a head-to-tail dimer in the solid state as confirmed by X-ray crystallography (Fig. 1).…”

“…Unless otherwise stated, all reagents were purchased from commercial sources and used without further purification. Compounds 1a, 15 , 197.2 μmol) in 3 mL of THF was then added and a colour change to green was observed. The reaction mixture was stirred for an additional 12 hours.…”

“…8 Hahn and coworkers reported the selective one-pot syntheses of Rh-Pd and Ir-Pd hetero-dinuclear complexes of a tricarbene ligand, where the different coordination behaviours of the metals allow for the high regioselectivity. 9 Our group has explored the coordination chemistry of 4,5-diazafluorene (LH) derivatives [10][11][12][13][14][15] and the resulting complexes have shown interesting reactivity towards a variety of small molecules. [10][11][12][13][14] The deprotonated LH derivatives have prompted our interest in the construction of heterobimetallic complexes because of the existence of multiple metal binding sites.…”

“…Cu(I) centre in 1a to the Rh I and Au I centres in [Rh I ]-Cl and [Au I ]-Cl starting materials resulting in macrocycle formation accompanied by the release of [Cu(IPr)Cl] 15. Herein, the presence of labile SMe 2 ligands in [PtPh 2 (μ-SMe 2 )] n (n = 2 or 3) and lack of halides prevent the L p − ligand transfer and allow for the isolation of heterobimetallic complexes 2a and 2b.Due to the distinct properties observed for both coordination sites within the L p − ligand, a one-pot synthesis…”

Transfer hydrogenation of aryl ketones with homogeneous ruthenium catalysts containing diazafluorene ligands

“…[7][8][9][10][11][12] Although some aspects of the chemistry of 4,5-diazafluoren-9one and 4,5-diazafluorene have been studied, little is known regarding the coordination chemistry of these ligands, which are closely related to phenanthroline and bipyridines. [13][14][15][16][17][18][19] Recently, a review on the coordination chemistry and applications of metal complexes of various 4,5-diazafluorenes in catalysis, photochemistry and photophysics as well as in bioinorganic chemistry was reported. [20] In recent years, transition metal complexes bearing diazafluorene ligands have attracted considerable interest due to their potential applications in organic devices.…”