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

We report the synthesis and characterization of a phosphine-functionalized 4,5-diazafluorene ligand, 9-(2-(diphenylphosphino)­ethyl)-4,5-diazafluorene (LpH), and its Cu­(IPr) complex (IPr = N,N′-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene) [Cu­(IPr)­Lp] (2a), which exhibits a monomeric structure in solution but dimerizes in the solid state. Compound 2a reacts with Rh­(PPh3)3Cl, [Rh­(COD)­Cl]2, Au­(SMe2)­Cl, and Au­(IPr)Cl to form the macrocyclic complexes [Rh­(PPh3)­Lp]2 (2b), [Rh­(COD)­Lp]2 (2c), and [AuLp]2 (2d) and the mononuclear complex [Au­(IPr)­Lp] (2f), respectively, via ligand transfer. Although 2b–d,f could also be synthesized from the deprotonated ligand Lp– and the corresponding metal starting materials directly, the reactions require longer time and give lower yields. The reaction between LpH and Au­(SMe2)Cl gives Au­(LpH)2Cl (2e) exclusively.