We report both the stepwise and one-pot syntheses of Pt(II)-Cu(I) hetero-dinuclear complexes using 4,5-diazafluorenide (L(-)) and 9-(2-(diphenylphosphino)ethyl)-4,5-diazafluorenide (L(p)(-)) as binucleating ligands. In the case of L(p)(-), the tethered phosphine arm helps anchor the Pt(II) centre onto the carbon site of the diazafluorenide and the Cu(I) centre is bound to the N,N-chelate site. In the case of L(-), the Cu(I) centre is bound to the carbon site of diazafluorenide and the Pt(II) centre is coordinated to the N,N-chelate site.

The coordination chemistry of the {RuCp*}+ fragment was studied toward several 4,5-diazafluorene derivatives. The ambidentate nature of these 4,5-diazafluorene derivatives with multiple coordination sites allowed for the syntheses of different linkage isomers and self-assembled macrocycles. Both a tetramer (2) and a monomer (3) of [RuCp*L] (where L – = 4,5-diazafluorenide) were prepared with the L – ligand. The dimeric head-to-tail macrocycles [Cp*Ru(LpH)]2Cl2 (4) and [Cp*RuLp]2 (5) were obtained with the ditopic L p H and L p – ligands (where L p H = 9-(2-(diphenylphosphino)ethyl)-4,5-diazafluorene and L p – = 9-(2-(diphenylphosphino)ethyl)-4,5-diazafluorenide). The bulky arene-substituted L Mes H ligand (where L Mes H = 3,6-dimesityl-4,5-diazafluorene) was prepared, and its coordination to {RuCp*}+ gave [Cp*Ru(L Mes H)]Cl (13). The selective syntheses of different linkage isomers of [RuCp*(L Mes )] (14 and 15) (where L Mes – = 3,6-dimesityl-4,5-diazafluorenide) were also demonstrated.

The syntheses and structures for a series of heterodinuclear complexes of 4,5-diazafluorenyl (L(-)) and 3,6-dimesityl-4,5-diazafluorenyl (LMes(-)) ligands are reported herein. In all these heterodinuclear complexes, the Ru(II) centre is sandwiched between a pentamethylcyclopentadienyl (Cp*) ligand and the C5 ring of L(-) or LMes(-) in a double η(5) fashion, while the other metal (Fe(II), Co(II), Pt(II), or Cu(I)) is bound to the N-donors.

The compound Pd(η3-1-PhC3H4)(η5-C5H5) reacts essentially quantitatively with a variety of phosphines L to form cross-coupling catalysts of the type PdL2 and has recently been shown to be a much more effective catalyst precursor for Suzuki–Miyaura cross-coupling reactions in comparison to more commonly utilized precursors such as Pd(PPh3)4, Pd2(dba)3, and Pd(OAc)2, which do not effectively generate two-coordinate species PdL2. This advantage is expected to apply also to e.g. Heck-Mizoroki and Sonogashira cross-coupling reactions, both of which are generally believed to be catalyzed by species of the type PdL2. Therefore, comparisons of the efficacies of catalyst systems based on Pd(η3-1-PhC3H4)(η5-C5H5), Pd(PPh3)4, Pd2(dba)3, and Pd(OAc)2 are made utilizing the conventional coupling reactions of aryl halides with methyl acrylate and styrene for Heck–Mizoroki coupling and with phenylacetylene for Sonogashira coupling. As anticipated, catalyst systems based on Pd(η3-1-PhC3H4)(η5-C5H5) are found to be significantly more active.