Self-Assembly of Heterometallic Metallomacrocycles via Ditopic Fluoroaryl Gold(I) Organometallic Metalloligands

Abstract

A series of heterometallic metallamacrocycles have been constructed from self-assembly reactions between the fluorinated Au(I) organometallic compounds [(AuC6F4py)2(μ2-diphosphane)] [diphosphane = bis(diphenylphosphanyl)methane (dppm) (1), 1,2-bis(diphenylphosphanyl)ethane (dppe) (2), trans-1,2-bis(diphenylphosphanyl)ethylene (dppet) (3), 1,3-bis(diphenylphosphanyl)propane (dppp) (4), 1,4-bis(diphenylphosphanyl)butane (dppb) (5), and 4,4′-bis(diphenylphosphanyl)-1,1′-biphenyl (dppdph) (6)] and the cis-blocked complexes [M(P–P)(H2O)2](OTf)2 (M = Pd) (P–P = dppp, dppf) (a,c), (M = Pt) (P–P = dppp, dppf) (b,d). Changes of the backbone of the diphosphanes were seen to have an influence on the resulting species. While the self-assembly reactions involving [(AuC6F4py)2(μ2-dppm)] (1), [(AuC6F4py)2(μ2-dppb)] (5), and [(AuC6F4py)2(μ2-dppdph)] (6) donors gave exclusively [2 + 2] heterometallomacrocycles, the assemblies arising from [(AuC6F4py)2(μ2-dppe)] (2) as well as the combinations between [(AuC6F4py)2(μ2-dppp)] (4) and [M(dppp)(H2O)2](OTf)2 (a, b) and [(AuC6F4py)2(μ2-dppet)] (3) and [M(dppf)(H2O)2](OTf)2 (c, d) consisted of an equilibrium between two macrocyclic species ([2 + 2] and a higher-order aggregate [3 + 3], [4 + 4],...). Multinuclear (1H, 19F, 31P) and diffusion NMR spectroscopy in combination with a complete set of ESI-FT-ICR mass spectrometry experiments were used to elucidate the nature of the different assemblies. DFT calculations were performed in order to calculate the molecular geometry and estimate the relative stability of different conformations of [2 + 2], [3 + 3], and [4 + 4] supramolecular species for two of the used diphosphanes.