Thermal Growth of Au-Fe Heterometallic Carbonyl Clusters Containing N-Heterocyclic Carbene and Phosphine Ligands.

ABSTRACT: The thermal reactions of [NEt₄][Fe(CO)₄(AuNHC)] [NHC = IMes ([NEt₄][1]) or IPr ([NEt₄][2]); IMes = C₃N₂H₂(C₆H₂Me₃)₂; IPr = C₃N₂H₂(C₆H₃ⁱPr₂)₂], Fe(CO)₄(AuNHC)₂ [NHC = IMes (3) or IPr (4)], Fe(CO)₄(AuIMes)(AuIPr) (5), and Fe(CO)₄(AuNHC)(AuPPh₃) [NHC = IMes (6) or IPr (7)] were investigated in different solvents [CH₂Cl₂, CH₃CN, dimethylformamide, and dimethyl sulfoxide (dmso)] and at different temperatures (50-160 °C) in an attempt to obtain higher-nuclearity clusters. 1 and 2 completely decomposed in refluxing CH₂Cl₂, resulting in [Fe₂(CO)₈(AuNHC)]^- [NHC = IMes (10) or IPr (11)]. Traces of [Fe₃(CO)₁₀(CCH₃)]^- (12) were obtained as a side product. Conversely, 6 decomposed in refluxing CH₃CN, affording the new cluster [Au₃{Fe(CO)₄}₂(PPh₃)₂]^- (15). The relative stability of the two isomers found in the solid state structure of 15 was computationally investigated. 4 was very stable, and only after prolonged heating above 150 °C in dmso was limited decomposition observed, affording small amounts of [Fe₃S(CO)₉]^2- (9), [HFe(CO)₄]^- (16), and [Au₁₆S{Fe(CO)₄}₄(IPr)₄]ⁿ⁺ (17). A dicationic nature for 17 was proposed on the basis of density functional theory calculations. All of the other reactions examined led to species that were previously reported. The molecular structures of the new clusters 11, 12, 15, and 17 were determined by single-crystal X-ray diffraction as their [NEt₄][11]·1.5toluene, [Au(IMes)₂][15]·0.67CH₂Cl₂, [NEt₄][12], and [17][BF₄]_n·solvent salts, respectively.

SUBMITTER: Berti B 

PROVIDER: S-EPMC7997394 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature