Group IB organometallic chemistry: XXXIII. ArAuPPh3, ArAu(CNR), (ArAu)n and Ar4Cu2Au2 compounds in which the aryl group contains 2-MeO, 2,6-(MeO)2, 2-Me2N, 2-Me2NCH2 and (S)- or (R)-2-Me2NCHMe substituents as potential ligands

The synthesis and structural characterization by ¹H NMR and ¹⁹⁷Au Mössbauer spectroscopy as well as by chiral labelling of the built-in ligands of three different types of arylgold(I) compounds is described.¹⁹⁷Au Mössbauer data revealed that the benzyl- and arylgold(I) triphenylphosphine complexes which bear potential coordinating substituents at an ortho position still contain linearly coordinated Au^I with 2c-2e gold(I)carbon bonds. The observation of isochronous NME resonances in (S)-2-Me₂NCH(Me)C₆H₄AuPPh₃ confirms that no additional intramolecular AuN coordination occurs in solution. Preliminary results of an X-ray diffraction study of 2,6-(MeO)₂C₆H₃AuPPh₃ are reported (R = 0.040, PAuC₁ angle 172.6°. Unsymmetrical AuC₁C₂ and AuC₁C₆ angles of 126.4 and 117.4°, respectively).Pure, uncomplexed arylgold(I) compounds have been isolated from the reaction of diarylgoldlithium compounds (arylaurates) with trimethyltin bromide. (S)-2-Me₂NCHMeC₆H₄Au has a dimeric structure which most likely consists of two monomeric units associated by intermolecular AuN coordination thus forming a ten-membered chelate ring. The structure of insoluble 2-Me₂NCH₂C₆H₄Au and 2-Me₂NC₆H₄Au are less clear. The former compound probably has a structure similar to (S)-2-Me₂NCHMeC₆H₄Au (IS/QS values for two-coordinate Au^I centers). However, the strongly deviating IS and QS values of 2-Me₂NC₆H₄Au indicate that a polynuclear structure for this compound similar to that proposed for 2-Me₂NC₆H₄Cu cannot be excluded (a polymeric structure containing 2-Me₂NC₆H₄ groups which span three Au atoms by 3c-2e Au₂C bonds and AuN coordination).The mixed Au/Cu cluster (2-Me₂NCH₂C₆H₄)₄Au₂Cu₂ is accessible via the $\text{1}\text{2}$ reaction of (2-Me₂NCH₂C₆H₄)₄Au₂Li₂ with CuI. Molecular weight and ¹H NMR studies point to a tetranuclear structure in solution, while mass spectrometry shows fragment ions with m/e corresponding to (2-Me₂NCH₂C₆H₄)₃Au₂Cu₂⁺, (2-Me₂NCH₂C₆H₄)₃Cu₂Au⁺, (2-Me₂NCH₂C₆H₄)₂CuAu₂⁺ and of (2-Me₂NCH₂C₆H₄)₂Au⁺.