Group IB organometallic chemistry. XXXII. Arylcopper compounds ArnCun as intermediates in organometallic synthesis. Single-step synthesis and dynamic NMR spectroscopy of diorganotin dihalides Ar2-nRnSnX2 (Ar 2-Me2NCH2C6H4 or (S)-2-Me2NCHMeC6H4; n 0 or 1)

The selective, single-step synthesis of (2-Me₂NCHZC₆H₄)RSnX₂, in which Z H or Me, R Me or Ph and X Cl or Br, starting from the tetranuclear copper cluster compound (2-Me₂NCHZC₆H₄)₄Cu₄ and RSnX₃ is described. Reaction of (2-Me₂NCH₂C₆H₄)₄Cu₄ with SnBr₄ in a 1/2 molar ratio afforded (2-Me₂NCH₂C₆H₄)₂SnBr₂ in almost quantitative yield. ¹H NMR spectroscopic data of these novel compounds, which are monomeric in solution, indicate that: (i) intramolecular SnN coordination renders the Sn atom in (2-Me₂NCHZC₆H₄)RSnX₂ pentacoordinate, with the organo ligands residing in the equatorial plane of a trigonal bipyramidal structure, and the Sn atom in (2-Me₂NCH₂C₆H₄)₂SnBr₂ hexacoordinate, with trans organo groups and a cis arrangement for the Br and the N atoms; (ii) in pyridine the Sn atom in (2-Me₂NCHZC₆H₄)RSnX₂ becomes hexacoordinate by complex formation with the solvent but that intramolecular SnN coordination has been retained. The stereochemical lability of the pentacoordinate Sn center in the diorganotin dihalides (2-Me₂NCHZC₆H₄)RSnX₂, which contain a dissymmetrical equatorial plane, has been established on the basis of the dynamic NMR spectra of.