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RESEARCH PRODUCT

Sterically crowded triazenides as novel ancillary ligands in copper chemistry

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Abstract We have synthesized copper salts MN3RR′ derived from the biphenyl- or m-terphenyl-substituted triazenes Tph2N3H (1a) and Dmp(Tph)N3H (1b) (Dmp = 2,6-Mes2C6H3 with Mes = 2,4,6-Me3C6H2; Tph = 2-TripC6H4 with Trip = 2,4,6-i-Pr3C6H2). The homoleptic copper triazenide [CuN3Tph2] (2a) was obtained in high yield from the metallation of 1a with mesityl copper in n-heptane, while the complex [CuN3(Dmp)Tph] (2b) was generated by the same method in situ only. Reaction of 2a with triphenylphosphane gave the 2:1 adduct [CuN3Tph2(PPh3)2] (3a), regardless of the used complex/donor ratio, while reaction of 2a or 2b with a stochiometric amount of t-butylisonitrile afforded the 1:1 adducts [Tph2N3CuCNtBu] (4a) and [Dmp(Tph)N3CuCNtBu] (4b). All new compounds (except 2b) have been characterized by 1H NMR, 13C NMR and IR spectroscopy, elemental analysis, melting point (not 2a), and X-ray crystallography. The IR spectroscopic examination of the ν(C N) stretch in the isonitrile adducts 4a and 4b revealed the weaker donor character of the supporting triazenido ligands compared to related β-diketiminato ligands.