title: Preparation of sterically congested diphenyldiazomethanes having a pyridine ligand and magnetic characterization of photoproducts of their 2:1 copper complexes.
abstract: [structure: see text] To confirm whether high-spin species can be generated as a result of ferromagnetic interaction between the 3d spin of metal ions and the 2p spins of triplet carbene through the pyridyl group located remote from the carbene center, [2,6-dibromo-4-(3- and 4-pyridyl)phenyl](4-tert-butyl-2,6-dimethylphenyl)diazomethanes were prepared and the corresponding carbenes were generated either in the absence or presence of Cu(hfac)2. These were characterized by ESR and UV/vis in a matrix at low temperature, and by laser flash photolysis in solution at room temperature. These studies indicated that although both carbenes generated a fairly stable complex with copper ions, the 4-pyridyl isomer formed a high-spin species as a result of ferromagnetic interaction between the 3d spin of metal ions and the 2p spins of triplet carbene. Such an interaction in the corresponding 3-isomer is likely to be antiferromagnetic. This is further confirmed by magnetic measurements using a Superconducting Quantum Interference Device (SQUID). The results demonstrate that extension of this method will enable stable high-spin polycarbenes to be obtained.
authors.affiliation: Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Matsuno
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Itoh
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Hirai
authors.forename: Hideo
authors.initials: H
authors.lastname: Tomioka