Preparation of a copper ion complex of sterically congested diphenyldiazomethanes having a pyridine ligand and characterization of their photoproducts.
To show that persistent high-spin polycarbenes can be realized by utilizing hetero spin systems, two diphenyldiazomethanes having pyridyl groups, i.e., bis{4-(4-pyridyl)-2,6-dimethylphenyl}diazomethane (4,4'-DPy-1-N(2)) and {2,4-di(4-pyridyl)-6-bromophenyl}(2,6-dimethyl-4-tert-butylphenyl)diazomethane (2,4-DPy-1-N(2)), were prepared. Triplet carbenes, 4,4'-DPy-1 and 2,4-DPy-1, generated by photolysis of the corresponding diazomethanes were characterized by spectroscopic means (ESR and UV/vis in matrix at low temperatures and laser flash photolysis in solution at room temperature). The results showed that they were fairly persistent. Magnetic properties of the photoproducts from a 1:1 complex between DPy-1-N(2) and Cu(hfac)(2) (hfac = hexafluoroacetylacetonate) were characterized by ESR and a superconducting quantum interference device (SQUID) magneto/susceptometer. The field dependences of magnetization for the complexes, expressed by using M versus H/T plots, were analyzed in terms of the Brillouin function to be S = 6.80 (F = 0.60) for the 1:1 complex of 4,4'-DPy-1 and Cu(hfac)(2) and S = 3.71 (F = 0.73) for the 1:1 complex of 2,4-DPy-1 and Cu(hfac)(2) at 2.0 K. Thus, it has been demonstrated that a high-spin species is actually generated in the photoproducts and that the complexed carbenes showed significant stability.
Itoh
Tetsuji
T
Chemistry Department for Materials, Faculty of Engineering, Instrumental Analysis Facilities, Life Science Research Center, Mie University, Tsu, Mie 514-8507, Japan. t-itoh@chem.mie-u.ac.jp
Matsuno
Masayoshi
M
Ozaki
Shuhei
S
Hirai
Katsuyuki
K
Tomioka
Hideo
H
D003300:Copper / Q000737:chemistry*; D003978:Diazomethane / Q000737:chemistry*; D006838:Hydrocarbons; D008024:Ligands; D008697:Methane / Q000031:analogs & derivatives; D010782:Photolysis; D011725:Pyridines
D006838:Hydrocarbons; D008024:Ligands; D011725:Pyridines; C030011:carbene; D003978:Diazomethane; D003300:Copper; C023666:pyridine; D008697:Methane