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,)) and {2,4-di(4-pyridyl)-6-bromophenyl}(2,6-dimethyl-4-tert-butylphenyl)diazom ethane (2,4-DPy-1-NA 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.