Diazomethane matrix isolation

Photochemistry of (2-nitrophenyl)diazomethane 70 has been studied by excitation at 350 nm in argon matrix isolation system54. That shows that at 10 K, 2-nitroso-benzaldehyde is formed by intramolecular oxygen migration from (2-nitrophenyl) carbene... 

Photolysis of matrix-isolated (trimethoxysilyl)diazomethane at X > 305 nm produced carbene 3e (equation 1), which was characterized by IR and UV-Vis spectroscopy23. Under these conditions, no other species besides the carbene could be detected spectroscopically. In an 02-doped (1%) argon matrix, the carbene rapidly reacted with oxygen to give carbonyl oxide 4 which was further photoisomerized to formylsilane 5. Again, the fast reaction of 3e with 302 points to a triplet ground state of the carbene. 

The matrix-isolation technique is the method of choice for the direct spectroscopic observation of carbenes . However, efforts to generate and to observe silylcarbenes in solid matrices at cryogenic temperatures met with limited success. When (trimethylsi-lyl)diazomethane, (dimethylsilyl)diazomethane or bis(trimethylsilyl)diazomethane were irradiated in an argon matrix at <10 K, no IR spectra of the corresponding carbenes 3a-c could be obtained " . However, weak ESR signals were observed which were typical for a linear carbene with a triplet ground state . These results indicate that at least small amounts of carbenes 3a-c were present in the matrix. 

Tomioka, H., Ichikawa, N., and Komatsu, K., Photochemistry of (2-nitrophenyl)diazomethane studied by a matrix isolation technique (nitrophenyl)carbene to (carboxylphenyl)nitrene rearrangement by successive reduction of nitro group with carbenic center, /. Am. Chem. Soc., 114, 8045, 1992. 

Recently, Moore and Pimentel have photolyzed diazirine isolated in a solid nitrogen matrix. They found that the photolysis did produce diazomethane. In order to decide whether the diazomethane arose by a photoisomerization reaction or by the reaction of methylene with the nitrogen of the matrix, experiments were carried out in a nitrogen matrix enriched in N. On the basis of these experiments they conclude that the photolysis of the diazirine produces methylene and nitrogen, and that the diazomethane arises from the reaction of the methylene with the matrix and not by photoisomerization. Photolysis of diazomethane does not... 

Matrix investigations of sulfur and phosphorus analogues of acarbonylcarbenes have also been reported. For example, diphenylsulfene (66) and diphenyl-a-sultine (67) were isolated in low-temperature matrices following the thermal reaction of SO2 and diphenylcarbene (65) and the stepwise photolysis of phenyl(phenylsulfonyl)diazomethane (68), as summarized in Scheme 8. The ultimate photoproduct was benzophenone (70). 

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