139167-86-5Relevant articles and documents
Synthesis and structure of rhodium complexes containing a photolabile η2-carbodiimide ligand. 1,3-Dipolar cycloaddition of phenyl azide to Tp′Rh(CNR)2 (Tp′ = hydrotris(3,5-dimethylpyrazolyl)borate)
Hessell, Edward T.,Jones, William D.
, p. 1496 - 1505 (2008/10/08)
The 1,3-dipolar cycloaddition of phenyl azide to the metal-coordinated isocyanide ligands in Tp′Rh(CNR)2 (Tp′ = hydrotris(3,5-dimethylpyrazolyl)borate, R = neopentyl, methyl, 2,6-xylyl; 1a-c) or Cp*Rh(CN-neopentyl)2 (Cp* = η5-1,2,3,4,5-pentamethylcyclopentadienyl; 3) in hexane produces the complexes Tp′Rh(CNR)(η2-PhN=C=NR) (R = neopentyl, methyl, 2,6-xylyl; 2a-c) and Cp*Rh(CNR)(η2-PhN= C=N-neopentyl) (4), respectively, in high yield. The reaction is regiospecific with respect to coordination of the unsymmetrical carbodiimide ligand. Reaction of 2,4-xylyl azide with Tp′Rh(CN-2-tolyl)2 (1d) gives Tp′Rh(CN-2-tolyl)(η2-2,4-xylyl-N=C=N-2-tolyl) (2d), for which the solid-state structure has been obtained by X-ray diffraction. Complex 2d crystallizes from toluene in the triclinic space group P1 with a = 10.962 (6) A?, b = 11.238 (4) A?, c = 8.691 (14) A?, α = 96.95 (5)°, β = 104.02 (5)°, γ = 101.00 (4)°, V = 2159 (5) A?3, and Z = 2. The structure of 2d confirms the bidentate bonding of the carbodiimide and shows that the nitrogen of the carbodiimide arising from the azide is coordinated to rhodium. Photolysis of 2a in benzene produces Tp′Rh(H)(Ph)(CN-neopentyl) (5) along with free PhN=O=N-neopentyl with a quantum yield of 1.0 ± 0.3, whereas complex 4 is photochemically unreactive in benzene solution. The conversion of 2a to 5 can also be effected thermally, although the rate is slow at 100°C. Photolysis of 2a in the solid state results in an intramolecular reaction to give Tp′Rh(H)(2-(N=C=N-neopentyl)C6H4)(CN-neopentyl) (7). Addition of excess neopentyl isocyanide to 2a gives the azametallacyclobutane complex Tp′RhC(= N-neopentyl)N(Ph)C(=N-neopentyl)(CN-neopentyl) (8).
