Reversible C 60 Binding to Dendrimer-Containing Ir(CO)Cl(PPh 2 R) 2 Complexes
1997; American Chemical Society; Volume: 36; Issue: 4 Linguagem: Inglês
10.1021/ic9612764
ISSN1520-510X
AutoresVincent J. Catalano, Nicholas Parodi,
Tópico(s)Molecular Junctions and Nanostructures
ResumoThe phosphine compounds PPh2(G-1) and PPh2(G-2), where G-1 is 3,5-bis(benzyloxy)benzyl and G-2 is 3,5-bis((3,5-bis(benzyloxy)oxy)benzyl, were synthesized. The complexes, trans-Ir(CO)Cl(PPh2(G-1))2, 1, and trans-Ir(CO)Cl(PPh2(G-2))2, 2, show reversible binding with C60. Thermodynamic data on the reversible binding were obtained in chlorobenzene by line width analysis of the 31P{1H} NMR spectra. The activation parameters ΔG265⧧ (kcal mol-1), ΔH⧧ (kcal mol-1), and ΔS⧧ (cal mol-1 K-1) were calculated as 1.3, 18, and 20 for 1·C60 and 1.3, 24, and 42 for 2·C60. The thermodynamic quantities ΔG265° (kcal mol-1), ΔH° (kcal mol-1), and ΔS° (cal mol-1 K-1) were determined to be −2.8, −25, and −105 for 1·C60 and −3.0, −18, and −57 for 2·C60. The rates of reaction with O2 for 1 and 2 were measured and are comparable to that for trans-Ir(CO)Cl(PPh3)2 under similar conditions. The compound PdI2(PPh2(G-1))2, 3, does not show reversible binding with C60. Crystal structures were obtained for 1 (a = 10.218(1) Å, b = 12.731(3) Å, c = 13.116(2) Å, α = 112.05(1)°, β = 108.30(1)°, γ = 102.22(1)°, V = 1392.2(4) Å3) and 3 (a = 10.243(2) Å, b = 12.689(2) Å, c = 13.146(2) Å, α = 112.33(1)°, β = 108.96(1)°, γ = 101.23(1)°, V = 1392.4(4) Å3).
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