Vibrational Solvatochromism in Vaska鈥檚 Complex Adducts

详细信息    查看全文

• 作者：Christopher J. Huber ; Timothy C. Anglin ; Brynna H. Jones ; Nagilthes Muthu ; Christopher J. Cramer ; Aaron M. Massari
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：September 20, 2012
• 年：2012
• 卷：116
• 期：37
• 页码：9279-9286
• 全文大小：337K
• 年卷期：v.116,no.37(September 20, 2012)
• ISSN：1520-5215

文摘

The vibrational solvatochromism of bis(triphenylphosphine) iridium(I) carbonyl chloride (Vaska鈥檚 complex, VC) was investigated by FTIR spectroscopy. The carbonyl stretching frequency (谓_CO) was measured in 16 different organic solvents with a wide range of Lewis acidities for VC and its dioxygen (VC-O₂), hydride (VC-H₂), iodide (VC-I₂), bromide (VC-Br₂), and sulfide (VC-S_X) adducts. The 谓_CO of the VC-O₂ complex was sensitive to the solvent electrophilicity, whereas minimal correlation was found for VC and the other adducts. The stretching frequency of the trans-O₂ ligand on VC-O₂ was measured to be anticorrelated with 谓_CO, supporting a model in which this ligand indirectly affects the carbonyl frequency by modulating the extent of metal-to-CO back-bonding. The 谓_CO values obtained from DFT calculations on VC adducts with solvent continua and explicit hydrogen bonds were used to aid the interpretations of the experimental results. The O₂ ligand is more susceptible to stronger specific solvent interactions and it binds in a fundamentally different mode from the monatomic ligands, providing a more direct communication channel with those metal d-orbitals that have the appropriate symmetry to back-bond into the carbonyl 蟺*-orbital.