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Structural and electrochemical properties of iridium-carbon bonded metalloporphyrins. Characterization of (OEP)Ir(C/sub 8/H/sub 13/) and (OEP)Ir(C/sub 8/H/sub 13/)(CO)

Journal Article · · J. Am. Chem. Soc.; (United States)
DOI:https://doi.org/10.1021/ja00284a030· OSTI ID:7203863
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An electrochemical and structural study of (OEP)Ir(C/sub 8/H/sub 13/), where OEP is the dianion of octaethylporphyrin and C/sub 8/H/sub 13/ is the cis-bicyclo(3.3.0)oct-1-yl group, is reported. (OEP)Ir(C/sub 8/H/sub 13/) was found to crystallize in the P anti 1 space group with a = 12.78 A, b = 13.33 A, c = 14.20 A, ..cap alpha.. = 58.75/sup 0/, ..beta.. = 69.57/sup 0/, ..gamma.. = 67.15 A, and z = 2. The Ir atom is displaced only 0.08 A from the porphyrin plane, and the iridinium-carbon bond distance was found to be 1.89 A. This is the first reported crystal structure of an iridium porphyrin complex as well as the first example where a bicyclic ligand is sigma bonded to a metalloporphyrin. Two-dimensional NMR techniques were also performed and demonstrate that the structure of (OEP)Ir(C/sub 8/H/sub 13/) is basically the same in solution as in the solid state. The five coordinate complex reversibly binds with CO to form (OEP)Ir(C/sub 8/H/sub 13/)(CO), and a formation constant of K/sub eq/ = 340 +/- 200 atm/sup -1/ was measured for this ligand binding reaction. In addition, detailed electrochemistry and spectroelectrochemistry of (OEP)Ir(C/sub 8/H/sub 13/)(CO) are reported in nonaqueous media, and a complete electrochemical mechanism for oxidation and reduction of both species is presented. Of particular interest is the fact that (OEP)Ir(C/sub 8/H/sub 13/) provides the first example of a sigma-bonded metalloporphyrin which can be reversibly oxidized at the sigma-bonded axial ligand without a cleavage of the metal-carbon bond.
Research Organization:
Univ. of Houston, TX
OSTI ID:
7203863
Journal Information:
J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:24; ISSN JACSA
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
BOND ANGLE
BOND LENGTHS
CARBOXYLIC ACIDS
CHEMICAL BONDS
CHEMICAL REACTIONS
CHEMISTRY
CRYSTAL STRUCTURE
DATA
DIMENSIONS
ELECTROCHEMISTRY
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IRIDIUM COMPOUNDS
LENGTH
LIGANDS
NMR SPECTRA
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIDATION
PORPHYRINS
REDUCTION
REFRACTORY METAL COMPOUNDS
SPACE GROUPS
SPECTRA
TRANSITION ELEMENT COMPOUNDS