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Unexpected Solvent Effects in the Isomerization of iPr PCPIr(η 2 ‐PhC≡CPh) to a 1‐Iridaindene
Author(s) -
WilklowMarnell Miles,
Brennessel William W.,
Jones William D.
Publication year - 2017
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.201700013
Subject(s) - chemistry , isomerization , dehydrogenation , diphenylacetylene , yield (engineering) , adduct , intramolecular force , solvent , medicinal chemistry , kinetic isotope effect , photochemistry , stereochemistry , organic chemistry , catalysis , materials science , physics , deuterium , quantum mechanics , metallurgy
The reaction of iPr PCPIr with diphenylacetylene ( iPr PCP=κ 3 ‐2,6‐C 6 H 3 (CH 2 P( i Pr) 2 ) 2 ), generated by dehydrogenation of iPr PCPIrH 4 with tert ‐butylethylene, readily provides the π‐adduct iPr PCPIr(η 2 ‐PhC≡CPh) in quantitative yield at room temperature. Heating solutions of iPr PCPIr(η 2 ‐PhC≡CPh) in aromatic hydrocarbon solvents leads to isomerization forming the 1‐iridaindene iPr PCPIr(C 8 H 5 (2‐Ph)). Surprisingly, this seemingly intramolecular reaction presents a kinetic isotope effect of 4.6 in C 6 H 6 versus C 6 D 6 solvent. The rate of this isomerization is effected by the availability of easily activated C−H bonds (i. e. aromatic C( sp 2 )‐H without ortho ‐substituents), and is strongly dependent upon the ratio of C−H to C−D bonds. Experiments indicate that many, or all, of the steps in this process may be reversible and that a highly fluxional C−H/D addition product is present during isomerization.