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Organic Matrix and Solution Photochemical Studies of (Allyl)dicarbonyl(cyclopentadienyl)molybdenum Compounds
Author(s) -
Bitterwolf Thomas E.,
Bays J. Timothy,
Scallorn Bruce,
Weiss Callie Ann,
George Michael W.,
Virrels Ian G.,
Linehan John C.,
Yonker Clement R.
Publication year - 2001
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200109)2001:10<2619::aid-ejic2619>3.0.co;2-7
Subject(s) - chemistry , conformational isomerism , photochemistry , cyclopentadienyl complex , photodissociation , molybdenum , ethylene , flash photolysis , medicinal chemistry , inorganic chemistry , organic chemistry , kinetics , molecule , catalysis , physics , quantum mechanics , reaction rate constant
Photolysis of fresh samples of the η 3 ‐allyl compounds [(η 5 ‐C 5 H 5 )Mo(CO) 2 (η 3 ‐C 3 H 5 )] or [(η 5 ‐C 5 H 5 )Mo(CO) 2 (η 3 ‐C 3 H 4 CH 3 )] in a Nujol matrix at ca. 90 K at a wavelength greater than 400 nm was found by IR spectroscopy to cause conversion of the endo rotamer to the exo rotamer. Photolysis of exo enriched samples of [(η 5 ‐C 5 H 5 )Mo(CO) 2 (η 3 ‐C 3 H 5 )] at wavelengths of between 360 and 400 nm reversed the photoconversion leading to an exo to endo conversion. At higher energies photochemical CO loss was also observed. In the case of the 2‐methylallyl derivative, a photoproduct believed to be [(η 5 ‐C 5 H 5 )Mo(H)(CO)(η 4 ‐C 4 H 6 )] was observed along with CO loss. Time‐resolved IR studies of the flash photolysis of [(η 5 ‐C 5 H 5 )Mo(CO) 2 (η 3 ‐C 3 H 5 )] in n ‐heptane confirm both endo to exo rotamer conversion and CO loss. Under these conditions, the species formed after CO loss is probably [(η 5 ‐C 5 H 5 )Mo(CO)( n ‐heptane)(η 3 ‐C 3 H 5 )]. When [(η 5 ‐C 5 H 5 )Mo(CO) 2 (η 3 ‐C 3 H 5 )] was dissolved in supercritical ethylene and photolyzed, [(η 5 ‐C 5 H 5 )Mo(CO)(C 2 H 4 )(η 3 ‐C 3 H 5 )] was formed. A mechanism involving two distinct excited states is proposed to account for the photoreversible endo / exo transformations.