Four (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds were synthesized, and their activities in transfer hydrogenations of carbonyl compounds and transfer dehydrogenations of alcohols were explored and compared to those of the well-established [2,5-(SiMe3)2-3,4-(CH2)4(η4-C4C═O)]Fe(CO)3 (3 3). A new compound, [2,5-bis(3,5-dimethylphenyl)-3,4-diphenylcyclopentadienone]iron tricarbonyl (7 7), was the most active catalyst in both transfer hydrogenations and dehydrogenations, and compound 3

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... 3 was the least active catalyst in transfer hydrogenations. Evidence was found for product inhibition of both 3 3 and 7 7 in a transfer dehydrogenation reaction, with the activity of 3 3 being more heavily affected. A monomeric iron hydride derived from 7 7 was spectroscopically observed during a transfer hydrogenation, and no diiron bridging hydrides were found under reductive or oxidative conditions. Initial results in the transfer hydrogenation of N-benzylideneaniline showed that 3 3 was a significantly less active catalyst in comparison to the (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds. ABSTRACT: Four (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds were synthesized, and their activities in transfer hydrogenations of carbonyl compounds and transfer dehydrogenations of alcohols were explored and compared to those of the well-established [2,5-(SiMe 3 ) 2 -3,4-(CH 2 ) 4 (η 4 -C 4 CO)]Fe(CO) 3 (3). A new compound, [2,5-bis(3,5dimethylphenyl)-3,4-diphenylcyclopentadienone]iron tricarbonyl (7) , was the most active catalyst in both transfer hydrogenations and dehydrogenations, and compound 3 was the least active catalyst in transfer hydrogenations. Evidence was found for product inhibition of both 3 and 7 in a transfer dehydrogenation reaction, with the activity of 3 being more heavily affected. A monomeric iron hydride derived from 7 was spectroscopically observed during a transfer hydrogenation, and no diiron bridging hydrides were found under reductive or oxidative conditions. Initial results in the transfer hydrogenation of Nbenzylideneaniline showed that 3 was a significantly less active catalyst in comparison to the (3,4-diphenylcyclopentadienone) iron tricarbonyl compounds. See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.