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Photoinduced FeCp Bond Cleavage and Insertion Reactions of Strained Silicon‐ and Sulphur‐Bridged [1]Ferrocenophanes in the Presence of Transition‐Metal Carbonyls
Author(s) -
Ieong Nga Sze,
Chan Wing Yan,
Lough Alan J.,
Haddow Mairi F.,
Manners Ian
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700961
Subject(s) - chemistry , cyclopentadienyl complex , dimer , metal carbonyl , transition metal , tetramethylethylenediamine , metal , photochemistry , bond cleavage , photodissociation , medicinal chemistry , catalysis , organic chemistry
The photochemical reactions of the moderately strained sila[1]ferrocenophane [Fe(η‐C 5 H 4 ) 2 SiPh 2 ] ( 1 ) and the highly strained thia[1]ferrocenophane [Fe(η‐C 5 H 4 ) 2 S] ( 8 ) with transition‐metal carbonyls ([Fe(CO) 5 ], [Fe 2 (CO) 9 ] and [Co 2 (CO) 8 ]) have been studied. The use of metal carbonyls has allowed the products of photochemically induced Fe‐cyclopentadienyl (Cp) bond cleavage reactions in the [1]ferrocenophanes to be trapped as stable, characterisable products. During the course of these studies the synthesis of 8 from [Fe(η‐C 5 H 4 Li) 2 ⋅ TMEDA] (TMEDA= N , N , N ′, N ′‐tetramethylethylenediamine) and S(SO 2 Ph) 2 has been significantly improved by a change of reaction solvent and temperature. Photochemical reaction of 1 with excess [Fe(CO) 5 ] in THF gave the dinuclear complex [Fe 2 (CO) 2 (μ‐CO) 2 (η‐C 5 H 4 ) 2 SiPh 2 ] ( 9 ). The analogous photolytic reaction of 8 with [Fe(CO) 5 ] in THF gave cyclic dimer [Fe(η‐C 5 H 4 ) 2 S] 2 ( 10 ) and [Fe 2 (CO) 2 (μ‐CO) 2 (η‐C 5 H 4 ) 2 S] ( 11 ), with the former being the major product. Photolysis of 1 with [Co 2 (CO) 8 ] afforded the remarkable tetrametallic dimer [(CO) 2 Co(η‐C 5 H 4 )SiPh 2 (η‐C 5 H 4 )Fe(CO) 2 ] 2 ( 13 ). The corresponding photochemical reaction of 8 with [Co 2 (CO) 8 ] gave a trimetallic insertion product in high conversion, [Co(CO) 4 (CO) 2 Fe(η‐C 5 H 4 )S(η‐C 5 H 4 )Co(CO) 2 ] ( 14 ). These reactivity studies show that UV light promotes FeCp bond cleavage reactions of both of the [1]ferrocenophanes 1 and 8 . We have found that, whereas the less strained sila[1]ferrocenophane 1 requires photoactivation for FeCp bond insertions to occur, the highly strained thia[1]ferrocenophane 8 undergoes both irradiative and non‐irradiative insertions, although the latter occur at a slower rate. Our results suggest that such photoinduced bond cleavage reactions may be general and applicable to other related strained organometallic rings with π‐hydrocarbon ligands.