TY - JOUR
T1 - Oxidative Addition of Trisubstituted Silanes To Photochemically Generated Coordinatively Unsaturated Species (»!12 34-c4h4)fe(co)2, (7)6-c5hs)mn(co)2, and (»j6-csh6)cr(co)2and Related Molecules
AU - Hill, Ross H.
AU - Wrighton, Mark S.
PY - 1987/3/1
Y1 - 1987/3/1
N2 - Irradiation of (r;4-C4H4)Fe(CO)3, (75-C6H5)Mn(CO)3, (75-C5Me6)Mn(CO)3, (7,6-C6H6)Re(CO)3, and(t6-C6H6)Cr(CO)3leads to dissociative CO loss to form 16e dicarbonyl species. At low temperatures, 85–157 K, the unsaturated dicarbonyl molecules can be spectroscopically (IR) characterized in inert organic solvents, such as methylcyclohexane or 3-methylpentane. In the presence of R3SiH the dicarbonyl species react to form 18e oxidative addition products of the formula (77n-C„R)MH(SiR3)(CO)2. For all dicarbonyl species the rate of reaction with Et3SiH was investigated. For the Fe and two Mn species a complete study of rate vs. temperature was made. The Cr species reacts too fast to measure quantitatively. The reaction of Et3SiH with the Re species occurs only above 157 K, and detailed studies were not made. The results give an overall reactivity trend for the dicarbonyls toward neat Et3SiH at 100 K of Cr > Mn > Fe > Re and C6Me6> C5H5. The difference in rate with C6Me5vs. C5H5is a factor of ~ 102over a wide temperature range, and the difference between Cr and Re at 100 K is at least 104. The reactivities of various silanes toward (n5-C6H5)Mn(CO)2 were also investigated as a function of temperature. The activation parameters, AHt and AS*, show only modest variation with silane such that AH* EtMe2SiH (25 ± 1 kJ mol-1) < Ph3SiH (28 ± 1 kJ mol-1) < i-Pr3SiH (29 ± 1 kJ mol-1) < n-Pr3SiH (30 ± 1 kJ mol-1) Et3SiH (30 ± 1 kJ mol-1) and AS* Et3SiH (-28 ± 5 J K-1mol-1) < n-Pr3SiH (-31 ± 5 J K-1mol-1) ~ Ph3SiH (-31 ± 5 J K-1mol-1) < i-Pr„SiH (-33 ± 5 J K-1mol-1) < EtMe.SiH (-40 ± 5 J K-1mol-1).
AB - Irradiation of (r;4-C4H4)Fe(CO)3, (75-C6H5)Mn(CO)3, (75-C5Me6)Mn(CO)3, (7,6-C6H6)Re(CO)3, and(t6-C6H6)Cr(CO)3leads to dissociative CO loss to form 16e dicarbonyl species. At low temperatures, 85–157 K, the unsaturated dicarbonyl molecules can be spectroscopically (IR) characterized in inert organic solvents, such as methylcyclohexane or 3-methylpentane. In the presence of R3SiH the dicarbonyl species react to form 18e oxidative addition products of the formula (77n-C„R)MH(SiR3)(CO)2. For all dicarbonyl species the rate of reaction with Et3SiH was investigated. For the Fe and two Mn species a complete study of rate vs. temperature was made. The Cr species reacts too fast to measure quantitatively. The reaction of Et3SiH with the Re species occurs only above 157 K, and detailed studies were not made. The results give an overall reactivity trend for the dicarbonyls toward neat Et3SiH at 100 K of Cr > Mn > Fe > Re and C6Me6> C5H5. The difference in rate with C6Me5vs. C5H5is a factor of ~ 102over a wide temperature range, and the difference between Cr and Re at 100 K is at least 104. The reactivities of various silanes toward (n5-C6H5)Mn(CO)2 were also investigated as a function of temperature. The activation parameters, AHt and AS*, show only modest variation with silane such that AH* EtMe2SiH (25 ± 1 kJ mol-1) < Ph3SiH (28 ± 1 kJ mol-1) < i-Pr3SiH (29 ± 1 kJ mol-1) < n-Pr3SiH (30 ± 1 kJ mol-1) Et3SiH (30 ± 1 kJ mol-1) and AS* Et3SiH (-28 ± 5 J K-1mol-1) < n-Pr3SiH (-31 ± 5 J K-1mol-1) ~ Ph3SiH (-31 ± 5 J K-1mol-1) < i-Pr„SiH (-33 ± 5 J K-1mol-1) < EtMe.SiH (-40 ± 5 J K-1mol-1).
UR - https://www.scopus.com/pages/publications/0013499915
U2 - 10.1021/om00146a033
DO - 10.1021/om00146a033
M3 - Article
AN - SCOPUS:0013499915
SN - 0276-7333
VL - 6
SP - 632
EP - 638
JO - Organometallics
JF - Organometallics
IS - 3
ER -