TY - JOUR
T1 - Metal-Metal Interaction in Fischer Carbene Complexes
T2 - A Study of Ferrocenyl and Biferrocenyl Tungsten Alkylidene Complexes
AU - van der Westhuizen, Belinda
AU - Speck, J. Matthaeus
AU - Korb, Marcus
AU - Friedrich, Joachim
AU - Bezuidenhout, Daniela I.
AU - Lang, Heinrich
PY - 2013/12/16
Y1 - 2013/12/16
N2 - A series of ferrocenyl (Fc = ferrocenyl; fc = ferrocen-1,1'-diyl) and biferrocenyl (Bfc = 1',1 ''-biferrocenyl; bfc = 1',1 ''-biferrocen-1,1'''-diyl) mono- and biscarbene tungsten(0) complexes of the type [(CO)(5)W=C(OMe)R] (1, R = Fe; 3, R = Bfc) and [(CO)(5)W=C(OMe)-R'-(OMe)C=W(CO)(5)] (2, R' = fc; 4, R' = bfc) were synthesized according to the classical synthetic methodology by reacting W(CO)(6) with LiR (R = Fc, fc, bfc), followed by a subsequent alkylation using methyl trifluoromethanesulfonate. Electrochemical investigations were carried out on these complexes to get a closer insight into the electronic properties of 1-4. The ferrocenyl and biferrocenyl moieties in 1-4 show reversible one-electron redox events. It was further found that the Fischer carbene unit is reducible in an electrochemical one-electron transfer process. For the tungsten carbonyl moieties, irreversible oxidation processes were found. In addition, charge transfer studies were performed on 1-4 using in situ UV-vis-NIR and infrared spectroelectrochemical techniques. During the UV-vis-NIR investigations, typical low energy transitions for the mixed-valent biferrocenyl unit were found. A further observed-high energy NIR absorption is attributed to a metal-metal charge transfer transition between the tungsten carbonyl fragment and the ferrocenyl/biferrocenyl group in the corresponding oxidized states, which can be described as class II systems according to Robin and Day. This assignment was verified by infrared spectroelectrochemical studies. The electrochemical investigations are supported by density functional theory calculations. The structural properties of 1-4 in the solid state were investigated by single-crystal X-ray diffraction studies showing no substituent effects on bond lengths and angles. The biferrocenyl derivatives exhibit syn-conformation of the ferrocenyl and carbene building blocks.
AB - A series of ferrocenyl (Fc = ferrocenyl; fc = ferrocen-1,1'-diyl) and biferrocenyl (Bfc = 1',1 ''-biferrocenyl; bfc = 1',1 ''-biferrocen-1,1'''-diyl) mono- and biscarbene tungsten(0) complexes of the type [(CO)(5)W=C(OMe)R] (1, R = Fe; 3, R = Bfc) and [(CO)(5)W=C(OMe)-R'-(OMe)C=W(CO)(5)] (2, R' = fc; 4, R' = bfc) were synthesized according to the classical synthetic methodology by reacting W(CO)(6) with LiR (R = Fc, fc, bfc), followed by a subsequent alkylation using methyl trifluoromethanesulfonate. Electrochemical investigations were carried out on these complexes to get a closer insight into the electronic properties of 1-4. The ferrocenyl and biferrocenyl moieties in 1-4 show reversible one-electron redox events. It was further found that the Fischer carbene unit is reducible in an electrochemical one-electron transfer process. For the tungsten carbonyl moieties, irreversible oxidation processes were found. In addition, charge transfer studies were performed on 1-4 using in situ UV-vis-NIR and infrared spectroelectrochemical techniques. During the UV-vis-NIR investigations, typical low energy transitions for the mixed-valent biferrocenyl unit were found. A further observed-high energy NIR absorption is attributed to a metal-metal charge transfer transition between the tungsten carbonyl fragment and the ferrocenyl/biferrocenyl group in the corresponding oxidized states, which can be described as class II systems according to Robin and Day. This assignment was verified by infrared spectroelectrochemical studies. The electrochemical investigations are supported by density functional theory calculations. The structural properties of 1-4 in the solid state were investigated by single-crystal X-ray diffraction studies showing no substituent effects on bond lengths and angles. The biferrocenyl derivatives exhibit syn-conformation of the ferrocenyl and carbene building blocks.
KW - INTRAMOLECULAR ELECTRON-TRANSFER
KW - ESI-MASS-SPECTROMETRY
KW - SOLID-STATE STRUCTURE
KW - AUXILIARY BASIS-SETS
KW - MOSSBAUER CHARACTERISTICS
KW - SUPPORTING ELECTROLYTE
KW - NONAQUEOUS SOLVENTS
KW - DELTA-E-1/2 VALUES
KW - CORRELATION-ENERGY
KW - TRANSITION-METALS
U2 - 10.1021/ic402202w
DO - 10.1021/ic402202w
M3 - Article
VL - 52
SP - 14253
EP - 14263
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 24
ER -