TY - JOUR
T1 - Electrochemical properties of a disilene, a tetrasila-l,3-butadiene, and their germanium analogues
AU - Schäfer, Annemarie
AU - Weidenbruch, Manfred
AU - Müller, Thomas
AU - Pravinkumar, Kendrekar
AU - Becker, James Y.
PY - 2009/8/24
Y1 - 2009/8/24
N2 - The redox properties of arylsubstituted disuene (1), tetrasila-l,3- butadiene (2), digermene (3), and tetragerma-l,3-butadiene (4) (in which the aryl group is 2,4,6-triisopropylphenyl) have been studied by cyclic voltammetry (CV) in two different solvents. In odichlorobenzene, disuene 1 exhibited reversible redox couples in both oxidation and reduction processes, whereas tetrasilabutadiene 2 showed a reversible behavior only in its oxidation and an irreversible wave in its reduction. Tetragermabutadiene 4 afforded a reversible couple in its reduction and an irreversible wave in its oxidation, whereas digermene 3 showed only an irreversible oxidation wave but no reduction one. In comparison, all observed oxidation and reduction waves in THF were irreversible. In both solvents, the same trend of decreasing ease of oxidation has been observed: 2>4>3>1. The calculated vertical ionization energies (E i) for the 2,6-dimethylphenyl-substituted model compounds 9-12 afforded a trend of ease of oxidation that decreases in the series tetrasilabutadiene 10 > tetragermabuta-diene 12 > disilene 9 > digermene 11. This predicted trend parallels the measured oxidation potentials in the sense that the heavy butadienes are easier to oxidize than the heavy alkenes. The trend in the reduction direction has been found to be different in the two solvents studied. The computed electron affinities (Eea) for compounds 912 indicated that the ease of reduction decreased in the sequence tetragermabutadiene 12 > tetrasilabutadiene 10 > digermene 11 > disilene 9. However, no straightforward relation between the computed electron affinities and the experimentally measured reduction potentials has been found.
AB - The redox properties of arylsubstituted disuene (1), tetrasila-l,3- butadiene (2), digermene (3), and tetragerma-l,3-butadiene (4) (in which the aryl group is 2,4,6-triisopropylphenyl) have been studied by cyclic voltammetry (CV) in two different solvents. In odichlorobenzene, disuene 1 exhibited reversible redox couples in both oxidation and reduction processes, whereas tetrasilabutadiene 2 showed a reversible behavior only in its oxidation and an irreversible wave in its reduction. Tetragermabutadiene 4 afforded a reversible couple in its reduction and an irreversible wave in its oxidation, whereas digermene 3 showed only an irreversible oxidation wave but no reduction one. In comparison, all observed oxidation and reduction waves in THF were irreversible. In both solvents, the same trend of decreasing ease of oxidation has been observed: 2>4>3>1. The calculated vertical ionization energies (E i) for the 2,6-dimethylphenyl-substituted model compounds 9-12 afforded a trend of ease of oxidation that decreases in the series tetrasilabutadiene 10 > tetragermabuta-diene 12 > disilene 9 > digermene 11. This predicted trend parallels the measured oxidation potentials in the sense that the heavy butadienes are easier to oxidize than the heavy alkenes. The trend in the reduction direction has been found to be different in the two solvents studied. The computed electron affinities (Eea) for compounds 912 indicated that the ease of reduction decreased in the sequence tetragermabutadiene 12 > tetrasilabutadiene 10 > digermene 11 > disilene 9. However, no straightforward relation between the computed electron affinities and the experimentally measured reduction potentials has been found.
KW - Computer chemistry
KW - Conjugation
KW - Cyclic voltammetry
KW - Germanium
KW - Silicon
UR - http://www.scopus.com/inward/record.url?scp=69249116985&partnerID=8YFLogxK
U2 - 10.1002/chem.200901001
DO - 10.1002/chem.200901001
M3 - Article
C2 - 19575430
AN - SCOPUS:69249116985
SN - 0947-6539
VL - 15
SP - 8424
EP - 8428
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 34
ER -