TY - JOUR
T1 - DFT/TD-DFT analysis of structural, electrochemical and optical data from mononuclear osmium and heterobinuclear osmium-ruthenium alkynyl complexes
AU - Kulasekera, Erandi
AU - Petrie, Simon
AU - Stranger, Rob
AU - Cifuentes, Marie P.
AU - Humphrey, Mark G.
PY - 2013
Y1 - 2013
N2 - Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations of the molecular structures, optical absorption spectra, and spectroelectrochemical behavior of the complexes trans-[Os(CCC6H 4-4-CCH)Cl(dppe)2] (1), trans,trans-[(dppe) 2ClOs(CCC6H4-4-CC)RuCl(dppe)2] (2), trans,trans-[(dppe)2ClOs(CCC6H4-4-CC) Ru(CCC6H4-4-CCH)(dppe)2] (3), trans-[Os(CCC6H4-4-CCC6H4-4-CCH) Cl(dppe)2] (4), and trans,trans-[(dppe)2ClOs(CCC 6H4-4-CCC6H4-4-CC)RuCl(dppe) 2] (5) were undertaken. The calculated structures for the mononuclear osmium complexes 1 and 4 are in good agreement with the X-ray data, a 0.3 Å lengthening of the Os-Cl bond in proceeding from the theoretical model for 4 to the experimental structure being rationalized on the basis of intermolecular H-bonding effects for the latter. For the non-oxidized forms of these five complexes, the lowest-energy bands are assigned to MLCT transitions along the main molecular axis from orbitals with mostly Os d, Cl p and alkynyl character to orbitals on the alkynyl backbone. The calculations indicate that the heterobimetallic complexes 2, 3 and 5 do not undergo metal-centred oxidation. Instead, the electron is lost from an orbital that is delocalized across the bridge and both metal centres. The mono-oxidized and di-oxidized species show new bands in the low-energy region arising from LMCT transitions, primarily corresponding to transitions from the dppe ligands to metal- and alkynyl-based orbitals. For structures involving two or more phenylethynyl units along the main axis of the molecule, the TD-DFT calculations are in significantly better agreement with the observed spectra when the phenyl groups adopt a non-coplanar conformation.
AB - Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations of the molecular structures, optical absorption spectra, and spectroelectrochemical behavior of the complexes trans-[Os(CCC6H 4-4-CCH)Cl(dppe)2] (1), trans,trans-[(dppe) 2ClOs(CCC6H4-4-CC)RuCl(dppe)2] (2), trans,trans-[(dppe)2ClOs(CCC6H4-4-CC) Ru(CCC6H4-4-CCH)(dppe)2] (3), trans-[Os(CCC6H4-4-CCC6H4-4-CCH) Cl(dppe)2] (4), and trans,trans-[(dppe)2ClOs(CCC 6H4-4-CCC6H4-4-CC)RuCl(dppe) 2] (5) were undertaken. The calculated structures for the mononuclear osmium complexes 1 and 4 are in good agreement with the X-ray data, a 0.3 Å lengthening of the Os-Cl bond in proceeding from the theoretical model for 4 to the experimental structure being rationalized on the basis of intermolecular H-bonding effects for the latter. For the non-oxidized forms of these five complexes, the lowest-energy bands are assigned to MLCT transitions along the main molecular axis from orbitals with mostly Os d, Cl p and alkynyl character to orbitals on the alkynyl backbone. The calculations indicate that the heterobimetallic complexes 2, 3 and 5 do not undergo metal-centred oxidation. Instead, the electron is lost from an orbital that is delocalized across the bridge and both metal centres. The mono-oxidized and di-oxidized species show new bands in the low-energy region arising from LMCT transitions, primarily corresponding to transitions from the dppe ligands to metal- and alkynyl-based orbitals. For structures involving two or more phenylethynyl units along the main axis of the molecule, the TD-DFT calculations are in significantly better agreement with the observed spectra when the phenyl groups adopt a non-coplanar conformation.
KW - Alkynyl
KW - Density functional theory
KW - Osmium
KW - Ruthenium
KW - Time-dependent density functional theory
UR - http://www.scopus.com/inward/record.url?scp=84887052871&partnerID=8YFLogxK
U2 - 10.1016/j.jorganchem.2013.07.010
DO - 10.1016/j.jorganchem.2013.07.010
M3 - Article
SN - 0022-328X
VL - 748
SP - 21
EP - 28
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
ER -