Premium
Synthesis, Crystal Structure, Spectroscopy, and Theoretical Investigations of Tetrahedrally Distorted Copper(II) Chelates with [CuN 2 S 2 ] Coordination Sphere
Author(s) -
Knoblauch Stephan,
Benedix Roland,
Ecke Martin,
Gelbrich Thomas,
Sieler Joachim,
Somoza Fernando,
Hennig Horst
Publication year - 1999
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199908)1999:8<1393::aid-ejic1393>3.0.co;2-3
Subject(s) - chemistry , crystallography , copper , coordination sphere , electron paramagnetic resonance , molecular orbital , antibonding molecular orbital , crystal structure , delocalized electron , ligand (biochemistry) , atomic orbital , molecule , nuclear magnetic resonance , electron , biochemistry , physics , receptor , organic chemistry , quantum mechanics
A series of tetrahedrally distorted copper(II) complexes with thiolate and imine coordination were synthesized. Schiff bases derived from 4‐benzoyl‐3‐methyl‐1‐phenyl‐2‐pyrazoline‐5‐thione and various diamines were used as tetradentate ligands to obtain tetrahedrally distorted metal chelates with [CuN 2 S 2 ] complex units. Crystal structures of the complexes 1 , 2 , 5 and 6 and of ligand H 2 5 have been determined by means of single‐crystal X‐ray structure analysis. The structure data show a strong influence of the diamine building blocks on the tetrahedral distortion of the copper(II) complexes. Results of Extended Hückel LCAO calculations correlate strongly with structural, electrochemical, UV/Vis‐ and EPR‐spectroscopic features obtained experimentally. The calculations confirm for the whole complex series a strong delocalization of the frontier orbitals. The highest fully occupied molecular orbital shows a weak contribution, resulting from thiolate donor atoms, whereas the antibonding singly occupied molecular orbitals (SOMOs) are distributed between the copper(II) centre (ca. 35–40%) and the N 2 S 2 donor set. The SOMO energy significantly lowers with increasing tetrahedral distortion of the coordination sphere. The influence of the tetrahedral distortion of copper(II) complexes on redox potentials, UV/Vis and EPR spectra is discussed.