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Insights into Different Donor Abilities in Bis(pyrazolyl)pyridinylmethane Transition Metal Complexes
Author(s) -
Hoffmann Alexander,
Flörke Ulrich,
HerresPawlis Sonja
Publication year - 2014
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/ejic.201400056
Subject(s) - chemistry , zinc , ligand (biochemistry) , isodesmic reaction , transition metal , metal , cobalt , medicinal chemistry , stereochemistry , crystallography , molecule , inorganic chemistry , catalysis , receptor , biochemistry , organic chemistry
Abstract We synthesised and characterised eleven complexes of the biomimetic bis(pyrazolyl)methanes (2‐pyridinyl)bis(pyrazolyl)methane [HC(Pz) 2 (Py)] and (2‐quinolinyl)bis(pyrazolyl)methane [HC(Pz) 2 (Qu)] with the transition metals cobalt, iron, copper and zinc. With the pyridinyl ligand HC(Pz) 2 (Py), we obtained the bifacial complexes [Co{HC(Pz) 2 (Py)} 2 ]Cl 2 · 2CH 3 CN ( C1 ), [Co{HC(Pz) 2 (Py)} 2 ][CF 3 SO 3 ] 2 ( C2 ), [Fe{HC(Pz) 2 (Py)} 2 ]Cl 2 · 2CH 3 OH [ C3 ], [Cu{HC(Pz) 2 (Py)} 2 ]Cl 2 · 2CH 3 OH ( C4a ) and [Cu{HC(Pz) 2 (Py)} 2 ][CuCl 3 H 2 O] ( C4b ) and the monofacial complex [CuCl 2 {HC(Pz) 2 (Py)}] · CH 3 OH ( C5 ); with the quinolinyl ligand HC(Pz) 2 (Qu), we obtained the bifacial complexes [Co{HC(Pz) 2 (Qu)} 2 ][CoCl 4 ] · 4CH 3 CN · 0.88CH 2 Cl 2 ( C6 ) and [Fe{HC(Pz) 2 (Qu)} 2 ][FeCl 4 ] · 2CH 3 CN ( C7 ), the monofacial complexes [FeCl 2 {HC(Pz) 2 (Qu)}] ( C8 ) and [CuBr 2 {HC(Pz) 2 (Qu)}] ( C9 ) and the bifacial zinc complex [Zn{HC(Pz) 2 (Qu)} 2 ][ZnCl 4 ] ( C10 ). We explored the donor properties of the free ligands and the ligands in these complexes and found that the delicate donor competition is an intriguing field. By second‐order perturbation theory, pyrazolyl units are the stronger donors, although pyridinyl units are more basic. Isodesmic reactions indicate that the pyridinyl donors give a stronger complex stabilisation. This small bias can be disturbed by subtle variations of the coordination geometry, which is important in the bioinorganic context.