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Coordination Chemistry of Unsymmetrical Tripodal Ligands with an NNO 2 Donor Set
Author(s) -
Ochs Christian,
Hahn F. Ekkehardt,
Fröhlich Roland
Publication year - 2001
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 - 10.1002/1099-0682(200109)2001:9<2427::aid-ejic2427>3.0.co;2-7
Subject(s) - chemistry , square pyramidal molecular geometry , copper , ligand (biochemistry) , coordination geometry , crystallography , stereochemistry , coordination complex , metal , yield (engineering) , radical , crystal structure , molecule , receptor , organic chemistry , hydrogen bond , biochemistry , materials science , metallurgy
The synthesis of two new tripodal ligands N(CH 2 CH 2 NH 2 )(CH 2 CH 2 CH 2 OH) 2 (H 4 ‐ 1 ) and N[2,3,5‐C 6 H 2 ‐(OH)(SCH 3 )(CH 3 )](CH 2 CH 2 CH 2 NH 2 )(CH 2 CH 2 CH 2 OH) (H 4 ‐ 2 ) is reported. Both tetradentate ligands contain a central tertiary nitrogen atom, as well as two OH and one NH 2 functionalized ligand arm. The tripods do not only exhibit an unsymmetrical N 2 O 2 donor set, but also possess two C 3 and one C 2 chains between the central nitrogen atom and the terminal donors. On coordination of the central tertiary nitrogen atom, the ligands are capable of forming both six‐ and five‐membered chelate rings in their metal complexes. Both ligands react with [Cu(OAc) 2 ·H 2 O] 2 to give the dinuclear copper(II) complexes [Cu(η 4 ‐μ‐O‐H 3 ‐ 1 ) 2 Cu](PF 6 ) 2 ( 3 ) and [(η 3 ‐H 3 ‐ 2 )Cu(μ‐OAc) 2 Cu(η 3 ‐H 3 ‐ 2 )]·2CH 3 CN ( 4· 2CH 3 CN). The molecular structures of 3 and 4· 2CH 3 CN have been determined by X‐ray diffraction. Complex 3 contains two slightly distorted square‐pyramidal (τ = 0.181) copper atoms, with O‐donors in the apical positions. The dinuclear complex 4 , which was synthesized to model the copper site in galactose oxidase, also shows a distorted square‐pyramidal coordination geometry (τ = 0.205 and τ = 0.101) around both copper(II) atoms. Complex 4 contains two uncoordinated primary alcohol functionalities of the ligands. In addition, both the ligand H 4 ‐ 2 and its dinuclear copper complex [(η 3 ‐H 3 ‐ 2 )Cu(μ‐OAc) 2 (η 3 ‐H 3 ‐ 2 )]·2CH 3 CN can easily be oxidized to yield free or coordinated phenoxyl radicals, which are stable on the time scale of cyclic voltammetry.