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Reaktionen des Tripod‐Co‐Templats CH 3 C(CH 2 PPh 2 ) 3 Co(II) mit funktionalisierten Hydrazinen
Author(s) -
Körner Volkmar,
Vogel Sabine,
Huttner Gottfried,
Zsolnai Laszlo,
Walter Olaf
Publication year - 1996
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19961290921
Subject(s) - chemistry , tripod (photography) , ligand (biochemistry) , cobalt , medicinal chemistry , stereochemistry , chelation , crystallography , inorganic chemistry , biochemistry , physics , receptor , optics
The coordination behaviour of ligands having the same basic constitution RN=NC(=X)R′ (X O, NR″, S) in their tripod cobalt derivatives has been analyzed. The ligands themselves may be considered as neutral heterodiene compounds and are in this respect vinylogues to diazenes RNNRy′. Two‐ electron reduction of these neutral species results in dianionic heterosubstituted heteroolefins RN ‐ ‐NC(X ‐ )R′. Due to their redox ambiguity the oxidation state of the metal M in chelate complexes is not a priori evident. Compounds tripod [ 5 : X, R′ O, Ph; 6 ; (X, R′) (py); 7 : X, R′ S, NH 2 ] are best described as containing low‐spin Co(III) and dianionic ligands. Co(II) species are obtained with diethyl azodicarboxylate EtOOCNNCOOEt as the ligand. In the mononuclear compound, with only one nitrogen and one carbonyl oxygen of the ligand acting as donor groups, the neutral ligand is coordinated to give the high‐spin cobalt(II) species tripod ( 8 ). In the dinuclear compound 9 with both of the nitrogen atoms and carbonyl groups involved in coordination the dianionic ligand bridges two high‐spin cobalt(II) centers to give tripod ( 9 ) as a derivative with two fused five‐membered chelate rings. In addition to the conventional analytical techniques X‐ray structure analyses, cyclovoltametric measurements, magnetic susceptibility and ESR data are used to characterize the compounds.