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Unexpected Behaviour of Pyridine‐2‐carbaldehyde Thiosemicarbazonatocopper( II ) Entities in Aqueous Basic Medium – Partial Transformation of Thioamide into Nitrile
Author(s) -
GómezSaiz Patricia,
GilGarcía Rubén,
Maestro Miguel A.,
Pizarro José Luis,
Arriortua María Isabel,
Lezama Luis,
Rojo Teófilo,
GarcíaTojal Javier
Publication year - 2005
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.200500326
Subject(s) - chemistry , semicarbazone , aqueous solution , thioamide , octahedron , ligand (biochemistry) , pyridine , medicinal chemistry , nitrile , copper , square pyramidal molecular geometry , ion , inorganic chemistry , stereochemistry , nuclear chemistry , organic chemistry , receptor , biochemistry
Unusual species are obtained from the HL/Cu II /NO 3 – system (HL = pyridine‐2‐carbaldehyde thiosemicarbazone) in basic aqueous solutions. A partial desulfurization process occurs for 1:1 Cu/HL molar ratio which gives rise to the precipitation of the mixed ligand [Cu(L)(L CN )] ( 1 ) complex [HL CN = C 7 H 6 N 4 , (pyridin‐2‐ylmethylene)hydrazinecarbonitrile]. This compound contains Cu II ions in a square‐pyramidal environment. On the other hand, distorted octahedral [Cu(L) 2 ] ( 2 ) entities are isolated in excess of the thiosemicarbazone ligand. Desulfurization of the thiosemicarbazone is detected even at physiological pH values. However, this reaction does not take place in absence of Cu II ions, and HL · 2.25H 2 O ( 3 ) or HL · H 2 O are obtained in these conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)