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Synthesis and Characterization of Potassium Complexes Containing Terminal η 2 ‐Pyrazolato Ligands
Author(s) -
Zheng Wenjun,
Heeg Mary Jane,
Winter Charles H.
Publication year - 2004
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.200400025
Subject(s) - chemistry , ligand (biochemistry) , crystallography , potassium , hydride , 18 crown 6 , metal , hydrogen bond , stereochemistry , inorganic chemistry , molecule , organic chemistry , receptor , biochemistry
The potassium complexes [K(η 2 ‐3,5‐R 2 pz)(η 6 ‐18‐crown‐6)] (R = Ph, t Bu; pz = pyrazolato) were prepared by treatment of 3,5‐diphenylpyrazole or 3,5‐di‐ tert ‐butylpyrazole with potassium hydride in the presence of 18‐crown‐6. These complexes contain η 6 ‐18‐crown‐6 and terminal η 2 ‐pyrazolato ligands, and constitute the first examples of group 1 metal complexes with this pyrazolato ligand coordination mode. In contrast to [K(η 2 ‐3,5‐Ph 2 pz)(η 6 ‐18‐crown‐6)] and [K(η 2 ‐3,5‐ t Bu 2 pz)(η 6 ‐18‐crown‐6)], the aqua complex [K(η 2 ‐3,5‐Me 2 pz)(H 2 O)(η 6 ‐18‐crown‐6)] was obtained when 3,5‐dimethylpyrazole was treated with potassium hydride and 18‐crown‐6 in the presence of a small amount of water. [K(η 2 ‐3,5‐Me 2 pz)(H 2 O)(η 6 ‐18‐crown‐6)] contains an η 2 ‐pyrazolato ligand that is bent towards being co‐facial with the best plane of the 18‐crown‐6 ligand, to allow hydrogen bonding between the pyrazolato ligand nitrogen atoms and the coordinated aqua ligand. The hydrogen bonding thus confers a novel terminal π‐facial η 2 ‐bonding mode to the pyrazolato ligand. All compounds were characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)