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Tetranuclear Complexes of Pd II with Tridentate [ C , N , O ] and [ O , N , O ] Ligands: Synthesis, Reactivity and Structural Isomerism
Author(s) -
Fernández Jesús J.,
Fernández Alberto,
VázquezGarcía Digna,
LópezTorres Margarita,
Suárez Antonio,
GómezBlanco Nina,
Vila José M.
Publication year - 2007
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.200700478
Subject(s) - chemistry , palladium , ligand (biochemistry) , medicinal chemistry , reactivity (psychology) , stereochemistry , toluene , catalysis , organic chemistry , receptor , medicine , biochemistry , alternative medicine , pathology
Treatment of the Schiff base ligand 2,3,4‐(MeO) 3 C 6 H 2 C(H)=N[2‐(OH)‐5‐ t BuC 6 H 3 ] ( a ) with palladium(II) acetate in toluene gave the cyclometallated complex [Pd{2,3,4‐(MeO) 3 C 6 HC(H)=N(2‐O‐5‐ t BuC 6 H 3 )}] 4 ( 1a ) with the tridentate ligand [ C , N , O ]. The complex showed a tetranuclear arrangement of the cyclometallated monomers with a P 4 O 4 core. Reaction of 2,6‐(Me) 2 C 6 H 3 C(H)=N[2‐(OH)C 6 H 4 ] ( b ) and 2,5‐(Me) 2 C 6 H 3 C(H)=N[2‐(OH)C 6 H 4 ] ( c ) with palladium(II) acetate under similar conditions yielded the tetranuclear complexes [Pd{6‐Me‐2‐CH 2 C 6 H 3 C(H)=N(2‐OC 6 H 4 )}] 4 ( 1b ) and [Pd{5‐Me‐2‐CH 2 C 6 H 3 C(H)=N(2‐OC 6 H 4 )}] 4 ( 1c ), respectively, in which the tridentate [ C , N , O ] ligand is bound through the aliphatic methyl carbon. Treatment of 2,4‐(Me) 2 C 6 H 3 C(H)=N[2‐(OH)C 6 H 4 ] ( d ) with palladium(II) acetate yielded a mixture of isomers, [Pd{4‐Me‐2‐CH 2 C 6 H 3 C(H)=N(2‐OC 6 H 4 )}] n [Pd{2,4‐(Me) 2 C 6 H 2 C(H)=N(2‐OC 6 H 4 )}] 4– n ( n = 0–4), also bearing a tetranuclear structure. However, thetetramer was assembled by two types of mononuclear Pd(ligand) building blocks: the ligand is coordinated through the aliphatic methyl carbon in one and through the aromatic ortho carbon in the other. The crystal structure of one such isomer confirmed the spectroscopic data. Treatment of 2‐(OH)‐4,6‐(MeO) 2 C 6 H 2 C(H)=N[2‐(OH)C 6 H 4 ] ( e ) and 2‐(OH)C 6 H 4 C(H)=N[2‐(OH)C 6 H 4 ] ( f ) with palladium(II) acetate yielded the tetranuclear complexes [Pd{2‐O‐4,6‐(MeO) 2 C 6 H 2 C(H)=N(2‐OC 6 H 4 )}] 4 ( 1e ) and [Pd{2‐OC 6 H 4 C(H)=N(2‐OC 6 H 4 )}] 4 ( 1f ), respectively, after double deprotonation of the ligand, which coordinates to the metal through the two phenoxy oxygen atoms and the imine nitrogen atom in these complexes. Reaction of compounds 1a – 1f with tertiary phosphanes in acetone gave mono‐ and dinuclear complexes, after cleavage of the tetranuclear structure. In these complexes, the tertiary phosphane is bonded trans to the nitrogen atom. The crystal structures for 1a , 1c , 1e , 1d / 1d′ are reported; they show the characteristic Pd 4 O 4 core.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)