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Maleamate(–1) and Maleate(–2) Copper(II)–2,2′‐Bipyridine Complexes: Synthesis, Reactivity and Structural and Physical Studies
Author(s) -
Lazarou Kateri.,
Boudalis Athanassios K.,
Perlepes Spyros P.,
Terzis Aris,
Raptopoulou Catherine P.
Publication year - 2009
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.200900485
Subject(s) - chemistry , amide , reactivity (psychology) , maleic acid , hydrolysis , metal , medicinal chemistry , copper , ligand (biochemistry) , stereochemistry , crystallography , organic chemistry , medicine , biochemistry , alternative medicine , receptor , pathology , copolymer , polymer
A systematic investigation of the 1:2:1:2 Cu(NO 3 ) · 2.5H 2 O/H 2 L/bpy/LiOH · H 2 O (H 2 L = maleamic acid) reaction system in MeCN/H 2 O was carried out. The compounds [Cu 2 (HL) 2 (bpy) 2 (H 2 O) 2 ](NO 3 ) 2 ( 1 ), [Cu 2 (HL) 2 (bpy) 2 (H 2 O) 2 ](NO 3 ) 2 · 2H 2 O ( 1· 2H 2 O), [Cu 2 Li 2 (L′) 2 (bpy) 2 (H 2 O) 6 ][Cu 2 (HL) 2 (bpy) 2 (H 2 O) 2 ](NO 3 ) 4 ( 2 ), [Cu 4 (L′) 2 (NO 3 ) 2 (bpy) 4 (H 2 O) 2 ](NO 3 ) 2 · 2H 2 O ( 3· 2H 2 O) and [Cu(L′)(bpy)] n · 2 n H 2 O ( 4· 2 n H 2 O) were isolated, depending on the crystallization method employed. Complexes 2 , 3· 2H 2 O and 4· 2 n H 2 O contain the maleate(–2) anion (L′ 2– ), which was formed in situ through metal‐ion‐assisted hydrolysis of the primary amide group of H 2 L. Efforts to prepare complex 3 from the direct use of maleic acid (H 2 L′) afforded compounds 4· 2 n H 2 O, [Cu 4 (L′) 2 (NO 3 ) 2 (bpy) 4 (H 2 O) 2 ](NO 3 ) 2 · 2[Li(NO 3 )(H 2 O) 3 ] · 4H 2 O ( 5· 4H 2 O) and [Cu(NO 3 )(bpy)(H 2 O) 3 ](NO 3 ) ( 6 ) from the 1:1:1:2 Cu(NO 3 ) · 2.5H 2 O/H 2 L′/bpy/LiOH · H 2 O reaction system in MeCN/H 2 O. The maleamate(–1) ligand presents the less common η 1 :μ 2 coordination mode in the cations of 1 , 1· 2H 2 O and 2 . The maleate(–2) ligand exhibits the η 1 :η 1 :η 1 :η 1 :μ 3 coordination mode in the [Cu II 4 ] cations of 3· 2H 2 O and 5· 4H 2 O and in the [Cu II 2 Li I 2 ] heterometallic cation of 2 . The crystal structures of the complexes are stabilized by various H‐bonding patterns. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the ligands. Magnetic susceptibility measurements for 3· 2H 2 O reveal weak ferromagnetic interactions along the periphery of the Cu 4 rhombus ( J = 3.3 cm –1 , –2 J ij S i S j Hamiltonian formalism), which stabilizes an S = 2 ground state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)