Binuclear metal complexes. 2. A unique mononuclear copper(I) complex with a potentially binucleating Schiff base ligand

Abstract

The attempted synthesis of binuclear copper(I) complexes with the binucleating Schiff base ligand (AEP)2IPAH derived from the condensation of 2-hydroxy-5-methylisophthalaldehyde and 2-(2-aminoethyl)pyridine leads to the isolation of the mononuclear complexes [Cu^AEP^IPAHJCu'C^a nd [CuI(AEP)2IPAH]BF4. Analytical data and spectral and magnetic studies support the proposed formulations of these complexes. The intense visible absorption band for the cation [Cu1 3-(AEP)2IPAH]+ is attributed to an intraligand -* transition within a keto amine tautomer of the Schiff base ligand which is stabilized by coordination with copper(I). [Cu!(AEP)2IPAH]+ reacts reversibly with carbon monoxide in acetonitrile or dimethyl sulfoxide solution at room temperature to form a terminally bonded CO adduct (yCo = 2075 cm™1). The copper(I) complexes are very sensitive toward oxygen, and air oxidation of [Cu*(AEP)2IPAH]CuICl2 leads to the binuclear copper(II) complex [Cu2(AEP)2IPA(OH)]Cl2, similar to those reported previously.

Double‐CO32− Centered [CoII5] Wheel and Modeling of Its Magnetic Properties

“…[15] The reaction of Hbpp with an equimolar amount of CoA C H T U N G T R E N N U N G (ClO 4 ) 2 in the presence of a strong base (NaOMe or NaOH) in MeOH or DMF leads to either a precipitate or crystals of 1, respectively, following CO 2 uptake from the atmosphere, according to Equation (1).…”

“…2,6-Bis(phenyliminomethyl)-4-methylphenolate (Hbpp) was prepared by a literature procedure. [15] All other chemicals and solvents were reagent grade materials and were used as received without further purification. All the reactions were performed in air at room temperature, unless otherwise indicated. )…”

“…[11][12][13] More recently, some of us have proposed a convenient model to treat the magnetic exchange within polynuclear clusters of axially distorted six-coordinate cobalt(II) ions invoking a perturbational approach, which greatly reduces the size of the matrices to be diagonalized. [14] We report here the synthesis and structure of a rare [Co II 5 ] wheel, assembled by the bridging action of the Schiffbase ligand Hbpp (2,6-bis(phenyliminomethyl)-4-methylphenol, Scheme 1) [15] and the template effect of two carbonate ions, with the formula [Co 5 - (1). The ligand Hbpp should favor the assembly of dinuclear moieties with vacant coordination sites, which should therefore be prone to bind to other exogenous donors, eventually facilitating the growth of the system into higher nuclearity species.…”

Antiferromagnetic super exchange and spectral studies on dimeric 8-quinolinolato complexes of copper(II) imides

“…However, the monomeric copper(I1) complexes of 8-hydroxyquinoline gave a band of low intensity and at lower energy, i.e., 23 200 cm-' (E = 7000). The presence of this band and its shift to higher energy with increased intensity in the dimeric complexes may be attributed to the combined effect of intra-ligand transition and L + M charge transfer transitions, a characteristic feature of 0x0-bridged copper(I1) complexes (29,30) and hence a diagnostic feature of a dimeric structure (31). Another band was observed at = I 4 000 cm-' (E = 150) while the planar monomeric copper(I1) complexes of 8-quinolinol (a) (27), succinimide, and phthalimide (28), gave the bands at 15 000 (E = 110), 15 000 (E = loo), and 14 900 cm-' (E = 110), respectively.…”

Reaction Medium pH Dependent Existence of MnII Bound [ON] Donor Zwitterionic Chelating Ligand and Self‐Assembly of Hydroxido‐Bridged MnII4 Cluster

“…The Schiff base 4-methyl-2,6-bis(phenylmethyliminomethyl)phenol (Hbip) was prepared (Scheme S1, Supporting Information) by following a literature procedure, [14] and its reaction with manganese(II) salts was investigated under different reaction conditions (Scheme 2 Mn 2 product such as 4 (Scheme 2) was observed, perhaps because of the additional stability of 1, which crystallizes as a bis-chelated mononuclear transition metal complex of any binucleating ligand assembled through H-bonding. A proposal for the formation of the Mn 2 complex comes from our endeavors reported recently on the cobalt(II) chemistry with this ligand.…”