Peroxo-Bridged Dinuclear Cobalt(III) Complexes Containing N-Glycoside Ligands from Tris(2-aminoethyl)amine and d-Glucose or Maltose

Abstract

Peroxo-bridged dinuclear cobalt(III) complexes, [{Co((D-Glc) 2 -tren)} 2 (µ-O 2 )]X 3 ‚5H 2 O (X ) Cl (2‚5H 2 O), Br (3‚5H 2 O)) and [{Co((Mal) , were prepared from CoX 2 ‚6H 2 O, tris(2-aminoethyl)-amine, and D-glucose (D-Glc) or maltose (R-D-glucopyranosyl-(1f4)-D-glucose; Mal), and were characterized by elemental analysis, UV-vis absorption, circular dichroism, 1 H and 13 C NMR spectroscopic techniques, and X-ray absorption and crystallographic analyses, where (aldose) 2 -tren is bis(N-aldosyl-2-aminoethyl)(2-aminoethyl)amine (aldose ) D-Glc, Mal). The structure of 2 and 4 were determined by X-ray crystallography to consist of two Co(III) ions bridged by a peroxo unit: 2‚4H 2 O‚CH 3 OH, orthorhombic, P2 1 2 1 2 1 (No. 19), a ) 19.384 (8) Å, b ) 23.468(5) Å, c ) 13.195(5) Å, V ) 6002(2) Å 3 , Z ) 4, D calcd ) 1.440 g cm -3 , T ) -99°C, R ) 0.078, R w ) 0.085 for 4961 reflections with I > 3σ(I); 4‚2.25H 2 O‚3.75CH 3 OH, monoclinic, P2 1 (No. 4), a ) 12.819(7) Å, b ) 49.168(18) Å, c ) 14.973(6) Å, ) 104.59(4)°, V ) 9130(7) Å 3 , Z ) 4, D calcd ) 1.459 gcm -3 , T ) -136°C, R ) 0.101 for 6837 reflections with I > 2σ(I). The hydrogen bondings between the sugar moieties deviates the Co-O-O-Co torsional angle from planarity to 100.4(6)°(2) and av 102(1)°(4). The electronic structures of the twisted Co 2 (µ-O) 2 core were discussed on the basis of extended Hückel MO calculations. The present discrete complexes have a tetravalent sugar domain around the dinuclear center and clearly demonstrated distinct sugarsugar interactions which could be a minimal model for so-called sugar clusters of glycoproteins on cell surfaces.

A Structurally Characterised Pair of Dicobalt(III) Peroxo/Superoxo Complexes withC2-Symmetrical Tetrapodal Pentadentate Amine Ligands, and Some Reactivity en route

“…[34] Intramolecular hydrogen bonding which significantly distorts the CoϪOϪOϪCo core of a dicobalt(III) peroxo species from planarity has been described for [(NH 3 ) 5 CoϪOϪOϪCo(NH 3 ) 5 ](SO 4 ) 2 ⋅4H 2 O, [25] and most recently also for a complex with carbohydrate-derived ligands. [64] [(1)CoϪOϪOϪCo (1) [24,26,36,65] Molecular symmetry requires the CoϪOϪOϪCo unit to be planar and, in the same way as in 5, implies that the CoN 4 ''squares'' are parallel and adopt an eclipsed orientation (Figure 2b). It can be seen from Table 3 that, while the metal centres in 7 are further apart than in 5, the other nonbonded distances within the (N 4 )CoϪOϪOϪCo(N 4 ) framework are similar in both structures.…”

Derivatization of Glucose and 2-Deoxyglucose for Transition Metal Complexation: Substitution Reactions with Organometallic99mTc and Re Precursors and Fundamental NMR Investigations

“…[1±3] However, nonfunctionalized carbohydrates are generally weak ligands; therefore, functionalization with chelating groups leads to stronger metal-binding compounds. Such carbohydrate derivatives often contain polyamine-chelating systems such as tris (2-aminoethyl)amine, [4,5] diaminopropane (dap), and diethylenediamine. [6] In most of these compounds at least one sugar hydroxy group is directly involved in the coordination sphere.…”

Synthesis and characterization of glycoconjugate tin(IV) complexes: In vitro DNA binding studies, cytotoxicity, and cell death

“…The six aromatic carbon peaks appeared in the range 146e116 ppm. The six distinct carbon signals of the D-glucosamine were exhibited in the range of 78.94e51.32 ppm [46,47]. The two carbons of the ethylenediamine moiety appeared in the range 45.54e39.91 ppm.…”