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Vol 50, No 6 (2024)
Articles
Samarium(III) Complex Based on 5-Phenyl-2,2´-bipyridine with the Diethylenetriaminotetraacetic Acid Residue in the C6 Position: Synthesis, Crystal Structure, and Photophysical Properties
Abstract
New samarium complex of 5-phenyl-2,2´-bipyridine with the diethylenetriaminotetraacetic acid (DTTA) residue in the C6 position, [(L2)Sm2Na5(H2О)9(C2O4)]n (I), is synthesized. The structure of complex I is studied by XRD (CIF file CCDC no. 2217968). The complex in the crystal is found to be a onedimensional coordination polymer, and the 2,2´-bipyridine fragments do not chelate the Sm3+ cation. The complex is characterized by a luminescence response to the addition of an excess of zinc cations.
356-362
Monomeric and Polymeric Cyclopentadienyl Dysprosium Complexes Based on the Acenaphthene-1,2-diimine Ligand
Abstract
The reaction of [(Dpp-bian)DyI(Dme)2] (Dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene, Dme is CH3OCH2CH2OCH3) with Cp*K (Cp* is C5Me5) in toluene followed by crystallization from benzene affords crystals of the 1D coordination polymer [(Dpp-bian)DyIKCp*]n (I)•2.6C6H6 (26%) and crystals of the monomeric complex [(Dpp-bian)DyCp*(Dme)] (II)•1.5C6H6 (12%). The same reaction in 1,2-dimethoxyethane followed by crystallization from benzene makes it possible to isolate only complex II•1.5C6H6 in a yield of 48%. The synthesized compounds are characterized by IR and UV spectroscopy and elemental and thermogravimetric analyses. Their molecular structures are determined by XRD (CIF files CCDC nos. 2298407 (I) and 2298408 (II)).
363-373
Interaction of Lyophilic Zinc(II) Porphyrins with Bovine Serum Albumin
Abstract
Palladium-catalyzed heterylation of monobromophenyl-substituted zinc(II) porphyrin with small heterocycles (benzothiazole, benzoxazole, and N-methylbenzimidazole) was carried out. As a result, unsymmetrical heterylphenyl-substituted zinc(II) porphyrins soluble in organic solvents were obtained. The interaction of heteryl-substituted zinc(II) porphyrins with alpha-helical proteins was studied by spectral methods using bovine serum albumin in aqueous organic solvents. It was found that the titration of the zinc(II) porphyrins with albumin in a sodium phosphate buffer involves a number of equilibria including complexation and aggregation. In the case of porphyrins containing N-methylbenzimidazole and benzoxazole residues, self-aggregation processes initiated by absorption of organic solvent molecules by the protein predominate. It was found that more hydrophobic nature of zinc(II) porphyrin with benzothiazole residue promotes the complex formation with the protein. The photochemical properties of zinc(II) porphyrin with a benzothiazole residue, capacity for the photooxidation of the alpha-helical protein, and the high affinity of protein to this porphyrin make it a promising candidate for the potential applicability for photodynamic inactivation.
374-384
Structural Diversity of Heteroligand 1,2,4-Triphenylcyclopentadienyl-Bipyridine Complexes of Rare Earth Metals
Abstract
The reaction of triphenylcyclopentadienyl potassium and bipyridine with lanthanum, praseodymium, erbium, lutetium, and scandium chloride tetrahydrofuranates results in the formation of binuclear [CpPh3Ln(Bipy)Cl(μ2-Cl)]2 (Ln = La (I), Pr (II)) and mononuclear [CpPh3Ln(Bipy)Cl2(THF)] (Ln = Er (III), Lu (IV), [CpPh3Sc(Bipy)Cl2] (V) complexes (CpPh3 = 1,2,4-triphenylcyclopentadienyl, Bipy = bipyridine). The decrease in the REE radius in the series La…Sc results in the formation of mononuclear instead of binuclear complexes and in a decrease in the coordination number of the central ion. The coplanar arrangement of two different π-systems gives rise to stacking interactions between the triphenylcyclopentadienyl ligand and bipyridine. The molecular structure of complexes I–V was established by X-ray diffraction analysis (CCDC nos. 2308609 (I), 2308608 (II), 2308610 (III), 2308611 (IV), 2308607 (V)).
385-393
Half-Sandwich Iminophosphonamide Rhodium Complexes as Highly Efficient Catalysts for Dehydrogenation of Dimethylamine-Borane
Abstract
The dehydrogenation of dimethylamine-borane (DMAB) catalyzed by the iminophosphonamide rhodium(III) complexes [Cp*RhCl{Ph2P(N–p-Tol)(NR)}] (Iа, R = p-Tol; Ib, R = Me) in situ formed fulvene [(η4-C5Me4CH2)Rh(NPN)] (IIa, IIb) and diene [(η4-C5Me5H)Rh(NPN)] (IIIa, IIIb) rhodium(I) derivatives is studied. Catalysts IIIa and IIIb turn out to be the most active and demonstrate a TOF activity of 110 (IIIа) and 540 h–1 (IIIb) at 40°С in toluene. The activity decreases significantly in more polar and coordinating THF. At the same time, the rate of DMAB dehydrogenation by complexes Iа and Ib is lower by 10–30 times, and fulvene complexes Iа and Ib are rapidly deactivated after the active initial period (<20% conversion). The kinetic studies show that the reaction has the first order with respect to the substrate and catalyst. The model 11В NMR experiments confirm that the reaction proceeds via the intermediate formation of a monomer Me2N=BH2, which rapidly dimerizes to (Me2N–BH2)2. The mechanism of DMAB dehydrogenation with the formation of unstable hydride intermediate [Cp*RhH{Ph2P(N–p-Tol)(NR)}] (IVa, IVb) is proposed on the basis of the preliminarily 31Р NMR results and published data.
394-401
Reaction of 2,3,4,5,6-Pentafluorobenzamide with Potassium Hydride: Unexpected Activation of the C–F Bond and Dimerization of Organofluorine Ligand
Abstract
The reaction of potassium hydride with 2,3,4,5,6-pentafluorobenzamide (FBAm) in dimethoxyethane results in activation of the C–F bond in the para-position to the C(O)NH2 group followed by dimerization of FBAm to form a potassium salt with one free amide group. The structure of the binuclear reaction product {(DME)2K+[C6F5–C(O)N–C6F4–C(O)NH2]–}2 (I) was determined by X-ray diffraction (CCDC 2311402), the purity of the product was confirmed by NMR spectroscopy.
402-410