Synthesis,characterization and catalytic applications of rhodium(I) organometallics with substituted tertiary phosphines

Organometallics of the type [Rh(COD)(L)Cl] (where, L = carboxyl/formyl/pyridyl tertiary phosphines) have been synthesized by treating the precursor [Rh(COD)Cl]₂ with substituted tertiary phosphines. [Rh(COD)(Ph₂P-2-C₆H₄COO)] and [Rh(COD)(Ph₂P-CH₂COO)] were synthesized by halide abstraction from the precursor [Rh(COD)Cl]₂ in the presence of AgPF₆ in tetrahydrofuran by involving 2-carboxy phenyl/carboxy methyl group of tertiary phosphines in coordination as bidentate ligands. Similarly, the cationic compounds of the type [Rh(COD)L₂]PF₆ were also synthesized by treating [Rh(COD)Cl]₂ in the presence of AgPF₆. All these compounds were characterized by elemental analysis, conductance measurements, IR, ¹H, ¹³C, ³¹P NMR, mass, and electronic spectral studies. [Rh(COD)(Ph₂-P-2-C₆H₄COOH)Cl] and [Rh(COD)(Ph₂-P-2-C₆H₄COO)] were studied on the catalytic reduction reactions of 2-nitroanisole, 3-nitro anisole, 4-nitroanisole, 2-nitrobenzoicacid, 3-nitrobenzoicacid, 4-nitrobenzoicacid under mild conditions and [Rh(COD)(Ph₂-P-2-C₆H₄COO)] was found to be more efficient than [Rh(COD)(Ph₂-P-2-C₆H₄COOH)Cl]. This article is dedicated to Dr. D. R. M Walton, who successfully completed his tenure as Editor-in-Chief, Transition Metal Chemistry.     

A Cytostatic Ruthenium(II)–Platinum(II) Bis(terpyridyl) Anticancer Complex That Blocks Entry into S Phase by Up‐regulating p27KIP1

Cytostatic agents that interfere with specific cellular components to prevent cancer cell growth offer an attractive alternative, or complement, to traditional cytotoxic chemotherapy. Here, we describe the synthesis and characterization of a new binuclear Ru^II–Pt^II complex [Ru(tpy)(tpypma)Pt(Cl)(DMSO)]³⁺ (tpy=2,2′:6′,2′′‐terpyridine and tpypma=4‐([2,2′:6′,2′′‐terpyridine]‐4′‐yl)‐N‐(pyridin‐2‐ylmethyl)aniline), VR54, which employs the extended terpyridine tpypma ligand to link the two metal centres. In cell‐free conditions, VR54 binds DNA by non‐intercalative reversible mechanisms (K_b=1.3×10⁵ M ^?1) and does not irreversibly bind guanosine. Cellular studies reveal that VR54 suppresses proliferation of A2780 ovarian cancer cells with no cross‐resistance in the A2780CIS cisplatin‐resistant cell line. Through the preparation of mononuclear Ru^II and Pt^II structural derivatives it was determined that both metal centres are required for this anti‐proliferative activity. In stark contrast to cisplatin, VR54 neither activates the DNA‐damage response network nor induces significant levels of cell death. Instead, VR54 is cytostatic and inhibits cell proliferation by up‐regulating the cyclin‐dependent kinase inhibitor p27^KIP1 and inhibiting retinoblastoma protein phosphorylation, which blocks entry into S phase and results in G1 cell cycle arrest. Thus, VR54 inhibits cancer cell growth by a gain of function at the G1 restriction point. This is the first metal‐coordination compound to demonstrate such activity.     

One-Pot Regioselective Synthesis of Some Novel Isoxazole-Phenothiazine Hybrids and Their Antibacterial Activity

Russian Journal of General Chemistry - Some novel isoxazole-phenothiazine hybrids have been synthesized regioselectively in high yields via Cu(I) catalyzed one-pot reaction of...     

Parity coding for page-oriented optical memories with intrapage intensity variations

A new form of modulation coding for page-oriented memories (POM's) based on parity is introduced. The parity-based codes are evaluated by use of simulated POM data pages. It is illustrated that the proposed parity codes can outperform balanced modulation codes in the presence of fixed-pattern noise and additive white Gaussian noise.     

Structural studies of palladium complexes with ligands containing the amide group

Summary Complexes of palladium(II) with 2-(acetylamino)benzoic acid, 2-(benzoylamino)benzoic acid, 2-[2-aminobenzoylamino]benzoic acid, 2-hydroxy benzanilide, 2-mercapto benzanilide, maleanilic acid, 2-(amino carbonyl)benzoic acid, 2-[(phenylamino)carbonyl]benzoic acid, 2-[(1-naphthalenylamino)carbonyl]benzoic acid, 2-[(2-aminophenylamino)carbonyl]benzoic acid, salicylanilide, 2-(aminobenzoyl)benzoic acid and 2-aminobenzamide have been prepared and characterized by chemical analyses, molar conductivity measurements, thermal data and i.r., electronic and n.m.r. spectra.     

Synthesis,characterization and hydroformylation activity of 7‐azaindolate‐bridged dinuclear rhodium(I)phosphines with pendant polar‐groups

New dinuclear Rh(I)–Phosphines of the types [Rh(µ‐azi)(CO)(L)]₂ ( 1,3 – 7 ) and [Rh(µ‐azi)(L)]₂ ( 8 ) with pendant polar groups, and a chealated mononuclear compound [Rh(azi‐H)(CO)(L)] ( 2 ) (where azi = 7‐azaindolate, L = polar phosphine) were isolated from the reaction of [Rh(µ‐Cl)(CO)₂]₂ with 7‐azaindolate followed by some polar mono‐ and bis‐phosphines ( L ₁ – L ₈ ). A relationship between Δδ³¹P‐NMR and ν(CO) values was considered to define the impact of polar‐groups on σ‐donor properties of the phosphines. These compounds were evaluated as catalyst precursors in the hydroformylation of 1‐hexene and 1‐dodecene both in mono‐ and biphasic aqueous organic systems. While the biphasic hydroformylations (water + toluene) gave exclusively the aldehydes, the monophasic one (aqueous ethanol) showed propensity to form both aldehydes and alcohols. The influence of bimetallic cooperative effects, and σ‐donor and hydrophilic properties of the phosphines with pendant polar‐groups in enhancing the yields and selectivity of hydroformylation products was emphasized. In addition, when strong σ‐donor phosphine was used, the π‐acceptor nature of pyridine ring of 7‐azaindolate spacer was found to be a considerable factor in facilitating the facile cleavage of CO group during hydroformylation and in supplementing the cooperative effects. Copyright © 2009 John Wiley & Sons, Ltd.     

Activation of nitriles by silver(I) N-heterocyclic carbenes: An efficient on-water synthesis of primary amides

A first example of silver(I) N-heterocyclic carbene (Ag(I)-NHC) catalyzed on-water synthesis of primary amides by hydration of nitriles under mild reaction conditions is described. This organometallic catalytic system has excellent tolerance for various homo-aromatic, hetero-aromatic and aliphatic nitriles to afford primary amides in good yields in neat water.     

Synthesis, characterization and biological evaluation of mononuclear Co(II), Ni(II), Cu(II) and Pd(II) complexes with new N2O2 Schiff base ligands

New tetradentate N(2)O(2) donor Schiff bases and their mononuclear Co(II), Ni(II), Cu(II), and Pd(II) complexes were synthesized and characterized extensively by IR, (1)H-, (13)C-NMR, mass, ESR, conductivity measurements, elemental and thermal analysis. Specifically the magnetic and electronic spectral measurements demonstrate the octahedral structures of cobalt(II), nickel(II) complexes and square planar geometries of copper(II), palladium(II) complexes. All the ligands and complexes were screened for their in vitro antibacterial activity against two gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus) and two gram-negative bacteria (Escherichia coli, Klebsiella pneumonia). In this study, Pd(II) complexes exhibited potent antibacterial activity against B. subtilis, S. aureus whereas other metal complexes also exerted good activity towards all tested strains even than standard drugs streptomycin and ampicillin.     

Catalytic reduction of pralidoxime in pharmaceuticals by macrocyclic Ni(II) compounds derived from orthophthalaldehyde

Efficient catalytic method for the reduction of pralidoxime to its amine derivative by macrocyclic Ni(II) compounds has been developed. Ten macrocyclic Schiff base Ni(II) compounds were synthesized via non-template synthesis by treating the corresponding macrocycles with nickel chloride in 1:1 ratio. The resulting compounds were characterized by elemental, IR, (1)H NMR, (13)C NMR, mass, electronic spectra, conductance, magnetic, thermal studies and their structures have been proposed. These compounds were used as catalysts for the reduction of pralidoxime to its amino derivative. The reduced pralidoxime was also characterized by spectral analysis and catalytic cycle has been established. The reduced product was determined spectrophotometrically by treating with ninhydrin reagent and the percent yields were found to be in the range of 75.12-82.36%.     

Ru(III)-catalyzed oxidation of pyridoxine and albuterol in pharmaceuticals

Ru(III) complexes with coordinated amide were synthesized and characterized by elemental, IR, mass, electronic, ESR spectral analysis, magnetic and conductance measurements and octahedral structures have been proposed. These complexes were used as catalysts for the oxidation of pyridoxine and albuterol in pharmaceuticals in presence of hydrogen peroxide. The role of co-oxidant and the effect of reaction time on the yields of oxidation products which were spectrophotometrically determined by condensing them with sulfanilic acid in acid medium were investigated. Structures of the oxidation products were established with the help of IR and NMR spectral analysis.