Syntheses and structures of dimeric sodium and potassium complexes of 2,6-diisopropyl-Anilidophosphine borane ligand

We report here the syntheses and structural studies of dimeric sodium and potassium complexes of composition [Na(THF)2{Ph2P(BH3)N(2,6- i Pr2C6H6)}]2 (2) and [K(THF)2{Ph2P(BH3)N(2,6- i Pr2C6H6)}]2 (3). The sodium complex 2 was readily prepared by the reaction of sodium bis(trimethylsilyl)amide with 2,6-diisopropylanilidophosphine-borane ligand [2,6- i Pr2C6H3NHP(BH3)Ph2] (1-H) at ambient temperature. The potassium complex 3 was prepared by two synthetic routes: in the first method, the ligand 1-H was made to react with potassium hydride at room temperature to afford the corresponding potassium complex. The potassium bis(trimethylsilyl)amides were made to react with protic ligand 1-H in the second method to eliminate the volatile bis(trimethyl)silyl amine. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 2, the sodium metal is coordinated by the anilido nitrogen (η 1) and borane group (η 1) attached to the phosphorus atom of ligand 1. In contrast, for compound 2, ligand 1 displays η 6 π-arene interaction from 2,6-diisopopylphenyl ring with potassium atom along with η 3 interaction of BH3 group due to larger ionic radius of potassium ion

Imidazol-2-ylidene-N′-phenylureate ligands in alkali and alkaline earth metal coordination spheres - heterocubane core to polymeric structural motif formation

The synthesis and isolation of two potassium, one lithium and two calcium complexes of imidazol-2-ylidene-N′-phenylureate ligands [ImRNCON(H)Ph] [(R = tBu (1a); Mes (1b) and Dipp (1c); Mes = mesityl, Dipp = 2,6-diisopropylphenyl] are described. Potassium complexes, [{κ2-(ImMesNCONPh)K}4] (2b) and [{κ3-(ImDippNCONPh)K}2{KN(SiMe3)2}2]n (2c), were prepared in good yields by the reactions of 1b and 1c, respectively, with potassium bis(trimethyl)silyl amide at ambient temperature in toluene. Lithium complex [{(2,6-tBu2-4-Me-C6H2O)Li(ImtBuNCON(H)Ph)}2{ImtBuNCON(H)Ph}] (3a) was isolated by a one-pot reaction between 1a and LiCH2SiMe3, followed by the addition of 2,6-tBu2-4-Me-C6H2OH in toluene. Calcium complex [{κ2-(ImtBuNCONPh)Ca{N(SiMe3)2}-{KN(SiMe3)2}]n (4a) was isolated by the one-pot reaction of 1a with [KN(SiMe3)2] and calcium diiodide in THF at ambient temperature. The solid-state structures of ligand 1a and complexes 2b, 2c, 3a and 4a were confirmed by single-crystal X-ray diffraction analysis. It was observed that potassium was coordinated to the oxygen atom of urea group and to the nitrogen atom of the imidazolin-2-imine group, in the solid-state structure of 2b. In complex 4a, the calcium ion was ligated to the monoanionic imidazol-2-ylidene-N′-phenylureate ligand in a bi-dentate (κ2) fashion through the oxygen and nitrogen atoms of the isocyanate building block leaving the imidazolin-2-imine fragment uncoordinated. In the solid state of the potassium complex 2c, tri-dentate (κ3) coordination from the imidazol-2-ylidene-N′-phenylureate ligand was observed through the oxygen and nitrogen atoms of the isocyanate building block and of the imidazolin-2-imine fragment. In contrast, in the dimeric lithium complex 3a, the neutral imidazol-2-ylidene-N′-phenylureate ligand was bound to the lithium centre in a mono-dentate fashion (κ1) through an oxygen atom of the isocyanate moiety. It is to be noted that in each complex thus observed, the elongated carbon-nitrogen bond distances indicate substantial electron delocalisation from the imidazole ring to the ureate group present in ligand 1

Synthesis and solid state structures of Chalcogenide compounds of Imidazolin-2-ylidene-1,1-Diphenyl-phosphinamine

We report the synthesis and solid state structures of 1,3-di-aryl-imidazolin-2-ylidine-1,1-diphenylphosphinamine [(aryl = mesityl (1a) and aryl = 2,6-diisopripyl (1b)] and their chalcogenide compounds 1, 3-di-aryl-imidazolin-2-ylidine- P,P-diphenylphosphinicamide (2a,b), 1,3-di-aryl-imidazolin-2-ylidine-P,P-diphenyl-phosphinothioicamide (3a,b) and 1,3-diaryl-imidazolin-2-ylidine- P,P-diphenyl-phosphinoselenoic-amide (4a,b). The compounds 1a,b were prepared in good yield by the reaction of 1,3-di-aryl-imidazolin-2-imine and chlorodiphenylphosphine in the presence of triethylamine in toluene. The reactions of 1a,b with elemental sulphur and selenium afforded the corresponding chalcogenide compounds 3a,b and 4a,b respectively. The corresponding oxo- derivative (2a,b) was obtained by reacting compound 1a,b with 30% aqueous hydrogen peroxide in THF. The molecular structures of 1a, 2a, 3a and 4a,b have been established by single crystal X-ray diffraction analyses. The molecular structures reveal that even C1–N1–P1 angle (124.62 ∘) in compound 1a is less obtuse compared to the corresponding C1–N1–Si1 angles (157.8 ∘) observed in related N-silylated 2-iminoimidazolines and trimethylsilyl iminophosphoranes. C1–N1–P1 angles are further widened in compounds 2a, 3a, and 4a,b due to the attachment of chalcogen atoms onto phosphorus atom

Nickel(II) complexes having Imidazol-2-ylidene-N′-phenylurea ligand in the coordination sphere - Syntheses and solid state structures

We report the syntheses and structural studies of two nickel(II) complexes of imidazol-2-ylidene- N′-phenylureate ligand of composition [{Im tBuNCON(H)Ph}2Ni(acac)2](1) and [(C6H5NH2)2Ni(acac)2][ImMes NCON(H)Ph] (2). The nickel complex 1 was readily prepared by the reaction of nickel(II) acetylacetonate [Ni(acac)2] with imidazol-2-ylidene-N′-phenylureate ligand [Im tBuNCON(H)Ph] (L1) in THF under reflux condition for 72 h. The nickel complex 2 was obtained by the reaction of [Ni(acac)2], mesityl derivative of imidazol-2-ylidene-N′-phenylureate ligand [Im MesNCON(H)Ph] (L2) in the presence of aniline as base under reflux condition in THF. Both the paramagnetic complexes have been characterized by FT-IR spectroscopy and elemental analyses. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 1 and 2, each nickel(II) ion is six fold coordinated and form a distorted octahedral geometry. The optical properties of both complexes have been explored. The Hirshfeld surfaces are used to view and analyze the intermolecular contacts in crystalline state for complex 2

Syntheses and solid state structures of zinc (II) complexes with Bi-dentate N-(Aryl)imino-acenapthenone (Ar-BIAO) ligands

We have synthesized five zinc complexes of molecular formulae [ZnCl 2 (2,6-dimethylphenyl- BIAO)] 2 ( 1a ), [ZnBr 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1b ), [ZnI 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1c ), [ZnBr 2 (mes- BIAO)] 2 ( 2b) and [ZnBr 2 (dipp-BIAO)] ( 3b) with rigid unsymmetrical imi noacenaphthenone ligands, (2,6- dimethylphenyl-BIAO) ( 1 ), (mesityl-BIAO) ( 2 ) and (2,6-diisopropylphenyl-BIAO) ( 3 ).Thezinccomplex 1a was prepared by the reaction of ZnCl 2 and neutral (mesityl-BIAO) ( 1 ). However, complexes 1b , 2b and 3b were obtained by the treatment of ZnBr 2 and neutral ligands 1 – 3 respectively in 1:1 molar ratio in dichloromethane at ambient temperature. In a similar reaction of ZnI 2 with (2,6-dimethylphenyl-BIAO) ( 1 ) in dichloromethane the corresponding iodo-complex 1c was obtained in good yield. All the zinc (II) complexes are characterized by FT-IR, 1 Hand 13 C{ 1 H} NMR spectroscopic techniques. The solid state structures of the complexes 1a , 1b , 1c , 2b and 3b are confirmed by single crystal X-ray diffraction analysis. The molecular structures of com- plexes 1a , 1b , 1c and 2b reveal the dimeric nature of the complexes and subsequently the centre atom zinc is penta-coordinated to adopt distorted trigonal bipyr amidal geometry around it. In contrast, the complex 3b is in monomeric in nature due to bulkier size of the ligand and zinc ion is tetra coordinated to adopt distorted tetrahedral geometry

STUDY OF ANTIOXIDANT PROPERTIES AND ACTIVITY OF TWO RICE BRAN EXTRACTS FROM LOCAL CULTIVARS IN INDIA

The rice bran varieties native to India, Oryza sativa L. CV. Mohara (RB-1) and Oryza sativa L. CV. Kedarnath (RB2), which are extensively cultivated, exhibit a noteworthy abundance of antioxidant components. Employing spectrophotometric techniques, the antioxidant attributes, including total phenolic content, 1, 1-diphenyl-2picryl-hydrazil (DPPH) scavenging, and 2, 22 - azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radicalscavenging, of rice bran extracts were assessed. The present study revealed that the isopropanolic extracts from rice bran yielded promising outcomes, with EC-50 values in the DPPH and ABTS assays for RB-1 measuring 0.64 ± 0.06 and 0.63 ± 0.05 mg/mL, respectively, and for RB-2, 0.69 ± 0.03 and 0.55 ± 0.03 mg/mL, respectively. The highest levels of total phenolic content within rice bran extracts were detected in RB-1, specifically 4.34 ± 0.062 mg gallic acid eq/g. As a result, it is conceivable that isopropanolic extracts derived from these rice bran varieties hold potential utility as natural antioxidant

Calcium Complexes Having Different Amidinate Ligands - Synthesis and Structural Diversity

A one-pot reaction of α-diimine ligand 1,4-disubstituted diazabutadienes (DAD) with potassium benzyl and anhydrous calcium iodide in 1:1:1 molar ratio afforded unprecedented 3-phenylprop-2-ene-di-amido calcium compound [κ2-(THF)4Ca{DippNC(=CHPh)CH2NDipp}] (1) (Dipp = 2,6-diisopropylphenyl) in good yield. The solid-state structure of the compound 1 revealed the formation of dianionic 3-phenylprop-2-ene-di-amido ligand having an exocyclic olefinic bond derived from neutral α-diimine fragment. However, analogous reactions with three different carbodiimides (RN=C=NR; R=Cy, iPr and tBu) with alkyl potassium and anhydrous calcium diiodide yielded corresponding homoleptic calcium compounds with amidinato ligand [κ2-(THF)2Ca{RN=C(CH2Ph)NR}2] [R=Cy (2), iPr (3) and tBu (4)]. A separate reaction of DAD ligand, LiCH2SiMe3 and anhydrous ZnCl2 in diethylether solvent produced tri-coordinated zinc compound [κ2- {DippN=C(CH2SiMe3)CH2NDipp}Zn[κ1-{DippN=C(CH2SiMe3)CH2N-Dipp}] (5) having amidinato moieties in the zinc coordination sphere in high yield. Molecular structures of compounds 2–5 in their solid states were also established

BIOSYNTHESIZED ZnO NANOPARTICLES FROM Rumex nepalensis (SPRENG.) PLANT EXTRACT SERVE AS EFFICIENT CATALYSTS FOR THE AQUEOUS SYNTHESIS OF 4H-ISOXAZOL-5-ONE DERIVATIVES

In this study, the biosynthesis of ZnO nanoparticles was accomplished using an aqueous extract derived from Rumex nepalensis (Spreng) plant. The application of these biosynthesized ZnO nanoparticles as catalysts was investigated for the synthesis of biologically active 4H-isoxazol-5-one-based heterocycles. This was achieved through a one-pot three-component reaction involving hydroxylamine hydrochloride, aryl or heteroaryl aldehydes, and ethyl acetoacetate. The reactions were conducted at room temperature in aqueous medium, employing a 10 mol% loading of the biosynthesized ZnO catalyst. The structure of the biosynthesized ZnO was characterized using X-ray diffraction and scanning electron microscopy analyses. The resulting condensation process using biosynthesized ZnO nanoparticles exhibited environmentally friendly features such as safety, high yield of products, good atom efficiency, low cost, mild reaction conditions, minimal waste generation, avoidance of hazardous organic solvents, catalyst recoverability, energy efficiency, and facile workup

Biosynthesis of CuO Nanoparticles Using Plant Extract as a Precursor: Characterization, Antibacterial, and Antioxidant Activity

Biosynthesis of metal nanoparticles presents a promising approach for their efficient and environmentally friendly production. In this study, CuO nanoparticles were successfully synthesized by using Rumex nepalensis Spreng. as a bio-reducing agent. The spectroscopic analysis confirmed the crystalline monoclinic structure of the synthesized CuO NPs, with particle sizes ranging from 21 to 97 nm. These biosynthesized CuO NPs exhibited notable antimicrobial activity against diverse microorganisms, suggesting their potential for antimicrobial applications. Moreover, the CuO NPs displayed significant antioxidant activity, demonstrated by their effective scavenging of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals. This study highlights the straightforward, cost-effective, non-toxic, and robust nature of CuO NPs synthesis using Rumex nepalensis Spreng., offering insights into their potential applications in antimicrobial and antioxidant fields