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Synthesis and some reactions of tris (pentafluorophenyl) antimony compounds

Abstract (C6F5)3Sb has been found to react with interhalogens and halo-pseudohalogens, IX(X = Cl, Br, N3 and NCO), pseudohalogen (SCN), and elemental sulphur to give oxidative addition products (I–VI). (C6F5)3SbS(VI) may also be prepared by the reaction of (C6F5)3SbCl2 with H2S. Metathetical reactions of (C6F5)3SbCl2 with appropriate metallic salts yield covalent pentacoordinate disubstituted products (V, VII–XII) of the general formula, (C6F5)3SbY2 (Y = NCS, NCO, −ONCMe2, −ONCMePh −NCO(CH 2 ) 2 C O and p-NO2C6H4OCO). Treatment of (C6F5)3SbCl2 with aqueous NaN3 gives the binuclear oxo-bridge compound, [(C6F5)3SbOSb(C6F5)3](N3)2·(III) and (IV) are also accessible by displacement reaction of (I) or (II) with the corresponding metallic salt. Molecular weight, conductance measurements, and IR spectra on the new organoantimony(V) derivatives have been obtained. Reductive cleavage reactions of (C6F5)3SbS with hexaaryldileads, Ar6Pb2(Ar = Phenyl, p-tolyl) produce (C6F5)3Sb and the corresponding bis(triaryllead) sulphide but treatment of (C6F5)3SbX2(X = NCO, Cl) with Ar6Pb2 gave Ar4Pb and Ar2PbX2 together with (C6F5)3Sb. (C6F5)3SbCl2 and bis(triorganotin)sulphides undergo exchange of anionic groups.

Synthesis of some novel 2-substituted benzoxazoles as anticancer, antifungal, and antimicrobial agents

Benzoxazole derivatives show various types of biological properties such as antiviral, antineoplastic, anti-HIV-1, antitubercular, anthelmintic, antimicrobial, and antifungal activities. In the last few years 2-substituted benzoxazole derivatives have been studied extensively for their antitumor, antiviral, and antimicrobial activities. In an effort to identify new candidates that may be of value in designing new, potent, selective, and less toxic anticancer, antiviral, and/or antimicrobial agents, we synthesized 2-[(arylhydrazono) cyanomethyl]-5-chloro benzoxazoles (II), 2-[(arylidene)cyanomethyl]-5-halo benzoxazoles (III), and 2-[(cycloalkylidine)cyanomethyl]-5-chlorobenzoxazoles (IV), and tested them for anticancer, antifungal, and antibacterial activities. Some of these (compounds 11, 14) were found to possess anticancer activity and remarkable antifungal as well as antibacterial activities.

Preparation and Structural Characterisation of Triaryl Metal(V) Complexes (M = As, Sb) of Tri-and Tetradentate Schiff Bases

Abstract Hitherto unreported penta-coordinated triaryl-arsenic(V) complexes of Schiff bases of the general formula Ar3AsL (Ar = C6H5, p-CH3C6H4, p-ClC6H4, p-FC6H4 and C6F5; L = dibasic tri-and tetradentate ligands with ONO and ONNO systems) have been synthesised along with some triarylantimony complexes with similar tridentate ligands. The complexes, which are yellow crystalline solids, have been characterised by elemental analyses, IR, 1H and 19F NMR spectral data sp3d and sp3d2 hybridisation has been suggested for the arsenic and antimony derivatives, respectively, on the basis of spectral data.

The preparation of pentafluorophenyl antimony(III) and antimony(V) halides and mixed halides

Abstract (C6F5)3Sb (I) has been found to undergo redistribution reactions with SbCl3 in 2 1 and 1 2 molar ratios to give quantitative yields of (C6F5)2SbCl (II) (C6F5)SbCl2 (III), respectively. Oxidative chlorination of ice cold solutions of (II) and (III) gave (C6F5)2SbCl3 (IV) and (C6F5)SbCl4 (V), respectively. Bromination of (II) and (III) at - 178°C yielded mixed halides, (C6F5)nSbCl3-nBr2 (n = 1 & 2).

On the Lewis acidity of tris(pentafluorophenyl)antimony(V) dichloride towards neutral monodentate O, N and S donor ligands

Abstract Hexa-coordinate neutral adducts (C 6 F 5 ) 3 SbCl 2 ·L( I ) [L=DMSO, DBSO, Ph 3 AsO, Ph 3 PO, DPF, DMF, Py, 3-Pic, TU] and penta-coordinate cationic complexes [(C 6 F 5 ) 3 Sb(Ph 3 AsO) 2 ][ClO 4 ] 2 ( II ) and [(C 6 F 5 ) 3 Sb(bipy)][ClO 4 ] 2 ( III ) have been synthesised. Molecular adducts are monomeric in benzene and non-electrolyte in acetonitrile. IR spectra and conductance measurement suggest the absence of coordination of ClO 4 group to Sb atom in cationic complexes. Spectroscopic data conform to the requirement of octahedral configuration for neural complexes ( I ) and a trigonal bipyramidal structure for complex cations ( II ) and ( III ).

Synthesis of organoantimony(V) and μ-oxy-bis(triarylantimony) selenocyanates using a phase-transfer catalyst

Abstract Several new, pentacoordinated, triorganoantimony bis-selenocyanates [R3Sb(SeCN)2 (R = Me, Ph, p-CH3C6H4, p-ClC6H4, p-F-C6H4 or C6F5)], tetraorganostibonium selenocyanates [R3R′Sb(SeCN) (R = R′ = Ph; R = Ph, and R′ = CH2CHCH2)] and μ-oxy-bis(triarylantimony) bis-selenocyanates {[Ar3SbOSbAr3](SeCN)2 (Ar = Ph, p-CH3C6H4, p-ClC6H4 or p-FC6H4)} have been synthesized from potassium selenocyanate and the corresponding organoantimony halide (chloride and/or bromide) in the presence of the phase-transfer catalyst 18-crown-6, and characterized. Spectroscopic evidence suggested an iso structure (Sb—NCSe). The compounds were also obtained in the absence of 18-crown-6 but in lower yields. Some of these compounds were found to exhibit a significant biological activity.

Cleavage of metal-aryl (M = Ge, Sn, Pb) bonds with iodine monochloride and monobromide

Abstract Tetraaryl-germanium, -tin and -lead compounds (aryl(Ar) = phenyl, p -tolyl) were treated with IX (X = Cl, Br) in dry carbon tetrachloride under various conditions. Iodine monochloride cleaved one MAr bond in case of Ge and two bonds in case of Sn and Pb to give triarylgermanium chloride and diaryl-tin and -lead dichlorides respectively. In contrast iodine monobromide reacted only to a small extent (~5%) with Ph 4 Ge in boiling ethylene bromide; with Ar 4 Pb the corresponding dibromides were formed, while Ar 4 Sn gave both mono- and dibromides. The SnAr bond is cleaved in preference to Sn—alkyl bonds in Bu n SnPh 4− n ( n = 2, 3). Reaction of Ph 3 SnCl with IBr or Br 2 produced a mixed halogeno-derivative, Ph 2 SnClBr, and the corresponding phenyl halide.

On the reactivity of less common halopseudohalogens towards metalcarbon- and metalmetal-bonded compounds

Abstract Freshly generated solutions of iodine azide (IN3) and iodine isocyanate (INCO) in acetonitrile or carbon tetrachloride add oxidatively to tertiaryaryl derivatives of group VB elements, Ar3M (Ar = Ph, p-tolyl, p-ClC6H4 or p-FC6H4, and M = As, Sb or Bi) and diaryltellurium(II), Ar2Te (Ar = Ph or p-CH3OC6H4) at −10°C to −5°C to give stable covalent monomeric products, Ar3MIX and Ar2TeIX, respectively (where X = N3 or NCO). The mode of bonding of the pseudohalide group to M has been established by solid-state IR spectra. Ar3MI(N3) failed to react with CS2 but reaction with PhNCY (Y = O or S) gave cyclic tetrazole derivatives. Contrasting behaviour was also observed in the metathetic reaction of Ar2MIX and Ar2TeIX with silver pseudohalides [AgX′ (X′ = NCO or NCS)]. The tetraorgano compounds, R4M (M = Sn or Pb, and R = Ph or p-tolyl), and Bu3SnPh failed to react with IN3 and Bu3SnPhINCO but IN3 cleaved one tin-aryl bond from Ar4Sn in the presence of AlCl3. Addition of IN3 and INCO across the olefinic bond of Ph3SnCH2CHCH2 is preferred to tin-allyl bond cleavage. Reactions of hexaaryldileads with IN3 and INCO under appropriate conditions proceeded with the cleavage of a PbPb bond. Parallel reactions of cyanogen halides (CNI and CNBr) resulted in the formation of corresponding triaryllead halides and pseudohalide derivatives.

Thicyanogen cleavage of some symmetrical tetraaryland and hexaaryldi-tin and-lead compounds

Abstract Ar4M and Ar4MMAE3 compounds (Ar=phenyl and P-tolyl, M=Sn, and Pb) were treated with freshyl prepared thiocyanogen (SCN)2 anhydrous carbon tetrachloride under various conditions. Unlike the tertraarylleads, the corresponding tin compounds reacted only to a small extent. the hexaaryldi-metals were quite reactive. The metal-containing reaction products have an iso-Ar3M-NCS structure.

Synthesis and reactions of diaryl antimony(III) amides

Abstract Some new three coordinated diaryl antimony(III) amides of the Ar2SbL (Ar = phenyl, pentafluorophenyl and L = NR2 =  NCOCH 2 CH 2 C O,  NCOC 6 H 4 C O,  NCOCOC 6H4,  NNNC 6H4,  NC(CH 3 )NCH · C H, NC(S)S C6H4,  NC(CH 2 Cl)N C6H4, - NC 6 H 4 C 6H4) have been isolated and characterized by elemental analysis, solid state IR spectra, conductivity and molecular weight measurements. The amides are unaffected by water, methanol and CS2. However, PhNCO was found to add across the SbN bond and Br2 and CH3COOH cleave the SbN bond in preference to the SbAr bond(s).