RESUMEN
The addition of BCl3 to the carbene-transfer reagent NHCâSiCl4 (NHC=1,3-dimethylimidazolidin-2-ylidene) gave the tetra- and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl3 ](+) and [(NHC)2 SiCl3 ](+) with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHCâSiCl4 served as a transfer reagent for the NHC ligand. The addition of BF3 â OEt2 , on the other hand, gave NHCâBF3 as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl)silane (C2 F5 )2 SiCl2 was treated with NHCâSiCl4 . In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl3 ](+) and [(NHC)2 SiCl3 ](+) were detected with [(C2 F5 )SiCl3 ](-) as counterion. A similar result was already reported for the reaction of NHCâSiCl4 with (C2 F5 )2 SiH2 , which gave [(NHC)2 SiCl2 H][(C2 F5 )SiCl3 ]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHCâSi(C2 F5 )2 Cl2 and NHCâSi(C2 F5 )2 ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron-poor silylenes. Furthermore, the reactivity of NHCâSiCl4 towards phosphines is discussed. The carbene complex NHCâPCl3 shows similar reactivity to NHCâSiCl4 , and may even serve as a carbene-transfer reagent as well.
RESUMEN
NHC(Me)SiCl4 (NHC(Me) = 1,3-dimethylimidazolidin-2-ylidene) was used to synthesise novel NHC(Me)-Pt(ii) complexes. An atypical trans-cis isomerisation process was also achieved for [(NHC(Me))2PtCl2], while the synthesis of the unique double-complex salt [(NHC(Me))Pt(cod)Cl] [(NHC(Me))PtCl3] (cod = 1,5-cyclooctadiene) revealed the first-ever N-heterocyclic carbene analogue of the Cossa's salt anion.
RESUMEN
We report a one-step synthesis of the phosphine, PPh(2)(i)C(3)F(7) from commercially available precursors. The stereoelectronic properties of the phosphine were probed by coordination to transition metals. Mo(CO)(5)PPh(2)(i)C(3)F(7) was synthesised and the synthesis and structure of trans-PtCl(2)(PPh(2)(i)C(3)F(7))(2) are described. PPh(2)(i)C(3)F(7) was found to be a bulky electron-withdrawing ligand.
Asunto(s)
Complejos de Coordinación/síntesis química , Fosfinas/química , Fosfinas/síntesis química , Complejos de Coordinación/química , Cristalografía por Rayos X , Conformación Molecular , Estereoisomerismo , Elementos de TransiciónRESUMEN
A novel microwave-assisted synthetic method has been used to synthesise a series of mixed ligand ruthenium(II) compounds containing diimine as well as bidentate thiosemicarbazone ligands. The compounds contain the diimine 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy) and the thiosemicarbazone is derived from 9-anthraldehyde. Based on elemental analyses and spectroscopic data, the compounds are best formulated as [(phen)(2)Ru(thiosemicarbazone)](PF(6))(2) and [(phen)(2)Ru(thiosemicarbazone)](PF(6))(2) where thiosemicarbazone = 9-anthraldehydethiosemicarbazone, 9-anthraldehyde-N(4)-methylthiosemicarbazone, and 9-anthraldehyde-N(4)-ethylthiosemicarbazone. Fluorescence competition studies with ethidium bromide, along with viscometric measurements suggests that the complexes bind calf thymus DNA (CTDNA) relatively strongly via an intercalative mode possibly involving the aromatic rings of the diimine ligands. The complexes show good cytotoxic profiles against MCF-7 and MDA-MB-231 (breast adenocarcinoma) as well as HCT 116 and HT-29 (colorectal carcinoma) cell lines.
Asunto(s)
Antineoplásicos/síntesis química , Complejos de Coordinación/síntesis química , Iminas/química , Microondas , Rutenio/química , Tiosemicarbazonas/química , 2,2'-Dipiridil/química , Animales , Antracenos/química , Antineoplásicos/química , Antineoplásicos/toxicidad , Bovinos , Línea Celular Tumoral , Complejos de Coordinación/química , Complejos de Coordinación/toxicidad , ADN/química , Ensayos de Selección de Medicamentos Antitumorales , Células HCT116 , Células HT29 , Humanos , Ligandos , Fenantrolinas/químicaRESUMEN
Simple chlorodiisopropylphosphine adducts of rhodium, either pre-formed or formed in situ, prove to be highly effective catalysts for the ortho-arylation of phenols.