Organic reactions involving transition metals. Part I. Formation of pentamethylcyclopentadienylrhodium complexes by reaction of hexamethylbicyclo[2,2,0]hexa-2,5-diene with rhodium trichloride

Abstract

Reaction of para-bonded hexamethylbenzene, hexamethylbicyclo[2,2,0] hexa-2,5-diene, with rhodium trichloride trihydrate in methanol gives a red solid, also obtained in high yield from the reaction of pentamethylcyclopentadiene with RhCI3,3H20 under similar conditions, and now considered to be di-p-chloro-dichloro(pentamethy1cyclopentadienyl)dirhodium(lll), (C5Me,RhC12)2, rather than the arene complex previously suggested. The same compound has also been obtained in good yields from the reactions of 1 -(I -methoxyethyl)-, 1 -(I -chloroe t h y I )or 1 -( 1 -ace tox y e t h y I)pen ta met h y I cyc I o p e n ta -2,4 -die n e and endo -1 ,2,3,5,6pent a m e t h y I -4met h y le n ebicyclo [3,1 ,O] hex-2-ene with RhC1,,3H20 under similar conditions. Evidence is presented that these last reactions and that of hexamethylbicyclo[2,2,0] hexa-2.5-diene occur via a rearrangement to pentamethylcyclopentadiene catalysed by the hydrochloric acid formed in the reaction of methanol with rhodium trichloride. Reaction of the compound (C5Me5RhC12)2 with sodium iodide gives the corresponding iodo-complex, (C5Me5Rh12),, and pyridine yields the compound (C5Me,) RhCI2(C5H5N).

Coligand tuning of the DNA binding properties of half-sandwich organometallic intercalators: Influence of polypyridyl (pp) and monodentate ligands (L=Cl, (NH2)2CS, (NMe2)2CS) on the intercalation of (η5-pentamethylcyclopentadienyl)-iridium(III)- dipyridoquinoxaline and -dipyridophenazine complexes

“…IrCl 3 AE xH 2 O and Ag(CF 3 SO 3 ) were obtained from Chempur, thiourea and (Me 2 N) 2 CS from Acros. The starting complex [{(g 5 -C 5 Me 5 )IrCl} 2 (l-Cl 2 )] [25,26], [(g 5 -C 5 Me 5 )IrCl(dppz)](CF 3 SO 3 ) (2) and the polypyridyl ligands dpq [27], dppz [28] and dppn [12] were synthesised according to literature procedures. The thermal denaturation temperatures T m of 1:10 complex/DNA mixtures [DNA concentration = M (nucleotide)] were determined in a 10 mM phosphate buffer at pH 7.2.…”

Antitumor pentamethylcyclopentadienyl rhodium complexes of maltol and allomaltol: Synthesis, solution speciation and bioactivity

“…The Rh III precursor [Rh III (Cp*)(m-Cl)Cl] 2 was synthesized according to literature procedures by reaction of RhCl 3 with pentamethylcyclopentadiene (Cp*) [26]. The maltol-based Rh III complex was obtained according to the procedure described by Abbott et al [27], which was adapted to prepare the analogous allomaltol organometallic complex.…”

Synthesis, characterisation and theoretical studies on some piano-stool ruthenium and rhodium complexes containing substituted phenyl imidazole ligands

“…Pentamethylcyclopentadiene, hydrated rhodium(III) chloride, hydrated ruthenium(III) chloride, 4-fluronitrobenzene, 4-fluorobenzaldehyde, 4-imidazol-yl-phenol and imidazole were procured from Sigma-Aldrich. The ligands 1-(4-nitrophenyl)-imidazole (NOPI) [30], 1-(4-formylphenyl)-imidazole (FPI) [31] and precursor complexes [{(g 6 -arene)Ru(l-Cl)Cl} 2 ] (arene = benzene [32], p-cymene [33]), [{(g 5 -C 5 Me 5 )Rh(l-Cl)Cl} 2 ] [34] were prepared and purified following the literature procedures. Elemental analyses on the complexes were performed on an Exter CE-440 CHN Analyzer.…”