Experimental and theoretical study of the kinetics of dissociation in cis-[RuCl2(P-P)(N-N)] type complexes

Abstract

-, onde P-P = 1,4-bis(difenilfosfino)butano e N-N = 2,2´-bipiridina, 4,4´-dimetóxi-2,2´-bipiridina, 4,4´-dimetil-2,2´-bipiridina e 4,4´-dicloro-2,2´-bipiridina, L = piridina (py) ou 4-metilpiridina (4-pic), foram estudadas sob condições de pseudo-primeira ordem. As reações ocorrem por um mecanismo dissociativo e as constantes de velocidade nas reações de substituição aumentam com o aumento do pK a dos ligantes N-heterocíclicos e com a diminuição dos potenciais de oxidação do centro metálico. Quanto mais alta é a porcentagem de participação dos orbitais atômicos d do metal na formação do HOMO, conforme calculado pelo método DFT, mais fácil é a dissociação do cloreto da esfera de coordenação do complexo. Nos espectros de 31 P{ 1 H} RMN da série de complexos de fórmula geral [RuCl(L)(P-P)(N-N)]PF 6 , há dois dubletos com Δσ < 1, o que é consistente com produtos formados pela dissociação do cloreto trans ao átomo de fósforo nos precursores.The substitution reactions [RuCl 2 (P-P)(, where P-P = 1,4-bis(diphenylphosphino)butane and N-N = 2,2´-bipyridine, 4,4´-dimethoxy-2,2´-bipyridine, 4,4´-dimethylpyridine-2,2´-bipyridine and 4,4´-dichloro-2,2´-bipyridine, L = pyridine (py) or 4-methylpyridine (4-pic), were studied under pseudo-first order conditions. The reactions proceeded by means of a dissociative mechanism. The rate constants of the substitution reactions increased as the pK a of the N-heterocyclic ligands increased and as the oxidation potential of the metal center decreased. The greater the participation of the atomic d orbitals of the metal in the HOMO, according to DFT calculations, the easier is the dissociation of the chloride from the coordination sphere of the complex. In the 31 P{ 1 H} NMR spectra of the series of complexes of general formula [RuCl(L)(P-P)(N-N)]PF 6 , there are two doublets with Δσ < 1. This is consistent with products formed by dissociation of the chloride trans to one of the phosphorus atoms in the precursors.

Modified glassy carbon electrode with AuNPs using cis-[RuCl(dppb)(bipy)(4-vpy)]+ as crossed linking agent

“…Calc. for C 46 TBAP, scan rate 100 mV s À1 , at room temperature, with E ox = 1200 mV and E 1/2 = 1125 mV, close to those found for similar chlorine complexes containing dppb, diimines and N-heterocyclic as ligands [20,21,32,[34][35][36][37][38].…”

“…Reagent grade solvents were distilled prior to use. The [RuCl(dppb)(bipy)(py)](PF 6 ) (1) and [RuCl(dppb)(bipy)(4-vpy)](PF 6 ) (2) were prepared as described previously [20][21][22][23][24]. Herein we will be discussing only unpublished results about these complexes.…”

“…The [RuCl(dppb)(bipy)(4-vpy)](PF 6 ) was prepared by ligand exchange from cis-[RuCl 2 (dppb)(bipy) as ascribed by Batista and co-workers [20]. Experimental and theoretical study of the kinetics of dissociation in the cis-[RuCl 2 (dppb)(bipy)] revealed that only the chloride trans to the phosphorus atom of the dppb ligand was dissociated, even in the presence of excess of monodentate ligand, such as monopyridine and functionalized monopyridine (Fig.…”

“…In order to apply these kinds of complexes as cross-link agents between glassy carbon electrode and AuNPs, the [RuCl(dppb) (bipy)(4-vpy)](PF 6 ) was prepared as previously described in the literature [20]. Cyclic voltammetry of [RuCl(dppb)(bipy)(4-vpy)](PF 6 ) has shown an oxidation potential (E ox ) at 1.19 V and a reduction potential (E red ) at 1.06 V due the redox pair Ru III /Ru II , with half wave potential (E ½ ) at 1.10 V. It also suggests a exchange between chlorine (p-donor group) and 4-vpy (p-acceptor group) in the cis-[RuCl 2 (dppb)(bipy)], producing a cationic ruthenium complex, with increasing of potentials.…”

Ruthenium(II) phosphine/diimine/picolinate complexes: Inorganic compounds as agents against tuberculosis

“…In this case only the complex SCAR06 presents chloride coordinated to the ruthenium, but it was showed that only one trans to the phosphorus atom is dissociated from the metal [37,38].…”