16 research outputs found
The interaction between heteroditopic pyridine–nitrogen NHC with novel sulfur NHC ligands in palladium(0) derivatives: Synthesis and structural characterization of a bis-carbene palladium(0) olefin complex and formation in solution of an alkene–alkyne mixed intermediate as a consequence of the ligandshemilability
We have synthesized a new class of heteroditopic chelating ligands bearing the phenylthiomethyl group
and variously substituted imidazole derivatives and the corresponding complexes [Pd(eta2-ma)(R-NHCCH2-
SPh) (ma = maleic anhydride; R = methyl, mesityl, di-i-propylphenyl). We have compared their
chemical characteristics and reactivity with those of similar palladium(0) complexes bearing the RNHC-
CH2-Py ligands.
The hemilability of the above-mentioned moieties is apparent when their palladium derivatives react
with an excess of the same or different heteroditopic ligands. In these cases, we obtained complexes bearing
maleic anhydride and two mono-coordinated heteroditopic ligands bound to the same metal center.
However, at variance with the generally accepted opinion, precipitation of AgBr does not warrant the
quantitative formation of the bis-heteroditopic Pd(0) derivative and in some cases, a reaction involving
a heterogeneous equilibrium is observed.
The reaction of the palladium(0) carbene–sulfur or carbene–nitrogen complexes with the alkyne
dimethyl-2-butynedioate (dmbd) to give palladacyclometallate derivatives is not always warranted
and formation of the intermediate [Pd(eta2-ma)(eta2-dmdb)(chi1-Mes-NHC-CH2-SPh)] is detected only in
one case.
Finally, we have carried out a diffractometric study on the solid-state structures of two derivatives and
in particular we describe the configurations of the complex [Pd(eta2-ma)(j1-Me-NHC-CH2-SPh)2] and of
[Pd(eta2-ma)(Me-NHC-CH2-SPh)]
Expanding access to primary care without additional budgets? A case study from Burkina Faso
Access, Burkina Faso, Cost analysis, Costing, Nouna, Primary care, Utilisation,