1426338-76-2Relevant academic research and scientific papers
Half-sandwich (η5-Cp?)Rh(iii) complexes of pyrazolated organo-sulfur/selenium/tellurium ligands: Efficient catalysts for base/solvent free C-N coupling of chloroarenes under aerobic conditions
Joshi, Raj Kumar,Sharma, Charu,Sharma, Kamal Nayan,Srivastava, Avinash Kumar
, p. 3599 - 3606 (2020/06/10)
Three new pyrazolated chalcogenoether ligated Rh(iii) half-sandwich complexes (1-3) were synthesised by the thermal reaction of chalcogenoether (S, Se and Te) substituted 1H-pyrazole ligands (L1-L3) and [(η5-C5Me5)RhCl]2 in methanol. The complexes were fully characterised by various spectroscopic techniques, and the molecular structures of complexes 1 and2 were also established through single crystal X-ray crystallographic analysis, which indicates a pseudo-octahedral half-sandwich piano-stool geometry around the rhodium metal. All three complexes were found to be thermally stable and insensitive towards air and moisture. One mol% of Rh(iii) complexes (1-3) along with 10 mol% of Cu(OAc)2 were explored for the Buchwald-Hartwig type C-N coupling reactions of amine and aryl chloride. Good to excellent yields (89-92%) of the coupling products were obtained with seleno- and thio-ether functionalised pyrazolated Rh(iii) complexes (1 and 2), while an average yield (39%) was obtained with the telluro-ether functionalised complex (3). In contrast to the previously reported C-N coupling reactions the present reaction works under solvent- and base-free conditions, and the coupling reaction is accomplished in just 6 h with a high yield of the coupling product. The present methodology was also found to be efficient for a wide variety of functionalised aryl halides, and aliphatic or aromatic amines (1° and 2°). Moreover, the reaction also enables the C-N coupling of electron-withdrawing substrates and base-sensitive functionalities.
(η6-Benzene)Ru(II) half-sandwich complexes of pyrazolated chalcogenoethers for catalytic activation of aldehydes to amides transformation
Sharma, Kamal Nayan,Ali, Munsaf,Srivastava, Avinash Kumar,Joshi, Raj Kumar
, p. 69 - 77 (2018/11/10)
The reaction of [(η6-C6H6)RuCl(μ-Cl)]2 with chalcogenoether substituted 1H-pyrazole ligands (L1-L3) in methanol have yielded three novel Ru(II) half-sandwich complexes [(η6-C6H6)RuCl(L)]PF6 (1–3) in high yield under the ambient reaction conditions. The NMR, MS and FT-IR analytical techniques were used to identify their structures. The molecular structures of the complexes 2 and 3 were established with X-ray crystallographic analysis and revealed a pseudo-octahedral half sandwich piano-stool geometry around ruthenium in each complex. Complexes 1–3 are thermally robust and were found to be insensitive towards the air and moisture. All the complexes were found to be catalytically active and produced the excellent yields of amides (up to 95%) from corresponding aldehydes. In contrast to the previous reported catalytic systems for aldehyde to amide transformation, the present complexes 1–3 are very efficient and have several advantages in terms of low catalyst loading, reaction time, temperature and wide applicability for various substituted aldehydes. Owing to the stronger σ-donor coordination properties of selenium containing ligands, the complex 2 was found to be more efficient as compare to the sulphur and tellurium analogues.
Palladium(ii) complexes of pyrazolated thio/selenoethers: Syntheses, structures, single source precursors of Pd4Se and PdSe nano-particles and potential for catalyzing Suzuki-Miyaura coupling
Sharma, Kamal Nayan,Joshi, Hemant,Singh, Ved Vati,Singh, Pradhumn,Singh, Ajai Kumar
, p. 3908 - 3918 (2013/03/28)
The reactions of 4-bromo-1-(2-chloroethyl)-1H-pyrazole prepared from 4-bromopyrazole with the in situ generated PhSNa, PhSeNa, Na2S and Na2Se have resulted in thio/selenoether ligands L1-L4 respectively. The complexes [PdL1/L2Cl
