Synthesis of mononuclear and PEPPSI type palladium diiodo complexes of 1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene without the use of strong bases and silver salts and at ambient conditions using Pd(OAc)2 is reported. Using stoichiometric amounts of bidendate ligands such as pyrazine, 4,4′-bipyridine and DABCO bridged binuclear palladium diiodo complexes were obtained in excellent yields. By simple variation of reagents and their stoichiometry, one can control the reactions towards the selective formation of mononuclear [(Tz)2Pd(I)2] complexes, iodo bridged binuclear complexes [(Tz)Pd(I)(μ-I)2Pd(I)(Tz)], mononuclear PEPPSI type complexes [(Tz)Pd(I)2(Py)], bridged binuclear PEPPSI type complexes [(Tz)Pd(I)2-(bridge biPy)-(I)2Pd(Tz)]. The catalytic activities of these three structurally different types of complexes are compared for Suzuki-Miyaura coupling reaction. © 2015 Elsevier B.V.

Sethuraman Sankararaman

Department Of Chemistry

Bemineni Sureshbabu

Venkatachalam Ramkumar

Bins

Catalyst activity

Chemical reactions

Organic compounds

Salts

Synthesis (chemical)

Cross-couplings

MESOIONIC NHC

N-heterocyclic carbenes

PD COMPLEX

PEPPSI

Palladium compounds

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Organometallic Chemistry

Synthesis of normal and mesoionic N-heterocyclic carbene Pd(ii) complexes in near quantitative yields from the corresponding NHC precursor salts under base free and ambient conditions is reported. A plausible mechanism involving charge-assisted hydrogen bonded intermediates is proposed. © 2014 the Partner Organisations.

Dalton Transactions

Facile base-free in situ generation and palladation of mesoionic and normal N-heterocyclic carbenes at ambient conditions

A palladium complex (3) of abnormal N-heterocyclic carbene (NHC) namely, 4-(hydroxymethyl)-3-methyl-1-phenyl-1H-1,2,3-triazol-5-ylidene was prepared via silver carbene transmetalation method and characterized by spectroscopic and single crystal XRD data. Single crystal analysis revealed the structure of the complex 3 to be a cis isomer. The synthesis of palladium complex 6 via silver carbene transmetalation method led to a mixture of cis-trans isomers. In this case trans isomer was formed as major product. We have reported earlier the synthesis and structural characterization of trans isomer (trans-6). However, the presence of cis isomer was not recognized until the crude reaction mixture was recrystallized from acetonitrile. Pure cis isomer (cis-6) was obtained by washing the cis-trans mixture with acetonitrile followed by slow evaporation of acetonitrile solution at 35 C. Structure of cis (cis-6) isomer was unambiguously established by single crystal XRD data.© 2013 Elsevier B.V. All rights reserved.

Synthesis and structural characterization of cis isomer of 1,2,3-triazol-5-ylidene based palladium complexes

trans-Bis(1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) dichloride has been shown to be an excellent catalyst for the multiple Suzuki-Miyaura coupling reactions of polybromoarenes to the corresponding fully substituted polyarylarenes. The reactions proceeded in excellent yields and with high turnover numbers. With 1,4-dibromobenzene the catalyst was found to be active for up to 13 consecutive cycles with a turnover number of 1260. The polyarylarenes were obtained in pure form after crystallization once without recourse to chromatographic purification. The single-crystal X-ray structures of the chloro (1) as well as the corresponding acetato (2) complexes are also reported and compared with the corresponding complexes of 1,4-diphenyl-3-methyl- 1,2,3-triazol-5-ylidene as the ligand. © 2013 Shaik et al.

Fulltext

Beilstein Journal of Organic Chemistry

Synthesis and structure of trans-bis(1,4-dimesityl-3-methyl-1,2,3-triazol- 5-ylidene)palladium(II) dichloride and diacetate. Suzuki-Miyaura coupling of polybromoarenes with high catalytic turnover efficiencies

An abnormal or mesoionic N-heterocyclic carbene (NHC), namely 1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene (Tz), formed from 1,4-diphenyl-3-methyl-1,2,3-triazolium iodide and silver oxide, gave the corresponding silver carbene complex. The transmetalation reaction of the silver carbene complex with PdCl2(CH3CN)2 gave a trans mononuclear complex, [(Tz)2PdCl2]. Reaction of the silver carbene complex with Pd(OAc)2 gave an acetate-bridged binuclear complex in which the palladium had undergone a C-H insertion at the ortho position of the phenyl group attached to the triazole nitrogen (1-position). The structures of these two complexes were established by single-crystal XRD data and spectroscopic data. The acetate complex was used as a catalyst for the stereoselective hydroarylation of alkynes. © 2011 American Chemical Society.

Organometallics

Synthesis and structure of 1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene palladium complexes and application in catalytic hydroarylation of alkynes

Chiral and achiral pincer type palladium complexes bearing abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazole are reported. Both complexes are effective as catalysts for non-asymmetric Suzuki coupling reaction for the synthesis of biphenyl derivatives. However, both the complexes failed to catalyze the formation of binaphthyl derivatives, by the asymmetric Suzuki coupling in case of the chiral complex and the non-asymmetric version in case of the achiral pincer complex. Instead deboronation of arylboronic acid occurred very efficiently leaving the aryl bromide intact. © 2009 Elsevier Ltd. All rights reserved.

Tetrahedron Letters

Palladium complexes with abnormal N-heterocyclic carbene ligands derived from 1,2,3-triazolium ions and their application in Suzuki coupling

A mild and efficient method for the synthesis of structurally diverse 1,2,3-triazolylidene palladium(II) diiodo complexes. Comparison of catalytic activities for Suzuki-Miyaura coupling

Journal	Data powered by TypesetJournal of Organometallic Chemistry
Publisher	Data powered by TypesetElsevier
ISSN	0022328X
Open Access	No