110370-69-9Relevant articles and documents
Structural diversity in Cu(i) complexes of the PNP ligand: From pincer to binuclear coordination modes and their effects upon the electrochemical and photophysical properties
Arce, Pablo,Vera, Cristian,Escudero, Dayra,Guerrero, Juan,Lappin, Alexander,Oliver, Allen,Jara, Danilo H.,Ferraudi, Guillermo,Lemus, Luis
, p. 13432 - 13445 (2017)
A set of new copper(i) complexes is synthesized and characterized using a labile PNP pincer ligand (PNP = N,N′-bis(diphenylphosphine)-2,6-diaminopyridine). A homoleptic Cu(i) complex [Cu(PNP-κP1:κN1)2]+, (1), was prepared, and taking advantage of the uncoordinated phosphorus atoms in (1), reaction with a second Cu(i) atom bearing secondary ligands (PPh3, phen or dmp) allows the formation of new complexes: a bimetallic helicate [CuI2(PNP)2(phen)]2+, (2), a mononuclear pincer complex [CuI(PNP)(PPh3)]+, (3), and a heteroleptic complex [CuI(PNP)(dmp)]+, (4). All complexes were characterized by X-ray crystallography, NMR (VT-NMR for (1) and (4)), cyclic-voltammetry, and steady-state and time-resolved luminescence spectroscopy. The fluxional behavior in (1) was studied by 31P VT-NMR, where an Ea value of 47.42 kJ mol-1 was calculated for the intramolecular alternating coordination of -PPh2 moieties in PNP to the metal atom. This set of compounds reveals the versatility of the PNP ligand when added to the coordinating properties of Cu(i). The four complexes exhibit emission in solution and complexes (2)-(4) display intense luminescence in the solid state. The oscillographic traces showing the decay of the luminescence were fitted to biexponential functions with time constants: 8.0 μs > τem,1 > 0.37 μs and 50 μs >τem, 2 > 2.2 μs for complexes (2), (3) and (4), respectively. Radiative relaxation is associated with electronic transitions in both the ligand PNP and metal-to-ligand charge transfer (MLCT).
RETRACTED ARTICLE: Catalytic activity of Fe(II) and Cu(II) PNP pincer complexes for Suzuki coupling reaction
Kumar, Lolakshi Mahesh,Ansari, Rasheeda M.,Bhat, Badekai Ramachandra
, (2018)
Iron and copper PNP pincer complexes of the type [Fe(L)SO4] and [Cu(L)OCOCH3] are reported and represented as C-1 and C-2 catalyst. Both the complexes were synthesized using bis(diphenylphosphino)pyridine-2,6-diamine [L], and salts of ‘Fe’ and ‘Cu’ by direct coordination method. The as synthesized complexes were characterized using FTIR, UV–Vis, mass analysis and TGA. The effect of reaction time, catalyst load, solvent and base on the reaction between phenylboronic acid and para substituted bromobenzenes in the presence of the catalysts were investigated for evaluating the catalytic efficiency of the complexes. The results obtained highlight the enhanced C-C coupling reactions with the use of 0.4?mol% of the catalyst C-1 in 14?h and 0.6?mol% of C-2 in 16?h respectively with Cs2CO3 base and ACN as solvent media. Of the two complexes reported, C-1 with iron as catalytically active metal is more stable and active towards coupling which is reflected in its better coupling yields in lesser reaction time compared to copper bearing C-2 complex.
Cobalt-Catalyzed Alkylation of Secondary Alcohols with Primary Alcohols via Borrowing Hydrogen/Hydrogen Autotransfer
Freitag, Frederik,Irrgang, Torsten,Kempe, Rhett
supporting information, p. 12110 - 12113 (2017/09/14)
Alcohols are promising sustainable starting materials because they can be obtained from abundant and indigestible biomass. The substitution of expensive noble metals in catalysis by earth abundant 3d metals, such as Mn, Fe, or Co, (nonprecious or base metals) is a related key concept with respect to sustainability. Here, we report on the first cobalt-catalyzed alkylation of secondary alcohols with primary alcohols. Easy-to-synthesize and easy-to-activate PN5P-pincer-ligand-stabilized Co complexes developed in our laboratory mediate the reaction most efficiently. The catalysis is applicable to a broad substrate scope and proceeds under relatively mild conditions. We have even demonstrated the coupling of a variety of purely aliphatic alcohols with a base or nonprecious metal catalyst. Mechanistic studies indicate that the reaction follows the borrowing hydrogen or hydrogen autotransfer concept.
