A bimetallic palladium(II) catalyst containing a triketone ligand and a bridging dinitrogen ligand oxidizes aromatic and cyclic aliphatic olefins in bromide-containing aqueous-THF to 1,2-dibromo compounds and bromohydrins. With aromatic olefins, the 1,2-dibromo products were obtained in a 70-80% yield and the bromohydrins in a 10-15% yield; this observation is opposition to that obtained in chloride containing medium where the chlorohydrin product predominates. The oxidation of 2,3-dihydrofuran gave trans-2,3-dibromotetrahydrofuran, 3-oxotetrahydrofuran, and 3-bromo-2-hydroxytetrahydrofuran in relative yields of 75%, 15%, and 10%, respectively. On the other hand, the oxidation of cyclopentene and cyclohexene affords only trans-1,2-dibromo products in about 90% yield. The stereochemistry is consistent with an anti-attack of bromide followed by decomposition involving attack of bromide from the coordination sphere of the Pd(II). The procedure outlined here is a convenient method for the one step synthesis of 1,2-dibromides.
Abstract The reaction of the pyridylquinoline with RhCl 3 , K 3 (RhBr 6 ) (prepared in situ) and MY 2 (PhCN) 2 (M: Pd, Pt; Y: Cl, Br, I) in CHCl 3 or acetone gives the complexes (I) and (II) in yields from 40‐85%.
Rhodium(III) complexes containing 2-(2'-pyridyl)quinoline (PQ) were prepared by the reaction of RhCl 3 .6H 2 O and PQ in 1:2 mole ratio followed by addition of an excess of sodium salts to the reaction mixture. The new complexes cis-[RhX 2 (PQ) 2 ]Y (where X = NO 2 - , Y = PF 6 - ; X = SCN - or NO 3 - , Y = Cl - ; X = Y = I - ) and cis-[Rh(N 3 ) 2 (H 2 O) 2 (PQ)]PF 6 were characterized by elemental analysis, conductivity measurements, IR, 1 H and 1 3 C NMR.
The structure of the symmetrical Schiff base, N,N '-[bis(pyridin-2-yl)formylidene]ethane-1,2diamine (bpfd) has been characterized by single crystal X-ray diffraction.The non-covalent supramolecular chemistry involved in the crystal structure of this ligand has been carefully investigated.The structure adopted different motifs of nitrogen-hydrogen interactions that led to the formation of centrosymmetric dimers.In addition, edge-edge and face-face nitrogen-nitrogen interactions were observed and reported.The Schiff base (bpfd) ligand crystallizes in a monoclinic space group C12/c1 with a = 19.128(2)Å; b = 5.8776(6) Å; c = 13.1403(15)Å; α = 90 o ; β = 121.970o (4); γ = 90 o and z = 4.This structure is an example of compounds with many symmetry-independent molecules in the asymmetric unit cell (Z > 2).
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