Versatility of the bis(iminopyrrolylmethyl)amine ligand: tautomerism, protonation, helical chirality, and the secondary coordination sphere with halogen bonds in the formation of copper(II) and nickel(II) complexes
DALTON TRANSACTIONS
Authors: Kumar, Rajnish; Guchhait, Tapas; Subramaniyan, Vasudevan; Schulzke, Carola; Mani, Ganesan
Abstract
The reaction of N,N-di(2,6-bis(isopropyl)phenylimino-pyrrolyl-alpha-methyl)-N-methylamine H(2)L1 with copper(i) sources such as CuX (X = Cl (1), Br (2), and I (3)) afforded bis(chelated) ionic copper(ii) complexes of the type (CuL1H)X. A similar type of mononuclear structure was obtained with Cu(NO3)(2).(H2O)(3). Conversely, binuclear copper(o) complexes [Cu-2(mu-L1)(mu-OOCCH3)(mu-OH)1(4) and (Cu-2(mu-L1H)(mu-OOCPh)(mu-O)] (5) were obtained from the reaction of Cu(O2CR)(2).H2O with H(2)L1. Notably, these reactions in the presence of a base yielded the neutral copper(o) complex (CuL1) (6). This product was also obtained from the reaction of complex 2 or 4 with NaOH in methanol. All structures feature a dianionic iminopyrrole motif and a protonated central amine function except 4. The reaction of H(2)L1 with NiCl2.DME gave the mononuclear complex (NiCl2(L1H(2))), 7. In contrast to this, the reaction of the newly synthesized sterically less encumbered ligand N,N-di(phenylimino-pyrrolyl-alpha-methyl)-N-methylamine H(2)L2 with NiCl2.DME gave the binuclear complex (NiCl(L2H(2))(HOMe)](2)[Cl](2 )(8). Both 7 and 8 show the amine-azafulvene ligand form and coordination of the central amine. The reaction of complex 7 with NaHBEt3 yielded a neutral complex [NiL1] (8) containing the imino-pyrrole form. In the molecular structures, interesting secondary coordination spheres incorporating guest molecules such as CHCl3 and MeOH in the crystal lattices and the presence of helical enantiomers were observed and analysed. In one case, CHCl3 was found inside an unusual cage-like structure supported by halogen bonds. Preliminary DFT calculations on the geometry of the nickel complex with H(2)L1 showed that the pentacoordinated tbp geometry is more stable than the square planar geometry.
Transfer of an erbium ion across the water/dodecane interface: Structure and thermodynamics via molecular dynamics simulations
CHEMICAL PHYSICS LETTERS
Authors: Karnes, John J.; Villavicencio, Nathan; Benjamin, Ilan
Abstract
The thermodynamics and structural changes involved in the transfer of the Er3+ ion across the water/dodecane interface are investigated by molecular dynamics simulations. We show that the Er3+ ion is transferred as a highly conserved 8-water coordinated species and that the transfer involves significant perturbation of the interfacial water structure. Several structural properties are used to quantify this process. Implications for the ion extraction process are discussed.