Monodentate Complex (monodentate + complex)

Distribution by Scientific Domains

Selected Abstracts

Hydrolysis of oxaliplatin,evaluation of the acid dissociation constant for the oxalato monodentate complex

Elin Jerremalm
Abstract Alkaline hydrolysis of the platinum anticancer drug oxaliplatin gives the oxalato monodentate complex and the dihydrated oxaliplatin complex in two consecutive steps. The acid dissociation constant for the oxalato monodentate intermediate was determined by a kinetic approach. The pKa value was estimated as 7.23. The monodentate intermediate is assumed to rapidly react with endogenous compounds, resulting in a continuous conversion of oxaliplatin via the monodentate form. 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:436,438, 2003 [source]

Preparation and Coordination Chemistry of n -Allylaminophosphane

Alexandra M. Z. Slawin
Abstract Reaction of allylamine with 1 equiv. of Ph2PCl in the presence of NEt3, proceeds in THF to give (allylamino)phosphane 1. 1 has been coordinated as a monodentate P ligand with Au, Pd, Pt, Ru, Rh, Ir and as a bidentate P,allyl ligand to Pt. Reaction of KOtBu with [PtCl2{Ph2PNH(C3H5)}2] in methanol gives [Pt{Ph2PNH(C3H8O)}2]. The X-ray structures of 1.Se and four demonstrative monodentate complexes all reveal intramolecular N,HCl hydrogen bonding. The structure of [Pt{Ph2PNH(C3H8O)}2] consists of an N,HO hydrogen-bonded dimer in the solid state. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Formation of 2,4,D complexes on montmorillonites , an ab initio molecular dynamics study

D. Tunega
Summary Sorption of the anionic form of the pesticide 2,4,D (2,4,dichlorophenoxyacetic acid) on the surface of the clay mineral montmorillonite was investigated using a short-time ab initio molecular dynamics (MD) simulation at room temperature. Three different situations were modelled: sorption on a dry surface, on a hydrated surface and an intercalation between montmorillonite layers. In all three cases, the calcium cation compensates the excess negative charge of the montmorillonite layer and the negative charge of the 2,4,D anion. It was found that in all models with direct contact of the Ca2+ cation with the montmorillonite layer, the most stable position of Ca2+ is above the ditrigonal hole of the mineral layer. While in the case of a dry surface very stable bidentate binding is created between the 2,4,D anion and the Ca2+ cation, the formation of the monodentate complexes is preferred in all models that include water molecules. Hydrogen bonds formed between water molecules and the 2,4,D anion make a considerable contribution to the formation of the monodentate complexes. Tetrahedral substitutions in the montmorillonite layer have a significant effect on the formation of the complexes of any type. However, the MD simulations did not support the role of Ca2+ as a cation bridge in the adsorption mechanism. Calculations showed that hydrated 2,4,DCa2+ complexes are thermodynamically more stable than complexes in which the Ca2+ cation acts as a bridge to the surface. On the other hand, it is possible that phyllosilicates with a greater concentration of isomorphic substitutions (e.g. mica) will be able to form stable surface complexes with a cation bridge mechanism. [source]