Alexander I. Yanovsky

Synthesis and structure of biologically active ferrocenylalkyl polyfluoro benzimidazoles

Abstract The title compounds were synthesized in quantitative yields by interacting α-hydroxyalkyl ferrocenes with polyfluoroalkyl benzimidazoles in an aqueous-organic medium in the presence of HBF4. The resulting diastereomers and enantiomers were resolved using HPLC on silica bonded chiral stationary phases based on chiral cyclodextrins and cyclic antibiotics. The X-ray determination of molecular and crystal structure of 1-ferrocenylmethyl-2-(trifluoromethoxyfluoromethyl)benzimidazole (1) was carried out.

Synthesis and antitumour activity of platinum(II) and platinum(IV) complexes containing ethylenediamine-derived ligands having alcohol, carboxylic acid and acetate substituents: Crystal and molecular structure of [PtL4Cl2]·H2O where L4 is ethylenediamine-N,N′-diacetate

Several cisplatin analogues of ethylenediamine-derived ligands containing alcohol, carboxylic acid and acetate substituents have been prepared and characterised. Oxidation of some of these square planar platinum(II) complexes using aqueous hydrogen peroxide gave octahedral platinum(IV) complexes, containing trans hydroxo ligands. Acetylation of the hydroxo ligands was achieved by reaction with acetic anhydride, giving complexes which are analogues of the antitumour drug, JM-216. Oxidation of the complex [Pt(H2L4)Cl2], where H2L4 is ethylenediamine-N,N-diacetic acid, with H2O2 gave the platinum(IV) complex [PtL4Cl2].H2O in which L4 is tetradentate as shown by a crystal and molecular structure. This complex was previously reported to be [Pt(HL4)(OH)Cl2] in which HL4 is tridentate. Several of the complexes were tested for antitumour activity against five human ovarian carcinoma cell lines. IC50 values range from 4.0 microM for cis,trans-PtCl2(OH)2(NH2CH2CH2NHCH2CH2OH) against the CH1 cell line to >25 microM indicating moderate to low activity relative to other platinum complexes.

Bonds and lone pairs in the flexible coordination sphere of lead( II )

The single crystal XRD characterisation of a mixed anion complex of Pb(II) with 1,10-phenanthroline, [Pb(phen)(O2CCH3)(O2ClO2)], shows the complex to be polymeric as a result of acetate ligand bridging, the Pb atom being in an unsymmetrical eight-coordinate, N2O6, environment and the crystal array reflecting a strong influence of π?π stacking of the heteroaromatic chelate ligands. The structure is used to raise issues concerning the coordination sphere of lead(II) which are of relevance to the rational design of solid state arrays

Synthesis of trans-bis (glycinehydroxamato) platinum (II) hydrate tans-dichlorobis (glycylglycine) platinum (II) dihydrate and the crystal and molecular structures of trans-dichlorobis (glycine) platinum (II) dihydrate and trans, trans-dichlorobis (glycinato) platinum (IV), hydrolysis products formed in reactions of the former complexes

Abstract The complex trans -bis (glycinehydroxamato) platinum (II) hydrate, trans -Pt (GHA) 2 ·H 2 O, in which the ligand is coordinated to the metal through its amino and deprotonated hydroxamate nitrogen atoms, has been synthesised. Reaction of this with HCl in aqueous solution produced crystals of trans -dichlorobis(glycine) platinum(II) dihydrate, trans -PtCl 2 (glyOH) 2 ·2H 2 O, resulting from hydrolysis of the glycinehydroxamate ligand. The crystal and molecular structures show that the complex is square planar with the chloride ligands trans to each other, as are the glycine ligands which are N-coordinated. The Ptue5f8Cl and Ptue5f8 bond distances are 2.283 and 2.037 a, respectively. Extensive intermolecular hydrogen bonding in the crystal gives rise to a layer structure and each water molecule is involved in three hydrogen bonds. The complex trans -dichlorobis (glycylglycine) platinum(II) dihydrate was also prepared but attempts to oxidise it with H 2 O 2 resulted in hydrolysis of the peptide ligand as well as oxidation, giving trans,trans -dichlorobis(glycinato) platinum(IV), trans,trans -PtCl 2 (glyO) 2 . The crystal and molecular structures of this complex, one of the very few known platinum(IV)-amino acid complexes, have also been determined. The complex is octahedral with both glycinates and chlorides bonded trans to one another. In the crystal there are two chemically identical but crystallographically distinct molecules each of which occupies a special position in the crystallographic inversion centre. The average bond distances in this complex are, Ptue5f8Cl 2.305 A, Ptue5f8N 2.051 A and Ptue5f8O 1.987 A. In the crystal there is e extensive intermolecular hydrogen bonding, each complex molecule hydrogen bonded to six others giving a sheet-like structure.

Reactions of N,N′-dicarboxamido-N,N′-dicarboxymethyl-1,2-diaminoethane (EDTA–diamide) with hydrated ruthenium(III) chloride and potassium tetrachloroplatinate(II). Crystal and molecular structures of the pentadentate EDTA–H complex NH4[Ru(EDTA–H)Cl] · 2H2O and the EDTA–imide complex PtCl2[2(HOOCCH2)NCH2CH2NCH2CONHCOCH2] · 2H2O

Abstract Treatment of ruthenium (III) chloride hydrate with N,N′-dicarboxamido-N,N′-dicarboxymethyl-1,2-diaminoethane (1) (EDTA–diamide) in refluxing HCl solution followed by cooling afforded the crystalline complex NH4[Ru(EDTA–H)Cl] · 2H2O (2), the EDTA–H ligand and the +NH4 cation resulting from the hydrolysis of the amide groups in 1. The crystal and molecular structure confirms that in this complex EDTA–H acts as a pentadentate ligand, bonded to the metal through the tertiary nitrogen atoms and three carboxylate oxygens. A chloride ligand completes octahedral geometry around the metal ion. Reaction of K2[PtCl4] with the same ligand in hot basic solution followed by acidification initially gave PtCl2[HOOCCH2(2HNOCCH2)NCH2CH2.

THE MM3 FORCE FIELD FOR 12-VERTEX BORANES AND CARBORANES

Abstract A model and parameters were developed which allow conformational calculations to be carried out on the 12-vertex boranes, carboranes and their derivatives, within the framework of the MM3 force field. In order to avoid description of all the bond angles, the molecule was represented as a superposition of two rings and two cap groups. The valence bonds between these moieties were described by a Buckingham potential. The statistical analysis of carborane molecules found in the Cambridge Structural Database has been carried out in order to find the mean values of the bond lengths and angles for these molecules. A parameter set was developed and used for the calculations on substituted carboranes, and the results show good agreement with the experimental data.

THE PREPARATION AND CRYSTAL AND MOLECULAR STRUCTURE OF THE COMPLEX CIS-PTCL2(RAZOXANE)

Abstract Treatment of K 2 [PtCl 4 ] with the anti-cancer drug razoxane (3,5-dioxopiperazin-1-yl-propane) in aqueous HCl solution gave the water-insoluble complex cis -PtCl 2 (razoxane), which is the first metal complex of razoxane to have been isolated. The crystal and molecular structure of the complex confirms that razoxane is present as a bidentate ligand, Pt-N = 2.095(11) and 2.080(9) A, and was not hydrolysed during complex formation as was previously observed in the presence of other metal ions. This is also one of the few examples in which platinum is bonded to a ligand via tertiary nitrogen atoms only. The presence in the complex of two cis chloride ligands, Pt-Cl = 2.299(4) and 2.277(3) A, and square planar geometry around the metal ion is also confirmed. Intermolecular hydrogen bonding between an imide oxygen atom of each molecule and an imide NH group of another results in a sheet-like ‘zig-zag’ structure. Crystal data for cis -PtCl 2 (razoxane): monoclinic, space group P 2 1 / c , a = 9.165(2), b = 16.573(3), c = 10.984(2) A, β = 114.60(3)°, Z = 4, R = 0.0341, R w = 0.0385.

Metal complexes of the angiotensin-converting enzyme inhibitor, lisinopril. Solution studies and the crystal and molecular structure of a dimeric copper( II )–lisinopril complex

The binding of the angiotensin-converting enzyme inhibitor lisinopril nto zinc(II), copper(II) and nickel(II) nhas been investigated in solution by pH-metric methods and the crystal nstructure of the dimeric copper(II)–lisinopril complex, n[Cu n 2 n(HA) n 2 n(H n 2 nO) n 2 n][ClO n 4 n n] n 2 n (H n 4 nA n 2+ n = fully nprotonated lisinopril), has been determined. In the case of the metal nions investigated a major species present in neutral or weakly acidic nsolution is M(HA) n + n, the formation constants of which suggest nthat co-ordination to the metal ions occurs through the amino nitrogen, ncarboxylate oxygen and the amide oxygen atoms. The crystal structure of nthe dimeric copper complex shows that each copper is in a distorted nsquare-pyramidal environment in which the basal plane is occupied by ncarboxylate (Cu–O 1.944 A) and carbonyl (Cu–O 1.996 nA) oxygens, and an amino group nitrogen (Cu–N 1.989 nA) from one ligand as well as the prolyl carboxylate of another nligand (Cu–O 1.909 A). An aqua ligand Cu–O (2.355 nA) is axially bonded to each copper.