H. J. Kemp

NUCLEOPHILIC ADDITION OF WATER AND ETHANOL TO COORDINATED DI-(2-PYRIDYL)KETONE IN RHENIUM(V) AND TECHNETIUM(V) COMPLEXES. THE CRYSTAL STRUCTURE OF DICHLORO(HYDROXY-DI-(2-PYRIDYL)METHOXIDE)OXORHENIUM(V)

Abstract Complexes of general formula MOCl2[(C5H4N)2C(O)(OR)] (M = Re, Tc; R = H, Et) were prepared by the reaction of trans-ReOCl3(PPh3)2 and (n-Bu4N)[TcOCl4] with di-(2-pyridyl)ketone (DPK) in ethanol (R = Et) under nitrogen and in benzene, containing trace amounts of water, in air (R = H). The compounds were characterized by elemental analysis, vibrational, optical and proton nuclear magnetic resonance spectroscopy. The evidence suggests that the coordinated DPK ligand has undergone addition of water and ethanol at the carbonylic carbon atom, and that the (C5H4N)2C(o)(OR) moiety acts as a uninegative, terdentate N,O,N-donor ligand. The X-ray crystal structure of the complex ReOCl2[(C5H4N)2C(O)(OH)] is also reported. Crystal data: C11H9N2O3Cl2Re, orthorhombic, space group Pcca; a = 14.935(5), b = 11.896(8), c = 14.937(11)A, and U = 2653.8 (2.7)A3 to give Z = 8 for D calc = 2.37 g cm−3. The structure was solved by Patterson and Fourier methods and refined by least-squares methods to R = 0.076. The comple...

Synthesis and Characterization of Bisubstituted Rhenium(V) OXO Complexes with Benzimidazolylalcohol Ligands Containing the N,O Donor-Atom Set

Abstract The reaction of the complex trans-ReOCl3(PPh3)2 with potentially bidentate N,O-donor benzimidazolyl-alcoholate ligands (HL) in the presence of triethylamine in ethanol and benzene produces the complexes ReO(OEt)(L)2 and ReOCl(L)2, respectively. These compounds were characterized by elemental analysis, NMR, vibrational and optical spectroscopy. Mechanisms for the formation reactions and probable configurations of the complexes are proposed, and these are supported by qualitative and spectroscopic studies.

Nucleophilic addition of water to coordinated di-(2-pyridyl)ketone (DPK) in rhenium(V) complexes. Synthesis and crystal structure of the adduct (DPK·H)+[{ReOCl2(DPK·OH)}2Cl]−

The crystalline adduct of formula (DPK·H)+[{ReOCl2(DPK·OH)}2Cl]− was prepared by the reaction of trans- ReOCl3(PPh3)2 with di-(2-pyridyl)ketone (DPK) in THF or dichloromethane. The compound was characterized by elemental analysis, vibrational, optical and 1H NMR spectroscopy. The evidence suggests that the coordinated DPK ligands have undergone addition of water at the carbonylic carbon atom, and that the (C5H4N)2C(O)(OH) moiety acts as a uninegative, terdentate N,O,N-donor ligand. The X-ray crystal structure of the compound is also reported. Crystal data: C33H27Cl5N6O7Re2, triclinic, space group P1; a=9.483(3), b=14.399(5), c=15.413(7) A, α=110.68(3), β=104.73(3), γ=92.66(3)° and U=1879.9(9) A3 to give Z=2 for Dcalc=2.07 Mg/m3.

Synthesis and characterization of six-coordinate cationic technetium(V) and rhenium(V) complexes with N-(2-oxidophenyl)salicylideneiminate and bidentate aromatic nitrogen-donor ligands

Abstract Six-coordinate cationic complexes of rhenium(V) and technetium(V) with the tridentate N-(2-oxidophenyl)-salicylideneiminate (OPhsal2-) and the bidentate aromatic nitrogen-donor ligands 2,2′-dipyridine, 1,10-phenanthroline, 2,2′-dipyridylamine and bis(2-pyridyl)ketone (NN) have been prepared. Complexes of general formula [MO(OPhsal)(NN)]X (M = Re, Tc; X = Cl, PF6) were isolated by the reaction of ReOCl(OPhsal)(PPh3) and TcOCl(O Phsal) with the bidentate nitrogen-donor ligands. The reaction of TcOCl(O Phsal) with bis(2-pyridyl)ketone (dpk) in ethanol produced the complex [TcO(OPhsal)-(dpk.EtOH)]Cl, in which alcoholation of ethanol across the ketone double bond of dpk has occurred. Spectroscopic and analytical results obtained for all the isolated complexes suggest terdentate coordination of OPhsal2- in the equatorial plane cis to the oxo oxygen, with the bidentate pyridyl nitrogen-donor ligands bridging the fourth equatorial site and the position trans to the oxo group.

Technetium(V) Complexes of Substituted Benzimidazolylalcohols and Thiols. Influence of the Donor Atom Type on the Configuration

Abstract Cationic square-pyramidal complexes of general formula (TcO(L)+ 2]Cl− were prepared by the reaction of (n-Bu4N)TcOCl4 with the potentially bidentate N,S-donor benzimidazolylthiols (HL) as ligands in the presence of triethylamine. The corresponding reaction with the N,O-donor benzimidazolylalcohols led to the formation and isolation of the neutral six-coordinate complexes TcOCl(L)2. These compounds were characterized by elementalanalysis, vibrational and optical spectroscopy. Mechanisms for the formation reactions and probable configurations of the complexes are proposed on the basis of qualitative studies and spectroscopic results.

Synthesis of oxorhenium(V) complexes of heterocyclic-N,O and -N,S ligands

Abstract The complex trans-ReOCl3(PPh3)2 reacts with potentially bidentate N,O- and N,S-donor benzimidazolylalcohols and benzimidazolylthiols (HL) in ethanol to produce the compounds ReOGl2(L)(PPh3) or ReOCl(OEt)(L)(PPh3), depending on the reaction conditions. The complexes were characterized by elemental analysis, NMR, vibrational and optical spectroscopy. Mechanisms for the formation reactions and probable configurations of the products are proposed, and these are supported by qualitative studies and spectroscopy.

COMPLEXES OF RHENIUM(V) AND TECHNETIUM(V) WITH 2-AMINO-1-CYCLOPENTENE-1-DITHIOCARBOXYLIC ACID AND ITS N-ALKYL AND S-ALKYL DERIVATIVES

Abstract The interaction of 2-amino-1-cyclopentene-1-dithiocarboxylic acid, and its N-and S-alkyl derivatives (HL2), with rhenium(V) and technetium(V) was investigated. Complexes of formula MOCl(L2)2 (M = Tc, Re) were isolated from the reaction of (n-Bu4N)[MOCl4] with a twofold molar excess of HL2, in acetone, at room temperature. Compounds of type ReOCl2(L2)(PPh3) were characterized with trans-ReOCl3(PPh3)2 as starting material in ethanol. In all the complexes L2 − acts as a bidentate NS− -donor ligand. Infrared and 1H n.m.r. data were used to establish the tautomeric forms of the ligands L2 − in the complexes.

ISOMERIZATION IN RHENIUM(V) COMPLEXES. THE ISOLATION AND CHARACTERIZATION OF CIS AND TRANS ISOMERS OF RHENIUM(V) COMPLEXES WITH DERIVATIVES OF 2-AMINO-1-CYCLOPENTENE-1-DITHIOCARBOXYLIC ACID

Abstract The complexes trans-ReOCl3(PPh3) (HL′) · Me2CO [HL′ = 2-(N-ethylamino)-1-cyclopentenedithio-carboxylate and 2-(N-cyclohexylamino)-1-cyclopentenedithiocarboxylate], with the ligand HL′ coordinated as a monodentate to rhenium(V) through the neutral thiocarbonyl sulfur atom in the position trans to the PPh3 molecule, were prepared under reflux conditions in acetone by the reaction of trans-ReOCl3(PPh3)2 with a molar excess of HL′. The products were isolated as light green precipitates from reaction solutions immediately after cooling to room temperature. The compounds cis-ReOCl3(PPh3) (HL′) · Me2CO were isolated as dark green crystals from the filtrate on slow evaporation of the solvent at room temperature over a period of 2 days. Physicochemical, infrared, 1H NMR and spectroscopic data are reported.

ISOLATION AND CHARACTERIZATION OF A COMPLEX FORMED BY THE REDUCTION OF YLETHANETHIOL FIVE-COORDINATE CATIONIC RHENIUM (V) PERRHENATE WITH 2-BENZIMIDAZOLE-2′-

Abstract Recently1 we reported the synthesis of the cationic complex [TcO(bls)2]+, which was formed by the direct reaction of NH4TcO4 with the ligand Hbls (Hbls = 2-benzimidazole-2′-ylethanethiol; Figure 1) in methanol at room temperature. This reaction is unusual in that the ligand Hbls simultaneously acts as an acid, to protonate the 0x0 oxygens of pertechnetate, as a reducing agent for Tc (VII) and as a chelating agent for Tc(V). Since five-coordinate cationic complexes of rhenium (V) are extremely rare, and since perrhenate is a weaker oxidizing agent than pertechnetate, we have repeated this reaction with perrhenate. The product of this reaction is the cationic five-coordinate rhenium (V) complex [ReO(bls)2]+, which was isolated as perrhenate and tetraphenylborate salts.