Volume 62, Issue 3

1-Hydroxyimidazole-3-oxides (2-H, 2-Me) were alkylated with (RO) 2 SO 2 (R =Me, Et) to give the new 1,3-di(alkyloxy)imidazolium cations which were isolated as hexafluorophosphates. Ion metathesis yielded new hydrophobic ionic liquids (bis(trifluoromethanesulfonyl)imides, tris(pentafluoroethyl) trifluorophosphates). Bromination afforded 2-bromo derivatives which were converted to Ni and Pd N-heterocyclic carbene complexes by oxidative insertion. Fifteen crystal structures were determined by X-ray diffraction. The N-alkyloxy groups are twisted out of the imidazole ring plane and adopt either syn or anti conformations in the solid state.

Electrospray ionization of solutions of dimethyl(1,5-cyclooctadiene)platinum(II) in methanol with traces of nitrogen-containing ligands L provides gaseous complexes of the type [(CH 3 )Pt(L)] + with L = pyridine (py), 2,2′-bipyridine (bipy), and 1,10-phenanthroline (phen). These [(CH 3 )Pt(L)] + cations are capable of activating the C-H bond in methane as shown by H/D exchange when using CD 4 as a neutral reactant. Most reactive is the complex [(CH 3 )Pt(py)] + bearing a monodentate nitrogen ligand. The cationic complexes [(CH 3 )Pt(bipy)] + and [(CH 3 )Pt(phen)] + also bring about activation of methane, though at a lower rate, whereas the bipyridine complex [(CH 3 )Pt(py) 2 ] + does not react with methane at thermal conditions. A detailed analysis of the experimental data by means of kinetic modeling provides insight into the underlying mechanistic steps, but a distinction whether the reaction occurs as σ bond metathesis or via an oxidative addition cannot be made on the basis of the experimental data available.

The synthesis and characterization of 16 new boryl-substituted zirconocene dichloride complexes are reported. After activation with methyl aluminoxane (MAO) these complexes are catalysts for homogeneous ethylene polymerization. The combination of these complexes with nickel catalysts containing Lewis basic substituents produces polymers with bimodal molecular weight distributions.

The poly(pyrazol-1-ylmethyl)benzenes L1 - L5 react with [PdCl 2 (NCMe) 2 ] or [PdClMe(COD)] to form dinuclear palladium complexes [{PdClX(3,5-Me 2 pzCH 2 ) 2 -1,2-C 6 H 4 } 2 ] (X = Cl (1), Me (2)), [{PdCl 2 (3,5-Me 2 pzCH 2 )2-1,3-C 6 H 4 } 2 ] (3), palladium complexes [{Pd 2 (μ-Cl) 2 Me 2 (3,5- Me 2 pzCH 2 ) 2 -1,3-C 6 H 4 }] (4), [{Pd 2 (μ-Cl) 2 X 2 (3,5-Me 2 pzCH 2 ) 2 -1,4-C 6 H 4 }] (X = Cl (5), Me (6)), [{Pd 2 (μ-Cl) 2 Cl 2 (3,5- t Bu 2 pzCH 2 ) 2 -1,4-C 6 H 4 }] (7), and tetranuclear [{Pd 2 (μ-Cl) 2 Cl 2 (3,5- Me 2 pzCH 2 ) 2 } 2 -1,4-C 6 H 4 ] (8). The structures of 1, 2 and 8 were confirmed by X-ray structure analysis. The complexes efficiently catalyse the coupling reaction of iodobenzene and butylacrylate at 80 °C.

The synthesis of copper(II) salicylaldiminato complexes and their application in the catalytic hydroxylation of phenol is reported. Tetracoordinated copper complexes (Cu(L n ) 2 ) were obtained by reacting the N-phenylsalicylaldimine ligands (HL 1 -HL 7 ) with copper acetate in a 2 : 1 mole ratio. The reaction of N-(2,6-diisopropyl)phenyl-3,5-di-tert-butylsalicylaldimine (HL 7 ) with copper acetate in a 1 : 1 mole ratio afforded a dinuclear complex, which was not obtained with the other ligand systems. All complexes were characterized using FT-IR and elemental analysis. X-Ray crystal structures of complexes 2, 5 and 8 have also been obtained. The catalytic activity of these complexes was evaluated in the hydroxylation of phenol using oxygen and hydrogen peroxide as co-oxidants in aqueous media in the pH range 3 - 6. All complexes studied were found to be active for the hydroxylation process over the pH range studied with higher selectivity for catechol formation.

The molecular structure of carbonylchlorobis(tri(3-pyridyl)phosphine)rhodium, 1, has been determined by X-ray diffraction methods. The N-protonated trifluoromethanesulfonate (triflate) complex 3 was synthesised as a model compound for the extraction of a rhodium complex bearing amphiphilic ligands which can allow catalyst recycling in the hydroformylation of alkenes by using their distribution behavior in organic and aqueous solvents of different pH. The high water-solubility of the employed ligand renders the recycling method as only partly successful due to insufficient extraction from the water phase into the organic phase. In the hydroformylation of 1-hexene the production of n-heptanal is slightly disfavoured when using the ligand tri(3-pyridyl)phosphine as compared to triphenylphosphine which can be ascribed to a higher amount of ligand-deficient active rhodium complexes of the less basic pyridyl phosphine ligand under CO pressure.

The reaction of [(CO) 5 Cr(THF)] with propynethioic acid amides, R-C≡C-C(=S)NMe 2 (R = H, SiMe 3 ), yields the thioamide complexes [(CO) 5 Cr-S=C(NMe 2 )C≡C-H] (1a) and [(CO) 5 Cr- S=C(NMe 2 )C≡C-SiMe 3 ] (1b). Treatment of solutions of 1a or 1b with methyllithium generates, via deprotonation or desilylation, the lithium salt Li[(CO) 5 Cr-S=C(NMe 2 )C≡C] (2). On filtration over silica, 2 is readily reprotonated. Complex 1a is inert towards methanol, however, adds diethylamine across the C≡C bond to give the thioacrylamide complex [(CO) 5 Cr-S=C(NMe 2 )C(H)=C(H)NMe 2 ] (3). Thiourea displaces the thioamide ligand to give [(CO) 5 Cr-S=C(NH 2 ) 2 ] (4). Complex 1a reacts with half an equivalent of diethylaminopropyne in a three-component coupling to form the homobinuclear complex [(CO) 5 Cr-S=C(NEt 2 )-C(CH 3 )=C(H)-C(H)=C(NMe 2 )-C≡C-C(NMe 2 )=S- Cr(CO) 5 ] (5) in high yield. The solid state structures of complexes 1a and 5 were established by X-ray structural analyses.

Reaction of lutidine-bridged dibenzimidazolium dibromides 1 - 4 with palladium acetate gives pincer-type palladium complexes of the type [Pd(L)Br]Br [5]Br-[8]Br. Crystals suitable for an X-ray diffraction study have been obtained by slow evaporation of the solvent from dichloromethane/methanol solutions of [7]Br and [8]Br. The crystal structure of [7] + reveals a pincer topology of the cationic complex with a distorted square-planar coordination geometry at the metal center. From a solution of complex [8]Br, a dinuclear byproduct [9] + was obtained with two bis(benzimidazolin- 2-ylidene) ligands coordinating in a bridging fashion. The pincer-type palladium complexes [5]Br- [8]Br were tested as precatalysts in Suzuki coupling reactions.

Two C 2 -symmetric metallocene catalysts in solution were exposed to light, and the rac-meso conversion followed by NMR spectroscopy. Both exposed and unexposed catalyst solutions were used, in conjunction with a suitable cocatalyst, to polymerize propylene. The polymers were characterized with respect to their microstructure and fractionated according to crystallinity. The relationship between the catalyst isomerization and the polymer structure is illustrated. The effect of pre-activation of the catalyst before exposure to light was also studied and is reported on.

Quantum chemical calculations using density functional theory at the B3LYP level of theory were carried out to investigate the reaction pathways for the addition of ethylene to WO(CH 3 ) 2 (CH 2 ) (W1). The results are compared to those of previous theoretical studies of the ethylene addition to OsO 3 (CH 2 ) (Os1) and ReO 2 (CH 3 )(CH 2 ) (Re1). The theoretically predicted reactions pathways exhibit significant differences. The energetically most favourable reaction of the tungsten system W1 is the [2+2] W,C addition across theW=C double bond yielding the metallacyclobutane W3a which then rearranges to the slightly more stable isomer W3b. The [2+2] Re,C addition of the rhenium compound yielding the metallacyclobutane Re3a has the lowest activation barrier for the ethylene addition to the rhenium system, but the reaction is endothermic while the exothermic formation of the more stable isomer Re3b has a much higher activation barrier. The [3+2] C,O addition Os1+C 2 H 4 →Os 2 is the thermodynamically most favorable reaction of the osmium compound.

Noting that current chemical theory is based almost exclusively on electronic energy and spin variables the equal importance of orbital angular momentum is explored in this paper. From its classical definition the angular momentum of electrons in an atom is shown to obey Laplace’s equation, which automatically leads to discrete values in terms of spherical harmonics. This analysis assumes a continuous distribution of electronic charge, which resembles a fluid at equilibrium. It serves to elucidate the success and failure of Bohr’s conjecture and the origin of wave-particle duality. Applied to atoms, minimization of orbital angular momentum leads to Hund’s rules. The orientation of angular momenta in lower-symmetry molecular environments follows from the well-known Jahn-Teller theorem.

The affinity of In(III) for N-donor ligands was investigated by differential pulse voltammetry, DFT calculations, and crystallography. The structure of [In(tpen)(CH 3 COO)](ClO 4 ) 2 ・ 0.5H 2 O (1) is reported (tpen = N,N,N´ ,N´-tetrakis(2-pyridylmethyl)ethylenediamine): Monoclinic, P2 1 /n, a = 8.687(4), b = 7.767(8), c = 20.432(10) Å , β = 93.372(8)°, Z = 4, R = 0.0518. The In(III) center is 7-coordinate, with six In-N bonds to the tpen ligand in the range 2.306 - 2.410 Å, and a unidentate acetate group with In-O = 2.247 Å. The formation constants of In 3+ in 0.1 M NaNO 3+ at 25 °C are (M = In(III), L = ligand, H = proton): L = triethylenetetramine, logβ (MLH 2 ) = 25.3±}0.3, logK 1 = 14.43±}0.09, and logβ (ML(OH) 2 ) = 27.7±}0.1; tetraethylenepentamine, logβ (MLH) = 20.8±}0.2, and ML (logβ (ML) = 20.1±}0.3); diglycolic acid, (logβ (MLH) = 8.06±}0.06), logK 1 = 6.02±} 0.06, logβ 2 = 9.40±}0.08; tpen, logK 1 = 17.71±}0.07; N,N´-bis(2-pyridylmethyl)ethylenediamine, logK 1 = 14.69±}0.05; 1,10-phenanthroline, logK 1 = 6.81±}0.07, logK 2 = 6.44±}0.07, logK 3 = 6.20±}0.08. Correlations are shown between the determined formation constants for the polyamines and logK 1 (NH 3 ) values for a wide variety of metal ions. For M(II) ions, the log K 1 (NH 3 ) values are experimental data, but for M(III) ions the data are predicted by an empirical dual-basicity equation, including logK 1 (NH 3 ) = 4.0 for In(III). DFT calculations are used to obtain ΔE for the reaction [M(H 2 O) 6 ] n+ + NH 3 ⇆[M(H 2 O) 5 NH 3 ] n+ + H 2 O for M(II) through M(IV) ions in water, represented as a structureless medium with the dielectric constant of water. Correlations are found that support the predicted value of logK 1 (NH 3 ) for In(III) of 4.0. The nature of the intercepts on such correlations are discussed.

Two improved routes to synthesize 1-benzyl-1,4,7,10-tetraazacyclododecane (6) and 1,4,7,10- tetraazacyclododecane-1-acetic acid ethyl ester (11) are described as well as the synthesis of 1-{2-[4-(maleimido-N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane- 4,7,10-triacetic acid (17) and its Y, Ho, Tm, and Lu complexes. The 1 H and 13 C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of the intermediates 4-benzyl-1,7-bis(p-toluenesulfonyl)diethylenetriamine (3) and 1,4,7-tris(p-toluenesulfonyl)diethylenetriamine (7) are reported and discussed. The rare earth complexes of 17 have been characterized by 1 H NMR spectroscopy and MALDI-TOF mass spectrometry.

The reaction of (SePPh 2 ) 2 CH 2 with group 11 metal complexes such as [Au(C 6 F 5 ) 3 (tht)] (tht = tetrahydrothiophene) affords the complex [Au(C 6 F 5 ) 3 (SePPh 2 CH 2 PPh 2 Se)] in which the ligand coordinates to the gold(III) center only through one selenium atom. The treatment of the ligand with Ag(OTf) or [Cu(NCMe) 4 ]PF 6 leads, depending on the molar ratio, to the complexes [Ag 2 {(SePPh 2 ) 2 CH 2 } 2 ](OTf) 2 or [M{(SePPh 2 ) 2 CH 2 } 2 ]X (M = Ag, X = OTf; M = Cu, X = PF 6 ; OTf = CF 3 SO 3 ) in which the phosphine selenide ligand coordinates as a bidentate bridging or chelating ligand through the Se,Se atoms. The reaction of (SePPh 2 ) 2 CH 2 with [Au(C 6 F 5 ) 2 (acac)] (acac = acetylacetonate) occurs with deprotonation of the methylene group, and the methanide complex, [Au(C 6 F 5 ) 2 (SePPh 2 CHPPh 2 Se)], is obtained, with a bidentate chelate Se,C coordination to the gold(III) center. The selenium atom can react further with other metal complexes such as [Au(C 6 F 5 ) 3 (tht)] to give the dinuclear species [Au(C 6 F 5 ) 2 {SePPh 2 CHPPh 2 SeAu(C 6 F 5 ) 3 }], in which the ligand coordinates in a tridentate Se,C,Se form. The crystal structure of [Au(C 6 F 5 ) 2 {SePPh 2 CHPPh 2 SeAu(C 6 F 5 ) 3 }] has been established by X-ray diffraction.

The reaction of the carbodiphosphorane C(PPh 3 ) 2 (1) with [Co 2 (CO) 8 ] results in the formation of the salt-like complex (HC{PPh 3 } 2 )[Co(CO) 4 ] (2) in high yield if THF is used as the solvent. The proton of the cation stems from THF degradation. When the reaction is carried out in toluene, the tetranuclear cluster [Co 4 (CO) 10 (PPh 3 )(μ 4 -CCPPh 3 )] (3) is formed in low yield as the only complex which could be identified by X-ray analysis. The solvate 3 ·C 7 H 8 crystallizes in the triclinic space group P1̄ with a = 1040.8(2), b = 1387.4(2), c = 1923.0(2) pm, α = 71.96(1)°, β = 88.69(1)°, γ = 71.46(1)°, Z = 2. The structure of the cluster with 64 CVE is that of a “spiked triangle” in which the triphenylphosphonioacetylide CCPPh 3 acts as a six-electron donor and the bonding mode is that of a μ 4 -η 2 coordination.

The 2,7-dilithiated substrates of 3,6-dimethylthieno[3,2-b]thiophene, N,N′-dimethylpyrrolo[3,2- b]pyrrole and N-methylthieno[3,2-b]pyrrole were reacted with W(CO) 6 to give, after subsequent alkylation with Et 3 OBF 4 , the ditungsten biscarbene complexes [(CO) 5 W{C(OEt)XXC(OEt)} W(CO) 5 ] (XX = condensed heteroaromatic spacers). Sites of attack during the dilithiation of the condensed rings were studied and compared, and the yields of the desired ditungsten biscarbene complexes optimized by changing the reaction conditions according to the role of the heteroatoms in the rings. The crystallographic data of the three ditungsten biscarbene complexes are reported and their structural features compared. The methyl substituents on the condensed heteroaromatic rings play an important role in determining the molecular configurations.

The diiron aminocarbyne complexes [Fe 2 {μ-CN(Me)(R)}(μ-CO)(CO)(NCMe)(Cp) 2 ][SO 3 CF 3 ] (R = Xy1, 1a; R = Me, 1b; R = CH 2 Ph, 1c; Xy1 = 2,6-Me 2 C 6 H 3 ) undergo replacement of the coordinated nitrile by halides, diethyldithiocarbamate, and dicyanomethanide to give [Fe 2 {μ-CN(Me) (R)}(μ-CO)(CO)(X)(Cp) 2 ] complexes (R = Me, X = Br, 4a; R = Me, X = I, 4b; R = CH 2 Ph, X = Cl, 4c; R = CH 2 Ph, X = Br, 4d; R = CH 2 Ph, X = I, 4e; R = Xy1, X = SC(S)NEt 2 , 5a; R = Me, X = SC(S)NEt 2 , 5b; R = Xy1, X = CH(CN) 2 , 7), in good yields. The molecular structure of 5a shows an unusual η 1 coordination mode of the dithiocarbamate ligand. Similarly, treatment of [M 2 {μ-CN(Me) (R)}(μ-CO)(CO)(NCMe)(Cp) 2 ][SO 3 CF 3 ] (M = Fe, R = Xy1, 1a; M = Fe, R = Me, 1b; M = Ru, R = Xy1, 2a; M = Ru, R = Me, 2b) with a series of phosphanes generates the cationic complexes [M 2 {μ- CN(Me)(R)}(μ-CO)(CO)(P)(Cp) 2 ][SO 3 CF 3 ] (M = Fe, R = Xy1, P = PPh 2 H, 6a; M = Fe, R = Xy1, P = PPh 3 , 6b; M = Fe, R = Xy1, P = PMe 3 , 6c; M = Fe, R = Me, P = PMe 2 Ph, 6d; M = Fe, R = Me, P = PPh 3 , 6e; M = Fe, R = Me, P = PMePh 2 , 6f; M = Ru, R = Xy1, P = PPh 2 H, 6g; M = Ru, R = Me, P = PPh 2 H, 6h), in high yields. The molecular structure of 6a has been elucidated by an X-ray diffraction study. The reactions of [Fe 2 {μ-CN(Me)(Xyl)}(μ-CO)(CO)(NCR′)(Cp) 2 ][SO 3 CF 3 ] [R′ = Me, 1a; R′ = t Bu, 3] with PhLi and PPh 2 Li yield [Fe 2 {μ-CN(Me)(Xy1)}(μ-CO)(CO)(Ph)(Cp) 2 ] (8) and [Fe 2 {μ-CN(Me)(Xy1)}(μ-CO)(CO)(PPh 2 )(Cp) 2 ] (9), respectively. The molecular structure of 8 has been ascertained by X-ray diffraction. Conversely, the reaction of 1a with MeLi generates the aminoalkylidene compound [Fe 2 {C(Me)N(Me)(Xy1)}(μ-CO) 2 (CO)(Cp) 2 ] (10). Finally, the acetone complex [Fe 2 {μ-CN(Me)(Xy1)}(μ-CO)(CO)(OCMe 2 )(Cp) 2 ][SO 3 CF 3 ] (12) reacts with lithium acetylides to give complexes [Fe 2 {μ-CN(Me)(Xy1)}(μ-CO)(CO)(C≡CR)(Cp) 2 ] (R = p-C 6 H 4 Me, 11a; R = Ph, 11b; R = SiMe 3 , 11c), in high yields. Filtration through alumina of a solution of 11a in CH 2 Cl 2 results in hydration of the acetylide group and C-Si bond cleavage, affording [Fe 2 {μ-CN(Me)(Xy1)}(μ-CO)(CO){C(O)Me}(Cp) 2 ] (12).

A novel calixarene derivative with dipyrromethane moieties on the lower rim was prepared. NMR spectroscopy revealed a high selectivity towards sodium cations and the ability to bind ion pairs.

The synthesis and characterisation of the 4-(o-R-C 6 H 4 )pzbipy [R = H, CH 3 or CF 3 ; pzbipy = 6-(2″- pyrazinyl)-2,2′-bipyridyl] ligands are described. Reaction of the 4-(o-MeC 6 H 4 )pzbipy ligand with [Pt(PhCN) 2 Cl 2 ] in the presence of AgSbF 6 affords [Pt{4-(o-MeC 6 H 4 )pzbipy}Cl]SbF 6 as a marooncoloured microcrystalline solid. The [Pt{4-(o-MeC 6 H 4 )pzbipy}Cl] + cation exhibits low intensity photoluminescence in dichloromethane that maximises at 543 nm and which is assigned to a 3 MLCT excited state (τ = 20 ns). The emission spectrum of the cation was also recorded in a frozen DME {1 : 5:5 (v/v) DMF / MeOH / EtOH} glass; a highly structured band is observed with vibrational spacings of ca. 1400 cm −1 , indicating emission from an intraligand 3π-π ∗ state (τ = 11 μs). Variable temperature solid emission spectra show maxima that occur at significantly lower energies than is observed in fluid solution and that shift to the red when the temperature is lowered; specifically, λ (em) max is 674 nm at 280 K (τ = 80 ns) and 723 nm at 80 K (τ = 1.3 μs). Emission behaviour of this type is typical of emission from a metal-metal-ligand charge transfer (MMLCT) excited state that has its origins in d z² (Pt)-d z² (Pt) orbital interactions in the crystal.

Reactions of (η 5 -RC 5 H 4 )Fe(CO) 2 I (R = H, Me) complexes with phosphine ligands PR′ 3 (R′ = Ph, m-Tol, p-C 6 H 4 OMe, p-C 6 H 4 Cl, p-C 6 H 4 F) have been performed under solvent-free conditions in the melt phase and generally yielded the ionic products [(η 5 -RC 5 H 4 )Fe(CO) 2 PR′ 3 ]I rather than the CO substituted products (η 5 -RC 5 H 4 )Fe(CO)(PR′ 3 )I. The complexes have been characterised by IR, NMR and MS techniques. By contrast, the same reactions studied in benzene solution have yielded mainly the CO substitution products. Factors that affect the solvent-free reaction include variation in R and R′ , reaction temperature and the addition of [CpFe(CO) 2 ] 2 as a catalyst. The mechanism of the reaction for the formation of the ionic complex is proposed to go via a 19 electron intermediate. This is in contrast to the reaction in bezene that occurs via a 17 electron intermediate, clearly indicating the role of the melt phase in the reaction.

The synthesis and full characterization of a series of (triphenylphosphine)gold complexes with thiol-containing amino acids and peptides is reported. Boc-Cys-Au(PPh 3 ) was prepared in solution by reaction of Boc-Cys-OH with (Ph 3 P)AuCl. The related Ac-Cys-Au(PPh 3 ) and an Au derivative of the cysteine-modified neuropeptide enkephalin (Enk), [Cys] 5 -Au(PPh 3 )-Enk, were prepared on the resin, using the orthogonal trityl-protecting group on Cys. For comparison, the metal-free [Cys] 5 -Enk and an S-tert-butyl-protected [Cys] 5 -Enk were also prepared. Most noteworthy, gold complexation works best when carried out on the resin, and the gold thiolate survives cleavage from the resin under optimized conditions. The new conjugates were comprehensively characterized, including 1D and 2D NMR spectroscopy, and mass spectrometry. Along with characteristic changes in the 1 H and 13 C NMR spectra, 31 P NMR spectra reveal a characteristic downfield shift of ca. 5 ppm upon complexation of the Au(PPh 3 )-fragment to Cys, which is also pertinent in the Au-labelled [Cys] 5 -Enk.

Starting from imidazole, 1-[2-(cyclopenta-2,4-dienyl)ethyl]-3-methylimidazolium iodide (3) was obtained as a mixture of isomers by a simple three-step synthesis. The reaction of 3 with Ti(NEt 2 ) 4 or Zr(NEt 2 ) 4 by double deprotonation of the imidazolium salt led to the isomerically pure cationic complexes [{η 5 -C 5 H 4 -(CH 2 ) 2 -NHC}M(NEt 2 ) 2 ] + I − (NHC = N-heterocyclic carbene) 4a (M = Ti) and 4b (M = Zr), respectively, in which a cyclopentadienyl and a methylimidazol-2-ylidene unit are linked by an ethylidene-1,2 bridge to form a novel chelating ligand system. In the case of the reaction of 3 with Zr(NEt 2 ) 4 the neutral compound [{η 5 -C 5 H 4 -(CH 2 ) 2 -NHC}Zr(NEt 2 )I 2 ] (5) is formed as an additional product. According to the X-ray structure analyses, the titanium atom of 4a is tetracoordinated while no coordinative interaction exists with the iodide anion; on the other hand, in 5 the zirconium centre is pentacoordinated.

Starting from 4-bromoacetophenone 1, the 4-bromo-β -hydroxydithiocinnamic acid 2 and the 4-bromo-β -hydroxydithiocinnamic acid hexyl ester 3 were prepared using carbon disulfide and potassium-tert-butylate as a base. Acting as a ligand, the acid gives 1,1-ethenedithiolato complexes with (Ph 3 P) 2 Pt(II) (4a), (Et 3 P) 2 Pt(II) (4b), dppePt(II) (4c), (Ph 3 P) 2 Pd(II) (4d), dppePd(II) (4e), and dppeNi(II) (4f). In contrast to the acid, the deprotonated ester 3 forms a monoanionic bidentate ligand. [O,S] Complexes of Pt(II) (5a), Pd(II) (5b) and Ni(II) (5c) were obtained. All complexes have been fully characterised using 1 H NMR, 13 C NMR and 31 P NMR spectroscopy, mass spectrometry, infrared spectroscopy and elemental analyses. The molecular structures of the complexes 4b and 5a - 5c were determined by X-ray diffraction analyses.

The production of 67 Ga at iThemba LABS is performed by the proton bombardment of a tandem nat Zn/ nat Zn target. 67 Ga is separated from the target material using a method based on target dissolution, in acidic media, and dual chromatographic methods on Amberchrom CG-161M. The result is a product with a high radionuclidic purity 67 Ga having such a low Fe content in the final product that it may be used in the labelling of peptides.

The imide derivatives Li 4 Ti 4 O 2 (NR) 2 (O i Pr) 12 (R = CH 2 C 6 H 5 , C 6 H 11 , C 4 H 9 ) were obtained either by reaction of the amine adduct Ti 2 (O i Pr) 8 (H 2 NR) 2 with lithium diiso- propylamide or butyllithium, or when the primary amine was first reacted with the base and then with Ti(O i Pr) 4 . The structures of the imide derivatives are the same as that of Li 4 Ti 4 O 4 (O i Pr) 12 (= Li 4 Ti 4 (μ 2 -O) 2 (μ 5 -O) 2 (μ 2 -O i Pr) 4 (μ 3 - O i Pr) 4 (O i Pr) 4 ) with the two μ 2 -oxo groups replaced by two μ 2 -NR groups.