Michael J. Went

Structural trends in copper(II) bis(thiosemicarbazone) radiopharmaceuticals

Redox-related changes in biological properties of copper bis(thiosemicarbazone) radiopharmaceuticals are induced by backbone alkylation. To determine whether these changes are mediated by changes in core structural parameters, eight X-ray structures of variously alkylated complexes were determined. The complexes include the hypoxia tracer diacetylbis(4-methyl-3-thiosemicarbazonato)copper(II) (CuATSM). The structures of the nickel analogue NiATSM and the corresponding free ligand ATSMH2 were also included. Distortions from planarity were slight and only present when there were significant intermolecular interactions (mainly pairs of N–H–N and N–H–S hydrogen bonds). These give rise to cross-linked flat or helical ribbons of complexes. Alkylation at the terminal nitrogen atoms interrupts hydrogen bonding, allowing complexes to become planar, but does not otherwise affect the coordination sphere. Alkylation at the backbone carbon atoms increases the backbone C–C bond length, allowing the metal to fit better into the ligand cavity with shorter Cu–S bonds.

Synthesis and Reactions of Polynuciear Cobalt-Alkyne Complexes

Publisher Summary This chapter presents the chemistry of polynuclear cobalt-alkyne complexes (dinuclear complexes, trinuclear clusters, tetranuclear complexes, and higher nuclearity complexes). The study of polynuclear cobalt-alkyne clusters has provided insight into the coordination, protection, and activation of the carbon–carbon triple bond. It is possible to draw analogies between alkynes coordinated to molecular species and those coordinated to surfaces. The chemistry of hexacarbonylalkyne-dicobalt complexes is the most developed and is finding many applications in organic synthesis. Considerable progress has been made with chiral systems involving mixed-metal cores or asymmetric phosphines. The detection of radical intermediates has led to coupling reactions applied to the high-yield synthesis of cyclic enediynes. Coupling of several dinuclear radical species offers the possibility of organometallic polymer formation. Continuing expansion of the chemistry of polynuclear cobalt-alkyne complexes is expected, especially in the areas of reactivity and synthetic applications, in the coming years.

The spectroscopic detection of drugs of abuse in fingerprints after development with powders and recovery with adhesive lifters

The application of powders to fingerprints has long been established as an effective and reliable method for developing latent fingerprints. Fingerprints developed in situ at a crime scene routinely undergo lifting with specialist tapes and are then stored in evidence bags to allow secure transit and also to preserve the chain of evidence. In a previous study we have shown that exogenous material within a fingerprint can be detected using Raman spectroscopy following development with powders and lifting with adhesive tapes. Other reports have detailed the use of Raman spectroscopy to the detection of drugs of abuse in latent fingerprints including cyanoacrylate-fumed fingerprints. This study involves the application of Raman spectroscopy for the analysis of drugs of abuse in latent fingerprints for fingerprints that had been treated with powders and also subsequently lifted with adhesive tapes. Samples of seized ecstasy, cocaine, ketamine and amphetamine were supplied by East Sussex Police and by the TICTAC unit at St. Georges Hospital Tooting. Contaminated fingerprints were deposited on clean glass slides. The application of aluminium or iron based powders to contaminated fingerprints did not interfere with the Raman spectra obtained for the contaminants. Contaminated fingerprints developed with powders and then lifted with lifting tapes were also examined. The combination of these two techniques did not interfere with the successful analysis. The lifting process was repeated using hinge lifters. As the hinge lifters exhibited strong Raman bands the spectroscopic analysis was more complex and an increase in the number of exposures to the detector allowed for improved clarification. Spectral subtraction was performed to remove peaks due to the hinge lifters using OMNIC software. Raman spectra of developed and lifted fingerprints recorded through evidence bags were obtained and it was found that the detection process was not compromised. Although the application of powders did not interfere with the detection process the time taken to locate the contaminant was increased due to the physical presence of more material within the fingerprint.

Synthesis and characterization of [186Re]rhenium(V)dimercaptosuccinic acid: A possible tumour radiotherapy agent

[186Re]Re(V)DMSA, a beta-emitting analogue of the tumour imaging radiopharmaceutical pentavalent [99mTc]Tc(V)DMSA of possible value in tumour therapy, is readily prepared by stannous reduction of [186Re]ReO4 in the presence of dimercaptosuccinic acid at 100 degrees C using a commercial DMSA kit as used for renal imaging with 99mTc, and purified using a disposable sample preparation column. The complex has been identified as [ReO(DMSA)2] by NMR, optical and i.r., spectroscopy and elemental analysis.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 15. Reactions of the complex [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) with iron carbonyls; crystal structures of [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)] and [FeW2(µ3-RC2R)(CO)5L(η-C5H5)2](L = CO or O)

The compound [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) in diethyl ether at room temperature reacts with [Fe2(CO)9] to give the dimetal complex [FeW(µ-CR)(CO)6(η-C5H5)](1), and the two trimetal species [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)](2) and [FeW2(µ3-RC2R)(CO)6(η-C5H5)2](3). Compound (2) with PMe2Ph or Ph2PCH2PPh2(dppm) affords [Fe2W(µ3-CR)(µ-CO)(CO)6L2(η-C5H5)][L = PMe2Ph (4), L2= dppm (5)], complexes in which the phosphine ligands are bonded to the two iron atoms. From the reaction between the complexes [Fe3(CO)12] and [W(CR)(CO)2(η-C5H5)], the trimetal compounds (2), (3), and [FeW2(O)(µ3-RC2R)(CO)5(η-C5H5)2](6) were isolated. Spectroscopic data (infrared and n.m.r.) for the new compounds are reported, and discussed in relation to their structures, which were firmly established for (2), (3), and (6) by single-crystal X-ray diffraction studies. Crystals of (2) are orthorhombic, space group P212121, Z= 4, in a unit cell with lattice parameters a= 10.078(8), b= 13.115(8), and c= 16.785(8)A. The structure was refined to R 0.030 (R′ 0.031) for 5 837 reflections having 2θ⩽ 60°(Mo–KαX-radiation) collected at 200 K. The molecule consists of a Fe2W triangle [Fe–W 2.805(2) and 2.756(2), Fe–Fe 2.538(2)A] capped by a triply bridging tolylidyne ligand [µ3-C–W 2.093(5), µ3-C–Fe 1.969(5) and 2.036(5)A]. The Fe–Fe bond is bridged by a CO group, the remaining carbonyl ligands being terminally bonded, two to the tungsten and three to each iron. Crystals of (3) are triclinic, space group P, Z= 2, in a unit cell with a= 8.622(2), b= 12.799(4), c= 13.443(8)A, α= 90.72(4), β= 108.45(4), and γ= 93.34(2)°. The structure has been refined to R 0.037 (R′ 0.039) for 4 337 reflections having 2θ⩽ 50° collected at room temperature. The molecule consists of a FeW2 triangle, the W–W distance [2.747(1)A] suggesting double bonding. The Fe–W separations [2.731(1) and 2.745(1)] are perceptibly different, and the shorter is transversely bridged by a RC2R alkyne group; one of the carbon atoms of the alkyne triply bridges the metal triangle [µ3-C–W 2.289(5) and 2.264(7), µ3-C–Fe 2.011(5)A]. There are five terminally bound CO ligands, three attached to the iron atom and one to each tungsten. In addition, the tungsten atom σ-bonded to the alkyne carries a CO group which semi-bridges the W–W edge [W–C-0 164.9(7)°]. Crystals of (6) are triclinic, space group P, Z= 2, in a unit cell with a= 8.694(2), b= 12.540(4), c= 13.365(7)A, α= 88.03(4), β= 108.44(3), and γ= 97.54(2)°. The structure has been refined to to R 0.049 (R′ 0.050) for 3 916 reflections having 2θ⩽ 50° collected at room temperature. The molecule has a structure very similar to that of (3) except that an oxygen atom has replaced the terminal CO ligand bonded to the tungsten atom µ-η2 co-ordinated to the alkyne.

The synthesis of dimetallic thioalkyne complexes of cobalt and molybdenum

Abstract Treatment of [Co2(μ-HOCR′2CCCR′2OH)(CO)6] with an excess of RSH in the presence of HBF4·OEt2 affords [Co2(μ-RSCR′2CCCR′2SR)(CO)6] (R′  H, R  Et, nBu, tBu, Ph, Bz; R′  Me, R  Et), which undergo substitution with bis(diphenylphosphino)methane (dppm) to give [Co2(μ-RSCR′2CCCR′2SR)(μ-dppm)(CO)4]. Similar treatment of [MoCo(μ-HOCH2CCCH2OH)(CO)5Cp] and [Mo2(μ-HOCH2CCCH2OH)(CO)4Cp2] with EtSH gives [MoCo(μ-EtSCH2CCCH2SEt)(CO)5Cp] and [Mo2(μ-EtSCH2CCCH2SEt)(CO)4Cp2], respectively. Reaction of [Co2(μ-HOCH2CCCH2OH)(CO)6] with a small excess of RSH (REt or Ph), ca. two equivalents, affords [Co2(μ-HOCH2CCCH2-SR)(CO)6], while reaction with only one equivalent of EtSH additionally gives an ether-bridged system containing two hexacarbonyldicobalt units, (Co2(CO)6(HOCH2CCCH2OCH2CCCH2SEt)-CO2(CO)6]. Treatment of [Co2(μ-HOCH2CCCH2SEt)(CO)6] with half an equivalent of HBF4·OEt2 affords [Co2(CO)6(EtSCH2CCCH2OCH2CCCH2SEt)Co2(CO)6]. Attempted preparation of mixed thioether complexes results in a mixture of products, and a mechanism is proposed for thioether scrambling. The IR, NMR and mass spectra of the new compounds are reported and discussed.

Detection of drugs of abuse by Raman spectroscopy.

Raman spectroscopy can provide rapid, sensitive, non-destructive analysis of a variety of drug types (e.g. amphetamines, alkaloids, designer drugs, and date rape drugs). This review concentrates on developments in the past 15 years. It considers identification and quantification of drugs of abuse in different types of forensic evidence, including bulk street drugs as well as traces found in drinks, on fibres/clothing, in fingerprints, on fingernails, on bank notes, and in body fluids.

Cyclic and acyclic polyamines as chelators of rhenium-186 and Rhenium-188 for therapeutic use

Several polyamine ligands L1-L7 were assessed as chelators for rhenium-188 (and by analogy, rhenium-186) for incorporation into the design of radiopharmaceuticals for targeted radiotherapy. Both ease of synthesis of the complexes and their kinetic stability in human serum were examined. Chelation of Re-188 by stannous reduction of perrhenate in the presence of acyclic ligands such as L1 and L2 (L1 = ethylenediamine, L2 = 1,4,8,11-tetraazaundecane) proceeded in acceptable yield (50-90%) under aqueous conditions (pH 11; 20-100 degrees C, 30 min) in a single step. In contrast, synthesis of complexes of the cyclic ligands such as L6 (L6 = 1,4,8,11-tetraazacyclotetradecane, cyclam) in acceptable yield (> 50%) required more involved procedures including use of nonaqueous solvents. The chelates were unambiguously identified as the cationic trans-dioxorhenium(V) tetrakis(amino) complexes, by chromatographic comparison with spectroscopically characterised nonradioactive samples. The complexes of tetradentate ligands L2 and L6 showed no evidence of degradation on incubation for up to 24 h in human serum. The complex of L1 degraded by less than 3% under these conditions. These preliminary studies indicate that the acyclic tetradentate ligands offer an appropriate compromise between biological stability and ease of synthesis, and they have potential as chelators for rhenium in radiopharmaceuticals.

Chloromethylation of poly(methylphenylsilane)

The chloromethylation of poly(methylsilane) is readily achieved using chloromethyl methyl ether in a tin(IV) chloride-catalysed reaction in chloroform solution at 0 °C. A convenient, less hazardous reaction, in which chloromethyl methyl ether is prepared in situ, is also reported. The accompanying variations of the polymer molecular-weight parameters are recorded for chloromethylations extending to 95% of the substituent phenyl groups, and discussed in terms of chain scissions arising at isolated siloxane linkages formed adventitiously during the isolation of the parent polymer.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 31. Synthesis and crystal structures of the compounds [AuW(µ-CHR)(CO)2(PPh3)(η-C5H5)]·CH2Cl2 and [AuPtW(µ3-CR)(CO)2(PMe3)3(η-C5H5)][PF6](R = C6H4Me-4)

Treatment of a mixture of the salts [N(PPh3)2][W2{µ-CH(C6H4Me-4)}(CO)7(η-C5H5)] and TIPF6 in tetrahydrofuran (thf) with [AuCl(PPh3)] affords the bridged p-tolylmethylidene complex [AuW{µ-CH(C6H4Me-4)}(CO)2(PPh3)(η-C5H5)], the structure of which has been established by a single-crystal X-ray diffraction study. As expected, the Au–W bond [2.729(1)A] is spanned by the CH(C6H4Me-4) group. The µ-C–W separation is relatively short [2.058(14)A] whereas the µ-C–Au distance is relatively long [2.268(14)A]. To account for these features a three-centre two-electron µ-C–Au–W interaction is postulated. Addition of [Au(PR′3)]+[PR′3= PPh3 or P(cyclo-C6H11)3] fragments, generated in situ from [AuCl(PR′3)] and TIPF6 in dichloromethane, to the alkylidynetungsten compounds [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4 or Me) affords the salts [AuW(µ-CR)(CO)2(PR′3)(η-C5H5)][PF6][R = C6H4Me-4, PR′3= PPh3or P(C6H11)3; R = Me, PR′3= PPh3]. N.m.r. studies (1H, 31P-{1H}, and 13C-{1H}) on solutions of these salts, however, reveal that the cations dissociate, affording equilibrium mixtures containing the species [Au{W(CR)(CO)2(η-C5H5)}2]+ and [Au(PR′3)2]+. The trimetal compound [AuPtW(µ3-CR)(CO)2(PMe3)3(η-C5H5)][PF6](R = C6H4Me-4) has been prepared by two routes: from the reaction between [Au{W(CR)(CO)2(η-C5H5)}2][PF6] and [Pt(C2H4)(PMe3)2], and by addition of [Au(thf)(PMe3)][PF6] to [PtW(µ-CR)(CO)2(PMe3)2-(η-C5H5)]. The structure of [AuPtW(µ3-CR)(CO)2(PMe3)3(η-C5H5)][PF6] has been established by X-ray crystallography. A triangular array of metal atoms [Au–W 2.801 (2), Au–Pt 2.956(2), and Pt–W 2.770(2)A] is asymmetrically bridged by the CR ligand [µ3-C–Au 2.21 (4), µ3-C–Pt 1.97(4), and µ3-C–W 2.01 (4)A]. The Au–Pt separation suggests that there is little or no direct metal–metal bonding between these two metal atoms. The tungsten atom carries the cyclopentadienyl ligand and two CO groups, but the latter are appreciably non-linear. The gold and platinum atoms are ligated by one and two PMe3 groups, respectively.