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Structurally variable organochalcogen clusters containing palladium(II) and nickel(II) ions were assembled starting from the salicylidene-substituted dichalcogenides (Y-C

A scalable synthesis of the novel and highly reactive [Tc(OH2)(CO)3(PPh3)2]+ cation is described. The ligand-exchange chemistry of this compound with neutral ligands coordinating through C, N, O, S, Se, and Te has been explored systematically. The complexes either retain the original mer-trans tricarbonyl core under exclusive exchange of the aqua ligand or form dicarbonyl complexes by thermal decarbonylation. Ligand exchange reactions starting from [Tc(OH2)(CO)3(PPh3)2]+ proceed under mild conditions and are generally almost quantitative. Some of the formed complexes are remarkably stable and inert, while others provide products with one labile ligand for further reactions. The derived complexes of the type [Tc(L)(CO)3(PPh3)2]+ and [Tc(L)2(CO)2(PPh3)2]+ represent an interesting opportunity for the development of 99mTc complexes with potential use in radiopharmacy. The ready displacement of the aqua ligand highlights the synthetic value of [Tc(OH2)(CO)3(PPh3)2]+ as a reactive entry point for further studies in the little explored field of the organometallic chemistry of technetium.

[Re(CO)Br(CNArDArF2)4] and [Tc(CO)Cl(CNArDArF2)4] (ArDArF = 2,6-(3,5-(CF3)2C6H3)2-4-F-C6H2) were prepared by reactions of [Re(CO)5Br] or (NBu4)[Tc2(CO)6(μ-Cl)3] with the sterically encumbered isocy...

Homoleptic eightfold coordinated methyl isocyanide complexes of W(IV) and W(V) have been prepared for the first time. The reaction of [NBu4]4[W(CN)8] with methyl triflate (MeOTf) gives [W(CNMe)8][O...

A series of technetium complexes with (η5-cyclopentadienyl)tris(dimethyl phosphito-P)cobaltate(III), also known as the "Klaui ligand" {LOMe}-, has been prepared. The products span seven different oxidation states (+1 to +7) of the radioactive transition metal and comprise nitrosyl, halide, oxido and nitrido complexes. All members of this series ([TcI(NO)Cl(PPh3)(LOMe)], [TcII(NO)Cl2(LOMe)], [TcIIICl2(PPh3)(LOMe)], [TcIVCl3(LOMe)], [TcVOCl2(LOMe)], [TcVNCl(PPh3)(LOMe)], [TcVINCl2(LOMe)], and [TcVIIO3(LOMe)] are air- and water-stable compounds, which recommends this class of technetium complexes as potential candidates for nuclear medical imaging procedures.

A series of technetium complexes with the sterically encumbered m-terphenyl isocyanides CNArDipp2 (Dipp = 2,6-diisopropylphenyl) and CNArMes2 (Mes = 2,4,6-trimethylphenyl) has been prepared. The pr...

One-pot reactions of the catechol-scaffolding aroylbis(N,N-diethylthiourea) H2Lcat with mixtures of CoCl2 and MCl (M+ = Cs+, Rb+, K+, Tl+, or NH4+) or with a Co(NO3)2/TlNO3 mixture lead to the self...

One-pot reactions of 2,6-dipicolinoylbis(N,N-diethylthiourea) (H2L) with Co(CH3COO)2·4H2O and LnCl3, where Ln = La, Ce, Nd, Sm, Gd, Dy, Er, and Yb, in warm methanol in the presence of Et3N, give st...

Reactions of [Tc(NO)Cl(Cp)(PPh3)] with a series of monodentate ligands X– (X– = I–, I3–, F3CSO3–, CF3COO–, or SCN–) result in a ready replacement of the chlorido ligand and the formation of complex...

Chagas disease remains a serious public health concern with unsatisfactory treatment outcomes due to strain-specific drug resistance and various side effects. To identify new therapeutic drugs agai...

Reactions of (NBu4)[MOCl4] complexes (M = Tc or Re) with an excess of hexafluoroacetylacetone (Hhfac) give products with a composition of (NBu4)[MOCl3(hfac)] as bright yellow (Tc) or red (Re) solids. The products are stable as solids but rapidly decompose in solution. A number of related phenylimidorhenium(V) complexes were synthesized starting from [Re(NPhF)Cl3(PPh3)2], where (NPhF)2– is a para-fluorinated phenylimido ligand. Products with compositions of [Re(NPhF)Cl2(PPh3)(acac)], [Re(NPhF)Cl2(PPh3)(hfac)], [Re(NPhF)Cl2(PPh3)(tfac)], [Re(NPhF)Cl2(PPh3)(naphtfac)], and [Re(NPhF)Cl2(PPh3)(tbutfac)] (Hacac = acetylacetone, Htfac = trifluoroacetylacetone, Hnaphtfac = naphthoyltrifluoroacetylmethane, and Htbutfac = tert-butyroyltrifluoroacetylmethane) were isolated from reactions of the quite soluble [Re(NPhF)Cl3(PPh3)2] with the corresponding β-diketones and studied spectroscopically and by X-ray diffraction. The β-diketonates are coordinated in a meridional arrangement with the phenylimide. The formation o...

Homoleptic eight-fold coordinated methylisocyanide complexes of W(IV) and W(V) have been prepared for the first time. The reaction of [NBu4]4[W(CN)8] with methyl triflate MeOTf gives [W(CNMe)8][OTf]4. The even stronger methylating mixture of methyl fluoride MeF and arsenic pentafluoride AsF5 in liquid sulfur dioxide SO2 is able to fully alkylate both [NBu4]4[W(CN)8] and [NBu4]3[W(CN)8]. The paramagnetic octakis(methylisocyanide)- tungsten(V) [W(CNMe)8][AsF6]5 is thermally highly unstable above −30 °C. All compounds have been characterized via single-crystal X-ray diffraction, IR and Raman, as well as NMR or EPR spectroscopy

The reaction of isophthaloylbis(N,N-diethylthiourea), H2L1, with UO2(CH3COO)2·2H2O and NEt3 as a supporting base gives a tetranuclear, anionic complex of the composition [{UO2(L1)}4(OAc)2]2–, in which the uranyl ions are S,O-chelate bonded. Each two of them are additionally linked by an acetato ligand. Similar reactions of various uranyl starting materials (uranyl acetate, uranyl nitrate, (NBu4)2[UO2Cl4]) with corresponding pyridine-centered ligands (pyridine-2,6-dicarbonylbis(N,N-dialkylthioureas), H2L2) yield mononuclear, neutral compounds, in which the thiourea derivatives are coordinated as S,N,N,N,S-five-dentate chelators. The equatorial coordination spheres of the formed hexagonal bipyramidal complexes [UO2(L2)(solv)] are completed by solvent ligands (H2O, MeOH, or DMF). Attempted reactions without a supporting base result in decomposition of the organic ligands and the formation of hexanuclear uranyl complexes with pyridine-2,6-dicarboxylato ligands, while the use of an excess of base results in co...

Herein we describe a platform technology for the synthesis and characterization of partially aminated, (35)S-labeled, dendritic polyglycerol sulfate (dPG(35)S amine) and fluorescent dPGS indocarbocyanine (ICC) dye conjugates. These polymer conjugates, based on a biocompatible dendritic polyglycerol scaffold, exhibit a high affinity to inflamed tissue in vivo and represent promising candidates for therapeutic and diagnostic applications. By utilizing a one-step sequential copolymerization approach, dendritic polyglycerol (Mn ≈ 4.5 kDa) containing 9.4% N-phthalimide protected amine functionalities was prepared on a large scale. Sulfation and simultaneous radio labeling with (35)SO3 pyridine complex, followed by cleavage of the N-phthalimide protecting groups, yielded dPG(35)S amine as a beta emitting, inflammation specific probe with free amino functionalities for conjugation. Furthermore, efficient labeling procedures with ICC via iminothiolane modification and subsequent "Michael" addition of the maleimide functionalized ICC dye, as well as by amide formation via NHS derivatized ICC on a dPGS amine scaffold, are described. The dPGS-ICC conjugates were investigated with respect to their photophysical properties, and both the radiolabeled and fluorescent compounds were comparatively visualized in histological tissue sections (radio detection and fluorescence microscopy) of animals treated with dPGS. Furthermore, cellular uptake of dPGS-ICC was found in endothelial cord blood (HUVEC) and the epithelial lung cells (A549). The presented synthetic routes allow a reproducible, controlled synthesis of dPGS amine on kilogram scale applying a one-pot batch reaction process. dPGS amine can be used for analysis via radioactivity or fluorescence, thereby creating a new platform for inflammation specific, multimodal imaging purposes using other attachable probes or contrast agents.

Novel synthetic routes to hexafluoridotechnetate(IV) are reported, and for the first time the single-crystal X-ray structures of several M2[TcF6] salts (M = Na, K, Rb, Cs, NH4, and NMe4) were determined. The ammonium and the alkaline metal salts crystallize in the trigonal space group P3m, while the NMe4(+) salt belongs to the space group R3. [TcF6](2-) salts are widely stable in aqueous solution. In alkaline media, however, a slow hydrolysis is observed, and the first hydrolysis product, the dimeric, oxido-bridged complex [F5Tc-O-TcF5](4-), could be studied structurally.

Cationic bis[1,3-diethyl-4,5-diarylimidazol-2-ylidene]gold(I) complexes with 4-OCH(3) or 4-F substituents in the aromatic rings and Br(-) (3a,b) or BF(4)(-) (7a,b) counterions were synthesized, characterized, and investigated for tumor growth inhibitory properties in vitro. Analogous to auranofin, the N-heterocyclic carbenes (NHCs) were also combined with a phosphine ligand (triphenylphosphine, 4a,b) and 2',3',4',6'-tetra-O-acetyl-β-D-glucopyranosyl-1-thiolate (5a,b). The growth inhibitory effect against MCF-7, MDA-MB 231, and HT-29 cells, which is more than 10-fold higher than that of cisplatin or 5-FU, was independent of the oxidation state (Au(III), 6a,b) and the anionic counterion. Bis[1,3-diethyl-4,5-bis(4-fluorophenyl)imidazol-2-ylidene]gold(I) bromide 3b as the most cytotoxic compound reduced the growth of MCF-7 cells with IC(50) = 0.10 μM (cisplatin, 1.6 μM; 5-FU, 4.7 μM). The thioredoxin reductase (TrxR), the estrogen receptor (ER), and the cyclooxygenase (COX) enzymes, which have to be considered as possible targets based on the drug design, can be excluded from being involved in the mode of action.

Reactions of 2-(diphenylphosphinomethyl)aniline, H(2)L(2), with (NBu(4))[ReOCl(4)] yield different oxo rhenium(V) complexes depending on the conditions applied. This comprises monomeric compounds such as [ReOCl(3)(H(2)L(2))] (1), [ReOCl(2)(OMe)(H(2)L(2))] (2), or [ReO(2)(H(2)L(2))(2)]Cl (5) as well as the dimeric μ-oxo complex [{ReOCl(2)(H(2)L(2))}(2)]O] (3) and the oxo-bridged trimer [{ReOCl(H(2)L(2))}O](3) (4). The latter compound represents the first example of a hitherto unknown trinuclear, cyclic oxo(V) core. [{ReOCl(H(2)L(2))}O](3) contains a tensed 6-membered metallacycle, which readily undergoes rearrangements and reactions with additional ligands. Compounds of the compositions 5 and [ReO(2)(H(2)L(2))(H(2)L(1))]Cl (6) were isolated either from the decomposition of 4 in CH(2)Cl(2)/n-pentane or from reactions with 2-(diphenylphosphino)aniline, H(2)L(1).

AgTcO(4) reacts with R(3)ECl compounds (E = C, Si, Ge, Sn, Pb; R = Me, (i)Pr, (t)Bu, Ph), (t)Bu(2)SnCl(2), or PhMgCl under formation of novel trioxotechnetium(VII) derivatives. The carbon and silicon derivatives readily undergo decomposition, which was proven by (99)Tc NMR spectroscopy and the isolation of decomposition products such as [TcOCl(3)(THF)(OH(2))]. Compounds [Ph(3)GeOTcO(3)], [(THF)Ph(3)SnOTcO(3)], [(O(3)TcO)Sn(t)Bu(2)(OH)](2), and [(THF)(4)Mg(OTcO(3))(2)] are more stable and were isolated in crystalline form and characterized by X-ray diffraction.

Reactions of N-[N',N'-diethylamino(thiocarbonyl)]benzimidoyl chloride with 4,4-dialkylthiosemicarbazides give a novel class of thiosemicarbazides/thiosemicarbazones, H(2)L, which causes a remarkable reduction of cell growth in in vitro experiments. These strong antiproliferative effects are also observed for oxorhenium(V) complexes of the general composition [ReOCl(L)], which are formed by reactions of the potentially tridentate ligands with (NBu(4))[ReOCl(4)]. A systematic substitution of the alkyl groups in the thiosemicarbazone building blocks of the ligands do not significantly influence the biological activity of the metal complexes, while the replacement of the chloro ligand by a PPh(3) ligand (by the replacement of the oxo unit by a nitrido ligand) completely terminated the cytotoxicity of the metal complexes.

N-[(Dialkylamino)(thiocarbonyl)]benzimidoyl chlorides react with functionalized amines such as 2-aminophenol, 2-methylaminopyridine, and 2-aminobenzoic acid in clean and high-yield procedures with the formation of the novel tridentate N-[(N",N"-dialkylamino)(thiocarbonyl)]-N'-substituted benzamidine ligands H 2 L 1 , HL 2 , and H 2 L 3 . By starting from (NBu 4 )[MOCl 4 ] (M = Re, Tc) or [ReOCl 3 (PPh 3 ) 2 ] and H 2 L 1 , a series of oxorhenium(V) and oxotechnetium(V) complexes of the composition [MOCI(L1)] were synthesized and characterized by spectroscopic methods and X-ray crystallography. The monomeric, five-coordinate compounds are air-stable and bind (L 1 ) 2- tridentate in the equatorial coordination sphere. Dimeric products of the compositions [(ReOCl(L 2 )} 2 O] and [ReOCl(L 3 )] 2 were isolated during reactions with HL 2 and H 2 L 3 . While dimerization in [(ReOCl(L 2 )} 2 O] is established via an oxo bridge, the metal atoms in [ReOCl(L 3 )] 2 are connected by the carboxylic group of the ligand, and the product represents the first example of a high-oxidation state rhenium complex displaying such a bonding feature.

The highly reactive mixed anhydrides [TcO3(OCOPh)] and [TcO3(OBF3)]- were synthesized by treatment of [TcO4]- with strong Lewis acids benzoyl chloride and BF3.OEt2. These mixed anhydrides, prepared in situ, were used as precursors for the synthesis of complexes containing the [TcO3]+ core. Subsequent reactions with bi- or tridentate ligands resulted in new complexes comprised of the [TcO3]+ core. As examples with bidentate ligands, the classical complexes [TcO3Cl(bipy)] (1) (bipy = 2,2'-bipyridine) and [TcO3Cl(phen)] (2) (phen = 1,10-phenanthroline) have been prepared by this strategy and structurally characterized. The new compounds [TcO3(bpza)] (3) (bpza = di-1H-pyrazol-1-ylacetate), [TcO3(bpza*)] (4) (bpza* = bis(3,5-dimethyl-1H-pyrazol-1-yl)acetate), [TcO3(tpzm*)]+ (6) (tpzm* = 1,1,1-methanetriyltris(3,5-dimethyl-1H-pyrazole), and [ReO3(tpzm*)][ReO4] (7) are examples of complexes with tripod ligands. The complexes have been structurally characterized, and their 99Tc NMR spectra have been recorded. As a common feature, the X-ray structures show a distinct widening of the O-Tc-O angles, almost to a tetrahedral angle. With the perspective of radiopharmaceutical applications, water stability and reactivities toward alkenes are described.

Polymeric technetium tetrachloride reacts with monodentate donor ligands such as THF, acetonitrile, DMSO, thioxane (1-oxa-4-thiacyclohexane), PMe2Ph, PPh3, OPPh3, or OH2 via cleavage of the polymeric network and the formation of [TcCl4(L)2] complexes. The configuration of the products is dependent on the donor atoms such that trans coordination is established with "soft" donor atoms such as sulfur or phosphorus, while cis-[TcCl4(L)2] complexes are formed with the "harder" donors oxygen or nitrogen. The ambivalent thioxane binds to technetium via the sulfur atom. The trans products are air stable and resistant to hydrolysis. The cis complexes, however, undergo stepwise hydrolysis, during which complexes of the composition [Cl3(L)2TcOTc(L)2Cl3] (L = CH3CN, DMSO, or OH2) are formed. They are the first representatives of a new class of technetium(IV) complexes with a bridging oxo ligand. The Tc-O bond lengths in these bridges are between 1.803(1) and 1.823(2) A.

Asymmetric, potentially pentadentate ligands (H 2 L 3 ) are formed by subsequent condensation of a semicarbazide and benzoylhydrazine on 2,6-diacetylpyridine. Two equivalents of H 2 L 3 reacts with CeCl 3 .7H 2 O, Ce(SO 4 ) 2 .4H 2 O, or EuCl 3 .6H 2 O under formation of [Ln I I I (HL 3 ) 2 ] + cations (Ln = Ce, Eu) with exclusive deprotonation of the benzoylhydrazone ligand arms. The Ce 4 + ion of the sulfate salt is reduced during the reaction and forms 10-coordinate singly charged complex cations, the structure of which is identical to the product of the reaction of cerium(lll) chloride. The exact position of deprotonation in the ligands is resolved by infrared spectroscopy, bond lengths considerations, and the hydrogen bonding in the solid-state structures of the products. A similar approach allows the synthesis of mixed semicarbazone/thiosemicarbazone ligands (H 2 L 4 ). The reaction of H 2 L 4 with Sm-(NO 3 ) 3 .6H 2 O leads to the first structurally characterized lanthanide complex with thiosemicarbazone coordination. The solid-state structure of the 10-coordinate complex [Sm(HL 4 ) 2 ]NO 3 .H 2 O shows exclusive deprotonation of the thiosemicarbazone arms of the ligands. All isolated complexes are air stable and do not undergo ligand exchange reactions or hydrolysis in the presence of water.

Air-stable rhenium(V) oxo complexes are formed when [ReOCl(3)(PPh(3))(2)] is treated with N-heterocyclic carbenes of the 1,3-dialkyl-4,5-dimethylimidazol-2-ylidene type, L(R) (R = Me, Et, i-Pr). Complexes of the compositions [ReO(2)(L(R))(4)](+), [ReOCl(L(R))(4)](2+), or [ReO(OMe)(L(R))(4)](2+) can be isolated depending on the alkyl substituents at the nitrogen atoms of the ligands and the reaction conditions applied. Despite the steric overcrowding of the equatorial coordination spheres of the metal atoms by each of the four carbene ligands, stable complexes with six-coordinate rhenium atoms are obtained. Steric demands of the alkyl groups allow control of the stability of the mono-oxo intermediates. Air-stable cationic complexes of the compositions [ReOCl(L(Me))(4)](2+), [ReOCl(L(Et))(4)](2+), and [ReO(OMe)(L(Me))(4)](2+) have been isolated, whereas reactions of [ReOCl(3)(PPh(3))(2)] or other rhenium(V) precursors with the more bulky 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (L(i)(-)(Pr)) directly yield the dioxo complex [ReO(2)(L(i)(-)(Pr))(4)](+). X-ray structures of [ReO(2)(L(i)(-)(Pr))(4)][ReO(4)], [ReO(2)(L(i)(-)(Pr))(4)][PF(6)], [ReO(2)(L(Me))(4)][ReO(4)](0.45)[PF(6)](0.55), [ReO(MeOH)(L(Me))(4)][PF(6)](2), and [ReOCl(L(Et))(4)][PF(6)](2) show that the equatorial coordination spheres of the rhenium atoms are essentially planar irrespective of the steric demands of the individual carbene ligands.

Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- = 2-(N,N-dimethylamino-methyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3-SH-2-R-3)2 (H2L1a: R = SiMe3, H2L1b: H) and P(C6H3-SH-2)3 (H3L2) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different oxidation states, +I and +III, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl4]-. A dinuclear complex having two Au(III) centres can be isolated from the reaction of [Au(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained which contains a three-coordinate gold atom. Comparatively short gold-gold distances have been found in the dinuclear complexes (2.978(2) A and 3.434(1) Å). They are indicative of weak gold-gold interactions, which is unusual for gold(III).

Novel rhenium(V) complexes were isolated from reactions of [NBu(4)][ReOCl(4)] with the potentially pentadentate Schiff base PhP{C(6)H(4)-2-(HC=N(C(6)H(4)-2-OH))}(2), H(2)L(1), and the corresponding amine PhP{C(6)H(4)-2-(CH(2)-NH(C(6)H(4)-2-OH))}(2), H(4)L(2). While the Schiff base undergoes partial hydrolytic decomposition and a redox reaction, the amine remains intact and acts as a pentadentate ligand, which encapsulates the metal atom of the {Re(V)O}(3+) core or stabilizes a {Re(V)Cl}(4+) center by the formation of an imido-type ligand system.

A novel tridentate thiosemicarbazide-type ligand class with an SNS donor set, H(2)L(1), was prepared by reactions of N-[N',N'-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with thiosemicarbazides. H(2)L(1) ligands readily react with (NBu(4))[TcOCl(4)] in MeOH under the formation of red oxotechnetium(V) complexes of composition [TcOCl(L(1))]. The monomeric, five-coordinate compounds are air-stable and bind (L(1))(2-) tridentate in the equatorial coordination sphere. The compounds represent the first examples of oxotechnetium(V) complexes with NS chelate-bonded thiosemicarbazones.

Starting originally from the organometallic precursor [NEt4]2[TcBr3(CO)3] (1b), substitution reactions were performed with the macrocyclic thioethers 1,4,7-trithiacyclononane (9-ane-S3), 1,4,7,10,13,16-hexathiacyclooctadecane (18-ane-S6), and 3,6,9,13,16,19-hexathiacycloicosanol (20-ane-S6-OH). The corresponding complexes fac-[Tc(9-ane-S3)(CO)3]Br (2), fac-[Tc2(tosylate)2(18-ane-S6)(CO)6] (3), and fac-[Tc2(20-ane-S6-OH)(CO)6][tosylate]2 (5) were isolated in good yields and characterized spectroscopically by IR, 1H, 99Tc NMR, and X-ray diffraction methods. In the case of 18-ane-S6 and 20-ane-S6-OH the formation of the 1:2 as well as the 1:1 complex could be observed in the 99Tc NMR experiment, depending on the ligand to metal ratio. Complex 2 crystallizes in the monoclinic space group P21/c, a = 14.79(2) A, b = 11.691(2) A, c = 16.94(2) A, β = 94.88(6)°, Z = 8. The tripodal ligand is coordinated through the sulfur atoms to the metal center, forming three favorable five-membered chelate rings. Complex 3 cry...

Hydrolytic pathways of the organometallic aqua ion [Re(CO)3(H2O)3]+ (2) in aqueous media were investigated by means of potentiometric titration experiments. The aqua complex 2 was obtained quantitatively by dissolving (NEt4)2[Re(CO)3Br3] (1) in water. Conventional alkalimetric titrations (0.1 M KNO3, 25 °C) allowed the determination of the formation constants of [Re3(CO)9(μ2-OH)3(μ3-OH)]- (3) and [Re2(CO)6(μ2-OH)3]- (4). The neutral dinuclear [Re2(CO)6(μ2-OH)2(H2O)2] (5) was observed as a minor species. A fast titration technique was used to investigate a rapid preequilibrium, consisting of the formation of the mononuclear deprotonation products [Re(CO)3(OH)(H2O)2] (6) and [Re(CO)3(OH)2(H2O)]- (7). The corresponding pKa values are 7.5(2) and 9.3(3). The immediate extraction of an aqueous solution of 2 with diethyl ether after base addition (1 equiv) led to the quantitative isolation of the well-known cubane cluster [Re(CO)3(OH)]4 (8), which was obtained as a DMF (8b) or OPPh3 adduct (8c). Attempts to isol...

Reactions of [TcNCl2(PPhR2)3] complexes (R = Me, Et) with 1,3-diethyl-4,5-dimethylimidazol-2-ylidene yield air-stable nitridotechnetium(V) complexes with N-heterocyclic carbenes with up to four of these bulky ligands and, depending on the reaction conditions applied, 1,1,3,3-tetramethyldisiloxane-1,3-diolato coligands which were abstracted from silicon-based grease.

[NEt4] 2 [Tc(CO) 3 Cl 3 ] reacts with thiosemicarbazones derived from 2,2'-dipyridyl ketone (HL 3 ) and 4-acetylpyridine (HL 4 ) to form stable technetium(I) complexes of the compositions [Tc(CO) 3 Cl-(HL 3 -N p y ,N p y )] and [Tc 2 (CO) 6 Cl 2 (μ-HL 4 -N p y ,S)]. Whereas exclusively the pyridine nitrogen atoms are involved in coordination in the monomeric complex, the binuclear compound represents the first technetium complex with a coordinated thiosemicarbazone functionality.

The derivatized 19- and 20-membered macrocyclic thio crowns 3,6,9,12,15,18-hexathianonadecanol C(13)H(26)OS(6) (19-aneS6-OH) (1) and 3,6,9,13,16,19-hexathiacycloicosanol C(14)H(28)OS(6) (20-aneS6-OH) (2) have been synthesized by [1 + 1] cyclization in about 30% yield. The ligands 1 and 2 react readily at room temperature with different silver(I) salts in water and in organic solvents to form in quantitative yields the complexes [Ag(19-aneS6-OH)](+) (3) and [Ag(20-aneS6-OH)](+) (4) for which crystals of X-ray quality were grown by slow diffusion of diethylether into methanol. [Ag(19-aneS6-OH)][CF(3)SO(3)] crystallizes in the triclinic space group Po with Z = 2, a = 10.760(1), b = 10.853(2) and c = 11.326(2)A, and alpha = 78.73(1), beta = 73.47(1), and gamma = 74.99(1) degrees. [Ag(20-aneS6-OH)][BF(4)] also crystallizes in the triclinic space group Po with Z = 4. The unit cell constants were determined with a = 10.076(4), b = 10.525(3), and c = 22.135(8)A, alpha = 93.32(2), beta = 102.43(2), and gamma = 100.32(2) degrees. The complex cations [Ag(19-aneS6-OH)](+) and [Ag(20-aneS6-OH)](+) are coordinated through only four sulfur atoms; thus, a distorted tetrahedral coordination geometry is exhibited. In addition we found a highly asymmetric Ag-S bond lengths distribution throughout all complex cations. The stability constants of [Ag](+) with 1 and 2 and, for comparison with [18-aneS6] (5), have been determined in methanol by potentiometric [Ag](+) measurements. Log K values for the formation of 3, 4, and [Ag(18-aneS6](+) (6) are 12.04 +/- 0.19, 11.49 +/- 0.15, and 12.67 +/- 0.13 respectively. Owing to a comparable macrocyclic effect, the similar log K values are reasonable but, since 6 coordinates octahedrally, not expected. (1)H and (13)C NMR investigations at various temperatures give evidence for fluxional coordinative behavior between all six sulfur atoms in solution. Consequently [Ag(19-aneS6-OH)](+), [Ag(20-aneS6-OH)](+), and [Ag(18-aneS6](+) seem to exhibit principally the same solution structures although the solid structures are very different.

Cationic dioxorhenium and dioxotechnetium complexes of the composition [MO(2)(L(1))(4)](+) (L(1) = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) have been prepared from various starting materials and studied spectroscopically and by X-ray crystallography. The metal-carbon distances range from 2.216(4) to 2.232(4) A indicating mainly sigma-bonding.

Technetium(V) complexes of the forms TcNL{sub 2} and (TcOL{sub 2})Cl (L = Et{sub 2}tcb{sup {minus}}, morphtcb{sup {minus}}, piptcb{sup {minus}}) with N-(thiocarbamoyl)-benzamidinato (tcb{sup {minus}}) ligands have been synthesized and characterized by elemental analysis and IR, {sup 1}H NMR, and uv/vis spectrocsopy. Selected compounds have been studied by EI and FAB mass spectrometry, including the MIKE technique. A single-crystal x-ray structure determination shows that the cation of bis(N-(N,N-diethylthiocarbamoyl)benzamidinato)oxo-technetium(V) chloride, formula weight 618.5, has a square-pyramidal structure with cis-coordinated ligands. This complex crystallizes in the triclinic space group P{bar 1} with a = 10.87 (2) {angstrom}, b = 11.587 (2) {angstrom}, c = 12.374 (2) {angstrom}, {alpha} = 91.94 (2){degree}, {beta} = 106.04 (2){degree}, {gamma} = 112.18 (2){degree}, and V = 1370.4 (4) {angstrom}{sup 3} with Z = 2 for 4723 independent observed reflections. 50 refs., 4 figs., 4 tabs.

Obtention des tenseurs hyperfins de tous les 13 C de l'anion et interpretation des couplages hyperfins. Des conclusions peuvent etre tirees sur la symetrie et la structure electronique de [Cu(mnt) 2 ] 2−

The anion pentachlorooxotechnetate(VI), TcOCl/sub 5//sup -/, has been prepared by reduction of TcO/sub 4//sup -/ with HCl in concentrated H/sub 2/SO/sub 4/ and investigated by means of the EPR technique. The axial symmetric spectrum suggests an in-plane ..pi..-type ground state of the MO of the unpaired electron. The Tc-Cl/sub eq/ bonding properties have been discussed in terms of MO theory, and a comparison has been given to the bonding properties in likely complexes of neighboring elements of Tc.