Bis(ligand) Rhenium(V) and Technetium(V) Complexes of Two Naturally Occurring Binding Moieties (Oxazoline and Thiazoline)

Attempts to prepare tris(ligand) metal complexes of technetium in intermediate oxidation states with potentially bidentate oxazoline- and thiazoline-containing ligands were unsuccessful; when pertechnetate was reduced in the presence of excess ligand, TcO(2).xH(2)O was produced. Instead, by reaction with preformed M.O cores, a series of oxotechnetium(V) and oxorhenium(V) complexes of the formula MOXL(2) (M = Re, X = Br; M = Tc, X = Cl) and HL = 2-(2'-hydroxyphenyl)-2-oxazoline (Hoz), 2-(2'-hydroxy-3'-methylphenyl)-2-oxazoline (Hmoz), 2-(2'-hydroxyphenyl)-2-thiazoline (Hthoz), and 2-(2'-hydroxyphenyl)-2-benzoxazoline (Hhbo) have been prepared. These compounds have been characterized by a variety of techniques including single-crystal X-ray diffraction. Crystals of Hthoz (C(9)H(9)NOS) are monoclinic, with space group P2(1)/n, a = 7.5342(6) ?, b = 12.2187(6) ?, c = 9.3942(8) ?, beta = 94.233(7) degrees, and Z = 4; those of TcOCl(thoz)(2) (C(18)H(16)ClN(2)O(3)S(2)Tc) are monoclinic, with space group P2(1)/n, a = 16.506(1) ?, b = 7.664(1) ?, c = 16.3216(6) ?, beta = 111.154(4) degrees, and Z = 4; those of ReOBr(oz)(2) (C(18)H(16)BrN(2)O(5)Re) are orthorhombic, with space group Pbca, a = 12.864(2) ?, b = 25.369(2) ?, c = 11.025(2) ?, and Z = 8. The structures were solved by direct (Hthoz) or Patterson (metal complexes) methods and were refined by full-matrix least-squares procedures to R = 0.033, 0.032, and 0.028 for 1600, 3152, and 2651 reflections with I >/= 3sigma(I), respectively. In the two complexes, the geometry around the metals is distorted octahedral with the halide ligands in each bound cis, and one phenolate oxygen from one ligand in each bound trans to the metal-oxo linkage. In ReOBr(oz)(2), the two oxazoline nitrogens are coordinated trans to one another; in TcOCl(thoz)(2), the two thiazoline nitrogens are found cis to one another.     

Trithiacyclononane as a ligand for potential technetium and rhenium radiopharmaceuticals: synthesis of [M(9S3)(SC2H4SC2H4S)][BF4] (M = 99Tc, Re, 188Re) via C-S bond cleavage

Chemical or electrochemical reduction of the 1,4,7-trithiacyclononane (9S3) complexes [MII(9S3)2][BF4]2 (M = Re (3a) or Tc (3b)) results in instantaneous C-S bond cleavage to yield ethene and the stable MIII thiolate complexes [MIII(9S3)L][BF4] (M = Re (4a) or Tc (4b), L = SCH2CH2SCH2CH2S). Compounds 4 have been characterized by 1H NMR spectroscopy, and the pseudo-octahedral geometry of 4b has been confirmed by X-ray crystallography. Upon electrochemical reduction 4a loses ethene, while 4b can be reversibly reduced to [TcII(9S3)L], which is then further reduced to Tc(I) with loss of ethene. Successive ethene loss is observed in the mass spectra of compounds 3 and 4. The radiosynthesis of 4a with 188Re can be comfortably completed within 10 min starting with 188ReO4- from a 188W/188Re generator, with a radiochemical yield in excess of 90%, and thus represents a practical approach to the preparation of stable 188Re (and 99mTc) thioether complex derivatives/conjugates for clinical use. Crystal data: 4b, C10H20S6Tc, orthorhombic Pbca, a = 12.233(2) A, b = 14.341(2) A, c = 20.726(3) A, Z = 8.     

Oxorhenium(V) and oxotechnetium(V) [NN][S]3 complexes of 2-phenylbenzothiazole derivatives

The reaction of 2-(2'-pyridyl)benzothiazole, [NN], with the ReO(V)(3+) and TcO(V)(3+) cores in the presence of thiophenols, [S] (RC(6)H(4)SH, R = H, 4-CH(3), 4-OCH(3)), as coligands led to the isolation of hexacoordinated complexes of the MO[NN][S](3) type (M = Re, Tc). In all cases, two geometric mer isomers were formed, as evidenced by NMR spectroscopy and confirmed by X-ray crystallography. In both isomers, the coordination geometry about the metal ion is a distorted octahedral defined by the two nitrogen atoms of the bidentate ligand, the three sulfur atoms of the monodentate thiols, and the oxygen atom of the oxo group. The apical positions of the octahedron are occupied by the oxygen of the oxo group and, in one of the isomers, the nitrogen of the pyridyl moiety of 2-(2'-pyridyl)benzothiazole, while, in the second isomer, the imine nitrogen of 2-(2'-pyridyl)benzothiazole. The complexes are stable, neutral, and lipophilic. Complete (1)H and (13)C NMR assignments are reported for all complexes. The synthetic reaction was also successfully transferred at the technetium-99m tracer level by ligand exchange reaction using (99m)Tc-glucoheptonate as precursor in the presence of 2-(2'-pyridyl)benzothiazole and 4-CH(3)C(6)H(4)SH. The structure of the technetium-99m complex was established by high-performance liquid chromatographic comparison with the analogous oxotechnetium and oxorhenium complexes. The 2-(2'-pyridyl)benzothiazole ligand serves as a preliminary model for 2-(4-aminophenyl)benzothiazole, which possesses interesting properties for the development of technetium and rhenium radiopharmaceuticals for tumor imaging and/or radiotherapy as well as in vivo diagnosis of Alzheimer's disease.     

Toward novel DNA binding metal complexes: structure and basic kinetic data of [M(9MeG)2(CH3OH)(CO)3]+(M = 99Tc,Re)

To study the interaction of the fac-[M(CO)(3)](+) moiety (M = (99m)Tc, (188)Re) with DNA bases, we reacted [M(OH(2))(3)(CO)(3)](+) with 9-methylguanine (9-MeG), guanosine (G), and 2-deoxyguanosine (2dG). Two bases bind to the metal center via the N7 atoms. X-ray structure analysis of [(99)Tc(CH(3)OH)(9-MeG)(2)(CO)(3)](+) (4) (monoclinic, I2/a, a = 28.7533(14) A, b = 8.0631(4) A, c = 32.3600(15) A, beta = 91.543(6) degrees, V = 7499.6(6) A(3), Z = 8) and [Re(OH(2))(9-MeG)(2)(CO)(3)](+) (7) (monoclinic, P2(1)/n, a = 12.2873(11) A, b = 16.0707(13) A, c = 14.1809(16) A, beta = 103.361(12) degrees, V = 2724.4(5) A(3), Z = 4) reveals that the two bases are in a head-to-tail (HT) orientation. Kinetic studies show that the rates of substitution of the purine bases are comparable to that of one of the active forms of cisplatin. The bis-substituted complexes are generally less stable than the platinum adducts, and metalation of the bases is reversible.     

Syntheses and reactivity of 'sulfur rich' Re(iii) and Tc(iii) complexes containing trithioperoxybenzoate, dithiobenzoate and dithiocarbamate ligands

Reduction-substitution reactions of [M(O)Cl(4)](-)(M=Re, (99)Tc) precursors with an excess of substituted dithiobenzoate ligands (R-PhCS(2))(-) in dichloromethane/methanol mixtures afford a series of six-coordinated neutral mixed-ligand complexes of the type M(III)(R-PhCS(3))(2)(R-PhCS(2))(M=Re; Rel--9; M=99)Tc; Tel--9). The coordination sphere is entirely filled by sulfur donor atoms, and the complexes adopt a distorted trigonal prismatic arrangement, as assessed by the X-ray crystal structure analysis of Re(4-Me-PhCS(3))(2)(4-Me-PhCS(2)), Re 2. These compounds show sharp proton and carbon NMR profiles, in agreement with the diamagnetism typical of low spin d(4) trigonal prismatic configurations. The red-ox processes involve reduction of the metal from Re(v) to Re(iii) and oxidation of dithiobenzoate to trithioperoxybenzoate. M2--9 complexes contain a substitution-inert [M(R-PhCS(3))(2)](+) moiety including the metal and two trithioperoxybenzoate fragments, while the third dithiobenzoate ligand is labile. The latter is efficiently replaced by reaction with better nucleophiles such as diethyldithiocarbamate giving a further class of mixed ligand complexes of the type M(III)(R-PhCS(3))(2)(Et(2)NCS(2))(M=Re; Re 10--18; M=(99)Tc; Tc--18), which retain the trigonal prismatic arrangement, as determined by the X-ray analyses of the representative compounds Re(PhCS(3))(2)(Et(2)NCS(2)), Re 10 and (99)Tc(PhCS(3))(2)(Et(2)NCS(2)), Tc 10.     

Synthesis, characterization, and stereochemistry of oxorhenium(V) complexes with 2-aminoethanethiolate

A series of oxorhenium(V) complexes with 2-aminoethanethiolate (aet), [ReO(aet-N,S)(D-pen-N,O,S)] (2), [[ReO(aet-N,S)(2)](2)O] (3), [ReO(Cl)(aet-N,S)(2)] (4), and [ReO(aet-N,S)(Haet-S)(2)]Cl(2) ([5]Cl(2)) was newly prepared starting from ReO(4)(-). The reaction of NH(4)ReO(4) with a 1:1 mixture of Haet.HCl and D-H(2)pen (D-penicillamine) in the presence of SnCl(2).2H(2)O in water gave 2, 3, and the known complex [ReO(D-Hpen-N,S)(D-pen-N,O,S)] (1). These complexes were fractionally precipitated by controlling the pH of the reaction solution. The complex 2 was also prepared in a higher yield by a similar reaction using methanol as a solvent. The crystal structure of 2 was determined by X-ray crystallography; 2 crystallizes in the tetragonal space group P4(3) with a = 9.621(1), c = 12.911(1) A, V = 1195.0(3) A(3), and Z = 4. The oxorhenium(V) core in 2 is coordinated by a bidentate-N,S aet ligand and a tridentate-N,O,S D-pen ligand, having a distorted octahedral geometry with a cis-N cis-S configuration in the equatorial plane perpendicular to the O-Re-O axis. The 1:2 reaction of NH(4)ReO(4) with Haet.HCl in the presence of SnCl(2).2H(2)O in methanol produced 4, which is interconvertible with 3, while the corresponding 1:3 reaction resulted in the isolation of [5]Cl(2). The complexes 4 and 5 were also structurally characterized; 4 crystallizes in the monoclinic space group P2(1)/c with a = 6.839(1), b = 10.0704(6), c = 14.1075(8) A, beta = 91.729(8) degrees, V = 971.2(2) A(3), and Z = 4, while [5]Cl(2) crystallizes in the triclinic space group P1 with a = 11.938(3), b = 12.366(3), c = 5.819(1) A, alpha = 102.71(2), beta = 101.28(2), gamma = 75.41(2) degrees, V = 802.0(3) A(3), and Z = 2. In 4, the oxorhenium(V) core is octahedrally coordinated by two bidentate-N,S aet ligands, which form a cis-N cis-S configurational equatorial plane with a Cl(-) ion trans to the oxo ligand. On the other hand, the oxorhenium(V) core in [5](2+) is coordinated by one bidenate-N,S aet and two monodentate-S Haet ligands, having a distorted trigonal-bipyramidal geometry with S and N donors at the apical positions.     

Convenient route leading to neutral fac-M(CO)3(NNO) complexes (M = Re, 99mTc) coupled to amine pharmacophores

The synthesis and characterization of three neutral tricarbonyl fac-M(CO)3(NNO) (M = Re, (99m)Tc) complexes based on the picolylamine N,N-diacetic acid (PADA) ligand is reported. One of the two carboxylate groups of the PADA ligand is efficiently and conveniently derivatized with an amine nucleophile through the use of the PADA anhydride. In this work, aniline, benzylamine and pyrrolidine were used as model amine nucleophiles. The rhenium complexes were synthesized using the [NEt4]2[Re(CO)3Br3] precursor and fully characterized by elemental analysis, spectroscopic methods, and X-ray crystallography. The analogous technetium-99m complexes were also prepared quantitatively using the [(99m)Tc(CO)3(H2O)3](+) precursor. The reaction scheme presented for the synthesis of the fac-M(CO)3(NNO) (M = Re, (99m)Tc) complexes can be applied to the development of target-specific radiopharmaceuticals because, in principle, any bioactive pharmacophore bearing an amine group can be used in the place of the model amine nucleophiles.     

Relative stability of mixed [3 + 1] Tc and Re complexes: a computational and conceptual DFT study

A computational and conceptual density-functional study has been performed on various [3 + 1] complexes of both Re(V) and Tc(V). The fully optimized complexes chloro(3-thiapentane-1,5-dithiolato)oxorhenium(V) and chloro(3-thiapentane-1,5-dithiolato)oxotechnetium(V) show geometries that compare favorably with the X-ray data. These structures were used as a starting point to investigate the relative stability of Tc(V) and Re(V) complexes with various ligands containing combinations of N, O, and S as chelating atoms and to evaluate the stabilizing/destabilizing influence of these N, O, and S combinations. For both Tc and Re complexes, the S content (number and position of S atoms) together with the presence of an oxygen as the central chelating atom turns out to be decisive in the stability of the tridentate complexes, the latter factor being strongly destabilizing and the former stabilizing. The stabilization sequences for both Tc and Re are shown to be identical in the gas phase and in aqueous solutions treated in a polarizable continuum model. The Re(V) complexes are found to be more stable than their Tc(V) analogues. All of the results are successfully interpreted in terms of the hard and soft acids and bases principle, applied at the local level. For this purpose, a softness value for Tc is obtained by interpolating softness trends in neighboring elements of rows 5 and 6 in the periodic table.     

A new [2 + 1] mixed ligand concept based on [99(m)Tc(OH2)3(CO)3]+: a basic study

Mixed ligand fac-tricarbonyl complexes of the general formula [M(L1)(L2)(CO)3](M = Re, 99(m)Tc, L1= imidazole, benzyl isocyanide, L2 = 1H-imidazole-4-carboxylic acid, pyridine-2,4-dicarboxylic acid, pyridine-2,5-dicarboxylic acid) have been prepared starting from the precursors [M(OH2)3(CO)3]+. The complexes can be obtained in good yield and purity in a two-step procedure by first attaching the bidentate ligand followed by addition of the monodentate. 99mTc compounds can also be prepared at the tracer level in one-pot procedures with L1 and L2 being concomitantly present. This [2 + 1] approach allows the labeling of bioactive molecules containing a monodentate or a bidentate donor site. Examples given in here are N-(tert-butoxycarbonyl)glycyl-N-(3-(imidazol-1-yl)propyl)phenylalaninamide, 5-((3-(imidazol-1-yl)propyl)aminomethyl)-2'-deoxyuridine and 4-(5-isonitrilpentyl)-1-(2-methoxyphenyl)-piperazine as L1 and N-((6-carboxypyridine-3-yl)methyl)glycylphenylalanine as L2. The corresponding second ligand can be used to influence the physico-chemical properties of the conjugate. The crystal structures of [99Tc(OH2)(imc)(CO)3], [Re(OH2)(2,4-dipic)(CO)3], [Re(bic)(2,4-dipic)(CO)3] and [Re(im)(2,5-dipic)(CO)3] are reported.     

Hydrothermal Synthesis and Crystal Structure of a Bivanadyl Capped Keggin Polyoxomet alate[Zn(2,2''''-bpy)_2(H_2O)]_2[HPMo_(12)O_(40)(VO)_2]

1 INTRODUCTION The design and synthesis of organic-inorganic hy-brid compounds are of great interest owing to theirextensive theoretical and practical applications in ca-talysis, medicine, analytical chemistry, nanotechno-logy, electrochromism, magnetism and photochemis-try[1～5]. In heteropolyoxometalate chemistry, a newadvance is the decoration of polyoxoanions with va-rious organic and transition metal complex moieties.In contrast to a large number of known organic andtransition-metal-s…     

Synthesis and characterization of six new quaternary actinide thiophosphate compounds: Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6)(,) K(10)Th(3)(P(2)S(7))(4)(PS(4))(2), and A(5)An(PS(4))(3), (A = K, Rb, Cs; An = U, Th)

Six new actinide metal thiophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction: Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6) (I), K(10)Th(3)(P(2)S(7))(4)(PS(4))(2) (II), K(5)U(PS(4))(3) (III), K(5)Th(PS(4))(3) (IV), Rb(5)Th(PS(4))(3) (V), and Cs(5)Th(PS(4))(3) (VI). Compound I crystallizes in the monoclinic space group P2(1)/c with a = 33.2897(1) A, b = 14.9295(1) A, c = 17.3528(2) A, beta = 115.478(1) degrees, Z = 8. Compound II crystallizes in the monoclinic space group C2/c with a = 32.8085(6) A, b = 9.0482(2) A, c = 27.2972(3) A, beta = 125.720(1) degrees, Z = 8. Compound III crystallizes in the monoclinic space group P2(1)/c with a = 14.6132(1) A, b = 17.0884(2) A, c = 9.7082(2) A, beta = 108.63(1) degrees, Z = 4. Compound IV crystallizes in the monoclinic space group P2(1)/n with a = 9.7436(1) A, b = 11.3894(2) A, c = 20.0163(3) A, beta = 90.041(1) degrees, Z = 4, as a pseudo-merohedrally twinned cell. Compound V crystallizes in the monoclinic space group P2(1)/c with a = 13.197(4) A, b = 9.997(4) A, c = 18.189(7) A, beta = 100.77(1) degrees, Z = 4. Compound VI crystallizes in the monoclinic space group P2(1)/c with a = 13.5624(1) A, b = 10.3007(1) A, c = 18.6738(1) A, beta = 100.670(1) degrees, Z = 4. Optical band-gap measurements by diffuse reflectance show that compounds I and III contain tetravalent uranium as part of an extended electronic system. Thorium-containing compounds are large-gap materials. Raman spectroscopy on single crystals displays the vibrational characteristics expected for [PS(4)](3)(-), [P(2)S(7)](4-), and the new [P(3)S(10)](5)(-) building blocks. This new thiophosphate building block has not been observed except in the structure of the uranium-containing compound Cs(8)U(5)(P(3)S(10))(2)(PS(4))(6).     

Iron oxide-filled micelles as ligands for fac-[M(CO)3]+ (M = (99m)Tc, Re)

Magnetite-filled micelles capture fac-[M(OH(2))(3)(CO)(3)](+) complexes (M = (99m)Tc, Re), creating versatile self-assembled constructs for multimodal SPECT/MR/optical imaging and radiopharmaceutical guided delivery.     

New monodentate amidine superbasic ligands with a single configuration in fac-[Re(CO)3(5,5'- or 6,6'-Me2bipyridine)(amidine)]BF4 complexes

Treatment of two precursors, fac-[Re(CO)(3)(L)(CH(3)CN)]BF(4) [L = 5,5'-dimethyl-2,2'-bipyridine (5,5'-Me(2)bipy) (1) and 6,6'-dimethyl-2,2'-bipyridine (6,6'-Me(2)bipy) (2)], with five C(2)-symmetrical saturated heterocyclic amines yielded 10 new amidine complexes, fac-[Re(CO)(3)(L)(HNC(CH(3))N(CH(2)CH(2))(2)Y)]BF(4) [Y = CH(2), (CH(2))(2), (CH(2))(3), NH, or O]. All 10 complexes possess the novel feature of having only one isomer (amidine E configuration), as established by crystallographic and (1)H NMR spectroscopic methods. We are confident that NMR signals of the other possible isomer (amidine Z configuration) would have been detected, if it were present. Isomers are readily detected in closely related amidine complexes because the double-bond character of the amidine C-N3 bond (N3 is bound to Re) leads to slow E to Z isomer interchange. The new fac-[Re(CO)(3)(L)(HNC(CH(3))N(CH(2)CH(2))(2)Y)]BF(4) complexes have C-N3 bonds with essentially identical double-bond character. However, the reason that the Z isomer is so unstable as to be undetectable in the new complexes is undoubtedly because of unfavorable clashes between the equatorial ligands and the bulky N(CH(2)CH(2))(2)Y ring moiety of the axial amidine ligand. The amidine formation reactions in acetonitrile (25 °C) proceeded more easily with 2 than with 1, indicating that the distortion in 6,6'-Me(2)bipy resulting from the proximity of the methyl substituents to the inner coordination sphere enhanced the reactivity of the coordinated CH(3)CN. Reaction times for 1 and 2 exhibited a similar dependence on the basicity and ring size of the heterocyclic amine reactants. Moreover, when the product of the reaction of 1 with piperidine, fac-[Re(CO)(3)(5,5'-Me(2)bipy)(HNC(CH(3))N(CH(2)CH(2))(2)CH(2))]BF(4), was challenged in acetonitrile-d(3) or CDCl(3) with a 5-fold excess of the strong 4-dimethylaminopyridine ligand, there was no evidence for replacement of the amidine ligand after two months, thus establishing that the piperidinylamidine ligand is a robust ligand. This chemistry offers promise as a suitable means for preparing isomerically pure conjugated fac-[(99m)Tc(CO)(3)L](n±) imaging agents, including conjugates with known bioactive heterocyclic amines.     

Syntheses of new ionic technetium(III) complexes containing four monodentate phosphine ligands. Crystal structures of trans-[Tc(PMe2Ph)4Cl2]PF6, trans-[Tc(PMe3)4Cl2]BPh4, and trans-[Tc(PMe3)4Cl2]PF6

New ionic technetium complexes of the type trans-[Tc(PR3)4Cl2]+ are synthesized by various methods. The simplest method is the reaction of [TcO4]- with the phosphine in methanol in the presence of a chloride salt. Compounds containing PMe2Ph and PMe3 are synthesized and characterized by crystallographic methods. The complexes containing the less bulky phosphine can be prepared from complexes containing the bulker phosphine. The compounds are paramagnetic, with two unpaired electrons. The complexes studied by X-ray diffraction methods are the trans isomers. [Tc(PMe2Ph)4Cl2]PF6 crystallizes in the monoclinic space group P2(1)/c, with a = 11.511(2) A, b = 26.713(7) A, c = 12.688(3) A, beta = 92.79(1) degrees, Z = 4, and R1 = 0.0574. [Tc(PMe3)4Cl2]BPh4 (II) crystallizes in the orthorhombic space group Pbcn, with a = 18.213(5) A, b = 22.950(5) A, c = 19.428(6) A, Z = 8, and R1 = 0.0691. [Tc(PMe3)4Cl2]PF6 crystallizes in the monoclinic space group P2(1)/c, with a = 18.152(7) A, b = 16.838(9) A, c = 18.090(6) A, beta = 106.63(1) degrees, Z = 8, and R1 = 0.0670. The compounds all have octahedral coordination, but an important tetrahedral deformation of the plane containing the Tc and the four P atoms is observed in each case. In II, the two independent Tc atoms are both located on 2-fold axes.     

Hydrothermal Syntheses and Crystal Structures of Two Complexes with 3,5- Dinitrosalicylate and 2,2′-Bipyridine Ligands

The two title complexes,[Cd{3,5-(NO2)2sal}(2,2′-bipy)]n 1 and [Mn{3,5-(NO2)2sal}(2,2′-bipy)]n 2 (3,5-(NO2)2sal=3,5-dinitrosalicylate,2,2′-bipy=2,2′-bipyridine),were synthesized by the hydrothermal reaction and structurally characterized. Complex 1 crystallizes in triclinic,space group P1,a=5.581(4),b=12.071(8),c=12.88(1),α=92.10(3),β=96.73(3),γ =102.02(2)°,C17H10N4O7Cd,Mr=494.69,V=841(1)3,Z=2,Dc=1.954 g/cm3,F(000)=488,μ =1.353 mm-1,R=0.0248 and wR=0.0761. Complex 2 crystallizes in monoclinic with space group P21/c,a=8.604(3),b=23.88(1),c=8.894(3),β=102.45(1)°,C17H10N4O7Mn,Mr=437.23,V= 1785(1) 3,Z=4,Dc=1.627 g/cm3,F(000)=884,μ=0.791 mm-1,R=0.0471 and wR=0.1250. Complex 1 possesses an infinite 1D polymeric chain structure consisting of the repeated basic four-membered ring units (Cd2O2) and eight-membered ring units (CdOCO)2. Compound 2 displays a linear 1D chain through Mn(Ⅱ) atoms and bridging carboxylate groups of 3,5-dinitrosalicylic acid ligands with the Mn…Mn separation of 4.472(2). The fluorescence properties and cyclic voltammetric behaviors of the complexes are also reported.     

Two-dimensional coordination polymers of copper(II) with oxalate: lattice water control of structure

Three oxalate copper(II) complexes, [Cu(bipy)(C(2)O(4))(H(2)O)].2H(2)O (1), [Cu(nphen)(C(2)O(4))(H(2)O)].2H(2)O (2), and [Cu(phen)(C(2)O(4))(H(2)O)].H(2)O (3) (bipy = 2,2'-bipyridine, nphen = 5-nitro-1,10-phenanthroline and phen = 1,10-phenanthroline), have been synthesized and their crystal structures have been determined. Compound 1 crystallizes in the triclinic space group P1 with a = 7.2554(10) A, b = 10.5712(14) A, c = 10.8178(15) A, alpha = 62.086(2) degrees, beta = 77.478(3) degrees, gamma = 81.773(3) degrees, and Z = 2. Compound 2 crystallizes in the triclinic space group P1 with a = 9.582(2) A, b = 10.086(2) A, c = 10.592(2) A, alpha = 64.18(3) degrees, beta = 79.47(3) degrees, gamma = 60.06(3) degrees, and Z = 2. Compound 3 crystallizes in the monoclinic space group P2(1)/n with a = 8.4655(7) A, b = 9.7057(8) A, c = 17.4572(14) A; beta = 103.865(2) degrees, and Z = 4. The crystal structures of all complexes consist of neutral [Cu(L)(C(2)O(4))(H(2)O)] (L = bipy, nphen, and phen) units and one or two lattice water molecules in the unit cell. Each copper atom in 1, 2, and 3 involves a five-coordinate CuN(2)O(2)O' environment, with a distorted square-pyramidal structure. In 1 and 2, two lattice water molecules are around each unit of [CuL(C(2)O(4))(H(2)O)] (L = bipy and nphen) and form two-dimensional networks. Only one lattice water molecule is found in the unit cell of 3 and the two-dimensional structure is different from 1 and 2. The extended three-dimensional structure is formed through pi-pi interactions between layers. The influences of hydrogen bonds and the sizes and Lewis basicity of ligands to the structures were discussed.     

Carboranes as ligands for the preparation of organometallic Tc and Re Radiopharmaceuticals. Synthesis of [M(CO)(3)(eta-2,3-C(2)B(9)H(11))](-) and rac-[M(CO)(3)(eta-2-R-2,3-C(2)B(9)H(10))](-) (M = Re, (99)Tc; R = CH(2)CH(2)CO(2)H) from [M(CO)(3)Br(3)](2-)

A new and high yielding method for the synthesis of [M(CO)(3)(eta(5)-2,3-C(2)B(9)H(11))](-) and the bifunctional metal complexes, rac-[M(CO)(3)(eta(5)-2-R-2,3-C(2)B(9)H(10))](-) (R = CH(2)CH(2)CO(2)H), from [M(CO)(3)Br(3)](2)(-) (M = Re, (99)Tc) was developed. The general approach entailed the addition of nido-[(C(2)B(9)H(12))(-)], or the acid substituted analogue, to [M(CO)(3)Br(3)](2)(-) (M = Re, (99)Tc) in the presence of TlOEt in THF. It was also possible to prepare the reported products in water using sodium carbonate in place of TlOEt. The reported approach led to the preparation, and X-ray crystallographic structure determination, of the first Tc-carborane complex reported to date (a = 13.606(17) A, b = 10.685(13) A, c = 15.534(16) A, alpha = gamma = 90 degrees, beta = 111.84(2) degrees). Because of the stabilities of the metal complexes, and the fact that the compounds can be prepared in water, the bifunctional derivatives can be considered as novel synthons for the preparation of organometallic (99m)Tc and (186/188)Re radiopharmaceuticals.     

Syntheses and characterization of dicarbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media: spectroscopic, structural, and DFT analyses

This work describes new synthetic routes to produce mixed carbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media. NaNO2, NOHSO4, and NO2(g) have been used to produce in situ nitrous acid as the primary source of NO+. Starting from the organometallic precursor fac-[MX3(CO)3]+, 1 (M = 99Tc, Re; X = Cl, Br), the formation of mixed dicarbonyl-mononitrosyl complexes was observed in aqueous hydrochloric and hydrobromic acid. Time-dependent analyses of the reactions by means of HATR-IR and 99Tc NMR spectroscopy in solution revealed the almost quantitative substitution of one CO ligand by NO+ and, thus, the formation of complexes with facial arrangement of the three pi-acceptor ligands. In the case of technetium, the monomeric complex (NEt4)[TcCl3(CO)2NO] (3a) and the dimeric, chloride-bridged, neutral complex [TcCl(mu-Cl)(CO)2NO]2 (4a) were produced. In the case of rhenium, the monomeric species (NEt4)[ReBr2X(CO)2NO] (X = Br (3b), NO3 (5)) was solely isolated. The X-ray structure of complexes 4a and 5 are discussed. The crystallographic analyses revealed the coordination of the NO+ group trans to the terminal chloride (4a) or the bromide (5), respectively. Crystal data: complex 4a (C4Cl4N2O(6)Tc2), monoclinic, Cc, a = 18.82(3) A, b = 6.103(6) A, c = 12.15(2) A, alpha = 90 degrees , beta = 105.8(2) degrees , gamma = 90 degrees , V = 1343(3) A(3), Z = 4; complex 5 (C10H20N3O(6)Br2Re), orthorhombic, P2(1)2(1)2(1), a = 10.2054(5) A, b = 12.5317(7) A, c = 13.9781(7) A, V = 1787.67(16) A(3), Z = 4. The isolated complexes and their potential facial isomers have been further investigated by density functional theory (DFT) calculations. The energy differences of the isomers are relatively small; however, the calculated energies are consistent with the formation of the observed and isolated compounds. The calculated bond lengths and angles of complex 5 are in good agreement with the data determined by X-ray diffraction. Experiments on the no-carrier-added level starting from fac-[99mTc(H2O)3(CO)3]+ revealed the formation of the complex fac-[99mTcCl(H2O)2(CO)2NO]+ in reasonable good yields. This aqueous-based, synthetic approach will enable the future evaluation of this novel, low-valent metal precursor for potential use in radiopharmacy.     

Very small and soft scorpionates: water stable technetium tricarbonyl complexes combining a bis-agostic (k(3)-H, H, S) binding motif with pendant and integrated bioactive molecules

The novel trihydro(mercaptoazolyl)borates Na[H(3)B(tim(Me))] (L(1)) (tim(Me) = 2-mercapto-1-methylimidazolyl), Na[H(3)B(tim(Bupip))] (L(2)) (tim(Bupip) = 1-[4-((2-methoxyphenyl)-1-piperazinyl)butyl]-2-mercaptoimidazolyl), and Na[H(3)B(bzt)] (L(3)) (bzt = 2-mercaptobenzothiazolyl) were synthesized by reaction of NaBH(4) with the corresponding azole. Ligands L(1)-L(3) represent a new class of light and soft scorpionates that stabilizes the [M(CO)(3)](+) core (M = (99)Tc, Re) by formation of the complexes fac-[M{kappa(3)-H(mu-H)(2)B(tim(Me))}(CO)(3)] (M = (99)Tc (1), Re (2)), fac-[Re{kappa(3)-H(mu-H)(2)B(tim(Bupip))}(CO)(3)] (3), and fac-[Re{kappa(3)-H(mu-H)(2)B(bzt)}(CO)(3)] (4), respectively. The soft scorpionates are coordinated to the metal in unique (kappa(3)-H, H', S) fashion, as confirmed by X-ray crystallography of 1, 2, and 4. These complexes with bis-agostic hydride coordination are formed in aqueous solution with the two hydrides replacing two coordinating aquo ligands. The agostic hydrogen atoms were located directly, confirming an unprecedented donor atom set combining one sulfur and two hydrogen atoms. Preliminary studies have shown the possibility of preparing some of these complexes at the no carrier added level ((99m)Tc), under conditions as required in radiopharmaceutical preparation. Due to their lipophilicity, small-size, and easy functionalization with adequate biomolecules, the trihydro(mercaptoazolyl)borate technetium tricarbonyl complexes are suitable for the design of CNS receptor ligand radiopharmaceuticals as exemplified with 3, comprising a pendant serotonergic 5-HT(1A) ligand. The integrated design of radiopharmaceuticals involving a bis-agostic scorpionate ligand is demonstrated by the synthesis of 4, with an integrated benzothiazolyl fragment for the recognition of beta-amyloid plaques.     

Thiophosphate phase diagrams developed in conjunction with the synthesis of the new compounds KLaP(2)S(6), K(2)La(P(2)S(6))(1/2)(PS(4)), K(3)La(PS(4))(2), K(4)La(0.67)(PS(4))(2), K(9-)(x)La(1+x/3)(Ps(4))(4) (x = 0.5), K(4)Eu(PS(4))(2), and KEuPS(4)

An alkali-metal sulfur reactive flux has been used to synthesize a series of quaternary rare-earth metal compounds. These include KLaP(2)S(6) (I), K(2)La(P(2)S(6))(1/2)(PS(4)) (II), K(3)La(PS(4))(2) (III), K(4)La(0.67)(PS(4))(2) (IV), K(9-x)La(1+x/3)(PS(4))(4) (x = 0.5) (V), K(4)Eu(PS(4))(2) (VI), and KEuPS(4) (VII). Compound I crystallizes in the monoclinic space group P2(1)/c with the cell parameters a = 11.963(12) A, b = 7.525(10) A, c = 11.389(14) A, beta = 109.88(4) degrees, and Z = 4. Compound II crystallizes in the monoclinic space group P2(1)/n with a = 9.066(6) A, b = 6.793(3) A, c = 20.112(7) A, beta = 97.54(3) degrees, and Z = 4. Compound III crystallizes in the monoclinic space group P2(1)/c with a= 9.141(2) A, b = 17.056(4) A, c = 9.470(2) A, beta = 90.29(2) degrees, and Z = 4. Compound IV crystallizes in the orthorhombic space group Ibam with a = 18.202(2) A, b = 8.7596(7) A, c = 9.7699(8) A, and Z = 4. Compound V crystallizes in the orthorhombic space group Ccca with a = 17.529(9) A, b = 36.43(3) A, c = 9.782(4) A, and Z = 8. Compound VI crystallizes in the orthorhombic space group Ibam with a = 18.29(5) A, b = 8.81(2) A, c= 9.741(10) A, and Z = 4. Compound VII crystallizes in the orthorhombic space group Pnma with a = 16.782(2) A, b = 6.6141(6) A, c = 6.5142(6) A, and Z = 4. The sulfur compounds are in most cases isostructural to their selenium counterparts. By controlling experimental conditions, these structures can be placed in quasi-quaternary phase diagrams, which show the reaction conditions necessary to obtain a particular thiophosphate anionic unit in the crystalline product. These structures have been characterized by Raman and IR spectroscopy and UV-vis diffuse reflectance optical band gap analysis.