Copper(I)-Purine-Phosphine Complexes. Syntheses and Molecular Structures of [Cu(2)(&mgr;-HL(1))(2)(&mgr;-dppm)(eta(1)-dppm)(2)] and {[Cu(3)(&mgr;(3)-Cl)(2)(&mgr;-dppm)(3)][Cu(HL(2))(2)]} (H(2)L(1) = 8-Mercaptotheophylline and H(2)L(2) = 8-Ethyl-3-methylxanthine)

Chelator-accelerated one-pot 'click' labeling of small molecule tracers with 2-[¹⁸F]fluoroethyl azide

2-[¹⁸F]Fluoroethyl azide ([¹⁸F]FEA) can readily be obtained by nucleophilic substitution of 2-azidoethyl-4-toluenesulfonate with [¹⁸F]fluoride (half-life 110 min), and has become widely used as a reagent for ‘click’ labeling of PET tracers. However, distillation of [¹⁸F]FEA is typically required, which is time-consuming and unpractical for routine applications. In addition, copper(I)-catalyzed cycloaddition of [¹⁸F]FEA with non-activated alkynes, and with substrates containing labile functional groups, can be challenging. Herein, we report a highly efficient and practical ligand-accelerated one-pot/two-step method for ‘click’ labeling of small molecule tracers with [¹⁸F]FEA. The method exploits the ability of the copper(I) ligand bathophenanthrolinedisulfonate to accelerate the rate of the cycloaddition reaction. As a result, alkynes can be added directly to the crude reaction mixture containing [¹⁸F]FEA, and as cyclisation occurs almost immediately at room temperature, the reaction is tolerant to labile functional groups. The method was demonstrated by reacting [¹⁸F]FEA with a series of alkyne-functionalized 6-halopurines to give the corresponding triazoles in 55–76% analytical radiochemical yield.

Bis[μ-bis-(diphenyl-phosphan-yl)methane-κ(2) P:P'](μ-1-ethyl-thio-urea-κ(2) S:S)bis-[iodidocopper(I)] acetonitrile sesquisolvate

In the dinuclear title compound, [Cu₂I₂(C₃H₈N₂S)(C₂₅H₂₂P₂)₂]·1.5CH₃CN, each Cu^I atom exhibits a distorted tetra­hedral coordination with two P atoms from two bis­(diphenyl­phosphan­yl)methane (dppm) ligands, one metal-bridging S atom from the 1-ethyl­thio­urea (ettu) ligand and one iodide ion. The dppm ligand and the bridging S atom of the ettu ligand force the two copper atoms into close proximity, leading to the formation of a close intra­molecular Cu⋯Cu contact [3.3747 (17) Å]. The conformation of the dimeric complex is such that the two dppm ligands are located on one side of the dinuclear metal complex, while the two iodine atoms are pointed towards the other side of the complex, a conformation that is stabilized by two intra­molecular N—H⋯I hydrogen bonds between the ettu NH₂ and NHEt moieties and the I atoms. Another pair of symmetry-equivalent N—H⋯I hydrogen bonds is established between neighboring mol­ecules across an inversion center, linking mol­ecules into dimers. The dimers are connected with each other and with the inter­stitial acetonitrile solvent mol­ecules via a range of weaker C—H⋯I and C—H⋯S inter­actions and through weak C—H⋯π inter­actions, leading to the formation of a three-dimensional network. One of the acetonitrile solvent mol­ecules is disordered in a 1:1 ratio across a crystallographic inversion center.

Synthesis and structural characterization of trinuclear Cu(II)-pyrazolato complexes containing mu(3)-OH, mu(3)-O, and mu(3)-Cl ligands. Magnetic susceptibility study of [PPN](2)[(mu(3)-O)Cu(3)(mu-pz)(3)Cl(3)]

The nine-membered [-Cu(II)-N-N-](3) ring of trimeric copper-pyrazolato complexes provides a sturdy framework on which water is twice deprotonated in consecutive steps, forming mu(3)-OH and mu(3)-O species. In the presence of excess chlorides the mu(3)-O(H) ligand is replaced by two mu(3)-Cl ions. The interconversion of mu(3)-OH and mu(3)-O and the exchange of mu(3)-O(H) and mu(3)-Cl are reversible, and the three species involved have been structurally characterized: [PPN][Cu(3)(mu(3)-OH)(mu-pz)(3)Cl(3)(thf)].CH(2)Cl(2) (1a), monoclinic P2(1)/n, a = 10.055(2) A, b = 35.428(5) A, c = 15.153(2) A, beta = 93.802(3) degrees, V = 5386(1) A(3), Z = 4; [Bu(4)N][Cu(3)(mu(3)-OH)(mu-pz)(3)Cl(3)] (1b), triclinic P-1, a = 9.135(2) A, b = 13.631(2) A, c = 14.510(2) A, alpha = 67.393(2) degrees, beta = 87.979(2) degrees, gamma = 80.268(3) degrees, V = 1643.2(4) A(3), Z = 2; [PPN](2)[Cu(3)(mu(3)-O)(mu-pz)(3)Cl(3)] (2), monoclinic P2/c, a = 12.807(2) A, b = 13.093(2) A, c = 23.139(4) A, beta = 105.391(3) degrees, V = 3741(1) A(3), Z = 2; [PPN](2)[Cu(3)(mu(3)-Cl)(2)(mu-pz)(3)Cl(3)].0.75H(2)O.0.5CH(2)Cl(2) (3a), triclinic P-1, a = 14.042(2) A, b = 23.978(4) A, c = 25.195(4) A, alpha = 76.796(3) degrees, beta = 79.506(3) degrees, gamma = 77.629(3) degrees, V = 7988(2) A(3), Z = 4; [Bu(4)N](2)[Cu(3)(mu(3)-Cl)(2)(mu-pz)(3)Cl(3)] (3b), monoclinic C2/c, a = 17.220(2) A, b = 15.606(2) A, c = 20.133(2) A, beta = 103.057(2) degrees, V = 5270(1) A(3), Z = 4; [Et(3)NH][Cu(3)(mu(3)-OH)(mu-pz)(3)Cl(3)(pzH)] (4), triclinic P-1, a = 11.498(2) A, b = 11.499(2) A, c = 12.186(2) A, alpha = 66.475(3) degrees, beta = 64.279(3) degrees, gamma = 80.183(3) degrees, V = 1331.0(5) A(3), Z = 2. Magnetic susceptibility measurements show that the three copper centers of 2 are strongly antiferromagnetically coupled with J(Cu-Cu) = -500 cm(-1).