Search

The functionalization of (R,R)-S,S′-di-tert-butylferrocene-1,1′-disulfoxide by deprotolithiation-electrophilic trapping sequences was studied towards polysubstituted, enantiopure derivatives for which the properties were determined. While the 2,2′-disubstituted ferrocene derivatives were obtained as expected, subsequent functionalization of the 2,2′-di(phenylthio) and 2,2′-bis(trimethylsilyl) derivatives occurred primarily at the 4- or 4,4′-positions. This unusual regioselectivity was discussed in detail in light of pKa values and structural data. The less sterically hindered 2,2′-difluorinated derivative yielded the expected 1,1′,2,2′,3,3′-hexasubstituted ferrocenes by the deprotometallation-trapping sequence. Further functionalization proved possible, leading to early examples of 1,1′,2,2′,3,3′,4,4′-octa, nona and even decasubstituted ferrocenes. Some of the newly prepared ferrocene-1,1′-disulfoxides were tested as ligands for enantioselective catalysis and their electrochemical properties were investigated. [ABSTRACT FROM AUTHOR]

1-(tert-Butyl)-1H-tetrazole (L) reacts with copper(ii) tetrafluoroborate hexahydrate to give the complexes [Cu2L8(H2O)2](BF4)4 (1) or [Cu3L6(H2O)6](BF4)6 (2) depending on the reaction conditions. These complexes, as well as compound L, were characterized using single crystal X-ray analysis. Complex 1 was found to comprise a dinuclear complex cation [Cu2L8(H2O)2]4+ (the Ci symmetry point group), with six tetrazole ligands L showing monodentate N4-coordination, and two ligands L providing two tetrazole ring N3,N4 bridges between the copper(ii) cations; water molecules complete the distorted octahedral coordination of the metal ions. Complex 2 includes a linear trinuclear complex cation [Cu3L6(H2O)6]6+ (the S6 symmetry point group), in which neighbouring copper(ii) cations are linked by three ligands L via tetrazole ring N3,N4 bridges; central and terminal metal ions show octahedral CuN6 and CuN3O3 coordination cores, respectively. The temperature-dependent magnetic susceptibility measurements of complex 2 revealed that the copper(ii) ions were weakly ferromagnetically coupled showing a coupling constant J of 2.2 cm−1 {H = −2J(S1S2 + S2S3)}. The quantum-chemical investigation of the electronic structure and basicity of ligand L was carried out. [ABSTRACT FROM AUTHOR]

A novel N,N′‐alkylene‐bridged bis(5‐pyridyltetrazole) ligand, namely 2,5‐bis[5‐(2‐pyridyl)‐tetrazol‐2‐yl]‐2,5‐dimethylhexane (bpt), was prepared by regioselective N2‐alkylation of 5‐(2‐pyridyl)tetrazole with 2,5‐dimethylhexane‐2,5‐diol in perchloric acid. The ligand bpt was found to react with copper(II) chloride to give the dinuclear complex [Cu2(bpt)Cl4]. According to single‐crystal X‐ray analysis of the complex, bpt acts as a chelating ligand, coordinated by the metal through the tetrazole ring N4 and the pyridine ring nitrogen atoms. In the complex molecule, two copper atoms are linked by double chlorido bridges, and ligand bpt plays the role of the third bridge. The temperature‐dependent magnetic susceptibility measurements of the complex revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of –1.04 cm–1. [ABSTRACT FROM AUTHOR]

The macrocyclic binuclear tetrazole, 2,2,5,5-tetramethyl-12-oxa-1,6,7,8,16,17,18,19-octaazatricyclo[13.2.1.16,9]nonadeca-7,9(19),15(18),16-tetraene (L), reacts with copper(II) chloride or copper(II) tetrafluoroborate hexahydrate to give complexes [Cu3Cl6L2] (1) or [CuL2(H2O)2](BF4)2(H2O) (2), respectively. According to single crystal X-ray analysis, both complexes were found to be coordination polymers. In the crystal structure of complex 1, there are neutral linear bibridged trinuclear units Cu3Cl6, in which the copper atoms are linked together by double chlorine bridges. Neighboring Cu3Cl6 units are bonded to each other by two bridging macrocyclic ligands L due to coordination bonds Cu-N between terminal copper atoms of Cu3Cl6 units and the tetrazole ring nitrogen atoms of ligands L to form polymeric chains. In complex 2, the copper atom is bonded to three ligands L via the tetrazole ring nitrogen atoms, and to two water molecules, with formation of a square-pyramidal coordination of the metal. In this complex, one of two independent ligands L shows monodentate coordination, whereas another ligand plays the role of a bridge between two neighboring copper atoms being responsible for formation of polymeric cationic chains [CuL2(H2O)2] n 2n+. A complex system of hydrogen bonds connects the chains and the anions BF4 - into a three-dimensional network. The temperature-dependent magnetic susceptibility measurements of complex 1 revealed that the copper(II) ions were ferromagnetically coupled showing a coupling constant J of 50 cm-1. [ABSTRACT FROM AUTHOR]

Complexation of the ambidentate ligand 4-mercaptobenzoate (4-SH-C6H4CO2H, H2mba) by the macrocyclic complex [Ni2L(μ-Cl)]ClO4 (L2- represents a 24-membered macrocyclic hexaazadithiophenolate ligand) has been examined. The monodeprotonated Hmba- ligand reacts with the Ni2 complex in a selective manner by substitution of the bridging chlorido ligand to produce μ1,3-carboxylato-bridged complex [Ni2L(Hmba)]+ (2+), which can be isolated as an air-sensitive perchlorate (2ClO4) or tetraphenylborate (2BPh4) salt. The reactivity of the new mercaptobenzoate complex is reminiscent of that of a "free" thiophenolate ligand. In the presence of air, 2ClO4 dimerizes via a disulfide bond to generate tetranuclear complex [{Ni2L}2(O2CC6H4S)2]2+ (32+). The auration of 2ClO4 with [AuCl(PPh3)], on the other hand, leads to monoaurated complex [Ni2IIL(mba)AuIPPh3]+ (4+). The bridging thiolate functions of the N6S2 macrocycle are deeply buried and are unaffected/unreactive under these conditions. The complexes were fully characterized by electrospray ionization mass spectrometry, IR and UV/vis spectroscopy, density functional theory, cyclic voltammetry, and X-ray crystallography [for 3(BPh4)2 and 4BPh4]. Temperature-dependent magnetization and susceptibility measurements reveal an S = 2 ground state that is attained by ferromagnetic coupling between the spins of the NiII ions in 2ClO4 (J = +22.3 cm-1) and 4BPh4 (J = +20.8 cm-1; H = -2JS1S2). Preliminary contact-angle and X-ray photoelectron spectroscopy measurements indicate that 2ClO4 interacts with gold surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Complexes ML1 2 and ML2 2, with M=FeII, CoII, NiII, and 1,3-bis(2-R-tetrazol-5-yl)triazenide ligands L1 (R=Me) and L2 (R= tBu), have been synthesized by the reaction of corresponding 1,3-bis(2-R-tetrazol-5-yl)triazenes with metal(II) salts in basic media and characterized by IR, UV–Vis spectroscopy, thermal and X-ray diffraction analyses. Both 1,3-bis(2-R-tetrazol-5-yl)triazenes were found to deprotonate on coordination and act as tridentate chelating ligands forming distorted MN6 octahedra around metal(II) cations. [ABSTRACT FROM AUTHOR]

Abstract: Tetrazol-2-ylacetic acid (2-TzaH) was found to react with CuCl2, PdCl2, and K2PtCl4 in water giving Cu(2-Tza)2, PdCl2(2-TzaH)2·2H2O and PtCl2(2-TzaH)2, correspondingly. Obtained complexes, being the first reported examples of coordination compounds derived from 2-TzaH, have been characterized by IR spectroscopy, thermal and X-ray diffraction methods. 2-TzaH was found to act as a monodentate ligand coordinated to the metal ion via N4 atom of heteroring in palladium complex and as tridentate bridging ligand coordinated via N4 atom and two oxygen atoms in copper complex. Cu(2-Tza)2 presents 2D coordination polymer, whereas PdCl2(2-TzaH)2·2H2O is molecular complex. [Copyright &y& Elsevier]

Abstract: For the first time, tetrazolate complexes have been prepared by direct synthesis. Two novel homo- and heterometallic mixed-ligand complexes, Cu(en)(tz)2 and Cu(en)2Zn(tz)4, have been synthesized using tetrazole (Htz), ethylenediamine (en), metallic copper and zinc oxide as starting materials. Both tetrazolates were characterized by single-crystal X-ray diffraction, IR spectroscopy and thermal analysis. The complexes present 1D coordination polymers, with tetrazolate anions acting as both monodentate and bridging ligands. [Copyright &y& Elsevier]