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A series of new monocationic iridium(III) complexes [Ir((CN)-N-boolean AND)(2)((NN)-N-boolean AND)]PF6 with "large-surface" alpha,alpha'-diimin ligands (NN)-N-boolean AND (dap = 1,12-diazaperylene, dmedap = 2,11-dimethyl-1,12-diazaperylene, dipdap = 2,11-diisopropyl-1,12-diazaperylene) and different cyclometalating ligands (CN)-N-boolean AND (piq = 1-phenylisoquinoline, bzq = benzo[h]quinoline, ppz = 1-phenylpyrazole, thpy = 2-(2-thienyl)pyridine, ppy = 2-phenylpyridine, meppy = 2-(4-methylphenyl)pyridine, dfppy = 2-(2,4-difluorophenyl)pyridine) were synthesized. The solid structures of the complexes [Ir(piq)(2)(dap)]PF6, [Ir(bzq)(2)(dap)]PF6, [Ir(ppy)(2)(dipdap)]PF6, [Ir(piq)(2)(dmedap)]PF6, [Ir(ppy)(2)(dap)]PF6 and [Ir(ppz)(2)(dap)]PF6 are reported. In [Ir(piq)(2)(dap)]PF6, the dap ligand and one of the piq ligands of each cationic complex are involved in pi-pi stacking interactions forming supramolecular channels running along the crystallographic c axis. In the crystalline [Ir(bzq)(2)(dap)]PF6 pi-pi stacking interactions between the metal complexes lead to the formation of a 2D layer structure. In addition, CH-pi interactions were found in all compounds, which are what stabilizes the solid structure. In particular, a significant number of them were found in [Ir(piq)(2)(dap)]PF6 and [Ir(bzq)(2)(dap)]PF6. The crystal structures of [Ir(ppy)(2)(dipdap)]PF6 and [Ir(ppy)(2)(dmedap)]PF6 are also presented, being the first examples of bis-cyclometalated iridium(III) complexes with phenanthroline-type alpha,alpha'-diimin ligands bearing bulky alkyl groups in the neighbourhood of the N-donor atoms. These ligands implicate a distorted octahedral coordination geometry that in turn destabilized the Ir-N-N boolean AND N bonds. The new iridium (III) complexes are not luminescent. All compounds show an electrochemically irreversible anodic peak between 1.15 and 1.58 V, which is influenced by the different cyclometalated ligands. All of the new complexes show two reversible successive one-electron "large-surface" ligand-centred reductions around -0.70 V and -1.30 V. Electrospray ionisation mass spectrometry (ESI-MS) and collision induced decomposition (CID) measurements were used to investigate the stability of the new complexes. Thereby, the stability agreed well with the order of the Ir-N-N boolean AND N bond lengths.
Ruthenium(II) complexes [Ru(L-N4Me2)(dape)](PF6)2 {[1](PF6)2}, [Ru(L-N4Me2)(tape)](PF6)2 {[2](PF6)2}, and [{Ru(L-N4Me2)}2(mu-tape)](PF6)4 {[3](PF6)4} were synthesized in two reaction steps by first reacting [Ru(DMSO)4Cl2] with tetraazamacrocyclic ligand N,N'-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane (L-N4Me2) in ethanol under microwave irradiation to the intermediate [Ru(L-N4Me2)Cl2], which was subsequently, without further isolation, reacted with 1,12-diazaperylene (dape) or 1,6,7,12-tetraazaperylene (tape). X-ray structures of [Ru(L-N4Me2)(dape)](PF6)2, [Ru(L-N4Me2)(tape)](PF6)2.acetone, and [{Ru(L-N4Me2)}2(mu-tape)](ClO4)4.MeCN were determined. The UV/Vis absorption spectra of [1](PF6)2, [2](PF6)2, and [3](PF6)4 in acetonitrile display intense low-energy dp(Ru)?p* (dape or tape) MLCT absorption bands centered at 579, 637, and 794 nm, respectively. Reversible metal oxidations for the bimetallic complex [{Ru(L-N4Me2)}2(mu-tape)]4+ ([3]4+) are detected at 1.69 and 1.28 V vs. SCE. The potential difference ?E = 410 mV and the intervalence-charge-transfer (IVCT) transition at 2472 nm indicate a high degree of electronic interaction between the two ruthenium ions mediated through the tape bridging ligand. All three complexes, [1]2+, [2]2+, and [3]4+, were characterized by UV/Vis spectroelectrochemistry. The monooxidized and monoreduced states, [1]3+, [2]3+, [3]5+, and [1]+, [2]+, [3]3+, are accessible by reversible one-electron oxidation and one-electron reduction processes, respectively, as documented by the observation of several stable isosbestic points in the spectral progressions. The second reduction in each complex and the second oxidation in [3]4+ prove to be irreversible in these spectroelectrochemical experiments. Monoreduced species [1]+, [2]+, and [3]3+ yield EPR signals indicating that the unpaired electron is mainly centered on the large surface ligands dape or tape.
The synthesis and single crystal X-ray structures of eight AgI, HgII, and PtII complexes with the thiacrown ethers maleonitrile-tetrathia-12-crown-4 (mn12S4), maleonitrile-tetrathia-13-crown-4 (mn13S4), and maleonitrile- pentathia-15-crown-5 (mn15S5) (1) are reported. The ligand mn15S5 was synthesized for the first time and characterized by X-ray diffraction. With silver(I) perchlorate and silver(I) tetrafluoroborate it forms the chiral complexes [Ag(mn15S5)]ClO4·CH3NO2 (2) and [Ag(mn15S5)]BF4·CH3NO2·0.25H2O (3) with half-sandwich moieties. AgI is located in a distorted tetrahedral coordination environment, involving three sulfur atoms of the crown cycle and a fourth one of the adjacent half-sandwich moiety, forming a helical structure. The reaction of Hg(ClO4)2 with mn13S4 yielded the dinuclear complex [Hg2(mn13S4)3](ClO4)4 (4) containing two half-sandwich moieties with a third ligand molecule as a bridging unit. Mercury(II) chloride and mercury(II) iodide react with mn12S4 and mn13S4 to form complexes of the general composition [HgX2(L)] (X = Cl, I; L = mn12S4, mn13S4): [HgCl2(mn12S4)] (5), [HgI2(mn12S4)] (6), [HgCl2(mn13S4)] (7) or [HgX2(L)2] (X = I; L = mn13S4): [HgI2(mn13S4)2] (8). Only one or two sulfur atoms of the ligand are involved in the complexation, and chain or ribbon structures are formed. In these compounds the HgX2 units (X = Cl, I) are preserved, coordinated by sulfur atoms of bridging mn12S4 or mn13S4 ligands. In all complexes of this type, the metal atoms are not coordinated inside the cavity, but in an exocyclic mode, because the diameter of the macrocycle is too small. Additionally, the PtCl2 complex of mn12S4 was investigated, where PtII is coordinated in an exocyclic mode forming the complex [PtCl2(mn12S4)] (9). Two of the four sulfur atoms of the macrocycle are bonded to the metal giving together with both chlorine atoms a square-planar coordination geometry. Together with a long-range interaction with a further sulfur atom of the macrocycle a square-pyramidal coordination environment is formed.
Narrow channels with polar walls are the structural and functional features responsible for the high capacity of a zinc-organic framework based on an imidazolate-amide-imidate ligand for the uptake of H2 and CO2 (see structure: orange Zn, blue N, red O, dark gray C, light gray H). The rigid and stable chelating ligand was synthesized in situ by partial hydrolysis of a dicyanoimidazole compound.
The phenylidenepyridine (ppy) palladacycles [PdCl(ppy)(IMes)] (4) [IMes = 1,3-bis(mesityl) imidazol-2-ylidene] and [PdCl(ppy){(CN)(2)IMes}] (6) [(CN)(2)IMes = 4,5-dicyano-1,3-bis(mesityl) imidazol-2-ylidene] were prepared by facile two step syntheses, starting with the reaction of palladium(II) chloride with 2-phenylpyridine followed by subsequent addition of the NHC ligand to the precatalyst precursor [PdCl(ppy)](2). Suitable crystals for the X-ray analysis of the complexes 4 and 6 were obtained. It was shown that 6 has a shorter NHC-palladium bond than the IMes complex 4. The difference of the palladium carbene bond lengths based on the higher pi-acceptor strength of (CN)(2)IMes in comparison to IMes. Thus, (CN)(2)IMes should stabilize the catalytically active central palladium atom better than IMes. As a measure for the pi-acceptor strength of (CN)(2)IMes compared to IMes, the selone (CN)(2)IMes center dot Se (7) was prepared and characterized by Se-77-NMR spectroscopy. The pi-acceptor strength of 7 was illuminated by the shift of its Se-77-NMR signal. The Se-77-NMR signal of 7 was shifted to much higher frequencies than the Se-77-NMR signal of IMes center dot Se. Catalytic experiments using the Mizoroki-Heck reaction of aryl chlorides with n-butyl acrylate showed that 6 is the superior performer in comparison to 4. Using complex 6, an extensive substrate screening of 26 different aryl bromides with n-butyl acrylate was performed. Complex 6 is a suitable precatalyst for para-substituted aryl bromides. The catalytically active species was identified by mercury poisoning experiments to be palladium nanoparticles.
The first heterodinuclear ruthenium(II) complexes of the 1,6,7,12-tetraazaperylene (tape) bridging ligand with iron(II), cobalt(II), and nickel(II) were synthesized and characterized. The metal coordination sphere in this complexes is filled by the tetradentate N,N-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane (L-N4Me2) ligand, yielding complexes of the general formula [(L-N4Me2)Ru(mu-tape)M(L-N4Me2)](ClO4)(2)(PF6)(2) with M = Fe {[2](ClO4)(2)(PF6)(2)}, Co {[3](ClO4)(2)(PF6)(2)}, and Ni {[4](ClO4)(2)(PF6)(2)}. Furthermore, the heterodinuclear tape ruthenium(II) complexes with palladium(II)- and platinum(II)-dichloride [(bpy)(2)Ru(-tape)PdCl2](PF6)(2) {[5](PF6)(2)} and [(dmbpy)(2)Ru(-tape)PtCl2](PF6)(2) {[6](PF6)(2)}, respectively were also prepared. The molecular structures of the complex cations [2](4+) and [4](4+) were discussed on the basis of the X-ray structures of [2](ClO4)(4)MeCN and [4](ClO4)(4)MeCN. The electrochemical behavior and the UV/Vis absorption spectra of the heterodinuclear tape ruthenium(II) complexes were explored and compared with the data of the analogous mono- and homodinuclear ruthenium(II) complexes of the tape bridging ligand.