A pyrrolo-tetrathiafulvalene belt and its TCNQ complex: syntheses and X-ray crystal structures.

A general and efficient four-step synthesis of a tetrathiafulvalene-belt 6, starting from the monopyrrolo-tetrathiafulvalene building block 1, is described, together with its 7,7,8,8-tetracyano-p-quinodimethane charge transfer complex. The complexation of the electron acceptor 7,7,8,8-tetracyano-p-quinodimethane by the tetrathiafulvalene-belt 6 was investigated both in solution and in the solid state. [reaction: see text]

4-metalated condensed pyrimidines: their preparation and reaction with aldehydes under Barbier-type conditions.

[reaction: see text] The organometallic intermediate obtained from halogen-metal exchanges of 4-iodo-6-phenylthieno[2,3-d]pyrimidine under Barbier-type conditions was reacted with aldehydes to form the corresponding alcohols in moderate yields. The reaction involving an organolithium intermediate proceeded only at low temperature, whereas the reaction involving a magnesium ate intermediate also proceeded at room temperature. A crystal structure confirms that the expected constitutional alcohol isomer is formed, where no migration has taken place. The conditions were also suitable for 9-benzyl-6-iodopurine.

A pyrrolo-tetrathiafulvalene cage: synthesis and X-ray crystal structure.

[reaction: see text] A novel type of tetrathiafulvalene-cage 4 containing three monopyrrolo-tetrathiafulvalene units has been prepared employing a general and efficient synthetic approach. X-ray crystal structure analysis revealed that the cage is able to accommodate solvent molecules within a cavity in the solid state.

A Pyrazole to Furan Rearrangement. Thermolysis of 5-Azido-4-formylpyrazoles.

5-Azido-3-benzyl-4-formyl-1-phenylpyrazoles 1a-c extrude dinitrogen upon heating in toluene to give the corresponding nitrenes, which immediately rearrange via a new ring-opening ring-closure reaction to produce an equimolar mixture of 4-cyano-2-phenyl-3-phenylazofurans 2a-c and 3-benzyl-4-cyano-1-phenylpyrazoles 3a-c. The formation of the 4-cyano-2-phenyl-3-phenylazofurans 2a-c is the first example in the pyrazole series of a nitrene rearrangement, in which the parent heterocyclic system of the product differs from that of the starting material. The isolation of equimolar amounts of the two products points to the fact that their formation occurs by two mechanistically interconnected pathways, between which the exchange of a redox equivalent takes place. Evidence for the existence of two mechanistically interlinked pathways is presented, and the insight into the stoechiometry of the reaction is taken advantage of to optimize the reaction with respect to either of the two products 2 or 3. Thus, it is demonstrated how one can bias the two pathways using external reagents, thereby changing the product distribution ratio 2:3 from 1:1 in the unbiased case, to 1:4 in one direction, and to better than 20:1 in the other direction.

Tetrathiafulvalene Belts with Large Cavities.

The latest member of the cyclophane family, the macrotricyclic tetrathiafulvalene (TTF) "belt", is now available. A general synthetic strategy for the construction of tetraconnected belt-type TTFs (shown schematically) has been developed, made possible by the use of a TTF with two different protecting groups. In the solid-state structure of one of the three TTF-belts prepared two chloroform molecules reside inside the spacious cavity.

The reaction between ZnO and molten Na2S2O7 or K2S2O7 forming Na2Zn(SO4)2 orK2Zn(SO4)2, studied by Raman spectroscopy and x-ray diffraction.

Reactions between solid zinc oxide and molten sodium or potassium pyrosulfates at 500 degrees C are shown by Raman spectroscopy to be 1:1 reactions leading to solutions. By lowering the temperature of the solution melts, colorless crystals form. Raman spectra of the crystals are given and tentatively assigned. Crystal structures of the monoclinic salts at room temperature are given. Na(2)Zn(SO(4))(2): space group = P2/n (No. 13), Z = 8, a = 8.648(3) Angstroms, b = 10.323(3) Angstroms, c = 15.103(5) Angstroms, beta = 90.879(6) degrees, and wR(2) = 0.0945 for 2748 independent reflections. K(2)Zn(SO(4))(2): space group = P2(1)/n (No.14), Z = 4, a = 5.3582(11) Angstroms, b = 8.7653(18) Angstroms, c = 16.152(3) Angstroms, beta = 91.78(3) degrees , and wR(2) = 0.0758 for 1930 independent reflections. In both compounds, zinc is nearly perfectly trigonally bipyramidal, coordinated to five oxygen atoms, with Zn-O bond lengths ranging from 1.99 to 2.15 Angstroms, equatorial bonds being slightly shorter on the average. The O-Zn-O angles are approximately 90 degrees and 120 degrees . The sulfate groups connect adjacent Zn(2+) ions, forming complicated three-dimensional networks. All oxygen atoms belong to nearly perfect tetrahedral SO(4)(2-) groups, bound to zinc. No oxygen atom is terminally bound to zinc; all zinc oxygens are further connected to sulfur atoms (Zn-O-S bridging). In both structures, some oxygen atoms are uniquely bound to certain S atoms. The sulfate group tetrahedra have quite short (1.42-1.45 Angstroms) terminal S-O bonds in comparison to the longer (1.46-1.50 Angstroms) Zn-bridging S-O bonds. The Na(+) or K(+) ions adopt positions between the ZnO(5) hexahedra and the SO(4) tetrahedra, completing the three-dimensional network of the M(2)Zn(SO(4))(2) structures. Bond distances and angles compare well with literature values. Empirical correlations between S-O bond distances and average O-S-O bond angles follow a previously found trend.

Coupling of metal-based light-harvesting antennas and electron-donor subunits: trinuclear ruthenium(II) complexes containing tetrathiafulvalene-substituted polypyridine ligands.

Three new tetrathiafulvalene-substituted 2,2'-bipyridine ligands, cis-bpy-TTF(1), trans-bpy-TTF(1), and cis-bpy-TTF(2) have been prepared and characterized. X-ray analysis of trans-bpy-TTF(1) is also reported. Such ligands have been used to prepare two new trinuclear Ru(II) complexes, namely, [[(bpy)(2)Ru(micro-2,3-dpp)](2)Ru(bpy-TTF(1))](PF(6))(6) (9; bpy=2,2'-bipyridine; 2,3-dpp=2,3-bis(2'-pyridyl)pyrazine) and [[(bpy)(2)Ru(micro-2,3-dpp)](2)Ru(bpy-TTF(2))](PF(6))(6) (10). These compounds can be viewed as coupled antennas and charge-separation systems, in which the multichromophoric trinuclear metal subunits act as light-harvesting antennas and the tetrathiafulvalene electron donors can induce charge separation. The absorption spectra, redox behavior, and luminescence properties (both at room temperature in acetonitrile and at 77 K in a rigid matrix of butyronitrile) of the trinuclear metal complexes have been studied. For the sake of completeness, the mononuclear compounds [(bpy)(2)Ru(bpy-TTF(1))](PF(6))(2) (7) and [(bpy)(2)Ru(bpy-TTF(2))](PF(6))(2) (8) were also synthesized and studied. The properties of the tetrathiafulvalene-containing species were compared to those of the model compounds [Ru(bpy)(2)(4,4'-Mebpy)](2+) (4,4'-Mebpy=4,4'-dimethyl-2,2'-bipyridine) and [[(bpy)(2)Ru(micro-2,3-dpp)](2)Ru(bpy)](6+). The absorption spectra and redox behavior of all the new metal compounds can be interpreted by a multicomponent approach, in which specific absorption features and redox processes can be assigned to specific subunits of the structures. The luminescence properties of the complexes in rigid matrices at 77 K are very similar to those of the corresponding model compounds without TTF moieties, whereas the new species are nonluminescent, or exhibit very weak emissions relative to those of the model compounds in fluid solution at room temperature. Time-resolved transient absorption spectroscopy confirmed that the potentially luminescent MLCT states of 7-10 are significantly shorter lived than the corresponding states of the model species. Photoinduced electron-transfer processes from the TTF moieties to the (excited) MLCT chromophore(s) are held responsible for the quenching processes.