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Four Schiff base ligands of the general formulas [6-(

Treatment of an open-cage fullerene, designated as MMK-9, with (Ph3P)4Pt in toluene solution at room temperature allows a (PPh3)2Pt unit to be incorporated into the rim of the cage so that it becomes an integral part of the carbon cage skeleton. The structure of the adduct has been determined by single crystal X-ray diffraction and reveals that the platinum atom has planar PtC2P2 coordination, rather than the usual η2-bonding to an intact C–C double bond of the fullerene.

Non-luminescent, isostructural crystals of [(C6H11NC)2Au](EF6)·C6H6 (E = As, Sb) lose benzene upon standing in air to produce green luminescent (E = As) or blue luminescent (E = Sb) powders. Previous studies have shown that the two-coordinate cation, [(C6H11NC)2Au]+, self-associates to form luminescent crystals that contain linear or nearly linear chains of cations and display unusual polymorphic, vapochromic, and/or thermochromic properties. Here, we report the formation of non-luminescent crystalline salts in which individual [(C6H11NC)2Au]+ ions are isolated from one another. In [(C6H11NC)2Au](BArF24) ((BArF24)− is tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) each cation is surrounded by two anions that prohibit any close approach of the gold ions. Crystallization of [(C6H11NC)2Au](EF6) (E = As or Sb, but not P) from benzene solution produces colorless, non-emissive crystals of the solvates [(C6H11NC)2Au](EF6)·C6H6. These two solvates are isostructural and contain columns in which cations and benzene molecules alternate. With the benzene molecules separating the cations, the shortest distances between gold ions are 6.936(2) Å for E = As and 6.9717(19) Å for E = Sb. Upon removal from the mother liquor, these crystals crack due to the loss of benzene from the crystal and form luminescent powders. Crystals of [(C6H11NC)2Au](SbF6)·C6H6 that powder out form a pale yellow powder with a blue luminescence with emission spectra and powder X-ray diffraction data that show that the previously characterized [(C6H11NC)2Au](SbF6) is formed. In the process, the distances between the gold(i) ions decrease to ∼3 Å and half of the cyclohexyl groups move from an axial orientation to an equatorial one. Remarkably, when crystals of [(C6H11NC)2Au](AsF6)·C6H6 stand in air, they lose benzene and are converted into the yellow, green-luminescent polymorph of [(C6H11NC)2Au](AsF6) rather than the colorless, blue-luminescent polymorph. Paradoxically, the yellow, green-luminescent powder that forms as well as authentic crystals of the yellow, green-luminescent polymorph of [(C6H11NC)2Au](AsF6) are sensitive to benzene vapor and are converted by exposure to benzene vapor into the colorless, blue-luminescent polymorph., Non-luminescent crystals of [(C6H11NC)2Au](AsF6)·C6H6 readily lose benzene to form the green-luminescent polymorph of [(C6H11NC)2Au](AsF6) rather than the blue-luminescent polymorph.

Variations in crystallization conditions produce dramatic changes in the composition and geometry of solvated porphyrin-fullerene cocrystals. The products obtained by cocrystallization from a benze...

Noncoordinating anions, which generally play a subordinate role in coordination chemistry, alter the structure, the luminescence, as well as the thermochromic and vapochromic behaviors of salts of the two-coordinate cation, [(C6H11NC)2Au]+. Thus whereas the yellow polymorphs of [(C6H11NC)2Au](PF6) and [(C6H11NC)2Au](AsF6) contain single chains of cations and are vapochromic, yellow [(C6H11NC)2Au](SbF6) does not form the same polymorph and is not vapochromic but contains two distinct chains of cations connected through aurophilic interactions. Mixed crystals such as [(C6H11NC)2Au](PF6)0.50(AsF6)0.50 have been prepared by adding diethyl ether to a dichloromethane solution containing equimolar amounts of [(C6H11NC)2Au](PF6) and [(C6H11NC)2Au](AsF6). The initial (kinetic) product for the three combinations of anions ((PF6)-/(AsF6)-, (PF6)-/(SbF6)-, and (AsF6)-/(SbF6)-) was a precipitate of fine yellow needles with a green emission, which were gradually transformed at rates that depended on the anions present into colorless crystals with a blue emission. Whereas neither polymorph of [(C6H11NC)2Au](PF6) nor [(C6H11NC)2Au](SbF6) is thermochromic, the colorless mixed crystal [(C6H11NC)2Au](PF6)0.50(SbF6)0.50 is thermochromic and converts from blue-emitting to green-emitting at 87-95 °C. The temperature required to transform a crystal of the type [(C6H11NC)2Au](PF6)n(AsF6)1-n from colorless (blue-emitting) to yellow (green-emitting) increases as the fraction of hexafluorophosphate ion in the crystal increases. The yellow crystals of [(C6H11NC)2Au](PF6)0.75(AsF6)0.25, [(C6H11NC)2Au](PF6)0.50(AsF6)0.50, and [(C6H11NC)2Au](PF6)0.25(AsF6)0.75 are vapochromic, whereas the yellow crystals of [(C6H11NC)2Au](PF6)0.50(SbF6)0.50 and [(C6H11NC)2Au](AsF6)0.50(SbF6)0.50 are not.

Treatment of an open-cage fullerene, designated as MMK-9, with (Ph

The synthesis of pyreno[a]pyrene-based helicene hybrids was achieved in good yield via a four-fold alkyne benzannulation reaction that was promoted by Bronsted acid. The molecules are configuration...

This investigation presents a systematic examination of the late transition metal octaethylporphyrins MII(OEP) with M = Co, Ni, Cu, and Zn as cocrystallization agents for C60. In each case, the ful...

Diastereoselective Lewis acid-mediated additions of nucleophilic alkenes to N-sulfonyl imines are reported. The canonical polar Felkin-Anh model describing additions to carbonyls does not adequately describe analogous additions to N-sulfonyl imines. Herein, we describe the development of conditions to produce both syn and anti products with high diastereoselectivity and good yields. A stereoelectronic model consistent with experimental outcomes is also proposed.

Purified samples of Ho3 N@C2 (22010)-C78 and Tb3 N@C2 (22010)-C78 have been isolated by two distinct processes from the rich array of fullerenes and endohedral fullerenes present in carbon soot from graphite rods doped with Ho2 O3 or Tb4 O7 . Crystallographic analysis of the endohedral fullerenes as cocrystals with Ni(OEP) (in which OEP is the dianion of octaethylporphyrin) shows that both molecules contain the chiral C2 (22010)-C78 cage. This cage does not obey the isolated pentagon rule (IPR) but has two sites where two pentagons share a common C-C bond. These pentalene units bind two of the metal ions, whereas the third metal resides near a hexagon of the cage. Inside the cages, the Ho3 N or Tb3 N unit is planar. Ho3 N@C2 (22010)-C78 and Tb3 N@C2 (22010)-C78 use the same cage previously found for Gd3 N@C2 (22010)-C78 rather than the IPR-obeying cage found in Sc3 N@D3h -C78 .

Examination of crystals of cis-Ir(CO)2X(p-toluidine) (X = Cl, Br, I), by single crystal X-ray diffraction shows that the individual monomers self-associate to form extended columns with Ir⋯Ir separations ranging from 3.33 A for the chloro complex to 3.68 A in the iodo complex. The columnar structure is reinforced by hydrogen bonding between the halide ligand in one molecule with an N-H group in an adjacent molecule. This hydrogen bonding causes adjacent molecules to adopt nearly eclipsed orientations. In contrast, the positions of the methyl groups in cis-Ir(CO)2Cl(o-toluidine) and cis-Ir(CO)2Cl(2,6-dimethylaniline) limit intermolecular interactions to the formation of dimers connected by Ir⋯Ir interactions, and hydrogen bonding again occurs between the halide ligand in one molecule and the N-H group in an adjacent molecule. The UV/vis spectrum of cis-Ir(CO)2Cl(p-toluidine) provides evidence that the self-association also occurs in solution. The positive ion mass spectrum of laser ablated crystals of cis-Ir(CO)2Br(p-toluidine) reveals the presence of monomeric, dimeric, and trimeric cations.

A titanium-based heterobimetallic single-source precursor [Y2Ti4(μ3-O)4(μ2-O)3(H2O)(TFA)8(THF)5].3(THF) (1) (where TFA = trifluoroacetato and THF = tetrahydrofuran) was successfully used to fabricate pyrochlore-structured Y2Ti2O7–2TiO2 composite thin films on fluorine-doped tin oxide (FTO) substrates using the aerosol-assisted chemical vapor deposition technique (AACVD). The precursor complex (1), isolated in crystalline form by reacting yttrium (III) acetate monohydrate with titanium (IV) isopropoxide and trifluroacetic acid in THF solution, was characterized by physicochemical methods such as melting point, microanalysis, FT-IR, 1H-NMR, thermogravimetric analyses (TGA/DTG), and single-crystal X-ray diffraction. Thin films prepared at 550 °C were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission gun-scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) which demonstrated the development of mesoporous structured microballs of Y2Ti2O7–2TiO2 with precise stoichiometry. The optical analysis showed that Y2Ti2O7–2TiO2 has a direct optical band gap of 1.8 eV. Photo-oxidation of water via Y2Ti2O7–2TiO2 thin films was carried out under simulated solar irradiation of AM 1.5 G (100 mW cm−2) using three-electrode photoelectrochemical cell in of in three separate 0.5 M electrolyte solutions of NaOH (pH = 13.5), Na2SO4 (pH = 7.2), and citrate buffer (pH = 4). A best photocurrent density of ~ 60 μA cm−2 at + 0.8 V vs. SCE was observed at pH of 13.5. These observations were further validated by electrochemical impedance spectroscopy (EIS) studies in terms of charge transportation and its recombination time.

Two new molecular boxes, the mono-bromo box [Au6 (Triphos)4 Br](SbF6 )5 ⋅6(CH2 Cl2 ), 4 mB, and the dibromo box, [Au6 (Triphos)4 Br2 ⋅H2 O](SbF6 )4 ⋅4(CH2 Cl2 ), 5 dB, have been prepared in crystalline form. Although constructed from non-luminescent components, both are strongly luminescent. Like its chloro counterpart, the mono-bromo box [Au6 (Triphos)4 Br](SbF6 )5 ⋅6(CH2 Cl2 ), 4 mB, is mechanochromic. Under grinding, it loses its luminescence. The bromo-bridged helicate, [(μ-Br){Au3 (Triphos)2 }2 ](CF3 SO3 )5 ⋅2(CH2 Cl2 ), 3μ-H, with a cation that is isomeric with the box [Au6 (Triphos)4 Br]5+ , has also been prepared and crystallographically characterized. Unlike its chloro analogue, [(μ-Br){Au3 (Triphos)2 }2 ](CF3 SO3 )5 ⋅2(CH2 Cl2 ) is not luminescent. Thus, the cation produced upon grinding may be the cation present in the bromo-bridged helicate, [(μ-Br){Au3 (Triphos)2 }2 ](CF3 SO3 )5 ⋅2(CH2 Cl2 ), 3μ-H. The dibromo box, [Au6 (Triphos)4 Br2 ⋅H2 O](SbF6 )4 ⋅4(CH2 Cl2 ), 5 dB, is not significantly mechanochromic.

Carbon disulfide is cleaved by n-propyldiphenylphosphine and nickel(II) bromide in a one-step process, to form two unprecedented complexes: orange, [Ni(S2 C2 (Pn PrPh2 )2 )Br(Pn PrPh2 )]Br⋅CS2 (1) and purple [Ni{η2 -SC(Pn PrPh2 )2 }Br(Pn PrPh2 )]Br⋅0.5CS2 (2). Orange (1) contains a dithiolene-related ligand that results from carbon-carbon bond formation, while purple (2) contains a remarkable ligand in which two n-propyldiphenylphosphine molecules have added to a carbon atom of a CS unit that is coordinated to nickel.

With aromatic and aliphatic thiol-S donor Schiff base ligands, the copper–sulfur clusters, [(L1)8CuI6CuII2](ClO4)2·DMF·0.5CH3OH (1) and [(L2)12CuI5CuII11(μ4-S)(μ4-O)6](ClO4)·4H2O, respectively, hav...

The discovery of a third, non-luminescent crystalline polymorph of [(C6H11NC)2Au]PF6 is reported. Remarkably, crystals of this polymorph are sensitive to mechanical pressure or to exposure to dichloromethane vapor. In both cases, the conversion produces the yellow, green luminescent polymorph of [(C6H11NC)2Au]PF6 and not the colorless, blue luminescent polymorph.

Cocrystallization of NiII(OEP) (where OEP is the dianion of octaethylporphyrin) with C70 in p-xylene produces black plates of 12NiII(OEP)·12C70·18p-xylene (1). Single crystal X-ray diffraction at 90 K reveals that the crystal contains 42 individual, well-ordered molecules in the asymmetric unit with distinctive interactions between each NiII(OEP)/C70 pair and each pair of neighboring C70 molecules. Warming the crystal to 186 K produces a phase change so that only four NiII(OEP)/C70 sites and six p-xylene molecules are present. Under the same conditions CuII(OEP) cocrystallizes with C70 to form CuII(OEP)·C70·1.5p-xylene (2) with a much simpler structure consisting of one molecule of the porphyrin and the fullerene along with 1.5 molecules of p-xylene in the asymmetric unit. Crystallization of C70 from toluene in the presence of NiII(etioporphyrin-I) produces the black solvate 6C70·6toluene (3). It seems that C70 has a tendency to crystallize so that several orientations of the oblong molecule are present in the solid.

Noncoordinating anions, which generally play a subordinate role in coordination chemistry, alter the structure, the luminescence, as well as the thermochromic and vapochromic behaviors of salts of the two-coordinate cation, [(C

The unsymmetrical coordination of gold(I) by 2,2'-bipyridine (bipy) in some planar, three-coordinate cations has been examined by crystallographic and computational studies. The salts [(Ph3P)Au(bipy)]XF6 (X = P, As, Sb) form an isomorphic series in which the differences in Au-N distances range from 0.241(2) to 0.146(2) A. A second polymorph of [(Ph3P)Au(bipy)]AsF6 has also been found. Both polymorphs exhibit similar structures. The salts [(Et3P)Au(bipy)]XF6 (X = P, As, Sb) form a second isostructural series. In this series the unsymmetrical coordination of the bipy ligand is maintained, but the gold ions are disordered over two unequally populated positions that produce very similar overall structures for the cations. Although many planar, three-coordinate gold(I) complexes are strongly luminescent, the salts [(R3P)Au(bipy)]XF6 (R = Ph or Et; X = P, As, Sb) are not luminescent as solids or in solution. Computational studies revealed that a fully symmetrical structure for [(Et3P)Au(bipy)]+ is 7 kJ/mol higher in energy than the observed unsymmetrical structure and is best described as a transition state between the two limiting unsymmetrical geometries. The Au-N bonding has been examined by natural resonance theory (NRT) calculations using the "12 electron rule". The dominant Lewis structure is one with five lone pairs on Au and one bond to the P atom, which results in a saturated (12 electron) gold center and thereby inhibits the formation of any classical, 2 e- bonds between the gold and either of the bipy nitrogen atoms. The nitrogen atoms may instead donate a lone pair into an empty Au-P antibonding orbital, resulting in a three-center, four-electron (3c/4e) P-Au-N bond. The binuclear complex, [μ2-bipy(AuPPh3)2](PF6)2, has also been prepared and shown to have an aurophillic interaction between the two gold ions, which are separated by 3.0747(3) A. Despite the aurophillic interaction, this binuclear complex is not luminescent.

The averages (average deviations from the mean are given in square brackets) of uncorrected Cl—O bond distances in a perchlorate anion from an X-ray diffraction analysis of (N-{2-[bis(pyridin-2-ylmethyl)amino]ethyl}pyridine-2-carboxamidato)(nitric oxide)manganese perchlorate acetonitrile disolvate, [Mn(C20H20N5O)(NO)]ClO4·2CH3CN or [Mn(PaPy3)(NO)]ClO4·2CH3CN, decrease from 1.447 [4] Å at 10 K to 1.428 [4] Å at 170 K. The 10 K value is close to the neutron value (1.441 [1] Å) at 18 K. Comparisons are made with a second X-ray study at 30 K [1.444 (8) Å] and to libration-corrected, density functional theory (DFT), and Cambridge Structural Database (CSD) values.

According to the well-accepted mechanism, methyl-coenzyme M reductase (MCR) involves Ni-mediated thiolate-to-disulfide conversion that sustains its catalytic cycle of methane formation in the energy saving pathways of methanotrophic microbes. Model complexes that illustrate Ni-ion mediated reversible thiolate/disulfide transformation are unknown. In this paper we report the synthesis, crystal structure, spectroscopic properties and redox interconversions of a set of NiII complexes comprising a tridentate N2 S donor thiol and its analogous N4 S2 donor disulfide ligands. These complexes demonstrate reversible NiII -thiolate/NiII -disulfide (both bound and unbound disulfide-S to NiII ) transformations via thiyl and disulfide monoradical anions that resemble a primary step of MCR's catalytic cycle.

The crystallization of two solvates of Au11(PPh3)7(SCN)3, 2Au11(PPh3)7(SCN)3·2C6H6·0.5EtOH (1) and Au11(PPh3)7(SCN)3·3EtOH (2), with (1) containing two independent molecules of the cluster, allows the positions of all of the ligands to finally be identified. Despite the bent nature of the thiocyanate ligands, they occupy similar sites to the ones that contain halogen ligands in Au11(PPh3)7Cl3, Au11(PPh3)7I3, and related molecules. However, the relative orientations of these thiocyanate ligands differ in the three cluster sites.

The mono- and di-chloroform solvates of [Au2 (μ-1,2-bis(diphenylarsino)ethane)2 ](AsF6 )2 undergo single-crystal-to-single-crystal transformations that result in gain (over 12 hours) or slow loss (over five years) of only one chloroform molecule. The change in solvation results in changes in the structure and luminescence of the digold cation. The cation consists of a pair of slightly bent As-Au-As units that are connected through the two bridging dpae ligands and by aurophilic interactions with Au⋅⋅⋅Au contacts of 3.05152(15) A in the disolvate or 2.9570(5) A in the monosolvate.

The solid-state structures of seven solvates of C60 (C60·4tetrachloroethylene, C60·2tetrachloroethylene, C60·3benzene, C60·n-pentane, C60·diethyl ether, C60·chlorobenzene, and C60·benzene·dichloromethane) were determined by single-crystal X-ray diffraction at low temperature. At 90 K, the fullerene and solvate components are generally well-ordered and do not show the orientational disorder that plagues similar structures determined at room temperature. Interactions between the solvate molecules and the fullerene and between adjacent C60 molecules were examined and analyzed. Van der Waals and weak charge-transfer interactions are important to help to organize the individual components in these structures. The weak Lewis acid behavior of C60, such as when it cocrystallizes with diethyl ether or chlorinated solvents, is apparent. In addition, π-stacking interactions are prevalent. The solvates of C60 reported here were frequently obtained from attempts to cocrystallize C60 with another chemical compound. Alt...

Aliphatic thiolato-S-bridged tri- and binuclear nickel(II) complexes have been synthesized and characterized as models for the Nip site of the A cluster of acetyl coenzyme A synthase (ACS)/carbon m...

A method has been developed for isolating a pure sample of Er2 C94 from the myriad of fullerenes and endohedral fullerenes that are formed in the electric arc process. Crystallographic analysis of Er2 C94 in a cocrystal formed with Ni(OEP) reveals that the molecule is the carbide Er2 C2 @D3 (85)-C92 . Crystals of Er2 C2 @D3 (85)-C92 ⋅Ni(octaethylporphyrin)⋅2 C7 H8 are isostructural with those of Sm2 @D3 (85)-C92 ⋅Ni(octaethylporphyrin)⋅2 (chlorobenzene). Comparisons are made between the four crystallographically characterized endohedrals (Er2 C2 @D3 (85)-C92 , Gd2 C2 @D3 (85)-C92 , La2 C2 @D3 (85)-C92 , and Sm2 @D3 (85)-C92 ) that utilize the chiral D3 (85)-C92 cage.

Luminescent gold(I) complexes ([Au6(Triphos)4Cl](PF6)5·2(CH3C6H5), [Au6(Triphos)4Cl](AsF6)5·8(CH3C6H5), and [Au6(Triphos)4Cl](SbF6)5·7(CH3C6H5) where Triphos = bis(2-diphenylphosphinoethyl)phenylphosphine) with a boxlike architecture have been prepared and crystallographically characterized. A chloride ion resides at the center of the box with two of the six gold(I) ions nearby. Mechanical grinding of blue luminescent crystals containing the cation, [Au6(Triphos)4Cl]5+, results in their conversion into amorphous solids with green emission that contain the bridged helicate cation, [μ-Cl{Au3(Triphos)2}2]5+. A mechanism of the mechanochromic transformation is proposed. The structures of the blue-emitting helicate, [Au3(Triphos)2](CF3SO3)3·4(CH3C6H5)·H2O, and the green-emitting bridged-helicate, [μ-Cl{Au3(Triphos)2}2](PF6)5·3CH3OH have been determined by single crystal X-ray diffraction.

Attempts to form covalent C S bonds between fullerenes and dithiolene complexes, Ni(S2C2R2)2, lead only to the formation of the cocrystals C60·Ni(S2C2Ph2)2·0.5C7H8 and 2C70·2Ni(S2C2Ph2)2·C7H8. Both cocrystals contained pairs of Ni(S2C2Ph2)2 molecules that make offset face-to-face contact with Ni⋯Ni distances of 3.8793(5) A in the C60 crystal and 3.7529(9) and 3.7983(9) A in the C70 crystal. The fullerenes are nestled near the NiS4 portion of the Ni(S2C2Ph2)2 molecules. In 2C70·2Ni(S2C2Ph2)2·C7H8 there are two distinctly different interactions between the fullerene and the nickel complex. In one C70·Ni(S2C2Ph2)2 pair, the long axis of the fullerene is nearly parallel to the long axis of the nickel complex, while in the other pair, the long axis of the C70 cage is oriented nearly perpendicular to the long axis of the nickel complex. Thus, the immediate intimate contact between molecules such as fullerenes and flat molecules like Ni(S2C2Ph2)2 is not fixed, but can be altered by other aspects of crystal packing. The structure of a new solvated form of Ni(S2C2Ph2)2, Ni(S2C2Ph2)2·2C6H6, is also reported.

The piperazine double addition product, e{N(CH2CH2)2N}2C60, has its donor atoms positioned to bind Lewis acids in two orthogonal directions. It has been used to construct crystalline, 1-d and 2-d polymers through reactions with diiodine and the rhodium(ii) acetate dimer.