Coordination complexes of chromium(0) with a series of 1,3-diphenyl-6-arylfulvenes

The synthesis and structural properties of a series of chromium tricarbonyl `piano-stool' complexes bearing substituted pentafulvene ligands were studied. The complexes, tricarbonyl(1,3,6-triphenylfulvene)chromium(0) benzene hemisolvate, [Cr(C24H18)(CO)3]·0.5C6H6 (I), tricarbonyl[1,3-diphenyl-6-(3-vinylphenyl)fulvene]chromium(0), [Cr(C26H20)(CO)3] (II), and tricarbonyl[1,3-diphenyl-6-(pyren-1-yl)fulvene]chromium(0), [Cr(C34H22)(CO)3] (III), each have a distorted octahedral geometry, with the fulvene coordinated in a π–η2:π–η2:π–η2 fashion. Significant deviation of the exocyclic fulvene double bond from the cyclopentadiene plane accompanies coordination. Evidence of non-covalent π–π interactions was observed in both (I) and (III), with centroid-to-centroid distances ranging from 3.330 (8) to 3.494 (8) Å

Crystal Engineering Gone Awry. What a Difference a Few Methyl Groups Make in Fullerene/Porphyrin Cocrystallization

Two related nickel­(II) porphyrins, etioporphyrin-I (Etio-I) and octaethylporphyrin (OEP), were cocrystallized with C₇₀ to produce the new cocrystal structures C₇₀·Ni­(Etio-I)­·2C₆H₆ and C₇₀·Ni­(OEP)­·2C₆H₆. Etio-I is a variant of OEP, where four alternating ethyl groups from OEP are replaced with methyl substituents. This isomer of etioporphyrin has the potential to act as an agent in chiral sorting of asymmetric fullerenes. However, the replacement of four ethyl groups has nontrivial structural consequences. Further host–guest investigation of M­(Etio-I) (M = Co, Ni, Cu, Zn) with C₆₀ or C₇₀ was conducted, producing new X-ray structures of Co­(Etio-I) and Zn­(Etio-I), and a redetermination of Ni­(Etio-I). Despite numerous and varied attempts, C₆₀ cocrystallized with M­(Etio-I) could not be obtained

Isolation and Crystallographic Characterization of Gd3N@D2(35)-C88 through Non-Chromatographic Methods.

While several nonchromatographic methods are available for the isolation and purification of endohedral fullerenes of the type M3N@Ih-C80, little work has been done that would allow other members of the M3N@C2n family to be isolated with minimal chromatography. Here, we report that Gd3N@D2(35)-C88 can be isolated from the multitude of endohedral and empty cage fullerenes present in carbon soot obtained by electric-arc synthesis using Gd2O3-doped graphite rods. The procedure developed utilizes successive precipitation with the Lewis acids CaCl2 and ZnCl2 followed by treatment with amino-functionalized silica gel. The structure of the product was identified by single-crystal X-ray diffraction

Isolation and Crystallographic Characterization of Gd3N@D2(35)-C88 through Non-Chromatographic Methods.

While several nonchromatographic methods are available for the isolation and purification of endohedral fullerenes of the type M3N@Ih-C80, little work has been done that would allow other members of the M3N@C2n family to be isolated with minimal chromatography. Here, we report that Gd3N@D2(35)-C88 can be isolated from the multitude of endohedral and empty cage fullerenes present in carbon soot obtained by electric-arc synthesis using Gd2O3-doped graphite rods. The procedure developed utilizes successive precipitation with the Lewis acids CaCl2 and ZnCl2 followed by treatment with amino-functionalized silica gel. The structure of the product was identified by single-crystal X-ray diffraction

New Insights into the Structural Complexity of C₆₀·2S₈: Two Crystal Morphologies, Two Phase Changes, Four Polymorphs

Three new polymorphs of C₆₀·2S₈ were discovered. The previously known structure (first reported by Roth and Adelmann in 1993 hereby designated as α) crystallizes in space group <i>C</i>2/<i>c</i> with <i>Z</i> = 4 and changes to a triclinic structure (β) in space group <i>P</i>1̅ with <i>Z</i> = 4 when the temperature is decreased below 260 K. The room-temperature structure was reinvestigated, and the new, ordered, low-temperature structure is described. A new, concomitant, polymorph (γ) crystallizes in space group <i>P</i>2₁/<i>c</i> with <i>Z</i> = 4 at room temperature and undergoes a phase change to <i>Pc</i> (δ) with <i>Z</i> = 4 when the temperature is decreased below 180 K. As indicated by geometric and temperature factor changes, it is clear that the low-temperature phases represent an increase in the level of order in the arrangement of C₆₀ molecules. Both of the phase changes are reversible

Synthesis and Isolation of the Titanium-Scandium Endohedral Fullerenes-Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 and Sc2 TiC2 @Ih -C80 : Metal Size Tuning of the Ti(IV) /Ti(III) Redox Potentials.

The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc-Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4 C2 @C80 (the most abundant EMF from this synthesis), Sc3 C2 @C80 , isomers of Sc2 C2 @C82 , and the family Sc2 C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3 CH@C80 . The Sc-Ti/CH4 system produces the mixed-metal Sc2 TiC@C2 n (2 n=68, 78, 80) and Sc2 TiC2 @C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 , and Sc2 TiC2 @Ih -C80 , were characterized by NMR spectroscopy. The structure of Sc2 TiC@Ih -C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2 TiC- and Sc2 TiC2 -containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster-cage strain in the endohedral fullerenes through electrochemical measurements

Mixed valence copper-sulfur clusters of highest nuclearity: a Cu8 wheel and a Cu16 nanoball.

Fully spin delocalized mixed valence copper-sulfur clusters, 1 and 2, supported by μ4-sulfido and NSthiol donor ligands are synthesized and characterized. Wheel shaped 1 consists of Cu2S2 units. The unprecedented nanoball 2 can be described as S@Cu4(tetrahedron)@O6(octahedron)@Cu12S12(cage) consisting of both Cu2S2 and (μ4-S)Cu4 units. The Cu2S2 and (μ4-S)Cu4 units resemble biological CuA and CuZ sites respectively

Synthesis and Isolation of the Titanium-Scandium Endohedral Fullerenes-Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 and Sc2 TiC2 @Ih -C80 : Metal Size Tuning of the Ti(IV) /Ti(III) Redox Potentials.

The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc-Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4 C2 @C80 (the most abundant EMF from this synthesis), Sc3 C2 @C80 , isomers of Sc2 C2 @C82 , and the family Sc2 C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3 CH@C80 . The Sc-Ti/CH4 system produces the mixed-metal Sc2 TiC@C2 n (2 n=68, 78, 80) and Sc2 TiC2 @C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 , and Sc2 TiC2 @Ih -C80 , were characterized by NMR spectroscopy. The structure of Sc2 TiC@Ih -C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2 TiC- and Sc2 TiC2 -containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster-cage strain in the endohedral fullerenes through electrochemical measurements

Incorporation of the Similarly Sized Molecules, Diiodine and Carbon Disulfide, into Cocrystals Formed with the Fullerenes, C₆₀ or C₇₀

Cocrystallization of diiodine and carbon disulfide with the two common fullerenes, C₆₀ and C₇₀, has been examined. The binary cocrystal, C₇₀·I₂, readily formed when a solution of diiodine in diethyl ether was layered over C₇₀ dissolved in toluene, chlorobenzene, or 1,2-dichlorobenzene, but no binary cocrystal of diiodine and C₆₀ could be obtained despite persistent efforts. The ternary cocrystal, C₇₀·0.85I₂·0.15CS₂, which was grown from a carbon disulfide solution of C₇₀ and a benzene solution of diiodine, is isostructural with C₇₀·I₂ but has 15% of the diiodine sites replaced with carbon disulfide. In contrast, C₇₀·0.68I₂·0.32CS₂, which was obtained from diffusion of a cyclohexane solution of diiodine into a carbon disulfide solution of C₇₀, is a unique ternary cocrystal that is not related to any binary cocrystal of C₇₀ with diiodine or carbon disulfide. Crystals of 2C₆₀<b>·</b>2.46CS₂<b>·</b>0.54I₂ were obtained from a saturated carbon disulfide solution of diiodine and C₆₀. Black crystals of 2C₆₀<b>·</b>2.46CS₂<b>·</b>0.54I₂ form in a different space group from those of the solvate 2C₆₀<b>·</b>3CS₂ but have a very similar structure. Remarkably, diiodine molecules fractionally replace carbon disulfide in only two of the three independent sites within this crystal