Unusual C2h -Symmetric trans-1-(Bis-pyrrolidine)-tetra-malonate Hexa-Adducts of C60 : The Unexpected Regio- and Stereocontrol Mediated by Malonate-Pyrrolidine Interaction.

A totally unanticipated regio- and stereoisomerically pure C2h -symmetric trans-1-(bis-pyrrolidine)-tetra-malonate hexa-adduct of C60 was obtained via a topologically controlled method, followed by a 1,3-dipolar cycloaddition reaction. The structures of the products were elucidated by 1 H and 13 C NMR and by X-ray crystallography. The unexpected regio- and stereoselectivity observed, supported by theoretical calculations, was found to be a consequence of malonate-pyrrolidine interactions.

Silver(I)-Mediated Modification, Dimerization, and Polymerization of an Open-Cage Fullerene.

The reactions of the open-cage fullerene, MMK-9, with an open 12-membered ring on its surface and silver(I) salts have been examined. The structure of MMK-9 itself has been determined by single-crystal X-ray diffraction. MMK-9 reacts with silver trifluoroacetate in air to form the dimer, {MMK-9(OCH3)5Ag(AgO2CCF3)}2. Remarkably, five MeO groups have added to the surface of the open cage in a pattern that surrounds a pentagon immediately adjacent to the opening in the cage. Dioxygen has been implicated as the oxidant in this unusual addition of five groups to the open cage. Two silver ions connected to each other by a short argentophillic interaction reside at the core of the centrosymmetric dimer. The reaction of silver nitrate with MMK-9 yields the crystalline polymer, [{MMK-9(OCH3)5Ag(AgOCH3)}2·H2O]n. This polymer consists of dimeric {MMK-9(OCH3)5Ag}2 units that are connected into strands through silver ions, which are chelated by the amine functions of one open cage and bound in η2-fashion to a pair of carbon atoms on an adjacent open cage.

Piperazine Functionalization of C70 for Incorporation into Supramolecular Assemblies.

The photochemical reaction of piperazine with C70 produces a mono-adduct (N(CH2 CH2 )2 NC70 ) in high yield (67 %) along with three bis-adducts. These piperazine adducts can combine with various Lewis acids to form crystalline supramolecular aggregates suitable for X-ray diffraction. The structure of the mono-adduct was determined from examination of the adduct I2 N(CH2 CH2 )2 NI2 C70 that was formed by reaction of N(CH2 CH2 )2 NC70 with I2 . Crystals of polymeric {Rh2 (O2 CCF3 )4 N(CH2 CH2 )2 NC70 }n ⋅nC6 H6 that formed from reaction of the mono-adduct with Rh2 (O2 CCF3 )4 contain a sinusoidal strand of alternating molecules of N(CH2 CH2 )2 NC70 and Rh2 (O2 CCF3 )4 connected through Rh-N bonds. Silver nitrate reacts with N(CH2 CH2 )2 NC70 to form black crystals of {(Ag(NO3 ))4 (N(CH2 CH2 )2 NC70 )4 }n ⋅7nCH2 Cl2 that contain parallel, nearly linear chains of alternating (N(CH2 CH2 )2 NC70 molecules and silver ions. Four of these {Ag(NO3 )N(CH2 CH2 )2 NC70 }n chains adopt a structure that resembles a columnar micelle with the ionic silver nitrate portion in the center and the nearly non-polar C70 cages encircling that core. Of the three bis-adducts, one was definitively identified through crystallization in the presence of I2 as 12 {N(CH2 CH2 )2 N}2 C70 with addends on opposite poles of the C70 cage and a structure with C2v symmetry. In 12 {I2 N(CH2 CH2 )2 N}2 C70 , individual 12 {I2 N(CH2 CH2 )2 N}2 C70 units are further connected by secondary I2⋅⋅⋅N2 interactions to form chains that occur in layers within the crystal. Halogen bond formation between a Lewis base such as a tertiary amine and I2 is suggested as a method to produce ordered crystals with complex supramolecular structures from substances that are otherwise difficult to crystallize.

Tethered bisadducts of C60 and C70 with addends on a common hexagonal face and a 12-membered hole in the fullerene cage.

The regioselective synthesis of easily isolable pure bismethano derivatives of C60 and C70 with high steric congestion is described using 1,3-dibenzoylpropane bis-p-toluenesulfonyl hydrazone as the addend precursor. When the addition occurs at two [6,6] ring junctions within the same hexagon, bisadducts with mirror symmetry are obtained for both C60 and C70. When the addition occurs at two [5,6] ring junctions in C60, a symmetrical adduct is formed, which readily undergoes photo-oxygenation and ring opening to yield a fullerene with a hole in the cage. In this work, we also propose a simple and general system to name all of the possible [6,6] bisadduct isomers on C70.

Piperazine-functionalized C60 and diiodine or iodine monochloride as components in forming supramolecular assemblies.

The reaction of the piperazine mono-adduct, N(CH2CH2)2NC60, with diiodine produced well ordered, black crystals of (I2N(CH2CH2)2NI2)C60·2.884(C6H6)·0.116I2, which contains two nearly linear N-I-I units. Reaction of N(CH2CH2)2NC60 with iodine monochloride produced two materials: the dihalogen adduct, (ClIN(CH2CH2)2NICl)C60·2.3(CS2)·0.7(CH2Cl2), when crystallization occurred rapidly from carbon disulfide/dichloromethane solution or the salt, [(N(CH2CH2)2NH)C60+][ICl2-]·CS2, when crystallization happened more slowly from toluene/dichloromethane solution where hydrolysis of the iodine monochloride by adventitious water presumably occurred.

Synthesis and characterization of bis-triruthenium cluster derivatives of an all equatorial [60]fullerene tetramalonate.

The reaction of the tetrakis[di(ethoxycarbonyl)methano]-C60 (1) with Ru3(CO)12 afforded the first bis-parallel C60-metal cluster complex: parallel-[Ru3(CO)9]2{µ3-η(2),η(2),η(2)-C60[C(COOC2H5)2]4}. The two triruthenium groups are found in either a parallel or a tilted orientation relative to each other, as determined by NMR. Only the parallel form was characterized by X-ray crystallography.

Synthesis and characterization of a trans-1 hexakis-fullerene linker that forms crystalline polymers with silver salts.

A new flexible hexakis-fullerene adduct with two bis(pyridin-4-ylmethyl)malonate groups located at trans-1 positions was synthesized. Via reaction with Ag(PF6) under two different conditions, two new 1D coordination polymers were obtained; under a nitrogen atmosphere, the silver ions are connected by argentophilic interactions but under an ambient atmosphere, the silver ions exhibit no interaction between them but coordination to the (H2PO4)(-) ions.

Zipping up fullerenes into polymers using rhodium(II) acetate dimer and N(CH2CH2)2NC60 as building blocks.

The reaction of Rh2(O2CCH3)4 with the functionalized fullerene N(CH2CH2)2NC60 can produce a linear, crystalline polymer or can trap free C60 or C70 molecules between similar chains.