Synthesis And Structure Studies On Exohedral Cuprofullerene Sulfonate Complexes

Fullerene molecules have attracted much attentions due to their unique spherical molecule structures.They show much more chemical activity than those ordinary olefin,in particular to react with transition metals to form exohedral metallofullerene complexes.These metallofullerene complexes show potential applications in charge storage,gas adsorption,catalysis and other fields,and have attracted much attentions of chemical researchers in this field.For copper-(?)silver-(?)and gold-(?)with closed shell electronic configurations,it is easy to form high-nuclear complexes and coordination polymers due to its low coordination number.Studying the coordination modification of fullerenes to construct various complexes,especially the spatial coordination mode of exohedral metallofullerene complexes is one of the important topics in this field.Eleven cuprofullerene complexes were synthesized under solvothermal conditions by using trifluoromethanesulfonate,benzenesulfonate,p-toluenesulfonate,naphthalene-2-sulfonate and ethylsulfonate as auxiliary ligands,Cu(?)as central metal and aromatic compounds as solvent.Their structures were characterized and analyzed,and the effects of substituent effect and steric hindrance on their structures were discussed.The spatial coordination mode of C₆₀ and the coordination bridging mode of auxiliary ligand sulfonate were summarized.Overall,the dimension of copper(?)fullerene complexes and the number of coordination copper(?)atoms on C₆₀ molecules are regulated,and the diversity of coordination modes of C₆₀ molecules is also regulated.Specific to carry out the following three aspects:In the first part,six cuprofullerene complexes(named Cu₄-1,Cu₄-2,Cu₆-1,Cu₆-2,Cu₆-3 and Cu₈)were prepared by using trifluoromethanesulfonate auxiliary ligand.All copper is coordinated by?²-C=C(C₆₀).These structures was determined by X-ray single crystal diffraction.They exhibit 4-,6-,and 8-nuclear cuprofullerene features.Among them,the trifluoromethanesulfonate ligands exhibit rich coordination modes.Through the five coordination bridging modes of(?₁-?¹)-CF₃SO₃^-,(?₂-?¹:?¹)-CF₃SO₃^-,(?₂-?²)-CF₃SO₃^-,(?₃-?¹:?¹:?¹)-CF₃SO₃^-,(?₃-?¹:?²)-CF₃SO₃^-,they are constructed into oligonuclear complexes,two-dimensional and three-dimensional coordination polymers.Interestingly,in the complexes Cu₄-1 and Cu₄-2,C₆₀ molecules exhibit two different four coordination modes,and in the complexes Cu₆-1,Cu₆-2 and Cu₆-3,C₆₀molecules exhibit four different coordination modes,which greatly enrich the coordination modes of C₆₀ molecule.Based on the work in the first part,four 2D cuprofullerene coordination polymers were prepared by using benzene sulfonic acid,p-toluene sulfonic acid and naphthalene-2-sulfonic acid as auxiliary ligands.Crystal structure analysis shows that the four structures are constructed by C₆₀ molecule connecting 1D copper(?)sulfonate chain,forming 2D sheet-like cuprofullerene coordination polymers.The number of coordinated copper on fullerene is 6-nuclear,which spatial coordination mode is planar hexagon and deformed octahedron.In the hexagonal coordination mode,the sulfonate adopts the?₂-?¹:?¹-C₇H₇SO₃^-and?₃-?¹:?¹:?¹-C₇H₇SO₃^-coordination bridging mode.In the deformed octahedron coordination mode,the sulfonate adopts the?₃-?¹:?¹:?¹-C₇H₇SO₃^-coordination bridging mode.There is a weak supramolecular interaction of?-?or C-H...?between the auxiliary ligands of the layers,which makes the copper unit of fullerene protected and the crystal relatively stable.Finally,a three-dimensional coordination polymer was synthesized by using ethyl as an auxiliary ligand with electron donor and small steric hindrance.The crystal structure analysis showed that the C₆₀ molecule exhibit 4 and 8-nuclear coordination mode.Ethyl sulfonic acid adopts?₂-?¹:?¹-C₂H₅SO₃^-,?₃-?¹:?¹:?¹-C₂H₅SO₃^-,?₄-?¹:?¹:?²-C₂H₅SO₃^-coordination bridge mode to form three-dimensional structure.Compared with the trifluoromethanesulfonic acid series,the crystals are also relatively stable.In summary,the structures of cuprofullerene sulfonate have been regulated by regulating the auxiliary ligand substituents and steric hindrance.In addition,this work enriches the types of exhedral metallofullerene;On the other hand,it reflects the diversity of sulfonate coordination bridge mode.The most important thing is that C₆₀molecules have supera spatial coordination modes,which have been experimentally verified in this work,especially the coordination mode of 6-nuclear complexes.This work gives us a new understanding to regulate of the coordination modification of C₆₀molecules and provides a new idea for the study of the spatial coordination mode of fullerene.