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Treatment of an open-cage fullerene, designated as MMK-9, with (Ph 3 P) 4 Pt in toluene solution at room temperature allows a (PPh 3 ) 2 Pt 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 PtC 2 P 2 coordination, rather than the usual η 2 -bonding to an intact C–C double bond of the fullerene. 

The discovery of a third, non-luminescent crystalline polymorph of [(C 6 H 11 NC) 2 Au]PF 6 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 [(C 6 H 11 NC) 2 Au]PF 6 and not the colorless, blue luminescent polymorph. 

Cocrystallization of Ni II (OEP) (where OEP is the dianion of octaethylporphyrin) with C 70 in p -xylene produces black plates of 12Ni II (OEP)·12C 70 ·18 p -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 Ni II (OEP)/C 70 pair and each pair of neighboring C 70 molecules. Warming the crystal to 186 K produces a phase change so that only four Ni II (OEP)/C 70 sites and six p -xylene molecules are present. Under the same conditions Cu II (OEP) cocrystallizes with C 70 to form Cu II (OEP)·C 70 ·1.5 p -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 C 70 from toluene in the presence of Ni II (etioporphyrin-I) produces the black solvate 6C 70 ·6toluene ( 3 ). It seems that C 70 has a tendency to crystallize so that several orientations of the oblong molecule are present in the solid. 

Non-luminescent, isostructural crystals of [(C 6 H 11 NC) 2 Au](EF 6 )·C 6 H 6 (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, [(C 6 H 11 NC) 2 Au] + , 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 [(C 6 H 11 NC) 2 Au] + ions are isolated from one another. In [(C 6 H 11 NC) 2 Au](BArF 24 ) ((BArF 24 ) − 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 [(C 6 H 11 NC) 2 Au](EF 6 ) (E = As or Sb, but not P) from benzene solution produces colorless, non-emissive crystals of the solvates [(C 6 H 11 NC) 2 Au](EF 6 )·C 6 H 6 . 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 [(C 6 H 11 NC) 2 Au](SbF 6 )·C 6 H 6 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 [(C 6 H 11 NC) 2 Au](SbF 6 ) 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 [(C 6 H 11 NC) 2 Au](AsF 6 )·C 6 H 6 stand in air, they lose benzene and are converted into the yellow, green-luminescent polymorph of [(C 6 H 11 NC) 2 Au](AsF 6 ) 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 [(C 6 H 11 NC) 2 Au](AsF 6 ) are sensitive to benzene vapor and are converted by exposure to benzene vapor into the colorless, blue-luminescent polymorph.