Partial Separation and Structural Characterization of C84 Isomers by Crystallization of (.eta.2-C84)Ir(CO)Cl(P(C6H5)3)2

Here we describe the results of reacting Ir(CO)Cl(PPh[sub 3])[sub 2] with C[sub 84]. In this case, not only is there the question of regioselectivity of addition, which was also a factor in the Ir(CO)Cl(PPh[sub 3])[sub 2]/C[sub 70] reaction, but there is also the question of selectivity between the isomeric forms of C[sub 84] itself. C[sub 84] was prepared by the contact arc process and separated from other fullerenes by high-pressure liquid chromatography. Treatment of a saturated benzene solution of a triply chromatographed sample of C[sub 84] with a 21-fold molar excess of Ir(CO)Cl(PPh[sub 3])[sub 2] produced a green-brown solution, from which black crystals of ([eta][sup 2]-C[sub 84])Ir(CO)Cl(PPh[sub 3])[sub 2][center dot]4C[sub 6]H[sub 6] were obtained by slow diffusion of diethyl ether into the mixture. The structure of the complex as determined by a single-crystal X-ray diffraction study is shown. While the complex itself has no crystallographically imposed symmetry, the geometry of the C[sub 84] moiety does correspond to that of the D[sub 2d] (23) isomer. The distance along the principal axis that bisects the C(32)-C(53) and C(42)-C(43) bonds is 9.61 [angstrom], while the distance across the two axes that are perpendicular to this is 8.34 [angstrom]. Within D[sub 2d] symmetry, theremore » are 19 different sets of C-C bonds for C[sub 84]. 18 refs.« less