Octapalladium Strings Trap C<sub>60</sub> and C<sub>70</sub> Fullerenes Affording Metal‐Chain‐Wired Bucky Balls
Tomoaki Tanase, Kanako Nakamae, Yasutaka Kitagawa, Takayuki Nakajima
Abstract
Abstract Reactions of Pd 8 strings supported by meso ‐Ph 2 PCH 2 P(Ph)CH 2 P(Ph)CH 2 PPh 2 ( meso ‐dpmppm) ligands, [Pd 8 ( meso ‐dpmppm) 4 (L) 2 ] 4+ (L=CH 3 CN ( 1 ), XylNC ( 2 )) with C 60 resulted in the exclusive formation of unprecedented metal‐chain‐wired C 60 bucky balls, [{Pd 4 ( meso ‐dpmppm) 2 (L)} 2 (C 60 )] 4+ (L=CH 3 CN ( 11 ), XylNC ( 12 )), in which a C 60 fullerene is trapped in the central Pd–Pd junction, as unambiguously established by spectroscopic, X‐ray crystallographic, and theoretical techniques. The similar reaction of Pd 8 strings supported by rac ‐dpmppm, [Pd 8 ( rac ‐dpmppm) 4 (CH 3 CN) 2 ] 4+ ( 3 ) also afforded a racemic mixture of [{Pd 4 (( R*,R* )‐dpmppm) 2 (CH 3 CN)} 2 (C 60 )] 4+ ( 13 ) without scrambling the Pd 4 fragments with ( R,R )‐ and ( S,S )‐dpmppm ligands. Consequently, those of enantiopure chiral Pd 8 strings, [Pd 8 (( R*,R* )‐dpmppm) 4 (CH 3 CN) 2 ] 4+ , certainly afforded chiral bucky balls of [{Pd 4 (( R*,R* )‐dpmppm) 2 (CH 3 CN)} 2 (C 60 )] 4+ ( 13 RR and 13 SS ), that exhibit mirror‐image circular dichroism spectra. The reactions of 1 and 2 were also applied for trapping a C 70 fullerene to give 2 : 1 adducts of [{Pd 4 ( meso ‐dpmppm) 2 (L)} 2 (C 70 )] 4+ (L=CH 3 CN ( 21 ), XylNC ( 22 )). These results provide useful information for creating a platform to develop dimensionally and chirality controlled metal–carbon nanocomposite materials.