Splendid symmetry: crystallization of an unbridged isomer of Co2(CO)8 in Co2(CO)8·C60

Abstract

Cocrystallization of Co2(CO)8 with C60 traps the cobalt carbonyl molecule as the D(3d) isomer that otherwise is not available for crystallographic analysis.

Coordination chemistry on carbon surfaces

“…The interactions between the CO ligands and C 60 are likely to play a significant role in orienting the C 60 molecule (Fig. 21) [269]. Similarly, co-crystallization of Hg[Co(CO) 4 ] 2 with C 60 in toluene produces a crystal were the cobalt complex rearranges to fit in the well-ordered fullerenes [270].…”

[1,1‐Co2(CO)6(CNAr)2]: A Structural Mimic of the Elusive D2d Isomer of [Co2(CO)8]

“…[5][6][7][8] Solution IR spectroscopy studies on di-A C H T U N G T R E N N U N G substituted Co 2 (CO) 6 L 2 dimers featuring mono-and bidentate neutral-donor ligands have similarly revealed an equilibrium between multiple isomers. [9][10][11][12][13] In the solid state, however, only the well-known C 2v isomer featuring two symmetric bridging carbonyl ligands [14] and the unbridged D 3d form have been established crystallographically for the parent octacarbonyl complex [15,16] and numerous substituted derivatives. [17,18] The third, D 2d -symmetric isomer, which is unbridged and possesses two mutually orthogonal trigonal bipyramidal Co centers, has thus far eluded structural characterization in all systems, [16,17,19] despite being proposed as the lowest energy isomer of Co 2 (CO) 8 [17,20] and a significant fraction of the Co 2 (CO) 8 isomeric mixture in solution at room temperature.…”

“…[9][10][11][12][13] In the solid state, however, only the well-known C 2v isomer featuring two symmetric bridging carbonyl ligands [14] and the unbridged D 3d form have been established crystallographically for the parent octacarbonyl complex [15,16] and numerous substituted derivatives. [17,18] The third, D 2d -symmetric isomer, which is unbridged and possesses two mutually orthogonal trigonal bipyramidal Co centers, has thus far eluded structural characterization in all systems, [16,17,19] despite being proposed as the lowest energy isomer of Co 2 (CO) 8 [17,20] and a significant fraction of the Co 2 (CO) 8 isomeric mixture in solution at room temperature. [7] Here we report the synthesis and solid-state characterization of the bis-m-terphenylisocyanide complex, 1,1-Co 2 (CO) 6 A C H T U N G T R E N N U N G (CNAr Mes 2 ) 2 (Ar Mes 2 = 2,6-(2,4,6-Me 3 C 6 H 2 ) 2 C 6 H 3 ), [21] which serves as a structural mimic of the D 2d isomer of Co 2 (CO) 8 .…”

A Dicobalt Coordination Complex with a Short Cobalt‐Cobalt Distance

“…Co 2 (CO) 8 exists in two conformations . The major conformer [(CO) 3 Co(μ‐CO) 2 Co(CO) 3 ] ( A ) (Scheme ) possesses two bridging carbonyls (CO) while the minor conformer [(CO) 4 Co−Co(CO) 4 ] ( A' ) has only terminal carbonyl groups. The latter has been co‐crystallized with C 60 .…”

“…The major conformer [(CO) 3 Co(μ‐CO) 2 Co(CO) 3 ] ( A ) (Scheme ) possesses two bridging carbonyls (CO) while the minor conformer [(CO) 4 Co−Co(CO) 4 ] ( A' ) has only terminal carbonyl groups. The latter has been co‐crystallized with C 60 . [(CO) 3 Co(μ‐CO) 2 Co(CO) 3 ] ( A ) does not possess a Co−Co bond and each Co(μ‐CO)Co unit of A can be regarded as a three center two electron bond .…”