SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF THE DIANION [CO-9(C-2)(CO)(19)](2-) AS ITS TETRAMETHYLAMMONIUM SALT

The dianion [Co-9(C-2)(CO)(19)](2-) 1 ([NMe4](+) salt) has been obtain ed by pyrolysis of [NMe4][Co6C(CO)(14)] in diglyme (2,5,8-trioxanonane ) at 130 degrees C, and, as the parent compound, is paramagnetic. The salt [NMe4](2)[Co-9(C-2)(CO)(19)] has been characterised by single cry stal X-ray diffraction. The Co-9(C-2) core of the anion can be describ ed as a D-3h tricapped trigonal prism of Co atoms with stretched inter basal edges encapsulating an acetylide C-2 unit [C-C 1.39(2) Angstrom] . Nine CO ligands are linearly bonded, one per metal atom, six are edg e bridging and four semibridging. The overall molecular symmetry is C- 2v or, more accurately, C-2.