Hexa- and nona-nuclear heterometallic clusters based on mercury-capped MCo₃(M = Fe or Ru) tetrahedral units

Cobalt/Mercury Carbide Clusters Based on Trigonal-Prismatic or Octahedral Co6C Skeletons − X-ray Crystal Structure of (NEt4)2[Co6C(CO)12{HgW(CO)3Cp}2]

“…Their 13 C NMR spectra featured signals corresponding to the CO and Cp ligands, but the carbide signal was not observed. For all the clusters of type 4, FABMS showed the [M ϩ H] Ϫ peak in accordance with the formula [Co 6 C(CO) 12 {HgM} 2 ] 2Ϫ .…”

“…The oxidation was a one-electron step, as shown by comparison with the height of the reduction wave (due to passivation phenomena, reliable coulometry could not be performed). When the oxidation was carried out in an EPR tube with [FeCp 2 ][PF 6 ] in CH 2 Cl 2 at Ϫ78°C, the radical species [Co 6 C(CO) 12 {HgM} 2 ]· Ϫ was detected. The X-band EPR spectrum consists of a single strong resonance centred at ca.…”

“…[19] Conclusions Reaction of the [Co 6 C(CO) 15 ] 2Ϫ and [Co 6 C(CO) 13 ] 2Ϫ anions with one mol of HgM ϩ gives the octanuclear species [Co 6 C(CO) 15 {HgM}] Ϫ and [Co 6 C(CO) 13 {HgM}] Ϫ , having spiked Co 6 C trigonal-prismatic and spiked octahedral skeletons, respectively. These species can be interconverted through the addition or elimination of CO. On the other hand, the use of an excess of HgM ϩ has been found to lead invariably to the cluster [Co 6 C(CO) 12 {HgM} 2 ] 2Ϫ , in which the Co 6 C octahedron is doubly-capped by HgM ϩ moieties. Finally, electrochemical studies on the dimercury complexes have revealed that their oxidation leads to radical species [Co 6 C(CO) 12 {HgM} 2 ] •Ϫ , which could be detected by EPR.…”

“…[11] In order to avoid the formation of oily materials and to determine whether the solvent plays an important role in our reactions, we allowed the [Co 6 C(CO) 15 ] 2Ϫ anion (1) to react with ClHgM in acetone at room temperature. Surprisingly, under these conditions, we were able to isolate brown crystals of (NEt 4 ) 2 [Co 6 C(CO) 12 {HgM} 2 ] [M ϭ W(CO) 3 Cp (4a), Mo(CO) 3 Cp (4b), Fe(CO) 2 Cp (4c), Co(CO) 4 (4d), Mn(CO) 5 (4e)] in moderate yields, accompanied by Co II salts. These complexes were characterized by elemental analyses, spectroscopic data, and mass spectrometry.…”

“…[12] The Co 6 Hg 2 metal framework found for 4a has no precedent in the chemistry of the Group 9 elements. Its formation re- quires the loss of three carbonyl ligands from the starting anion in order to permit both the skeletal rearrangement from the prism to the octahedron and the redox process that gives the double negative charge on the cluster.…”