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Dynamic processes in hydrido-carbonyl trirhenium clusters containing bridging nitrogen heterocyclic ligands: An NMR investigation

“…Indeed 1 is two-electron richer than 2 (48 v.e.s instead of 46 v.e.s) and its apical unit is a closed-shell (18 v.e.s) H 2 Re(CO) 4 À complex [22]. Therefore the description of this cluster in terms of a p-complex is not appropriate and 1 should rather be viewed as a s-complex [23] 24] or bridging [25] "ligand" towards coordinatively unsaturated dinuclear Re fragments, allowing the rational synthesis of chain or ring clusters. It is clear that in the case of 1 the activation energy of the rotational process must take into account the breaking of two bonds with the bridging hydrides, rather than one, as in the case of the dianion 2.…”

Anionic Oligomerization as a Route to Chain Clusters

“…Other initiators are currently under investigation in our laboratory. [35] So far we have succeeded in isolating as a single crystal suitable for X-ray analysis only one of these oligomers, namely the Cl[Re 2 H 2 (CO) 8 . [23] The initiator X and one hydrido ligand are terminally bound to the opposite ends of the chains.…”

“…[35] Another major problem hindering the formation of higher oligomers arises from the low solubility of 1, particularly at low temperatures: it is known that the formation of long-chain polymers is favored by high monomer concentrations. The possible use of more effective solvents is under investigation at present.…”

“…On the contrary, some preliminary experiments suggest that for the Re chains the use of electrophiles as potential ªterminatorsº results in destabilization of the oligomeric structure. [35] …”

Diverse Roles of Hydrogen in Rhenium Carbonyl Chemistry: Hydrides, Dihydrogen Complexes, and a Formyl Derivative

“…Similar acidification of the HRe 2 (CO) 9 -anion, obtained from the reaction of Re 2 (CO) 10 with hydroxide ion, 2 leads to H 2 Re 2 (CO) 9 , which is unstable above -20°C but has been characterized spectroscopically. 3 The instability of H 2 Re 2 (CO) 9 has so far prevented its definitive structural elucidation by methods such as X-ray crystallography. However, a detailed 13 C and 1 H NMR study on the HRe 2 (CO) 9 -acidification product suggests an unusual HRe 2 (µ-H)(CO) 9 structure with one terminal and one bridging hydrogen atom (Figure 1).…”