Synthesis and fluxional behavior of [Bis(trialkylphosphine)nickelio]anthracene (Alkyl = Et, Bu)
- Lawrence Berkeley Lab., CA (United States)
The title compounds were prepared from the respective (R{sub 3}P){sub 2}NiCl{sub 2} complexes and magnesium-anthracene-(THF){sub 3} (or anthracene in the presence of Mg or C{sub 8}K). The assignment of the anthracene proton NMR signals using NOE in conjunction with magnetization-transfer techniques is described. The complexes undergo haptotropic rearrangements in which the (R{sub 3}P){sub 2}Ni moiety migrates between the two terminal rings of the coordinated anthracene. The rates of these processes are concentration independent and unaffected by the presence of free anthracene and tris(trialkylphosphine)nickel. Kinetic studies in the temperature range-60 to +70 {degrees}C using line shape analysis and spin saturation transfer techniques were carried out. It was found that {Delta}H{sup {double_dagger}} = 13.6 kcal mol{sup {minus}1} and {Delta}S{sup {double_dagger}} = 4.3 eu for the haptotropic rearrangement in 2, and similar values were found for 1. Possible mechanisms are discussed. According to {sup 1}H, {sup 13}C, and {sup 31}P NMR data, the coordination number between the anthracene and the (R{sub 3}P){sub 2}Ni moiety is 4. However, an equilibrium between two {eta}{sup 2} structures with {Delta}G{sup {double_dagger}} {le} 4 kcal mol{sup {minus}1} cannot be ruled out. 19 refs., 4 figs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 263718
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 1 Vol. 11; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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