Solution dynamics of tin and lead iron carbonyl compounds and the solid state structure of [Et4N]2[Sn{Fe2(CO)8}{Fe(CO)4}2]
| Autor: | Juanita M. Cassidy, Alan M. Kook, Kenton H. Whitmire |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Trigonal planar molecular geometry
Stereochemistry Chemistry Organic Chemistry chemistry.chemical_element Atmospheric temperature range Biochemistry Ion Inorganic Chemistry Crystallography Main group element Materials Chemistry Moiety Physical and Theoretical Chemistry Tin Single crystal Monoclinic crystal system |
| Zdroj: | Journal of Organometallic Chemistry. 456:61-70 |
| ISSN: | 0022-328X |
| DOI: | 10.1016/0022-328x(93)83318-p |
| Popis: | The dynamic rearrangement processes of CO ligands on the Main Group-iron carbonyl compounds, E[Fe2(CO)8]2 (Ia, E Pb), [Et4N]2[E{Fe2(CO)8}{Fe(CO)4}2]([Et4N]2[IIa], E Pb; [Et4N]2[IIb], E Sn) and [Et4N]2[Pb{Fe(CO)4}3] ([Et4N]2[IIIa], E Pb; [Et4N]2[IIIb], E Sn) were investigated by variable temperature 13C NMR spectroscopy. In Ia, all of the carbonyl ligands exhibit fast exchange over the entire temperature range studied. Limiting spectra were obtained for [Et4N]2[II] while the fluxional processes for [Et4 N]2[IIIa] were slowed but not completely resolved. Variable temperature spectra for [Et4N]2[II] provide evidence for the occurrence of two simultaneous independent carbonyl rearrangement processes, one centered on the Fe(CO)4 groups and one on the Fe2(μ-CO)2(CO)4 moiety. The dynamics of [Et4N]2[IIIa] suggest that the trigonal planar geometery is preserved in solution. Calculated activation energies for CO scrambling in [Et4N]2[II] and [Et4N]2[IIIa] range from 5.8 to 9.2 kcal/mol. The single crystal structure of [Et4N]2[IIb] was determined: monoclinic space group, Cc (No. 9) with a = 11.572(6) A, b = 22.46(1) A, c = 17.049(4) A, β = 103.00(3)°, V = 4318(3) A3 and Z = 4. The structure was refined to R = 4.8% and Rw = 5.5% for 2665 observed reflections. The anion exhibits a distorted tetrahedral configuration around Sn, with the Main Group element coordinated to two Fe (CO)4 groups and one Fe2(CO)8 unit. |
| Databáze: | OpenAIRE |
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