13C- und 15N-NMR-spektroskopische Untersuchungen einiger Pentacarbonylchrom-Aminophosphan-Komplexe/13C and 15N NMR Spectroscopic Study of Some Pentacarbonylchromium-Aminophosphane Complexes
2014
Wrackmeyer, Bernd | Schamei, Klaus | Herberhold, Max
¹³C and ¹⁵N NMR data are reported for the free aminophosphanes ʹBu₃₋ₙP(NH₂)ₙ (n = 1 (1), 2 (2)), for the corresponding pentacarbonylchromium complexes (OC)₅Cr-P(ʹBu)₃₋ₙ(NH₂)ₙ (n = 1 (3), n = 2 (4), n = 3 (5)), and for other (OC)₅Cr-aminophosphane complexes such as (OC)₅Cr-P(NMe₂)₃, (6) and a binuclear complex (7) in which the sulfurdiimide derivative ʹBu(NH₂)P-NSN-P(NH₂)ʹBu serves as the phosphane ligand. Various techniques (e.g. INEPT and reverse two-dimensional (2D) ¹H {¹⁵N}-experiments) have been used for recarding the ¹⁵N NMR spectra at natural abundance. In contrast to suggestions in the literature, the relationship between the ¹³C NMR parameters for the axial and equatorial CO groups and the σ-donor/π-acceptor properties of the phosphane ligand is not straightforward. The ¹⁵N resonances of the (OC)₅Cr complexes 3, 4, 6 are shifted to higher frequencies with respect to those of the free ligands, and there is a regular decrease in ¹⁵N nuclear shielding in the series of 3, 4, 5. The |¹J(³¹P¹⁵N)| values vary between 17 and 65 Hz, the smaller values being observed for the (OC)₅Cr complexes. The lack of a regular change in the magnitude of ¹J(³¹P¹⁵N) in the series 3, 4, 5 indicates that this parameter is influenced by the nature of both the Cr-P and the P-N bonds as a function of the number of amino groups.
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