NMR parameters of the tetrahedrane [Fe2(CO)6(μ-SNH)], studied by experiment and DFT

Abstract

The intramolecular dynamic behavior of the tetrahedrane-type cluster [Fe 2 (CO) 6 (µ-SNH)] 1 was studied by 13 C NMR spectroscopy. The 57 Fe chemical shift of 1 and the coupling constants 1 J( 57 Fe, 13 C) were measured. These NMR parameters, and also 1 J( 57 Fe, 15 N), were found to be in good agreement with data calculated by using density functional theory (DFT) methods (B3LYP), based on the geometry calculated at the 6-311 + G(d,p) level of theory. The isolobal replacement of the Fe(CO) 3 with BH fragments leads to the tetrahedranes [Fe(CO) 3 (BH)(µ-SNH)] 2 and [(HB) 2 (µ-SNH)] 3. Both were identified by calculations as minima on the respective potential energy surface (PES). However, the tetrahedrane-type structure of 3 is much higher in energy when compared with the planar cyclic isomers 3a and 3b.

57Fe NMR spectroscopy of ferrocenes derived from aminoferrocene and 1,1′-diaminoferrocene

“…Calculation of 57 Fe nuclear magnetic shielding is known to reproduce major trends of experimental data, [31,32] although large errors have to be expected, as pointed out for ferrocene itself, [33] considering the strong dependence (i) of the calculated data on the basis functions and (ii) of the experimental data on subtle structural changes. The same argument applies to the calculated absolute shielding tensors (e.g.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 17, 2006) and the discipline

“…Wrackmeyer and Herberhold [49] report on intramolecular dynamic behavior of the tetrahedrane-type cluster [Fe 2 (CO) 6 (l-SNH)] as observed by using 13 C NMR spectroscopy and theoretical approach. They concluded that isolobal replacement of the Fe(CO) 3 fragments with BH units leads to tetrahedrane-type structures which are preferred as long as one Fe(CO) 3 moiety remains, whereas it becomes energetically less favored if both Fe(CO) 3 units are replaced.…”