Electronic effects in the cyclopentadienyl ring. The 13C NMR spectraof monosubstituted ferrocenes

Indirect nuclear 57Fe13C and 57Fe1H spin–spin coupling in ferrocenes and cyclopentadienyliron complexes: measurements and DFT calculations

“…14,15 All samples for NMR measurements were freshly dissolved under argon in dry deuterated solvents, filtered through silica or Al 2 …”

“…However, two representative series of 57 Fe-labeled iron compounds, namely ferrocenes and cyclopentadienyl iron derivatives, have been prepared and studied by 13 C NMR, including 13 Cf 57 Feg double resonance experiments, in order to obtain the information on both J 57 Fe, 13 C and chemical shifts υ 57 Fe. 14,15 In the present work, we used some of these compounds for direct observation of 57 Fe NMR signals, for 13 C NMR measurements at higher field strength † Dedicated to Professor Wolfgang von Philipsborn on the occasion of his 75th birthday. and also for 2D 13 C/ 1 H HETCOR in order to obtain relative signs of coupling constants involving 57 Fe.…”

“…Furthermore, we attempted to calculate the values J 57 Fe, 13 C and J 57 Fe, 1 H by using methods of density functional theory (DFT). The molecules 1-11 considered for calculations are shown in Scheme 1, and experiments, in addition to those known from previous work, 14,15 were carried out for 1, 4, 12 (the methyl group in 2 is replaced by the neopentyl group) and 13 (the ethylene ligand in 10 is replaced by cycloheptene).…”

“…This correlation includes experimental data given in Table 1 and others taken from the literature. 1,14,15,38 The ideal slope ( 1) of the correlation is not observed. It is conceivable that structural differences (calculated in the gas phase and experimental in solution) are responsible, together with solvation and thermal effects.…”

“…14,15 The appearance of the 13 C NMR signals of the cyclopentadienyl carbon atoms in 1, 12 and 4, measured at 125.8 MHz (Fig. 2) Quantum chemical treatment of transition metal complexes is still a formidable task, aiming for accurate information on structure and NMR parameters.…”