Solution structures and dynamics of Co4(CO)12 and HFeCo3(CO)12−xLx (x = 0–3; L = group V Ligand)

Multinuclear NMR Study of HFeCo3(CO)9[P(OCH3)3]3 in the Solid State and in Solution

“…This fact supports the hypothesis of a single correlation time τ C and validates the use of eqs 15 and 17. It also indicates that the relaxation is not influenced by the carbonyl scrambling process which has often been proposed to occur in tetrahedral clusters . As already mentioned, the main contributions to relaxation must arise from the quadrupolar and chemical shift interactions, the corresponding relaxation times being given by eqs 15 and 17.…”

“…The experimental 59 Co NMR spin-echo spectra of HFeCo 3 -(CO) 9 [P(OCH 3 ) 3 ] 3 at the two available field strengths are reported in Figure 4. As previously observed on analogue compounds, 17 the central transition line shape varies with B 0 , demonstrating that the magnitudes of the second-order quadrupolar and first-order chemical shift interactions are comparable.…”

“…The second-order quadrupolar effects transmitted to the 31 P spin-1/2 nucleus are found to be consistent with the ones directly observed at the 59 Co high-spin nucleus. As a consequence of the large quadrupole coupling constant (|Q CC | g 15 MHz), the 59 Co Q and CS interaction tensors corresponding to each crystallographic site could not be determined. However, the relevant interaction parameters which are necessary for the interpretation of the molecular dynamics in solution have been evaluated by a moment analysis of the central transition powder patterns.…”

“…Chemical shifts are reported downfield from the external references, i.e., K 3 [Co(CN) 6 ] saturated in D 2 O and an aqueous solution of H 3 PO 4 (85%) for 59 Co and 31 P resonances, respectively. The 31 P spectra in both the solid and liquid states were simulated directly in the frequency domain according to eqs 4 and 19, respectively.…”

“…1,3,5,7,8 The field of solid-state NMR methods applied to organometallic and coordination chemistry is growing rapidly. 10 In particular, 59 Co NMR has been recently applied to the study of tetrahedral clusters both in solution [11][12][13][14][15] and in the solid state, 16,17 these compounds being of structural and catalytic interest. 18 Moreover, in derivatives containing phosphorus ligands, complementary information may be obtained by 31 P NMR.…”