Phosphorus-31 solid-state NMR studies of cyclic and acyclic phosphine-metal complexes. Determination of chemical shift anisotropy, scalar coupling 1JM-P (M = manganese-55, molybdenum-95/97, tungsten-183), and 55Mn quadrupolar coupling constants

Aspects of equivalence as illustrated by phosphine complexes of transition metals

“…The 31 P CP/MAS spectra of the cis-(DBP) 2 M(CO) 4 series indicate two inequivalent DBP ligands, which in the case of cis-(DBP) 2 Cr(CO) 4 has been verified by X-ray crystallography (54). In contrast to the insensitivity of 33 , the two other principal components of the phosphorus chemical shift tensor change in a characteristic and almost constant manner to lower frequencies on descending the group, viz., by 17-32 ppm from Cr to Mo and by 25-37 ppm from Mo to W. Such effects have been observed previously in 31 P NMR spectra of molybdenum and tungsten phosphine complexes (53,58) and are analogous to changes in carbon chemical shift tensors of the hexacarbonyls (63). Clearly, variations in 11 pendicular to the M-P bond (i.e., 11 and 22 ) to the nature of the metal is not unexpected.…”

“…The coupling constants listed in Table 14 have typical values with 1 J(WP) being about twice 1 J(MoP). Coupling to 53 Cr is expected to be smaller still and is probably masked by the strong and broad central resonance.…”

“…NMR spectra of (a) (DBP) 3 AuCl, (b) (DBP) 3 AuBr, (c) (DBP) 3 AuI, and (d) (Ph 3 P) 3 (52). Of these, couplings to 95 Mo are most common because it has the smallest nuclear quadrupole moment, Q = 0 022 × 10 −28 m 2 , compared to those of 97 Mo, Q = 0 255 × 10 −28 m 2 , and 53 Cr Q = −0 15 × 10 −28 m 2 . Generally, these nuclei relax efficiently via the quadrupolar mechanism.…”

Dithiafulvenylphosphine as P- and P,S-ligand towards metal carbonyl fragments

“…Reaction of [MnBr(CO) 5 ] with one equivalent of 2 in refluxing CH 2 Cl 2 for 3 h leads mainly to the monosubstituted complex 7, [MnBr(CO) 4 (P-DTF)] in 56% yield after column chromatography. Actually, investigation of the reaction medium by 31 P NMR shows two signals one at 27 ppm, assigned to complex 7, and another one at lower field, 78.7 ppm attributed to complex 8 where 2 behaves as a bidentate ligand towards Mn and form a chelate ring [15,16]. As previously observed for the molybdenum derivative described above, the signal of the phosphorus atom in this five-membered metallacycles is shifted of about 50 ppm downfield.…”

Phosphorus-31 Chemical Shift Anisotropies in Solid, Octahedral Chromium(0) Triphenylphosphine Derivatives

“…Phosphorus-31 NMR spectroscopy has been widely used in organometallic chemistry since the chemical shift is extremely sensitive to electronic, steric, and geometric environments of the 31 P nuclei . Upon coordination to a metal, the chemical shifts are also influenced by such factors as the bonding interaction between the phosphorus ligand and the metal, the nature and the oxidation state of the metal, the coordination number, the influence of the trans ligand, and the position of the phosphorus ligand within the coordination sphere.…”