Monocyclopentadienylmolybdenum(iii) Chemistry

Abstract

The synthesis, structure, properties, and reactivity of complexes of Mo(II1) containing one cyclopentadienyl or substituted cyclopentadienyl ring are reviewed. In particular, the electronic structure of mononuclear (radical) compounds and the synergistic stabilization through X"Mo and M&L interactions are discussed, as well as the effect of these interactions on the molecular structure and on the redox potentials of the compounds.

Diene-Containing Half-Sandwich MoIII Complexes as Ethylene Polymerization Catalysts: Experimental and Theoretical Studies

“…All observable trends for the reversible (Mo II /Mo III couple) potentials are as expected. All potentials are shifted with respect to the corresponding Cp complex by about À 0.2 V. Analogous shifts were previously reported for other complexes, for example, [Cp/Cp*Mo(PMe 3 ) 2 I 2 ] 0/ (À 0.19 V), [Cp/Cp*Mo(PMe 3 ) 2 Cl 2 ] 0/ (À 0.32 V), [40,41] [Cp/Cp*MoCl(PMe 3 ) 3 ] 0/ (À 0.14 V), [39] and [Cp/Cp*Cr(NO)(PPh 3 )I] 0/ (À 0.30 V). [42] The substitution of both Cl ligands by Me groups causes a negative shift of about 0.9 V, while a much smaller but significant negative shift is also induced by the additional methyl group on the diene [37] .…”

“…This class of half-sandwich Mo III compounds exhibit redox properties that are highly dependent on the nature of the ligands, [39] thus compounds 1 ± 4 were investigated by cyclic voltammetry. Each compound displays a reversible oneelectron reduction wave and a chemically irreversible oxidation wave at the potentials shown in Table 1.…”

Half-sandwich molybdenum(III) compounds containing diazadiene ligands and their use in the controlled radical polymerization of styrene

“…Half-sandwich complexes of Mo(III) having a four-legged piano stool structure and a 17-electron configuration now represent a relatively large family of stable organometallic radicals [1]. Their susceptibility to be oxidized to 16-electron (generally spin triplet) Mo(IV) derivatives or else to be reduced to saturated Mo(II) derivatives depends very strongly on the electronic properties of the ligands.…”

Half-sandwich complexes of molybdenum-(III), -(IV) and -(V) with P–O and P–N bifunctional ligands Ph2PCH2X (X = 2-oxazolinyl, or C(O)NPh2)

“…Our own work in this area has been summarized in review articles. [41][42][43][44] Interest in these compounds ranges from modelling the activity of nitrogenase enzymes and hydrodesulfurization catalysts to the quest for new poly-merization catalysts. The possibility to link bifunctional ligands having a soft and a hard donor atom may open new opportunities in terms of chemical reactivity and catalysis by virtue of the hemilability concept and in terms of establishing new building blocks for the assembly of heterobimetallic architectures.…”