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)

Abstract

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Monocyclopentadienyl complexes of niobium, tantalum and tungsten containing heterodifunctional P,O ligandsDedicated to Prof. P. Royo on the occasion of his 65th birthday, with our warmest congratulations.

“…Complexes 5a-c were stable in solution for several hours and in the solid state for a few days, in the absence of oxygen. Contrary to the situation reported for the Mo complexes mentioned in the introduction, 20,22,23 there was no observed tendency for chelation for 1 in complexes 5a-c.…”

Synthesis, characterisation, and molecular and electronic structure of CpMoCl2(R1CCR2) (R1, R2 = Ph, Et, Me): a new class of half-sandwich 17-electron molybdenum(III) organometallics

“…The oxidation process, on the other hand, is completely irreversible up to 5 V s -1 for all derivatives. In this respect, these compounds behave similarly to the previously described diene complexes, CpMoCl 2 (η 4 -diene), [26][27][28]30 while derivatives with more electron donating ligands (phosphines, phosphine-thioethers, phosphine-oxazolines, and phosphineamides) 35,39,40 show a reversible oxidation process at much lower potentials and no reduction process or, at the most, an irreversible reduction before the solvent discharge. A closer comparison of the reduction potentials between the isoelectronic complexes with the 4-electron donors alkyne (σ + π) and diene (2σ) ligands in Table 3 indicates that the alkynes transfer about the same amount of electron density to the metal center.…”

“…28, and the corresponding antibonding component in orbital no. 40. The alkyne-to-M σ donation is in a deeper energy orbital, while the orbitals no.…”

“…This solution was filtered through Celite and evaporated to dryness to yield an oily residue. The product 2 was extracted with 40…”

A phosphino-oxazolineligand as a P,N-bridge in palladium/cobalt or P,N-chelate in nickel complexes: catalytic ethylene oligomerization

“…Phosphine 1 has proven to be an efficient and versatile bidentate ligand. As seen in this and previous works, it can readily form stable monochelated nickel(II), 4 palladium(II), 9 platinum(II) 6 and molybdenum(III) 25 complexes, bischelated octahedral ruthenium(II) 8 or nickel(II) complexes, such as 3 and 4, and much more rarely, act as a bridging ligand. To the best of our knowledge, this situation has only been encountered in a Fe-Co, 13 Fe-Cu 14 and Co-Co 11 complex and in [{PdCl(1)} + (m-1)(CoCl 3 ) -] (2) which contains in addition a P,N-chelating ligand 1.…”