Abstract

The dinuclear anionic complexes [NBu4]- [(RF)2MII(μ-PPh2)2M′II(N∧O)] (RF = C6F5. N∧O = 8-hydroxyquinolinate, hq; M = M′ = Pt 1; Pd 2; M = Pt, M′ = Pd, 3. N∧O = o-picolinate, pic; M = Pt, M′ = Pt, 4; Pd, 5) are synthesized from the tetranuclear [NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-Cl)}2] by the elimination of the bridging Cl as AgCl in acetone, and coordination of the corresponding N,O-donor ligand (1, 4, and 5) or connecting the fragments “cis-[(RF)2M(μ-PPh2)2]2−” and “M′(N∧O)” (2 and 3). The electrochemical oxidation of the anionic complexes 1−5 occurring under HRMS(+) conditions gave the cations [(RF)2M- (μ-PPh2)2M′(N∧O)]+, presumably endowed with a M(III),M′(III) core. The oxidative addition of I2 to the 8-hydroxyquinolinate complexes 1−3 triggers a reductive coupling between a PPh2 bridging ligand and the N,O-donor chelate ligand with formation of a P−O bond and ends up in complexes of platinum(II) or palladium(II) of formula [(RF)2MII(μ-I)(μ-PPh2)M′II(P,N-PPh2hq)], M = M′ = Pt 7, Pd 8; M = Pt, M′ = Pd, 9. Complexes 7−9 show a new Ph2P-OC9H6N (Ph2P-hq) ligand bonded to the metal center in a P,N-chelate mode. Analogously, the addition of I2 to solutions of the o-picolinate complexes 4 and 5 causes the reductive coupling between a PPh2 bridging ligand and the starting N,O-donor chelate ligand with formation of a P−O bond, forming Ph2P-OC6H4NO (Ph2P-pic). In these cases, the isolated derivatives [NBu4][(Ph2P-pic)(RF)PtII(μ-I)(μ-PPh2)MII(RF)I] (M = Pt 10, Pd 11) are anionic, as a consequence of the coordination of the resulting new phosphane ligand (Ph2P-pic) as monodentate P-donor, and a terminal iodo group to the M atom. The oxidative addition of I2 to [NBu4][(RF)2PtII(μ-PPh2)2PtII(acac)] (6) (acac = acetylacetonate) also results in a reductive coupling between the diphenylphosphanido and the acetylacetonate ligand with formation of a P−O bond and synthesis of the complex [NBu4][(RF)2PtII(μ-I)(μ-PPh2)PtII(Ph2P-acac)I] (12). The transformations of the starting complexes into the products containing the P−O ligands passes through mixed valence M(II),M′(IV) intermediates which were detected, for M = M′ = Pt, by spectroscopic and spectrometric measurements.

Autore Pugliese

• Gallo Vito , Latronico Mario

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Anno di pubblicazione

2013

ISSN

0020-1669

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