The reaction of [NBu 4 ] 2 [{(C 6 F 5 ) 2 Pt(µ-PPh 2 ) 2 Pt(µ-Cl)} 2 ] with AgClO 4 in CH 2 Cl 2 (1:2 mol ratio) gives the neutral tetranuclear compound [Pt 4 (µ-PPh 2 ) 3 {µ 3 -PPh(1,2-η 2 -Ph)-κ 3 P)}(C 6 F 5 ) 4 ] ( 5), a 58-electron cluster that displays three Pt-Pt bonds and a 1,2-η 2 -Ph (of the PPh 2 ligand) Pt interaction. This complex reacts with bipy or phen (L-L), giving the tetranuclear clusters [Pt 4 (µ-PPh 2 ) 4 (C 6 F 5 ) 4 (L-L)] (L-L ) bipy 6, phen 7), while its reaction with CO in CH 2 Cl 2 renders [{Pt 2 (µ-PPh 2 ) 2 (C 6 F 5 ) 2 (CO)} 2 ] (8). The molecular structures of complexes 5 and 6 have been established by X-ray crystallography, and the structure of 8 is inferred by 31 P NMR spectroscopy. † Part 7. See ref 3d.
The binuclear complexes [NBu 4 ][(C 6 F 5 ) 2 M(µ-PPh 2 ) 2 M′(acac-O,O′)] (M ) M′ ) Pt, 1a; M ) Pt, M′ ) Pd, 1b; M ) M′ ) Pd, 1c) have been prepared by reacting [NBu 4 ] 2 [(C 6 F 5 ) 2 M(µ-PPh 2 ) 2 M′(µ-Cl) 2 M′(µ-PPh 2 ) 2 M(C 6 F 5 ) 2 ] with Tl(acac). Complexes 1a,b react with [Ag(OClO 3 )-(PPh 3 )], yielding [MPtAg(µ-PPh 2 ) 2 (C 6 F 5 ) 2 (acac)(PPh 3 )] (M ) Pt, 2a; M ) Pd, 2b). The X-ray structures of both complexes are rather similar, the main difference being related with the Pt-Ag bonds. While in 2b it is clear that there are Pt-Ag and Pd-Ag bonds, in 2a it seems that only one Pt-Ag bond is connecting both Pt and AgPPh 3 moieties. The formation of a Pd-Ag bond is rather surprising, because of the known reluctance of the Pd center to engage in this sort of bonding. 1a,b react with equimolar amounts of AgClO 4 in CH 2 Cl 2 to give [PtMAg(µ-PPh 2 ) 2 (C 6 F 5 ) 2 (acac)] x (M ) Pt, 4a; M ) Pd, 4b). The X-ray structure of 4a indicates that the "Pt 2 (acac)(C 6 F 5 ) 2 (µ-PPh 2 )" fragments are connected to the silver center through two Pt-Ag bonds (2.875(1), 2.864(1) Å) and one C γ -Ag bond (of the acac ligand). On the other hand, when the homodinuclear palladium derivative reacts with [Ag(OClO 3 )(PPh 3 )] or AgClO 4 , decomposition takes place and [(C 6 F 5 )(PPh 3 )Pd(µ-PPh 2 ) 2 Pd(acac)] can be detected in the former reaction. These processes are in agreement with the well-known tendency of the pentafluorophenyl-palladate substrates to participate in arylating processes.
The synthesis of the trinuclear phosphido complexes [NBu 4 ] 2 [(C 6 F 5 ) 2 M(µ-PPh 2 ) 2 M′(µ-PPh 2 ) 2 M′′(C 6 F 5 ) 2 ] (M, M′, M′′ ) Pd(II), Pt(II), 1-5) is described. A study of the electrochemical behavior of these complexes is reported. The chemical oxidation of the homonuclear platinum derivative involving two electrons yields the complex [(C 6 F 5 ) 2 Pt(µ-PPh 2 ) 2 Pt(µ-PPh 2 ) 2 Pt(C 6 F 5 ) 2 ] (6), which contains Pt in average formal oxidation state 2.67. The structure of the complexes has been established by spectroscopic means, and X-ray diffraction studies have been carried out on 1 and 6. Quantum chemical calculations at the B3LYP level of theory, using the LANL2DZ basis set, provide a satisfactory description of the structural, bonding, energetic, and electronic properties of these phosphido-bridged trinuclear M 3 (II) compounds modeled as [(CF 3 ) 2 M(µ-PH 2 ) 2 M′(µ-PH 2 ) 2 M′′(CF 3 ) 2 ] 2-(M, M′, M′′ ) Pd(II), Pt(II), 1M-5M) and the oxidation product [Pt 3 (µ-PH 2 ) 4 (CF 3 ) 4 ] (6M).a The symmetry transformation used to generate equivalent P(2′) atom is -x, -y, -z.
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