Reactions of trinuclear platinum clusters with electrophiles: ionisation isomerism with [Pt3(μ2-I)(μ-PPh2)2(PPh3)3]I and [Pt3(μ-PPh2)2I2(PPh3)3]. Structures of [Pt3(μ2-Cl)(μ-PPh2)2(PPh3)3]PF6, [Pt3(μ-PPh2)2I2(PPh3)3] and of the Pt-Ag cluster [Pt3{μ3-AgBF4}(μ2-I)(μ-PPh2)2(PPh3)3]BF4

Abstract

A reaction of the 44 electron cluster [Pt3(μ-PPh2)3Ph(PPh3)2] (1) with wet AgBF4 afforded the cationic cluster [Pt3(μ2-OH)(μ-PPh2)2(PPh3)3]BF4 (3(BF4)) which slowly transformed into [Pt3(μ2-Cl)(μ-PPh2)2(PPh3)3]BF4 (4(BF4)) upon recrystallization from CH2Cl2. These 44 electron clusters have been characterized by (31)P{(1)H} NMR, and the crystal structure of 4(PF6) has been determined by X-ray diffraction, as well as that of [Pt3(μ-PPh2)2I2(PPh3)3] (5), which was obtained by recrystallization of the known cluster [Pt3(μ2-I)(μ-PPh2)2(PPh3)3]I (2(I)) from toluene and represents a neutral formula isomer of the latter. In addition, we have prepared the adducts of cluster 1 containing the moieties [Cu(NCMe)2](+) and [Au(PPh3)](+) in 6 and 7, respectively, and on the basis of their spectroscopic data, it was concluded that these complexes have similar structures to that previously established for the adduct of 1 with Ag(TFA) (TFA = OC(O)CF3), [Pt3{μ3-Ag(TFA)}(μ-PPh2)3Ph(PPh3)2] (8). The cationic clusters in 3(BF4) and 4(BF4) react with Ag(TFA) to afford cationic adducts in [Pt3{μ3-Ag(TFA)}(μ2-X)(μ-PPh2)2(PPh3)3]BF4 (9(BF4), X = OH; 10(BF4), X = Cl). The structure of the mixed-metal cluster [Pt3(μ3-AgBF4)(μ2-I)(μ-PPh2)2(PPh3)3]BF4 (11(BF4)), obtained by reaction of the complex 2(I) with AgBF4, was determined by X-ray diffraction.