PPh3-Derivatives of [Pt3n(CO)6n]2鈥?/sup> (n = 2鈥?) Chini鈥檚 Clusters: Syntheses, Structures, and 31P NMR Studies
文摘
The reaction of the [Pt3n(CO)6n]2鈥?/sup> (n = 2鈥?) Chini鈥檚 clusters with increasing amounts of PPh3 has been investigated in detail by combined FT-IR, 31P{1H} NMR, and electrospray ionization-mass spectrometry (ESI-MS) studies, showing that up to three CO ligands are gradually substituted by PPh3, resulting in isonuclear phosphine-substituted anionic clusters of general formula [Pt3n(CO)6n鈭?i>x(PPh3)x]2鈥?/sup> (n = 2鈥?; x = 1鈥?). Further addition of PPh3 results in the elimination of the neutral Pt3(CO)3(PPh3)3 species and formation of lower nuclearity anionic clusters. [Pt12(CO)22(PPh3)2]2鈥?/sup> and [Pt9(CO)16(PPh3)2]2鈥?/sup> have been structurally characterized, and they maintain the trigonal prismatic structures of the parent homoleptic clusters, with the two PPh3 ligands bonded to different external Pt3-triangles in relative cis-position. Conversely, the crystal structure of [Pt6(CO)10(PPh3)2]2鈥?/sup> shows that its metal cage is transformed from trigonal prismatic to trigonal antiprismatic after CO/PPh3 exchange.