Construction of the Tetrahedral Trifluorophosphine Platinum Cluster Pt4(PF3)8 from Smaller Building Blocks

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• 作者：Peigang Hu ; Qiong Luo ; Qian-shu Li ; Yaoming Xie ; R. Bruce King ; Henry F. Schaefer
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：May 19, 2014
• 年：2014
• 卷：53
• 期：10
• 页码：5300-5310
• 全文大小：554K
• 年卷期：v.53,no.10(May 19, 2014)
• ISSN：1520-510X

文摘

The experimentally known but structurally uncharacterized Pt₄(PF₃)₈ is predicted to have an S₄ structure with a central distorted Pt₄ tetrahedron having four short Pt鈺怭t distances, two long Pt鈥揚t distances, and all terminal PF₃ groups. The structures of the lower nuclearity species Pt(PF₃)_n (n = 4, 3, 2), Pt₂(PF₃)_n (n = 7, 6, 5, 4), and Pt₃(PF₃)₆ were investigated by density functional theory to assess their possible roles as intermediates in the formation of Pt₄(PF₃)₈ by the pyrolysis of Pt(PF₃)₄. The expected tetrahedral, trigonal planar, and linear structures are found for Pt(PF₃)₄, Pt(PF₃)₃, and Pt(PF₃)₂, respectively. However, the dicoordinate Pt(PF₃)₂ structure is bent from the ideal 180掳 linear structure to approximately 160掳. Most of the low-energy binuclear Pt₂(PF₃)_n (n = 7, 6, 5) structures can be derived from the mononuclear Pt(PF₃)_n (n = 4, 3, 2) structures by replacing one of the PF₃ groups by a Pt(PF₃)₄ or Pt(PF₃)₃ ligand. In some of these binuclear structures one of the PF₃ groups on the Pt(PF₃)_n ligand becomes a bridging group. The low-energy binuclear structures also include symmetrical [Pt(PF₃)_n]₂ dimers (n = 2, 3) of the coordinately unsaturated Pt(PF₃)_n (n = 3, 2). The four low-energy structures for the trinuclear Pt₃(PF₃)₆ include two structures with central equilateral Pt₃ triangles and two structures with isosceles Pt₃ triangles and various arrangements of terminal and bridging PF₃ groups. Among these four structures the lowest-energy Pt₃(PF₃)₆ structure has an unprecedented four-electron donor 畏²-渭₃-PF₃ group bridging the central Pt₃ triangle through three Pt鈥揚 bonds and one Pt鈥揊 bond. Thermochemical studies on the aggregation of these Pt-PF₃ complexes suggest the tetramerization of Pt(PF₃)₂ to Pt₄(PF₃)₈ to be highly exothermic regardless of the mechanistic details.