Cluster growth and fragmentation in the highly fluxional platinum derivatives of Sn9 4-: synthesis, characterization, and solution dynamics of Pt2@Sn17 4- and Pt@Sn9H 3-.
Sn94- reacts with Pt(PPh3)4 in ethylenediamine/toluene solvent mixtures in the presence of 2,2,2-cryptand to give four different complexes: "Rudolph's complex" of proposed formula [Sn9Pt(PPh3)x]4- (2), the previously reported [Pt@Sn9Pt(PPh3)]2- ion (3), and the title complexes Pt2@Sn174- (4) and Pt@Sn9H3- (5). The use of Pt(norbornene)3 instead of Pt(PPh3)4 gives complex 4 exclusively. The structure of 4 contains two Pt atoms centered in a capsule-shaped Sn17 cage. The complex is highly dynamic in solution showing single, mutually coupled 119Sn and 195Pt NMR resonances indicative of an intramolecular liquidlike dynamic exchange process. Complex 5 has been characterized by selectively decoupled 1H, 119Sn, and 195Pt NMR experiments and shows similar liquidlike fluxionality. In addition, the H atom scrambles across the cage showing small couplings to both Sn and Pt atoms. Neither 3 nor 4 obeys Wades rules; they adopt structures more akin to the subunits in alloys such as PtSn4. The structural and chemical relevance to supported PtSn4 heterogeneous catalysts is discussed.
Kesanli
Banu
B
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
Halsig
Jordan E
JE
Zavalij
Peter
P
Fettinger
James C
JC
Lam
Yiu-Fai
YF
Eichhorn
Bryan W
BW
D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D017671:Platinum Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D017971:Tin Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D017671:Platinum Compounds; D017971:Tin Compounds