Two novel tris(tert-butoxy)siloxy complexes of Pt(II) and Pt(IV) were prepared in high yields, (cod)Pt[OSi(O t Bu)3]2 (1; 87%; cod = 1,5-cyclooctadiene) and Me3Pt(tmeda)[OSi(O t Bu)3] (2; 81%; tmeda = N,N,N′,N′-tetramethylethylenediamine). The structures of these compounds were determined by multinuclear NMR spectroscopy and by single-crystal X-ray analysis. The thermolytic chemistry of 1 and 2 in the solid state was studied by thermogravimetric analysis. The thermal decomposition of these complexes resulted in the formation of Pt metal, with the elimination of HOSi(O t Bu)3. Precursors 1 and 2 react with the surface Si−OH groups of mesoporous SBA15 silica to generate surface-supported Pt centers. The coordination environments of the supported Pt centers in these new materials, termed Pt(II)SBA15 and Pt(IV)SBA15, were investigated using Fourier-transform infrared spectroscopy, X-ray absorption near-edge spectroscopy, and extended X-ray absorption fine structure analysis. These materials were also characterized using N2 porosimetry, powder X-ray diffraction and transmission electron microscopy. Comparisons with the molecular precursors 1 and 2 revealed many similarities, and the results are indicative of isolated Pt(II) and Pt(IV) centers. In addition, isolated Pt centers proved to be robust in inert atmosphere to 150−200 °C, which is similar to the decomposition temperatures of 1 and 2.

The reaction of one equiv of 1-alkynylphosphines, R2PCCR′ (R = Et, i Pr, or Ph and R′ = Ph or Mes), with Cp2Zr(pyr)(η2-Me3SiCCSiMe3) resulted in formation of monoalkyne complexes. In the case where R = Et, i Pr, or Ph and R′ = Ph, a “ligand free” zirconacyclopropene complex is produced. These complexes are stabilized by intermolecular donation of the phosphorus lone-pair in the dimeric complexes [Cp2Zr(η2-R2PCCPh)]2 (R = Et, i Pr, or Ph). However, with R = Ph and R′ = Mes, the zirconocyclopropene-pyridine complex Cp2Zr(pyr)(η2-Ph2PCCMes) is formed. Homocoupling of the 1-alkynylphosphines was demonstrated by reaction of a second equiv of Ph2PCCPh with [Cp2Zr(η2-Ph2PCCPh)]2 to give the diphosphinozirconacyclopentadiene Cp2Zr[2,5-(Ph2P)2-3,4-Ph2C4] with high regioselectivity (77%). The zirconacyclopropene complexes also react with one equiv of PhCCPh or EtCCEt to give zirconacyclopentadienes in which the phosphino substituent preferentially adopts the 2-position (α) of the zirconacyclopentadiene ring. These unsymmetrical zirconacyclopentadienes undergo substitution of the R2PCCR′ moiety with the less bulky alkynes PhCCPh or EtCCEt. The substituents on the 1-alkynylphosphines significantly influence the rates of alkyne substitution such that sterically more demanding substituents in either the α- (-P i Pr2) or β- (-Mes) position of the zirconacycle lead to faster exchange. The α-phosphinozirconacyclopentadienes were readily converted to 1-phosphinobutadienes via reaction with benzoic acid. The zirconacyclopentadiene Cp2Zr[2-Ph2P-3,4,5-Ph3C4] was converted to the corresponding thiophene oxide by the oxo-transfer reaction with sulfur dioxide. In the case of ((1Z,3E)-3-ethyl-2-phenylhexa-1,3-dienyl)diphenylphosphine and (3,4,5-triphenylthiophen-2-yl oxide)diphenylphosphine, the molecules were isolated as their phosphine oxides. Reactions of the zirconacyclopropene complexes [Cp2Zr(η2-Ph2PCCPh)]2 and Cp2Zr(pyr)(η2-Ph2PCCMes) with the diyne (F5C6)CC−1,4-C6H4−CC(C6F5) gave bis(zirconacycle)s terminated with phosphino groups. These bis(zirconacycle)s were converted to the corresponding phosphino-terminated oligomers by protonolysis with hydrochloric acid. In addition, the Ph2PCCMes moiety of Cp2Zr[2-Ph2P-3-Mes-4-(C6F5)C4]−1,4-C6H4−Cp2Zr[2-Ph2P-3-Mes-4-(C6F5)C4] was exchanged with PhCCPh to give the phenylene(zirconacyclopentadiene) Cp2Zr[2,3-Ph2-4-(C6F5)C4]−1,4-C6H4−Cp2Zr[2,3-Ph2-4-(C6F5)C4].

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Two highly methylated fluorene derivatives have been synthesized and used for the preparation of mixed-ligand fluorenyl ruthenocenes. Specifically, reaction of 2,2‘,3,3‘,4,4‘,5,5‘-octamethylbiphenyl with paraformaldehyde in the presence of CF3CO2H provided 1,2,3,4,5,6,7,8-octamethylfluorene (C13Me8H2), which was subsequently methylated by reaction with n-BuLi followed by addition of MeI to yield 1,2,3,4,5,6,7,8,9-nonamethylfluorene (C13Me9H). Reaction of the lithium fluorenyl derivatives with [Cp*RuCl]4 generated the mixed-ligand ruthenocenes Cp*(C13Me8H)Ru and Cp*(C13Me9)Ru. Electrochemical measurements indicate that these ruthenocene derivatives undergo quasi-reversible oxidations at low potentials consistent with strongly donating character for the highly methylated fluorenyl ligands. X-ray diffraction studies on C13Me8H2, C13Me9H, and Cp*(C13Me9)Ru revealed a twisted fluorene core in all cases.