24833-61-2Relevant academic research and scientific papers
Structure and Reactivity of Titanium/Platinum and Palladium Heterobinuclear Complexes with μ-Methylene Ligands
Ozawa, Fumiyuki,Park, Joon Won,Mackenzie, Peter B.,Schaefer, William P.,Henling, Lawrence M.,Grubbs, Robert H.
, p. 1319 - 1327 (1989)
A series of titanium/platinum and palladium heterobinuclear μ-methylene complexes has been prepared: M=Pt, X=Cl, L=PMe3 (2b), PMe2Ph (2c), PMePh2 (2d); M=Pt, X=Me, L=PMe2Ph (2e, 2f); M=Pd, X=Cl, L=PMe3 (2g).The μ-CH2/μ-Cl complex 2c crystallizes in the monoclinic system in space group P21/n (No. 14), with a=13.249(3) Angstroem, b=11.646(3) Angstroem, c=14.542(5) Angstroem, β=114.45(2) deg, V=2042.6(10) Angstroem3, Z=4, and density =1.87 g cm-3.The μ-CH2/μ-CH3 analogue 2e is isostructural to 2c and also crystallizes in space group, P21/n (No.14) with a=13.333(4) Angstroem, b=11.686(2) Angstroem, c=14.351(2) Angstroem, β=115.03(2) deg, V=2026.0(8) Angstroem3, Z=4, and density=1,82 g cm-3.Structural studies indicate the following: (1) the Ti-CH2 bond possesses residual double-bond character, (2) there is a dative Pt --> Ti interaction, which may be regarded as ? back-donation from the platinum atom to the Ti=CH2 group, and (3) the μ-CH3 group in 2e is bound to the titanium atom through a three-center, two-electron agostic bond.Complexes 2c and 2d react with tertiary phosphines to give Cp2(Cl)TiCH2Pt(Me)L2 species, which form μ-(C,O)-ketene complexes Cp2(Cl)TiOC(=CH2)Pt(Me)L2 upon carbonylation.The palladium complex 2g undergoes a reductive elimination reaction to give Cp2Ti(Et)Cl and Pd0PMe3 complexes.
Alkylthio bridged 44 eve triangular platinum clusters: Synthesis, oxidation, degradation, ligand substitution, and quantum chemical calculations
Albrecht, Christian,Schwieger, Sebastian,Bruhn, Clemens,Wagner, Christoph,Kluge, Ralph,Schmidt, Harry,Steinborn, Dirk
, p. 4551 - 4566 (2007/10/03)
Acetylplatinum(II) complexes trans-[Pt(COMe)Cl(L)2] (L = PPh3, 2a; P(4-FC6H4)3, 2b) were found to react with dialkyldisulfides R2S2 (R = Me, Et, Pr, Bu; Pr = n-propyl, Bu = n-butyl), yielding trinuclear 44 cve (cluster valence electrons) platinum clusters [(PtL)3(μ-SR)3]Cl (4). The analogous reaction of 2a-b with Ph2S2 gave SPh bridged dinuclear complexes trans-[{PtCl(L)}2(μ-SPh)2] (5), whereas the addition of Bn2S2 (Bn = benzyl) to 2a ended up in the formation of [{Pt(PPh3)} 3(μ3-S)(μ-SBn)3]Cl (6). Theoretical studies based on the AIM theory revealed that type 4 complexes must be regarded as triangular platinum clusters with Pt-Pt bonds whereas complex 6 must be treated as a sulfur capped 48 ve (valence electrons) trinuclear platinum(II) complex without Pt-Pt bonding interactions. Phosphine ligands with a lower donor capability in clusters 4 proved to be subject to substitution by stronger donating monodentate phosphine ligands (L′ = PMePh2, PMe 2Ph, PBu3) yielding clusters [(PtL′) 3(μ-SR)3]Cl (9). In case of the reaction of clusters 4 and 9 with PPh2CH2PPh2 (dppm), a fragmentation reaction occurred, and the complexes [(PtL)2(μ-SMe)(μ-dppm)]Cl (12) and [Pt(μ-SMe)2(dppm)] (13) were isolated. Furthermore, oxidation reactions of cluster [{Pt(PPh3)}3(μ-SMe) 3]Cl (4a) using halogens (Br2, I2) gave dimeric platinum(II) complexes cis-[{PtX(PPh3)}2(μ-SMe) 2] (14, X = Br, I) whereas oxidation reactions using sulfur and selenium afforded chalcogen capped trinuclear 48 ve complexes [{Pt(PPh 3)}3(μ3-E)(μ-SMe)3] (15, E = S, Se). All compounds were fully characterized by means of NMR and IR spectroscopy, microanalyses, and ESI mass spectrometry. Furthermore, X-ray diffraction analyses were performed for the triangular cluster 4a, the trinuclear complex 6, as well as for the dinuclear complexes trans-[{Pt(AsPh3)}2(μ-SPh)2] (5c), [{Pt(PPh3)}2(μ-SMe)(μ-dppm)]Cl (12a), and [{{PtBr(PPh3)}2(μ-SMe)2] (14a).
A multinuclear NMR study of asymmetrically coordinated η3-allyls in [PtCl(η3-allyl)(phosphine)] and [Pt(phenyl)(η3-allyl)(phosphine)] complexes
Clark, Howard C.,Hampden-Smith, Mark J.,Ruegger, Heinz
, p. 2085 - 2093 (2008/10/08)
The title complexes were prepared and fully characterized by multinuclear (1H, 31P, 13C, 195Pt) NMR methods. The 1H NMR resonances of the allyl groups were unequivocally assigned by using a combination of one- and two-dimensional NMR spectroscopic techniques. The spectroscopic data have been interpreted in terms of contributions of asymmetric η1-η2-allyl bonding modes to the more familiar symmetrical η3-allyl arrangement. The relative orientation and extent of the asymmetric η1-η2-bonding were shown to be markedly dependent upon the nature of the other ligands coordinated to platinum. On prolonged standing in chloroform solution, the title complexes rearranged to give the known complexes [X(R3P)Pt(μ-Cl)]2 and trans-XClPt(PR3)2 (X = Cl, Ph). Conversion of the allyl moiety to propene gas was shown by 1H NMR and gas chromatographic analysis.
Selectivity and reactivity in reactions of methylaryltitanium(IV) complexes with electrophiles
Puddephatt, Richard J.,Stalteri, Maria A.
, p. 1400 - 1405 (2008/10/08)
Methyl or phenyl for halogen-exchange reactions occur between [TiMe2(η-C5H5)2] or [TiPh2(η-C5H5)2] with [TiX2(η-C5H5)2], X = halogen, to give [TiXMe(η-C5H5)2] or [TiXPh(η-C5H5)2], respectively. The reactions are complicated by parallel decomposition of the methyl- or phenyltitanium complexes, which is catalyzed by [TiX2(η-C5H5)2] or [TiXR(η-C5H5)2]. In general, there is little difference in the rates of reaction of [TiMe2(η-C5H5)2] and [TiPh2(η-C5H5)2] toward the symmetrization reactions. These reagents also transfer a methyl group or phenyl group to platinum(II) or gold(III), but there are again side reactions. The complex [TiMePh(η-C5H5)2] reacts with electrophiles HCl, HOAc, HgCl2, and MeHgCl to give cleavage of both methyl- and phenyltitanium bonds with little selectivity. In cleavage of [TiMe(C6H4X)(η-C5H5) 2] there is a correlation of the selectivity for cleavage of the aryl group by electrophiles HCl or HgCl2 with the σ+ parameters of substituents X. A mechanism of reaction involving electron transfer from the complex to the electrophile followed by rapid cleavage is tentatively suggested.
