13517-35-6Relevant academic research and scientific papers
Reaction of silafluorenes with (Ph3P) 2Pt(η2-C2H4): Generation and characterization of Pt-Si monomers, dimers and trimers
Braddock-Wilking, Janet,Corey, Joyce Y.,Trankler, Kevin A.,Dill, Kimberly M.,French, Lisa M.,Rath, Nigam P.
, p. 4576 - 4584 (2004)
The reaction of silafluorene (1; H2SiC12H 8) with (Ph3P)2Pt(η2-C 2H4) (2) at room temperature in C7D8 initially provided the mononuclear complex (Ph3P) 2Pt(H)[Si(H)C12H8] (3), followed by the appearance of the unsymmetrical dinuclear complex (Ph3P) 2(H)Pt(μ-SiC12H8)(μ-η2- HSiC12H8)Pt(PPh3) (4) and finally the novel trinuclear complex [(Ph3P)Pt(μ-SiC12H 8)]3 (5). The three complexes were characterized by multinuclear NMR spectroscopy and by X-ray crystallography (5). The molecular structure of 5 exhibits a nonplanar Pt3Si3 core. When the reaction was conducted at low temperature until the silafluorene was consumed and the mixture then warmed to room temperature, the dinuclear complex 4 could be isolated. The related substituted silafluorene system 3,7-di-tert- butylsilafluorene (6; H2SiC20H24) also reacted with 2 to provide both mono- and dinuclear complexes (7 and 8) analogous to 3 and 4. The dinuclear complex 8 was isolated and crystallographically characterized. Each of the two Pt centers in complex 8 exhibits a unique environment. In solution at low temperature 8 is best described as having one platinum center with a terminal hydride, [Pt(H)(PPh3)2], and the second platinum with a nonclassical [Si...H...Pt(PPh 3)] unit. However, in the solid state, the two hydrides may both adopt a bridging environment. Heating a sample of the unsymmetrical dimer 8 led to the formation of several products, one of which was the trimer 9, analogous to 5.
Reactions of organotin(IV) compounds with platinum complexes. Part(III). Reactions of (R2Sn)n, (R = Me or Ph, n = 6; R = Et, n = 9) with platinum complexes
Al-Allaf, Talal A.K
, p. 21 - 28 (2002)
The R2Sn moieties formed when the cyclic compounds (R2Sn)n, R = Me or Ph, n = 6; R = Et, n = 9, are exposed to light, react with the platinum(II) complexes [PtCl2L2], L = PEt3, PPr3, PBu3, PEtPh2, PPh3 to give new complexes of the general formula [PtCl(SnR2Cl)L2]. Similarly, Et2Sn from (Et2Sn)9 reacts with [PtMe(Cl)L2] to give [PtMe(SnEt2Cl)L2] and Ph2Sn from (Ph2Sn)6 reacts with [PtPh(Cl)L2] or [PtPh2L2] to give [PtPh(SnPh2Cl)L2] or [PtPh(SnPh3)L2] (L = PEt3), respectively. Reactions involving (R2Sn)n and the bridged complex [{Pt(μ-Cl)ClL}2] give a mixture of [PtCl(SnR2Cl)L2] and [PtCl(SnRCl2)L2], R = Me or Et, L = PBu3. It is suggested that these reactions initially involve insertion of R2Sn moieties into Pt-Cl bonds of the complexes [PtX(Cl) L2] or [{Pt(μ-Cl)ClL}2] then generate R2SnXCl (X = Cl, Me, Ph) and the Pt(0)complex [PtL2], which undergoes oxidative-addition of the formed tin(IV) species to give complexes containing Pt-Sn bonds. With (Ph2Sn)6 and [PtPh2L2], the mechanism takes a different course. Reactions under similar conditions involving the Pt(0) complexes [Pt(C2H4(PPh3)2] or [Pt(COD)2], (COD = 1,5-cyclooctadiene) and (R2Sn)6, R = Me or Ph, gave no detectable complexes containing Pt-Sn bonds. The complex [Pt(PEt3)4] and (MeSn)6 likewise gives no species containing Pt-Sn bonds but with (Ph2Sn)6, two complexes, tentatively identified as trans-[PtPh(Sn2Ph5)(PEt3)2] and trans-[PtPh(Sn6Ph11)(PEt3)2], were detected in the solution. In all cases, the products were identified by 31P-NMR spectroscopy.
Reactivity of o-Diphenylphosphinobenzaldehyde toward . X-Ray Structure of *C6H6
Ghilardi, Carlo A.,Midollini, Stefano,Moneti, Simonetta,Orlandini, Annabella
, p. 1833 - 1836 (1988)
The compound o-diphenylphosphinobenzaldehyde reacts with under mild conditions to give the acyl hydride .In the presence of butanol a complete decarbonylation of the aldehyde occurs with formation of .The X-ray crystal structure of the acyl complex has been determined.The crystals are orthorombic, space group Pn21a, with a = 17.673(9), b = 16.586(8), and c = 12.160(6) Angstroem.The structure has been solved by three-dimensional Patterson and Fourier syntheses and refined by least squares to final R and R' of 0.049 and 0.046 respectively.The metal atom is surrounded in a distored square-planar geometry by the acyl ligand, a triphenylphosphine and hydride ligand.
Forging Unsupported Metal–Boryl Bonds with Icosahedral Carboranes
Saleh, Liban M. A.,Dziedzic, Rafal M.,Khan, Saeed I.,Spokoyny, Alexander M.
, p. 8466 - 8470 (2016)
In contrast to the plethora of metal-catalyzed cross-coupling methods available for the installation of functional groups on aromatic hydrocarbons, a comparable variety of methods are currently not available for icosahedral carboranes, which are boron-rich three-dimensional aromatic analogues of aryl groups. Part of this is due to the limited understanding of the elementary steps for cross-coupling involving carboranes. Here, we report our efforts in isolating metal-boryl complexes to further our understanding of one of these elementary steps, oxidative addition. Structurally characterized examples of group 10 M?B bonds featuring icosahedral carboranes are completely unknown. Use of mercurocarboranes as a reagent to deliver M?B bonds saw divergent reactivity for platinum and palladium, with a Pt?B bond being isolated for the former, and a rare Pd?Hg bond being formed for the latter.
The Mechanism of Hydrogenolysis of Dineopentylbis(triethylphosphine)platinum(II)
Reamey, Robert H.,Whitesides, George M.
, p. 81 - 85 (1984)
Dineopentylbis(triethylphosphine)platinum(II) reacts with H2 (34 psi) at 32 deg C in hydrocarbon solvents and yields neopentane and trans-dihydridobis(triethylphosphine)platinum(II).The addition of triethylphosphine (L) changes the rate-limiting step of the reaction.When = 0 M, the overall rate-limiting step is the dissociation of triethylphosphine from L2PtR2: no isotope effect is observed on substitution of D2 for H2, and the rate is independent of pressure of H2.When > 0.1M, phosphine loss is reversible,and a later step,either addition of H2 to platinum or (more probably) elimination of neopentane from platinum, is rate limiting: the rate of reaction depends on the first order of the H2 pressure, and an isotope effect of kH/kD ca. 1.9 is observed on substitution of H2 by D2.Activation parameters obtained at 0.0, 0.1 and 0.5 M triethylphosphine are presented.These data are useful in understanding the differences in rates of inter- and intramolecular oxidative additions to platinum(II).The rate of reaction of H2 with several structurally related bis(phosphine)dialkylplatinum(II) compounds was surveyed under similar reaction conditions.In general, bulky substituents on platinum accelerate the reaction.This observation suggests that phosphine dissociation is a general feature of reaction of bis(phosphine)dialkylplatinum(II) compounds with dihydrogen.
Hydrosilylation of aromatic aldehydes and ketones catalyzed by mono- and tri-nuclear platinum(0) complexes
Tsuchido, Yoshitaka,Abe, Ryota,Kamono, Megumi,Tanaka, Kimiya,Tanabe, Makoto,Osakada, Kohtaro
, p. 858 - 864 (2018/05/23)
Hydrosilylation of aromatic aldehydes and acetophenone with H2SiPh2 was studied by using Pt complexes as the catalyst. Reaction of aromatic aldehydes, such as PhCHO, 4-FC6H4CHO, 4-MeC6H4CHO and 4-CF3C6H4CHO with H2SiPh2 in the presence of [Pt(PPh3)3] cata
A new approach to light-gated Pt catalysts for the hydrosilylation
Buchner, Magnus R.,Bechlars, Bettina,Ruhland, Klaus
, p. 60 - 67 (2013/10/01)
A new concept for a light-gated transition metal catalyst is presented based on a photo-active moiety in the outer ligand sphere of the complex which on irradiation reacts irreversibly with some part of the inner ligand sphere releasing a free coordination site. The principle is exemplified on a platinum complex for the hydrosilylation. It is proven that the catalytic properties of the complex and the properties of the photo-gate can be fine-tuned on the chemical problem independently of each other.
Mechanistic study of β-hydrogen elimination from organoplatinum(II) enolate complexes
Alexanian, Erik J.,Hartwig, John F.
, p. 15627 - 15635 (2009/03/12)
A detailed mechanistic investigation of the thermal reactions of a series of bisphosphine alkylplatinum(II) enolate complexes is reported. The reactions of methylplatinum enolate complexes in the presence of added phosphine form methane and either free or coordinated enone, depending on the steric properties of the enone. Kinetic studies were conducted to determine the relationship between the rates and mechanism of β-hydrogen elimination from enolate complexes and the rates and mechanism of β-hydrogen elimination from alkyl complexes. The rates of reactions of the enolate complexes were inversely dependent on the concentration of added phosphine, indicating that β-hydrogen elimination from the enolate complexes occurs after reversible dissociation of a phosphine. A normal, primary kinetic isotope effect was measured, and this effect was consistent with rate-limiting β-hydrogen elimination or C-H bond-forming reductive elimination to form methane. Reactions of substituted enolate complexes were also studied to determine the effect of the steric and electronic properties of the enolate complexes on the rates of β-hydrogen elimination. These studies showed that reactions of the alkylplatinum enolate complexes were retarded by electron-withdrawing substituents on the enolate and that reactions of enolate complexes possessing alkyl substituents at the β-position occurred at rates that were similar to those of complexes lacking alkyl substituents at this position. Despite the trend in electronic effects on the rates of reactions of enolate complexes and the substantial electronic differences between an enolate and an alkyl ligand, the rates of decomposition of the enolate complexes were similar to those of the analogous alkyl complexes. To the extent that the rates of reaction of the two types of complexes are different, those involving β-hydrogen elimination from the enolate ligand were faster. A difference between the rate-determining steps for decomposition of the two classes of complexes and an effect of stereochemistry on the selectivity for β-hydrogen elimination are possible origins of the observed phenomena.
Expedient, direct synthesis of (L)Pt(0)(1,6-diene) complexes from H 2PtCl6
Berthon-Gelloz, Guillaume,Schumers, Jean-Marc,Lucaccioni, Fabio,Tinant, Bernard,Wouters, Johan,Marko, Istvan E.
, p. 5731 - 5734 (2008/10/09)
The one-pot synthesis of useful [Pt2(0)(η4-1,6- diene)3] complexes, directly from H2PtCl 6·xH2O, has remained an unaddressed problem. We have found that the treatment of an i-PrOH solution of H2PtCl 6-XH2O by (Me3SiO)2MeSi(CH=CH 2), in the presence of allyl ether (AE), followed by reaction of the in situ generated Pt(O) species with IPr carbene (IPr =1,3-bis(2,6- diisopropylphenyl)imidazol-2-ylidene) enables the isolation of (IPr)Pt(AE) (I) in 50-70% yield. The scope of this method has been extended to other (L)Pt(1,6-diene) complexes (L = 1,3-dicyclohexylimidazol-2-ylidene, triphenylphoshine; 1,6-diene = diethyl 2,2-diallylmalonate (DAM)), and the molecular structure of the (IPr)Pt(DAM) (4) complex has been unequivocally determined by a single-crystal X-ray diffraction analysis. These results are significant for the formation of active L-Pt(O) fragments in catalysis.
Elimination-addition mechanism for nucleophilic substitution reaction of cyclohexenyl iodonium salts and regioselectivity of nucleophilic addition to the cyclohexyne intermediate
Fujita, Morifumi,Kim, Wan Hyeok,Sakanishi, Yuichi,Fujiwara, Koji,Hirayama, Sayaka,Okuyama, Tadashi,Ohki, Yasuhiro,Tatsumi, Kazuyuki,Yoshioka, Yasunori
, p. 7548 - 7558 (2007/10/03)
The reaction of 4-substituted cyclohex-1-enyl(phenyl)iodonium tetrafluoroborate with tetrabutyl-ammonium acetate gives both the ipso and cine acetate-substitution products in aprotic solvents. The isomeric 5-substituted iodonium salt also gives the same mixture of the isomeric acetate products. The reaction is best explained by an elimination-addition mechanism with 4-substituted cyclohexyne as a common intermediate. The cyclohexyne formation was confirmed by deuterium labeling and trapping to lead to [4 + 2] cycloadducts and a platinum-cyclohexyne complex. Cyclohexyne can also be generated in the presence of some other mild bases such as fluoride ion, alkoxides, and amines, though amines are less effective bases for the elimination. Kinetic deuterium isotope effects show that the anionic bases induce the E2 elimination (k H/kD > 2), while the amines allow formation of a cyclohexenyl cation in chloroform to lead to E1 as well as SN1 reactions (k H/kD ≈ 1). Bases are much less effective in methanol, and methoxide was the only base to efficiently afford the cyclohexyne intermediate. Nucleophiles react with the cyclohexyne to give regioisomeric products in the ratio dependent on the ring substituent. The observed regioselectivity of nucleophilic addition to substituted cyclohexynes is rationalized from calculated LUMO populations, which are governed by the bond angles at the acetylenic carbons: The less deformed carbon has a higher LUMO population and is preferentially attacked by the nucleophile.
