Platinum complexes physical properties

Tin, nitratodiphenyltris(dimethy) sulfoxide)-structure, 1,77 Tin, nitratotris(triphenyltin)-structure, 1, 47 Tin,tetrakis(acetato)-stereochemistry, 1,94 Tin, tetrakis(diethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetrakis(ethyldithiocarbamato)-angular parameters, 1, 57 Tin, tetranitrato-stereochemistry, 1, 94 Tin, tri-n-butylmethoxy-, 3, 208 Tin alkoxides physical properties, 2, 346 Tin bromide, 3, 194 Tin bromide hydrate, 3,195 Tin carboxylates, 3, 222 mixed valence, 3, 222 Tin chloride, 3, 194 hydroformylation platinum complexes, 6, 263 Tin chloride dihydrate, 3,195 Tin complexes, 3, 183-223 acetyl ace tone... 

Isomorphic monomers, 19 762 Isoniazid, 25 798 Isonicotinic hydrazide, 21 103 Isonitrile complexes, platinum, 19 656 Isonitrile-nitrile rearrangement, 21 149 Isononanoic acid, physical properties, 5 35t Isononyl alcohol, properties of commercial, 2 12t... 

A large number of heterogeneous catalysts have been tested under screening conditions (reaction parameters 60 °C, linoleic acid ethyl ester at an LHSV of 30 L/h, and a fixed carbon dioxide and hydrogen flow) to identify a suitable fixed-bed catalyst. We investigated a number of catalyst parameters such as palladium and platinum as precious metal (both in the form of supported metal and as immobilized metal complex catalysts), precious-metal content, precious-metal distribution (egg shell vs. uniform distribution), catalyst particle size, and different supports (activated carbon, alumina, Deloxan , silica, and titania). We found that Deloxan-supported precious-metal catalysts are at least two times more active than traditional supported precious-metal fixed-bed catalysts at a comparable particle size and precious-metal content. Experimental results are shown in Table 14.1 for supported palladium catalysts. The Deloxan-supported catalysts also led to superior linoleate selectivity and a lower cis/trans isomerization rate was found. The explanation for the superior behavior of Deloxan-supported precious-metal catalysts can be found in their unique chemical and physical properties—for example, high pore volume and specific surface area in combination with a meso- and macro-pore-size distribution, which is especially attractive for catalytic reactions (Wieland and Panster, 1995). The majority of our work has therefore focused on Deloxan-supported precious-metal catalysts. 

Synthesis, reactions, and physical properties of stable mononuclear platinum and zirconium complexes of cyclohexyne reported prior to the late 1980s have been comprehensively covered in earlier reviews.2-8 More recently, reaction of the zirconocene complex of cyclohexyne with trimethyla-luminum and trimethylgallium has been reported to give 247 and 248, respectively [Eq. (36)].57-58 These products are novel because four atoms (carbons Cl and C3, the transition metal, and the main group metal) are covalently bonded to an sp2 hybridized carbon (C2) in a planar tetracoordi-nate fashion. Synthesis of this type of complex, which Erker describes as anti-van t Hoff/LeBel, does not require the strained cycloalkyne ring zirconocene complexes of acyclic alkynes react similarly.57-58... 

The partial confusion arising after Dewar s and Chatt s reviews were published, was resolved after Chatt and Duncanson reported in 1953 in the Journal of the Chemical Society the results of infrared spectroscopic studies on a range of olefin platinum(II) complexes [38]. In this highly cited paper they proposed, with particular reference to Dewar s model, that in the olefin platinum(II) complexes the cr-type bond would be formed by overlap of the filled re-orbital of the olefin with a vacant 5d6s6p2 hybrid orbital of the platinum atom, and the re-type bond by overlap of a filled 5d6p hybrid orbital of the metal with the empty antibonding re-orbital of the olefin (Fig. 7.8). In addition, Chatt and Duncanson illustrated how the model could be used to interpret not only the physical properties of the olefin platinum compounds, such as the spectroscopic data and dipole moments, but also their reactivity and their greater stability compared to the olefin silver salts. 

The polysiloxane network is formed during part fabrication. In injection molding, the acetylenic alcohol, which acts as a fugitive inhibitor of the vinyl-addition reaction, is volatilized at low temperature as the pellets enter the feed throat. The platinum complex is activated at the process temperature of the urethane (170-185 °C). The vinyl-addition reaction is initiated by the melt state, and the parts generated demonstrate mechanical properties consistent with the formation of a silicone IPN. The fabricated parts are translucent. The physical properties of this formulation (PTUE 205) are given in Table 1. 

Physical properties of the Xe-PtFt adduct.—The adduct is yellow when deposited in thin films but in bulk is deep red. The solid becomes glassy in appearance when heated to 115°, but does not melt below 165°, when it decomposes to produce xenon tetrafluoride. X-ray powder photographs of the adduct of composition XePtFe show no diffraction pattern. Complex patterns are observed with samples of material richer in platinum. The plasticity of the material made the preparation of good powder samples difficult. Even well-cooled samples did not grind well. 

Although a number of complex fluorides of quinquevalent iridium, (e.g. KIrF,) are known, previous attempts to establish the simple fluoride have failed. The absence of a pentafluoride of iridium has become increasingly anomalous as the pentafluorides of the neighbouring elements, rhenium, osmium, and platinum have been prepared. Previous work - indicated that reactions which might have yielded the pentafluoride gave the tetrafluoride instead. The physical properties of this tetrafluoride. (m.p. 106—107 b.p. > 300 ), however, resembled those of a pentafluoride or oxide tetrafluoride. This indicated that iridium tetrafluoride differed structurally from its neighbouring tetrafluorides. 

Each of the three isomeric forms of the dach ligand, fran.s-(R, R)-dach, frans-(S, S)-dach, and cis-dach, gives a platinum-ascorbate chelate that has unique physical properties. A detailed procedure is given here only for the synthesis of [Pt(trans-(R,R)-dach)(ascorbato-C, 0 )]-3H20. With minor variations, the same method is used in the syntheses of the platinum-ascorbate complexes of trans-(S, 5)-dach and c/s-dach. 

A great deal could be learned by further synthetic studies of unusual complexes of platinum and cobalt, as well as other metals, but the syntheses are long and multistep and few chemists have the patience to attempt them. Knowledge gained by work on the complexes of one metal can be used only indirectly in studies of another the chemistries of the complexes of cobalt(III) and chromium(III), for example, are quite different, although these substances closely resemble each other in physical properties. 

Stacking of a d8 platinum(II) complex in the solid state leads to weak Pt- Pt interaction, influencing physical properties. 

Caution must be exercised in interpretation of the physical data for the tetracyanoplatinate complexes (as well as all other one-dimensional systems) because purity and morphology are extremely critical for one-dimensional systems. For example, a 1.00 x 0.01 x 0.01 mm perfect needle crystal of K2Pt(CN)4Xo.3 would contain — lx 10 parallel strands each of 3.5 x 10 collinear platinum atoms. Thus, purity (foreign impurities, end groups, and/or crystalline defects) levels of one part per million indicate that each strand averages more than three defects, which may drastically alter some (and in particular transport) measurements. Besides the intrinsic purity problem of one-dimensional systems, the physical properties of K2Pt(CN)4-Xo.3(H20)a are a strong function of hydration. Dehydration alters the crystal structure and thus properties of the complexes (78). Care must be maintained to ensure that dehydration is not caused by the measurement technique. For... 

In the past dozen years, there has been renewed interest in a variety of polyplatinum oxides. Crystallographic investigation of several of these compounds has revealed one-dimensional chains of platinum atoms in more than one direction. Careful studies are necessary to verify the dimensionality of these materials. Recently, a mercury complex has been reported. It is an additional example of this multidimensional one-dimensionality. The chemical and physical properties of such compounds are reviewed below. 

The auxiliary phosphine ligands also play an important role in controlling the physical properties of platinum(ii) alkynyl complexes. Monomeric complexes of trans-[Pt(PR3)2(C=CR )2] usually exist in the crystalline state at room temperature. Cooper et al. recently communicated the synthesis and isolation of platinum alkynyls in the liquid state at room temperature using trioctylphosphine as the auxiliary ligands [97]. It was proposed that these liquids may possess enhanced nonlinear optical properties. 

Many complexes and coordination compounds exist as isomers, compounds that contain the same numbers of the same atoms but in different arrangements. For example, the ions shown in (13a) and (13b) differ only in the positions of the Cl ligands, but they are distinct species, because they have different physical and chemical properties. Isomerism is of more than academic interest for example, anticancer drugs based on complexes of platinum are active only if they are the correct isomer. The complex needs to have a particular shape to interact with DNA molecules. 

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