Syntheses of the Metal Complexes

Methanol solutions of COaEtHLl (0.1 M, 1 mL), cadmium acetate (0.1 M, 2 mL), sodium acetate (0.1 M, 1 mL) and sodium hexafluorophosphate (0.1 M, 3 mL) were combined with methanol (2 mL) and the yellow solution was left to evaporate slowly at room temperature. White crystals were obtained after 5 days. After recrystaUization from a minimum of hot methanol the complex was obtained in a 66 % yield (40 mg). 

C02EtHL2 (180 mg, 0.34 mmol) was dissolved in methanol and cadmium(II) acetate dihydrate (183 mg, 0.68 mmol) and sodium acetate (56 mg, 0.68 mmol) added. The yellow solution was subsequently refluxed for 30 min and then allowed to cool to room temperature and sodium hexafluorophosphate (115 mg, 0.68 mmol) added. After filtration the yellow solution was left to evaporate at room temperature to leave a yellow oil. Attempts to crystallize the complex from a range of solvents were unsuccessftil. The complex was, however, readily formed as confirmed by mass spectroscopic measurements. After repeated (5x) evaporation of the methanolic complex solution a white powder was obtained. 

Method 2 (X-ray suitable crystals were obtained with this procedure) All solutions were made up in degassed methanol and combined under nitrogen in a Schlenk flask. A flask containing diethyl ether (10 mL) was attached to the Schlenk flask. When the diffusion was complete, the pink solution was poured in a beaker and left to evaporate for 3 days to yield pink needles which were subsequently analyzed by X-ray crystallography. The mass spectra of the crystals obtained by methods 1 and 2 were identical. 

C02EtHL2 (100 mg, 0.19 mmol) was dissolved in methanol (4 mL) and was combined with a solution of cobalt(II) acetate tetrahydrate (95 mg, 0.38 mmol) in methanol (6 mL). Subsequently solid sodium hexafluorophosphate (95 mg, 0.57 mmol) was added. The solution was left in a beaker at room temperature to evaporate. Pink crystals which were suitable for X-ray crystallography were obtained in 70 % yield (120 mg). 

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Phthalocyanine Dyes. These days are synthesized as the metal complex on the textile fiber from, eg, phthalonittile and metal salts. A print paste typicaUy contains phthalonittile dissolved in a suitable solvent and nickel or copper salts. During a heat or steam fixation of 3—5 min, the dye is formed. The color range is restricted to blue and green shades and can be influenced to some extent by the choice of metal salt. A hot acid bath during afterscouting completes the process. 

The formation of monomer and dimer of (salen)Co AIX3 complex can be confirmed by Al NMR. Monomer complex la show Al NMR chemical shift on 5=43.1 ppm line width =30.2 Hz and dimer complex lb 5=37.7 ppm line width =12.7 Hz. Further instrumental evidence may be viewed by UV-Vis spectrophotometer. The new synthesized complex showed absorption band at 370 nm. The characteristic absorption band of the precatalyst Co(salen) at 420 nm disappeared (Figure 1). It has long been known that oxygen atoms of the metal complexes of the SchifT bases are able to coordinate to the transition and group 13 metals to form bi- and trinuclear complex [9]. On these proofs the possible structure is shown in Scheme 1. 

A number of the heavier group 10 metallacarboranes have been synthesized and many structurally characterized. As part of their investigations of the metal complexes of the monocarbaboranes, Stone and co-workers studied the reactions of the hydrido complexes [PtH(PEt3)2(T]S-7-CB10H11)] with [AuCl(PPh3)], [HgCIPh], and [CuCl(PPh3)]4 to... 

Within the monohydridic route, apart from the already explained inner-sphere mechanisms, there is another possibility involving the concerted outer-sphere transfer of one hydride and one proton to the corresponding substrate (Scheme 4b). This mechanism is very common to the so-called bifunctional catalysts. This term was proposed by Noyori for those catalysts having one hydrogen with hydridic character directly bonded to the metal center of the catalyst, a hydride ligand, and another hydrogen with protic character bonded to one of the ligands of the metal complex (20). In Scheme 9, examples of bifunctional catalysts that are synthesized... 

Many syntheses of supported metal complexes involve simply the reaction of an organometallic precursor in an organic solvent with a support surface alternatively, a gas-phase precursor may be used in the absence of a solvent. The surface reactions are typically analogous to molecular reactions known from solution organometallic chemistry. The surface chemistry has been reviewed (Lamb, Gates, and Knozinger, 1988 Basset, Lefebvre, and Santini, 1998), and only a few examples are given here. 

Reactions of the (Tj5-C5Hs)cobaIt-olefin complexes (26) prepared according to Eqs. (25) and (26) with alkali metals (Li, Na, K) in the presence of olefins lead to the elimination of the second C5H5 ligand from the cobalt (Scheme 5). Complexes 27a and 27b, or the mixed complex 27c are obtained in high yields [Eq. (28)]. The syntheses of the pure complexes 27a and 27b do not, of course, require the isolation of intermediates 26a and 26b. As mentioned previously, synthesis is readily achieved from cobaltocene (24) by reaction with either stoichiometric amounts or excess alkali metal in the presence of COD or ethylene [Eq. (24)]. The alkali metal cyclopentadienides which are formed are easily separated from the cobalt complexes and can be used for the synthesis of cobaltocene (51) [Scheme 5 Eq. (29)]. 

Figure 3.2S The structure of (a) [Dy(H20)(DTPA)] and (b) [Dy2(DTPA)2] [Dy, black (large balls) O, grey N, black (small balls) C, white H, omitted)]. (Redrawn from the CIF files of J. Wang et al, Syntheses and structural determinations of the nine-coordinate rare earth metal Na4[Dy "(dtpa)(H20)]2 l6H20, Na[Dy "(edta)(H20)3]-3.25H20 and Na3[Dy (nta)2(H20)]-5.5H20, Journal of Coordination Chemistry, 60 (20), 2221-2241, 2007 [106] and Y. Inomata, T. Sunakawa and F.S. HoweU, The syntheses of lanthanide metal complexes with diethylenetriamine-N, N, N, N", N"-pentaacetic acid and the comparison of their crystal structures, Journal of Molecular Structure, 648 (1-2), 81-88, 2007 [107].)...

Inomata, Y, Sunakawa, T., and Howell, F.S. (2007) The syntheses of lanthanide metal complexes with diethylenetriamine-N, N, N, N",N"-pentaacetic acid and the comparison of their crystal structures. Journal of Molecular Structure, 648 (1-2), 81-88. 

The literature was reviewed to describe the newest efforts to synthesize and characterize supported polynuclear metal complexes as adsorbents and catalysts. This review includes our attempts to model the equilibrium structures and properties of the metal complexes, using simple quantum mechanics, as a means to understand better the interactions between the surface and the metal complexes. Special attention is directed towards the characterization of the supported metal complexes before and after ligand removal. We compare these modeling results with observations in the literature so as to understand better the fundamental processes that govern the interactions between the metal complexes and the surfaces. With this enhanced understanding of these governing factors, it should be easier to prepare oxide solids decorated with metal complexes having the desired physico-chemical properties. 

The use of polynuclear metal complexes provides a novel approach to the synthesis of supported metals and metal oxides. Mark White (Georgia Tech) shows how these materials can be synthesized and characterized. Quantum mechanics are used to compare predicted and experimental results of the interactions of the metal complexes and surfaces. The use of these materials as both adsorbents and catalysts suggests the importance of understanding both how they are synthesized, and their post-synthesis structure. 

Metal ion directed (template) syntheses of the macrobicyclic complexes are effected through cyclization of the preformed tris-complexes or semiclathrochelate as well as via interaction of metal ion bis-complexes with cross-linking agents. 

Hybrid systems have been constructed in which a metal complex is covalently linked to an organic species so as to produce a donor-acceptor dyad, with either subunit functioning as the chromophore. Thus, ruthenium(II) tris(2,2 -bipyridyl) complexes have been synthesized bearing appended anthraquinone or tyrosine functions. Both systems enter into intramolecular electron-transfer reactions. With an appended anthraquinone moiety, direct electron transfer occurs from the triplet excited state of the metal complex to the quinoid acceptor. This is not the case with tyrosine, which is an electron donor, but the metal complex can be photooxidized by illumination in the presence of an added acceptor. The bound tyrosine residue reduces the resultant ruthenium(III) tris(2,2 -bipyridyl) complex... 

NHC precursors 47a and 47b may be used to generate the corresponding free carbene because an alcohol or chloroform readily eliminates from carbon (equation 10.20). Chemists can synthesize and isolate these precursors before allowing them to react with metal complexes or simply generate them in situ in the presence of the metal complex. 

Hsu et al. [75,76] reported a new method for incorporating metal complexes into polyfluorenes to prepare phosphorescent polymers (polymer 47 and 48). A pyridine end-capped polyfluorene has been synthesized. The pyridine was used to form a polymer metal complex with 2,2-bipyridyl(tri-carbonyl)rhenium(I) chloride. Using the end-capping approach not only can control the molecular weight of polymer, but also avoid the interference of the metal complex and conjugated polymer in energy transfer. They can... 

More recently, a similar approach was taken by Macartney and coworkers to synthesize [2]rotaxanes (Figure 4). Rotaxane 2 is self-assembled efficiently in solution from a-CD, [Fe(CN)5(H20)] and l,l -( f5 -alkanediyl)bis(4,4 -pyridyl-pyridium) ion. The [2]rotaxane is also formed by the addition of a-CD to a solution of the dumbbell component [(CN)5Fe(bpy(CH2)nbpy)Fe(CN)5]. This result infers a slow dissociation of the terminal metal complex, followed by formation of an intermediate pseudorotaxane and reassociation of the metal complex. 

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