Aryls rhenium

Scheme 9.5 Herrmann s preparative routes to alkyl and aryl rhenium(VII) trioxides 12 [R = Me, Et, nPr, iBu, CH2SiMe3, CH2CHMe2, CH2CH—CH2, C(Me)—CH2, Ph, p-Tol, o-Tol, Mes, CgF5, C5H5, C5Me5, etc.] with 11 and 13 as the precursors...

Non-ionic thiourea derivatives have been used as ligands for metal complexes [63,64] as well as anionic thioureas and, in both cases, coordination in metal clusters has also been described [65,66]. Examples of mononuclear complexes of simple alkyl- or aryl-substituted thiourea monoanions, containing N,S-chelating ligands (Scheme 11), have been reported for rhodium(III) [67,68], iridium and many other transition metals, such as chromium(III), technetium(III), rhenium(V), aluminium, ruthenium, osmium, platinum [69] and palladium [70]. Many complexes with N,S-chelating monothioureas were prepared with two triphenylphosphines as substituents. 

As with their trans isomers, treatment of the nitrile complexes cw-[ReCl(NCR)(dppe)2] (R = aryl) with [Et20H][BF4] or TMSCF3SO3 in CH2CI2 leads to the formation of the methylenamide compounds cA-[ReCl NC(E)R (dppe)2] (E = H, TMS) and tra x-[ReCl(NCHR)-(dppe)2]. The products undergo deprotonation by bases such as [NBu4]OH to form the trans isomers of the corresponding nitrile complexes [ReCl(NCR)(dppe)2]. Reactions of cis-[ReCl(NCR)(dppe)2] complexes with [Et30][PFg] result in oxidation and isomerization to afford the rhenium(II) complexes tra 5-[ReCl(NCR)(dppe)2][PF6]. ... 

It was later found that some aldehyde complexes of rhenium, [Re(NO) (PPh3) 0=C(Aryl)H (Tj-C5H5)]BF4, are also present in solution as a rapidly interconverting mixture of rf isomers and the if isomer.48,49 With the exception of solvent dependence, similar dependencies of the equilibrium constants on the aryl substituents and on the temperature were observed. The solvent dependence was found to be opposite, which, however, is easily understood when taking into account that the rhenium aldehyde complexes are cationic whereas the chromium and tungsten thio- and selenoaldehyde complexes are neutral. 

A rhenium catalyst is quite valuable for the direct allylation of cr-aryl-substituted propargyl alcohols with 10 (Equation (58)).220 Benzyl alcohols are efficiently allylated with allylchlorodimethylsilane under catalysis by InCl3.221... 

Apart from the platinum and nickel compounds with cr-bonded alkyl or aryl ligands, Chatt s group reported between 1961 and 1966 the synthesis of an impressive series of related cobalt(II), iron(II), rhodium(III), iridium(III), rhe-nium(III) and rhenium(V) complexes [39-42]. The paramagnetic cobalt(II) and iron(II) derivatives MR2(PR 3)2 were stable when R was an aryl group with... 

Since the organometallic chemistry of rhenium is surveyed in the companion series Comprehensive Organometallic Chemistry,6 every effort has been made to minimize overlap with these topics, although an occasional reference is made in the present review to certain alkyl, aryl, carbonyl and isocyanide complexes that may be covered more fully in the excellent review by Boag and Kaesz.6... 

The lability of the N2 ligand towards alkyl and aryl isocyanides has been demonstrated by equation (2) which occurs readily with both alkyl and aryl isocyanides.40 The resulting complexes are electron rich , the alkyl isocyanide derivatives ReCl(CNR)(dppe) (R = Me or Bul) undergoing electrophilic attack upon treatment with HBF4 to form the carbyne complexes trcms-[ReCl(CNHR)(dppe)2]BF4.41 Other noteworthy features of the series of complexes ReCl(CNR)(dppe)2 and ReCl(CNAr)(dppe)2, are the low value of v(CN), the presence of a bent M—CNR coordination mode, and their ease of oxidation (as measured by cyclic voltammetry) to the corresponding rhenium(II) monocations.40... 

When the reactions between various aryl isocyanides ArNC and (Bu4N)2Re2Cl8 are carrried out in methanol at room temperature, then rhenium(III)-containing complexes of the types [Re(C-NAr)6]+[ReCl4(CNAr)2] and ReCl3(CNAr)3 can be isolated.21 These compounds display well-defined electrochemistry (cyclic voltammetry) in 0.2 M (Bu4 N)PF6-CH2Cl2, the mononuclear Re111... 

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