Transition metal halides reagents

A variety of complexes of the thionyl imide anion [NSO] with both early and late transition-metal complexes have been prepared and structurally characterized. Since both ionic and covalent derivatives of this anion are readily prepared, e.g., K[NSO], McsMNSO (M = Si, Sn) or Hg(NSO)2, metathetical reactions of these reagents with transition-metal halide complexes represent the most general synthetic method for the preparation of these complexes (Eq. 7.10 and 7.11). ... 

The synthesis involves the nickel-catalyzed coupling of the mono-Grignard reagent derived from 3-alkyl-2,5-diiodothiophene (82,83). Also in that year, transition-metal halides, ie, FeQ3, MoCb, and RuCl3, were used for the chemical oxidative polymerization of 3-substituted thiophenes (84). Substantial decreases in conductivity were noted when branched side chains were present in the polymer structure (85). 

Similar arguments are also valid for the successful preparation of hydridophosphinemetalates (shown in Figure 5) from the reaction of transition metal halide complexes with KH and suitable crown ether reagents <1998JA13138>. These materials are quite interesting for their reactivity as strong nucleophiles and reductants. 

Allylmagnesium halide and lithio reagents are available from allyl halides by lithiation and Mg reaction techniques. These active reagents combine with binary or complex transition-metal halides to form transition-metal-allyl complexes, including both homoleptic and ligand-substituted tj -allyl complexes with substituted and unsubstituted allyl groups. 

Ashby et al. have studied reductive dehalogenation by the combined use of LAH and first row transition metal halides (Co", Ni", Fe", Fe" , Mn", Ti " and V" ). - Table 2 shows that C0CI2, NiCh and TiCb notably elevate the reducing ability of LAH, and the added salts need only be present in catalytic amounts (10 mol %). Among them, the reagent system LAH-NiCh shows the highest reactivity that is, primary, secondary and cyclic halides (I, Br, Cl) are reduced in essentially quantitative yield at room temperature. 

Reaction of a transition metal halide with organolithium, organomagnesium, or organoaluminum reagent. 

The standard method of synthesis involves the reaction of suitable transition metal halides with Fc-Li [49, 113, 171 — 180, 189, 190], although HgFcj has also been used as ferrocenyl transfer reagent [181 — 183]. A different approach to ferrocenyl complexes proceeds via thermal or photo-induced decarbonylation of the corresponding ferrocenoyl compounds [178,184]. All three routes have been applied to prepare the half-sandwich/sandwich complex CpFe(CO)2-Fc, which contains two different iron centers (Scheme 5-24). It is surprising that Fc-SnMej has rarely been used [185] for ferrocenyl transfer. 

Obviously the used cyclopentadienyl donor ligand late transition metal halides are unsuitable reagents to form silyl complexes with 1. In order to determine the molecular stmcture of CpFe(CO)2Si6Meii (9), it was finally prepared from KCpFe(CO)2 and MenSiel [6]. The results of the X-ray structure analysis are shown in Table 1 and Fig. 1 [7]. 

Recent developments in catalysis at the atomic level are described. The use of transition metal halides which form intermediate metal n-complexes can promote both the catalytic and stoichiometric coupling of aryl Grignard reagents, the stereospecific coupling of 1,2 disubstituted vinyl groups and the double coupling of ethylene to dimers of butadiene. 

Reaction of transition metal halides with organolithium, organomagne-sium, or organoaluminum reagent. 

A versatile method for the preparation of olefin metal complexes has been developed by E. 0. Fischer and his coworkers a Grignard reagent (preferably isopropyl magnesium bromide) is reacted with a mixture of a transition metal halide and an olefin in ether. Subsequent irradiation increases the yield and accelerates the formation of the corresponding metal complexes. 

Few reagents are available for the preparation of organometallic and coordination complexes of the early transition metals. The anhydrous metal halides often lead to disproportionation reactions, and the nitrile derivatives,1 MX (NCR)>, are not suitable because of the reactivity of the nitrile with many other reagents. The procedures described below provide simple, high-yield routes to the tetrahydrofuran (THF) complexes of selected, early transition metal halides.2 They have been useful for the synthesis of a wide variety of organometallic complexes.3... 

Use of main-group metal silyls to prepare transition-metal silyls appears to be a generally applicable method that is primarily limited by the availability of suitable starting materials, since these silyl anion reagents are sometimes rather difficult to obtain. Typically an alkali-metal silyl is generated in solution and then treated with the appropriate transition-metal halide. Displacement of halide by the silyl anion, with salt elimination, then leads to product (equations 17-19)46 49. The lithium silyl in equation... 

Wilkinson and coworkers obtained stable alkyl complexes by the reaction of transition metal halides or complex halides with trimethylsilylmethyl lithium 72 With these alkyl complexes, no /3-elimination reaction proceeds. The action of Grignard or organolithium reagents on halogen complexes of Pt(II) and Pd (II) has been widely used for the preparation of alkyl complexes, and quite stable alkyl complexes of noble metals can be prepared 73K... 

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