Salt metathesis

Amidinate- and guanidinate-substituted boron halides are normally prepared using the two standard synthetic routes, i.e., salt-metathesis between suitable... 

The synthesis, structures, and reactivity of neutral and cationic mono- and bis(guanidinato)zirconium(rV) complexes have been studied in detail. Either salt-metathesis using preformed lithium guanidinates or carbodiimide insertion of zirconium amides can be employed. Typical examples for these two main synthetic routes are illustrated in Schemes 73 and 74. Various cr-alkyl complexes and cationic species derived from these precursors have been prepared and structurally characterized. 

Two principle strategies have been employed for the synthesis of siloxide-containing molecular precursors. The first involves a silanolysis, or condensation, reaction of the Si - OH groups with a metal amido, alkyl, hahde, or alkoxide complex. The second method involves salt metathesis reactions of an alkali metal siloxide with a metal hahde. Much of our work has been focused on formation of tris(tert-butoxy)siloxide derivatives of the early transition metals and main group elements. The largely imexplored regions of the periodic table include the lanthanides and later transition metals. 

An alternative pathway to Tc(I) complexes of the general composition [( -CsRs Tc(CO)3] has been described. This method follows the salt metathesis procedure of Fischer, in that [TcI(CO)s] is allowed to react with LifCsRs) or its derivatives, to produce the complexes [(fj5-C5R5)Tc(CO)3] and Lil in good yield, in short reaction time, and at room temperature [52], Beside the common H(CsRs) ligands, the more complicated system (HCjMe CF NN )... 

Several Ga, cube derivatives 31 have been synthesized by salt metathesis reaction, starting from R GaCl2 29 and dilithium organophos-phandiides 30 (Eq. 18) (57, 60, 61). Their formation occurred via cyclic intermediates, but Ga=P intermediates could not be detected. 

Germanium(iv) and tin(rv) compounds M(BH4)4 (M = Ge 51, Sn 52) have been synthesized by simple salt metathesis and characterized by IR spectroscopy.49 The cyclic Lewis acid/base adducts between (o-C6F4FIg)3 and [BH4]-, for example, [( -C6F4Hg)3(BFI4)2]2- 53 and [ ( -C6F4Hg)3 2(BH4)]- 54, have been characterized by IR and NMR spectroscopies.50... 

The dianionic Ga8 cluster [Ga8(flu)8]2 453 (flu = fluorenyl) has been synthesized by salt metathesis reaction between a metastable Ga Br solution and fluorenyllithium.344 The eight Ga atoms form a square antiprismatic core. This is rather unexpected because 453, which is a z/oro-cluster according to the Wade-Mingos rules, was expected to adopt the dodecahedral structure as was observed for the corresponding boron clusters. However, computational calculations demonstrated that in the case of eight Ga atoms, the formation of a square antiprismatic structure is energetically favored (Figure 33). 

Metastable solutions of GaX (X = C1, Br) as well as conventionally prepared Gal react with lithium or sodium organometallics in standard salt metathesis reactions with formation of M2R4 (Section 3.07.4.1) as well as neutral and anionic clusters of the type MnRm]x m > n) (chapter 4.1). Moreover, metalloid clusters [MnRm]x (m < n), which feature different types of metallic core structures, have been obtained. Their formation strongly depends on the reaction conditions, in particular the reaction temperature, and the (donor) solvent. 

In analogy, K[BHEt3] can be used to prepare the potassium salt. Metathesis is employed for preparing tetraalkyl ammonium salts. The Li cation in [Li(thp)3]2-... 

Spirocompound 43 was prepared in low yields (20%) by salt metathesis reaction of tetrakis(lithiomethyl)silane with l,2-dichloro-l,l,2,2-tetramethyl disilane <20000M4223>. 

For laboratory use, the dehydration of LnCl3 (H20)x (x = 6,7) using NH4C1 is the favorite method of preparing anhydrous lanthanide chlorides [96b]. However, simple thermal dehydration, as accessible to lanthanide trif-lates, leads to the formation of undesirable lanthanide oxychlorides. Because the Ln-halide precursor is insoluble in aliphatic and aromatic hydrocarbons, the preparation of organolanthanides via salt metathesis is performed in coordinating solvents such as THF. 

The full-sandwich lanthanacarborane [Na(THF)2] [O75 -C2B9H11 )2La(THF)2] has been prepared by direct salt metathesis between Na2[C2B9Hn] and LaCb in THF. The structure of the anion is shown in Fig. 13.4.14(a). The average La-cage atom distance is 280.4 pm, and the ring centroid-La-ring centroid angle is 132.7°. 

Complexes of dmit2- are commonly generated either via ligand transfer from [Zn(dmit)2]2- (see Section III.G) or by salt metathesis using Na2dmit. Alkali metal salts of dmit2- are prepared by hydrolysis of the thioester dmit[C(0)Ph)]2. This dithioester is prepared by treatment of [Zn(dmit)2]2- with PhC(Q)Cl and... 

The majority of the ionic liquids in use are prepared via salt metathesis reactions and one of the greatest challenges in the field of ionic liquids concerns their synthesis in high purity. Until ionic liquids of well-defined purity... 

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