Non coordination

The BH4 ion is essentially non-coordinating in its alkali metal salts. However, despite the fact that it is isoelectronic with methane, BH4 has been found to act as a versatile ligand, forming many coordination compounds by means of 3-centre B-H M bonds to somewhat less electropositive metals. " Indeed, BH4 ... 

Aqueous solutions of salts with non-coordinating anions contain the pale-pink, [Mn(H20)6] +, ion which is one of a variety of high-spin octahedral complexes which have been... 

THF. Non-coordinating solvents sucli as toluene or mixed toluene/cliloroalkane solvent systems afford tlie higliest tt values. 

ILs are considered to be polar solvents, but can be non-coordinating (mainly depending on the IL s anion). Solvatochromatic studies indicate that ILs have polarities similar to those of short-chain alcohols and other polar, aprotic solvents... 

Simple metal compounds are poorly soluble in non-coordinating ILs, but the solubility of metal ions in an IL can be increased by addition of lipophilic ligands. LLowever, enhancement of lipophilicity also increases the tendency for the metal complex to leach into less polar organic phases. 

Sect. 2.1.1) and [3C+2S] cyclopentene derivatives. The product distribution can be controlled by choosing the appropriate reaction conditions [72]. Moreover, the cyclopentene derivatives are the exclusive products from the coupling of fi-pyrrolyl-substituted carbene complexes [72b,c] (Scheme 25). The crucial intermediate chromacyclobutane is formed in an initial step by a [2+2] cycloaddition. This chromacyclobutane rearranges to give the rf-complex when non-coordinating solvents are used. Finally, a reductive elimination leads to the formal [3C+2S] cyclopentene derivatives. 

Wulff et al. examined the necessary reaction conditions for a,fi-unsaturated aminocarbene complexes to react in a benzannulation reaction [23]. The reaction of dimethylamino(alkenyl)carbene complexes 18 with terminal alkynes in non-coordinating and non-polar solvents afforded phenol products in acceptable yields (Scheme 12). 

In the low molecular weight fraction a relatively high content of the 3,4-linkages is formed, characteristic of the polymers produced in the presence of TMEDA. On this basis it was concluded that the unassociated polymers coordinated with TMEDA propagate more slowly than those unassociated and non-coordinated with the diamine, a conclusion concordant with the previously discussed findings of Fontanille84) and confirmed by Schue, 55> for lithium polyisoprene. 

The introduction in the polymer of non-coordinative -0-(CH2)x-CH3 side chains (Table 13) leads to a decrease of the conductivity from 1.29x10 for x=2 to 1.9x10 S cm for x=9, which shows that a great number of donor sites is primordial for the ion transport [278]. 

Kinetic studies of the hydride cluster [W3S4H3(dmpe)3] with acids in a non-coordinating solvent, i.e., dichloromethane, under the pseudo-first-order condition of acid excess, show a completely different mechanism with three kineti-cally distinguishable steps associated to the successive formal substitution of the coordinated hydrides by the anion of the acid, i.e., Ch in HCl [37]. The first two kinetic steps show a second-order dependence with the acid concentration. 

The accumulation of carbonates is another reason for gold catalyst deactivation [9]. The in-situ FTIR experiments in Fig. 6 show that the carbonate build-up is slower in the 03/02-treated gold catalyst (Fig. 6a) compared to the air-treated sample (Fig. 6b). Also, the air-treated catalyst displays a strong band at 1435 cm" corresponding to the non-coordinated carbonate. Although our understanding of the process is incomplete, it is clear from the results that O3 pretreatment inhibits the deactivation of gold catalyst. 

The C(arene)- Br bonding does not markedly perturbed the geometry of the dibromine, which is rather sensitive to coordination/ polarization effects and the bond readily elongates from 2.284 A in the non-coordinated molecule to 2.53 Ain the [Br3] anion [41]. Indeed, the Br-Br bond lengths of 2.301 (2) A... 

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