Coordinated triflate

What specific properties of these complexes have allowed isolation of five-coordinate Pt(IV), in the form of the trimethyl complex and the dihy-dridosilyl complexes These two types of complexes are significantly different, and their stability is apparently due to different factors. Comparing the trimethyl complex in Scheme 21(A) with the related but six-coordinate complexes of a similarly bulky oc-diimine ligand (98), shown in Scheme 23, is instructive. In Scheme 23A, triflate is clearly coordinated, exhibiting an O-Pt distance of 2.276(3) A (98), which is typical for Pt-coordinated triflate (108). This triflate complex A in Scheme 23 was obtained from dry tetrahydrofuran. The aqua complex cation B, also structurally characterized, was obtained from acetone containing trace water. An equilibrium between coordinated triflate and coordinated water, very likely via a common five-coordinate intermediate, was indicated by NMR spectroscopy (98). 

A cationic species with phosphorus in a four-membered ring with a 7t-delocal-ized system is provided by the l,3-diaza-2-phosphetin system. Majoral and coworkers [159] first reported such a ring, and more recently Despagnet-Ayoub and Grubbs [160] presented an X-ray structure of 31 (R /-Pr, Ar Mes, 2,6-diisopropyl-phenyl, Scheme 23) with the non-coordinating triflate anion. However, the rather... 

Fig. 11 (a) Formation of the cylindrical cage 37 by self-assembly. (b,c) Structure of 37 as determined by X-ray diffraction analysis ((b) side view, (c) top view, substituents and coordinated triflate ions omitted)... 

Compounds 460a and 460b possess cationic structures both in the solid state and in solution. The n-butyltin derivatives 460c and 460d dissociate also into ionic species in solution but are nonionic in the solid state and involve coordinating triflates, though the... 

A general approach to alkenylplatinum(II) complexes involves the use of alkenyl triflates. Reaction of [Pt(PPh3)4] produces an alkenyltris(triphenylphosphine)-platinum(II) cation, whereas with [Pt(PPh3)2(C2H4)] a complex with coordinated triflate is obtained ... 

Introduction of the weakly coordinating triflate ion at the axial positions of the M6Y12 "+ cluster is accomplished by the reactions... 

The triflato complex may be regenerated from other pentaammine complexes as described in Section 68. Such a property is useful since it allows a regeneration of the starting materials from products. Characteristic spectral properties of the complex include the presence of bands due to coordinated triflate in the IR spectrum, and electronic [X 315(sh), nm e 150 A/" cm", and 270 (220)]... 

The presence of coordinated triflate is also evident in the IR spectra, where all the triflate bands are split due to the presence of ionic and coordinated triflate. The complexes aquate relatively slowly for triflato complexes (0.1 M CFjSOjH) and have half-lives of aquation of 1 hr at 25°. The stereospecificity of their syntheses and subsequent reactions makes them useful intermediates in syntheses. 

A cationic 7r-complex is fonned when aryl triflates are employed with dppp, ° a strongly coordinating difunctional phosphine (Scheme 11). Thus, ionization occurs by dissociation of the weakly coordinating triflate counterion.Alternatively, a neutral TT-complex is generated after phosphine dissociation of one of the arms of a bidentate ligand (Scheme 12). ... 

The major synthetic methods utilized are described in the following sections. Methods for the syntheses of triflate salts are also described, because of their general use in nonaqueous chemistry in place of the perchlorate salts. Syntheses of specific trifluoromethanesulfonato complexes are described in cited references, and in Volumes 22 and 24 of Inorganic Syntheses. A review of coordinated triflates has also appeared recently. ... 

It then became clear that only certain ortl o-substituted or heterocyclic carboxylic acids undergo this reaction. To overcome this limitation, Goossen and coworkers [33] employed aryl sulfonates instead of aryl halides as the coupling partners in combination with a catalyst generated in situ from Pdl2, tolyl-2,2 -bis(diphenylphosphino)-l,l -binaphthyl (Tol-BINAP) or P(p-Tol)3, CUjO, and phenanthroline. The weakly coordinating triflate ions, released in the cross-coupling step, are unable... 

The efQcient one-pot two step procedure through intermediate triflate derivative 194 was elaborated for substitution of chloride in 176 with less reactive O- and N-nucleophiles [108] (Scheme 50). On the first stage [(Cl)BSubPcFi2] is treated with Me3SiOS02CF3 at 100-150 °C or with Ag0S02CF3 at 20 °C to form reactive species 194 - [ BSubPcFn] cation with weakly coordinated triflate anion. 

Thuery et al. reported about ytterbium (III) complexes of 72b. A 1 1 complex is formed starting from the metal nitrate, that is similar in structure to the Nd(III) complex. The replacement of the nitrate counterion by less coordinating triflate ion results in the formation of a 2 1 sandwich complex between 72b and ytterbium(III) which is hexacoordinated to six phenoxides of two ligands [67]. 

In 2010, Xia, Huang and co-workers reported an iron-assisted chiral phosphoric acid catalyst for the Fridel-Crafts reaction between indole and 3-aryl a -hydroxy enones (Fig. 16) [70]. Due to the evidence from electron spray ionization mass spectrometry (ESI-MS) analysis for the presence of iron phosphate salt, an iron/ proton dual activation mechanism was proposed to account the observed reactivity/ selectivity trends. Addition of a third acid component, silver triflate, was shown to be beneficial for the enantioselectivity, presumably by exchanging chloride to the less coordinating triflate anion. 

The relative reactivities of the most common aryl halides and pseudohahdes, regarding the oxidative addition, foUow the trend Arl > ArOTf > ArBr > ArCl > ArOTs. However, these trends can be altered selecting an appropriate catalytic system. For instance, Fu and coworkers demonstrated that the combination of Pd(dba)2 and P(t-Bu)3 selectively reacted with ArCl in preference for ArOTf [40]. Potentially, this could be explained by a more stable oxidative addition complex obtained from ArCl compared to the ArOTf, comprising the weakly coordinating triflate counterion, provided that the oxidative addition is indeed reversible in such cases. Moreover, oxidative addition complexes obtained from aryl chlorides are known to dimerize when isolated, which could possibly stabilize the T-shaped triligated palladium(ll) intermediate even further [36]. 

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