Transmetalation as a Route to a Cyclic Heteronuclear Bifunctional Lewis Acid Containing Tin and Gallium

Tschinkl, Martin; Hoefelmeyer, James D.; Cocker, T. Matthew; Bachman, Robert E.; Gabbaı̈, François P.

doi:10.1021/om0002024

Cited by 25 publications

(11 citation statements)

References 44 publications

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“…The second pyridine molecule may either coordinate to the Lewis acidic tin group or to boron thus replacing chloride under formation of a boronium cation. Coordination of pyridine to tin has, for example, been recently reported by Gabbaï and co‐workers for a heteronuclear bifunctional Lewis acid featuring tin and gallium atoms adjacent to each other 39. Formation of boronium cations from organoboron halides on the other hand is a common process,40 and we indeed found that the monofunctional Lewis acid [FcB(Cl)Me] readily forms a boronium cation with two equivalents of pyridine (see vide infra).…”

Section: Resultssupporting

confidence: 72%

“…Steric congestion around tin results in rotation of the stannyl moiety thereby providing maximum space for the two axial chloride ligands. However, significant steric strain in the zwitterion 7 is still encountered as reflected in a strong upward tilt of the stannyl group of 11.7° relative to the Cp plane as well as strong distortions of the angles C(2)‐C(1)‐Sn(1) of 134.5(3)° and C(5)‐C(1)‐Sn(1) of 117.0(3)° between tin and the Cp ring (undistorted angle: 126°) 45. The Sn–Cl(2) distance of 2.7827(12) Å is significantly longer than that observed for Sn–Cl(1) of 2.5549(13) Å.…”

Section: Resultsmentioning

confidence: 99%

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Binding Cooperativity of Two Different Lewis Acid Groups at the Edge of Ferrocene

Boshra¹,

Sundararaman²,

Zakharov³

et al. 2005

Chemistry A European J

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The binding properties of heteronuclear bidentate Lewis acids, in which an organoboron and an organotin moiety are attached adjacent to each other at one of the Cp rings of ferrocene, have been studied. Treatment of [1,2-fc(SnMe2Cl)(BClMe)] (1-Cl) (fc = ferrocenediyl) with one equivalent of pyridine or 4-dimethylaminopyridine (DMAP) resulted in diastereoselective complexation of boron. Adducts 2 and 3 have been studied by multinuclear NMR, and the stereoselectivity of complexation was further confirmed by single crystal X-ray diffraction of 2. The importance of cooperative effects that involve an intramolecular B-ClSn interaction on the diastereoselectivity is evident from comparison with binding studies on the phenyl-substituted analogue [1,2-fc(SnMe2Cl)(BPhMe)] (1-Ph). Complexation of 1-Ph led to diastereomeric mixtures of adducts 4 and 5, respectively, which were identified by multinuclear NMR including NOESY experiments. The solid-state structure of one of the diastereomers of 5 was confirmed by X-ray crystallography. Facile isomerization was found in solution and the barrier of activation was determined by VT NMR studies (4: Delta(#)(298) = 54.9+/-0.4 kJ mol(-1); 5: Delta(#)(298) = 70.3+/-0.1 kJ mol(-1)). Competitive binding of pyridine to 1-Cl and [FcB(Cl)Me] (Fc = ferrocenyl) showed that cooperative effects between tin and boron lead to significant Lewis acidity enhancement. Binding of a second nucleophile in the presence of excess of base occurred also at boron. The novel zwitterionic complexes [1,2-fc(BMe(py)2)(SnMe2Cl2)] (6) and [1,2-fc(BMe(dmap)(2))(SnMe(2)Cl2)] (7) formed, which consist of boronium cation and stannate anion moieties. The structure of 7 in the solid-state was confirmed by X-ray crystallography. Multinuclear NMR data and competition experiments indicate weak binding of chloride to tin in 7 and partial dissociation in solution.

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Binding Cooperativity of Two Different Lewis Acid Groups at the Edge of Ferrocene

Boshra¹,

Sundararaman²,

Zakharov³

et al. 2005

Chemistry A European J

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“…When using a bulkier radical, such as 2,4,6-trisisopropylphenyl (Trip), instead of Mes in the starting nickel complex, [NiBr(Ar)(PPh 3 ) 2 ], the formation of a product analogous to {dmit(Mes)} 2 ({dmit(Trip)} 2 , 5) occurs, but as the major product of the reaction. Although [Ni(dmit)(PPh 3 )] 2 (1) is obtained as well, the related thiolate thioether derivative (3) [Ni(Trip)(dmitTrip)(PPh 3 )] is not, probably as a consequence of steric factors.…”

Section: Resultsmentioning

confidence: 99%

S,C- and S,S-coupling via dithiolate transfer reactions from tin to nickel complexes

2009

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Dithiolate tin(iv) complexes [SnMe(2)(SS)] (SS = 4,5-dimercapto-1,3-dithiol-2-thione, dmit; 1,2-benzene dithiolate, bdt; and 3,4-toluene dithiolate, tdt) are used as transmetallating agents in the reaction with nickel derivatives [NiBrR'(PR(3))(2)] (R' = mesitylene (Mes) and 2,4,6-trisisopropylphenyl (Trip), and PR(3) = PPh(3) and PPh(2)Me). The reaction results in the isolation of different complexes with a great variety of stoichiometries, including mono-, di- and trinuclear nickel complexes with the general formulae: [Ni(SS)(PR(3))](2), [Ni(Mes)(SS-Mes)(PR(3))], [Ni(SS-Mes)(2)] and [Ni(3)(bdt)(3)(PPh(2)Me)(2)], and the organic compounds {dmit(Mes)}(2), {dmit(Trip)}(2), {dbt(Mes)(2)} and {tbt(Mes)(2)} as a consequence of S,C- and S,S-coupling processes. In the case of [Ni(Mes)(dmitMes)(PPh(2)Me)], {dmit(Trip)}(2), [Ni(3)(bdt)(3)(PPh(2)Me)(2)] and [Ni(bdtMes)(2)] the X-ray analyses are also presented to confirm the proposed structures.

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“…Upon addition of pyridine, both Lewis acidic metals are independently coordinated. 27 In related studies, Gabbai and coworkers showed the same 1,8-bis(trimethylstannyl)naphthalene precursor can be transmetalated with indium trichloride to yield a dimeric indium macrocycle. The reported diindacycle synthesized by transmetalation is isolated in 65% yield, whereas metathesis of a 1,8-dilithionaphthalene with InCl 3 and tmeda gives the diindacycle in only 25% yield by NMR spectroscopy.…”

Section: Supramolecular Transmetalation: Direct Exchangementioning

confidence: 99%

Transmetalation of self-assembled, supramolecular complexes

2014

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Substituting one metal for another in inorganic and organometallic systems is a proven strategy for synthesizing complex molecules, and in some cases, provides the only route to a particular system. The multivalent nature of the coordination in metal-ligand assemblies lends itself more readily to some types of transmetalation. For instance, a binding site can open up for exchange without greatly effecting the many other interactions holding the structure together. In addition to exchanging the metal and altering the local binding environment, transmetalation in supramolecular systems can also lead to substantial changes in the nature of the secondary and tertiary structure of a larger assembly. In this tutorial review we will cover discrete supramolecular assemblies in which metals are exchanged. First we will address fully formed structures where direct substitution replaces one type of metal for another without changing the overall supramolecular assembly. We will then address systems where the disruptive exchange of one metal for another leads to a larger change in the supramolecular assembly. When possible we have tried to highlight systems that use supramolecular self-assembly in tandem with transmetalation to synthesize new structures not accessible through a more direct approach. At the end of this review, we highlight the use of transmetalation in self-assembled aqueous inorganic clusters and discuss the consequences for material science applications.

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Transmetalation as a Route to a Cyclic Heteronuclear Bifunctional Lewis Acid Containing Tin and Gallium

Cited by 25 publications

References 44 publications

Binding Cooperativity of Two Different Lewis Acid Groups at the Edge of Ferrocene

Binding Cooperativity of Two Different Lewis Acid Groups at the Edge of Ferrocene

S,C- and S,S-coupling via dithiolate transfer reactions from tin to nickel complexes

Transmetalation of self-assembled, supramolecular complexes

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