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A good example is the formation of adducts between the Lewis acid borane and the oxygen atom in the Lewis bases, tetrahydrofuran (THF): BH 3 ·O(CH 2) 4 or diethyl ether: BH 3 ·O(CH 3 CH 2) 2. Many Lewis acids and Lewis bases reacting in the gas phase or in non-aqueous solvents to form adducts have been examined in the ECW model. [3]
Acids and bases. A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in ...
Non-nucleophilic. Weak. v. t. e. A frustrated Lewis pair (FLP) is a compound or mixture containing a Lewis acid and a Lewis base that, because of steric hindrance, cannot combine to form a classical adduct. [1] Many kinds of FLPs have been devised, and many simple substrates exhibit activation. [2][3] The discovery that some FLPs split H 2[4 ...
Examples of these unstable tetrahalodiborane-lewis base adducts include the bis-diethyl ether adduct formed with B 2 Cl 4 or B 2 F 4, the bis-adduct of B 2 Cl 4 and either SH 2 or PH 3, and adducts formed by B 2 Cl 4 or B 2 F 4 and weak phosphine donors such as PCl 3 or PBr 3. [11] There are, however, some adducts that are stable beyond room ...
Boron trifluoride is a versatile Lewis acid that forms adducts with such Lewis bases as fluoride and ethers: CsF + BF3 → Cs [BF4] O (CH 2 CH 3) 2 + BF3 → BF3·O (CH2CH3)2. Tetrafluoroborate salts are commonly employed as non-coordinating anions.
Since Lewis adducts are formed by dative bond between Lewis bases and Lewis acids, the orbital overlap between the Lewis base and σ*(Sb–X) orbital is the source of the acidity. According to Gabbaï et al., NBO analysis of the Sb(C 6 F 5) 3 P(O)Ph 3 adduct indicates a donor-acceptor interaction between lp(O) and σ*(Sb–C 6 F 5). [7] [8]
In chemistry, phosphine-boranes are organophosphorus compounds with the formula R 3−n H n PBH 3. They are Lewis acid-Lewis base adducts derived from organophosphines (PR 3−n H n) and borane (BH 3 ). They are generally colorless or white solids. Since these adducts are air-stable, they represent a protected form of the parent organophosphine.
Interaction of triethylphosphine oxide with a Lewis acid Boron trihalides are archetypal Lewis acids and have AN values between 89 (BF 3 ) and 115 (BI 3 ). [ 2 ] The Gutmann–Beckett method has been applied to fluoroarylboranes [ 7 ] [ 8 ] such as B(C 6 F 5 ) 3 (AN 82), and borenium cations, and its application to these and various other boron ...