Search results
Results from the WOW.Com Content Network
A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct. For example, NH 3 is a Lewis base, because it can donate its lone pair of electrons. Trimethylborane (()) is a Lewis acid as it is capable of accepting a ...
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]
HSAB theory. HSAB is an acronym for "hard and soft (Lewis) acids and bases ". HSAB is widely used in chemistry for explaining the stability of compounds, reaction mechanisms and pathways. It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemical species. 'Hard' applies to species which are small, have high charge states (the ...
ECW model. In chemistry, the ECW model is a semi-quantitative model that describes and predicts the strength of Lewis acid – Lewis base interactions. Many chemical reactions can be described as acid–base reactions, so models for such interactions are of potentially broad interest. The model initially assigned E and C parameters to each and ...
The Lewis definition is not limited to these examples. For instance, carbon monoxide acts as a Lewis base when it forms an adduct with boron trifluoride, of formula F 3 B←CO. Adducts involving metal ions are referred to as co-ordination compounds; each ligand donates a pair of electrons to the metal ion. [23]
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 ...
The adduct with diethyl ether, boron trifluoride diethyl etherate, or just boron trifluoride etherate, (BF 3 ·O(CH 2 CH 3) 2) is a conveniently handled liquid and consequently is widely encountered as a laboratory source of BF 3. [15] Another common adduct is the adduct with dimethyl sulfide (BF 3 ·S(CH 3) 2), which can be handled as a neat ...
[15] In Lewis theory an acid, A, and a base, B, form an adduct, AB, where the electron pair forms a dative covalent bond between A and B. This is shown when the adduct H 3 N−BF 3 forms from ammonia and boron trifluoride, a reaction that cannot occur in water because boron trifluoride reacts violently with water in a hydrolysis reaction. [16]