Table 2. CH and C=C Stretch Frequencies of an Ion-paired Cation with the {Cl₁₁^–} Anion in Comparison with Those of Their Neutral Analogues.

cation or neutral analogue	phase	CH stretches for =CH2 or =CH+		C=C stretches			ΔνC=Cc
CH2=C+–CH2–CH3	solid	3112	3056	1589a	1576	1561
CH2=CH–CH2–CH325	gas	3090	3008			1645	56
CH2=C+–CH3	solid	3104	b	1589	1576	1565
CH2=CH–CH322	gas	3087	2990			1642	66–77
	solid	3040				1556
(CH3)2C=CH222	gas	3088	2980			1660	104

^aThe most intense bands are underlined.

^bNot determined.

^cThe difference between C=C stretching frequencies of neutral alkenes and their corresponding carbocations.