Table 1. Effect of solvent and LAs on the rate of CO₂ insertion into 1.

Entry	Solvent	k 1 (M–1 s–1) at RT	Rate increase	Activation parameters a
1a	THF	6.8 ± 0.7	—	ΔH‡ = 6.3 (3)
				ΔS‡ = –33 (1)
				ΔG‡298 K = 16.3 (4)
1b b	THF + LiPF6	6.6 ± 0.7	—	—
1c b , c	THF + NaBArF4	6.7 ± 0.7	—	—
2	Benzene	15 ± 2	2	—
3	1,4-Dioxane	15 ± 2	2	—
4	Acetone	51 ± 5	8	—
5	1,2-DCE d	1.2 (1) × 102	18	—
6	DMI e	1.3 (1) × 102	19	—
7	Pyridine	1.3 (1) × 102	19	—
8	MeCN	2.2 (2) × 102	32	ΔH‡ = 6.0 (3)
				ΔS‡ = –28 (1)
				ΔG‡298 K = 14.3 (3)

^aΔH^‡ and ΔG^‡ in kcal mol^–1 and ΔS^‡ in cal mol^–1 K^–1.

^b[LA] = 6.0 mM (20 equivalents with respect to 1).

^cNaBArF₄ = sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

^d1,2-DCE = 1,2-dichloroethane.

^eDMI = 1,3-dimethyl-2-imidazolidinone.