Effect of Lewis acids on rate of CO₂ insertion into (^tBuPBP)Pd(CH₃) in THF at 40 °C and 1 atm of CO₂.

Entry	Additive (20 equiv.)	k obs b (s−1 × 10−3)	Rate enhancement
1	None	1.6	1
2	(NBu4)PF6	2.3	1.4
3	LiNTf2a	2.2	1.4
4	NaNTf2a	2.1	1.3
5	KNTf2a	2.3	1.4
6	LiPF6	2.4	1.5
7	LiBPh4·3DME	2.5	1.6
8	LiOTf	2.1	1.3

^aNTf = triflimide.

^bThese values are the average of two trials and the errors are ±10%.