Table 1.

Polymerization of L-Lactide and ε-caprolactone using complexes 1–2, 4 at 50°C^a.

Entry	Monomer	Solvent	Cat.	{[M]0:[Zn]0}:[BnOH]	Time (min)	Mn (obsd)b	Mn (calcd)c	Conv.(%)d	Yield (%)e	Mw/${\text{M}}_{\text{n}}^{\text{b}}$
1		Toluene	1	50:1	15	10,600 (6,200)	6,900	94	79	1.16
2		Toluene	2	50:1	15	11,800 (6,800)	6,900	94	75	1.07
3		Toluene	4	50:1	120	–	–	15	–	–
4		Toluene	4	50:1	1,440	21,000 (12,200)	7,200	98	82	1.38
5		Toluene	1	200:1	45	40,300 (23,400)	28,400	98	86	1.35
6		Toluene	1	300:1	50	27,700 (16,100)	42,100	97	88	2.20
7		Toluene	2	100:1	15	28,000 (16,200)	13,500	93	82	1.05
8		Toluene	2	150:1	30	34,100 (19,800)	18,900	87	73	1.09
9		Toluene	2	200:1	45	46,200 (26,800)	27,200	94	84	1.21
10		Toluene	2	300:1	50	38,200 (22,200)	41,600	96	83	1.35
11f		THF	2	50:1	120	6,600 (3,700)	5,200	90	78	1.21
12f		DCM	2	50:1	120	–	–	Trace	–	–
13f		Toluene	2	50:1	120	15,100 (8,500)	5,800	99	80	1.22
14f		THF	1	50:1	120	–	–	62	–	–
15f		DCM	1	50:1	120	–	–	13	–	–
16f		Toluene	1	50:1	120	14,100 (7,900)	5,500	95	80	1.35
17f		THF	4	50:1	120	–	–	60	–	–
18f		DCM	4	50:1	120	–	–	27	–	–
19f		Toluene	4	50:1	120	10,300 (5,800)	4,400	75	–	1.12
20		Toluene	1	50:1	8	11,100 (6,200)	4,900	84	72	1.14
21		Toluene	2	50:1	8	11,200 (6,300)	5,600	97	83	1.08
22		Toluene	4	50:1	60	4,900 (2,700)	5,800	99	78	1.16
23		Toluene	2	100:1	15	21,800 (12,200)	11,000	95	82	1.11
24		Toluene	2	150:1	20	32,300 (18,100)	16,900	98	87	1.27

^aFor L-Lactide: 10 mL solvent, [Zn]₀ = 0.005M, [BnOH] = 0.005M; for ε-caprolactone: 15 mL solvent. [Zn]₀ = 8.33mM; [BnOH] = 8.33mM.

^bObtained from GPC analysis and calibrated by polystyrene standard. Values in parentheses are the values obtained from GPC times 0.58 for PLA; 0.56 for PCL.

^cCalculated from [Mw(monomer) × [M]₀/[Zn]₀ × conversion /([BnOH]_(eq)] + M(BnOH)).

^dObtained from ¹H NMR analysis.

^eIsolated yield.

^fT = 26°C.