4. Transfer Hydrogenation of CO₂ Using Ru Complexes 1–7 .

entry	complex	n HCOOK/10–6	TON
1	---	---	---
2	1	17	1.3
3	2	22	1.7
4	3	27	2.1
5	4	20	1.5
6	5	27	2.1
7	6	31	2.4
8	7	24	1.8

^aReactions conducted using 13 μmol of catalyst, 50 bar of CO₂, 0.5 M KOH in H₂O/iPrOH (20:5 mL) at 100 °C for 22 h.

^bTON = mol of formate/mol of catalyst.