The reduction of CO
2 is of great importance. In this paper, different types of bis(phosphinite) (POCOP) pincer nickel complexes, [2,6-(R
2PO)
2C
6H
3]NiX (R =
tBu,
iPr, Ph; X = SH, N
3, NCS),
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The reduction of CO
2 is of great importance. In this paper, different types of bis(phosphinite) (POCOP) pincer nickel complexes, [2,6-(R
2PO)
2C
6H
3]NiX (R =
tBu,
iPr, Ph; X = SH, N
3, NCS), were applied to the catalytic hydroboration of CO
2 with catecholborane (HBcat). It was found that pincer complexes with
tBu
2P or
iPr
2P phosphine arms are active catalysts for this reaction in which CO
2 was successfully reduced to a methanol derivative (CH
3OBcat) with a maximum turnover frequency of 1908 h
−1 at room temperature under an atmospheric pressure of CO
2. However, complexes with phenyl-substituted phosphine arms failed to catalyze this reaction—the catalysts decomposed under the catalytic conditions. Complexes with
iPr
2P phosphine arms are more active catalysts compared with the corresponding complexes with
tBu
2P phosphine arms. For complexes with the same phosphine arms, the catalytic activity follows the series of mercapto complex (X = SH) ≈ azido complex (X = N
3) >> isothiocyanato complex (X = NCS). It is believed that all of these catalytic active complexes are catalyst precursors which generate the nickel hydride complex [2,6-(R
2PO)
2C
6H
3]NiH in situ, and the nickel hydride complex is the active species to catalyze this reaction.
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