We describe a new metal-free synthesis of bis(pyrazolyl)alkanes by the condensation between bis(pyrazolyl)methanones and carbonyls. This strategy avoids the transition metals, high temperatures, regent excess, and air-sensitive reagents. Significantly, this method accommodates sterically hindered and electronically diverse azoles and aldehydes, applicable to the synthesis and optimization of new polytopic N-heterocyclic carbene ligands and heteroscorpionate catalysts. Several main group and early-transition metal complexes have been prepared in good yields by this method. Especially, a family of bis-heteroscorpionate dinucleating ligands and their dinuclear zinc complexes have been prepared including both neutral and cationic complexes. The cationic complexes show enhanced reactivity in lactide polymerization compared to the analogous monometallic complex that we attribute to metal-metal cooperativity.

Synthesis of Bis(pyrazolyl)alkane ligands and their cationic dinuclear zinc complexes for lactide polymerization

ACS Spring Meeting 2021

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