Copper(I) complexes supported by a heavily fluorinated bis(pyrazolyl)borate: syntheses and characterization of [H2B(3,5-(CF3)2Pz)2]CuL (where L = PPh3, NCCH3, HCCPh, H2CCHPh) and {[H2B(3,5-(CF3)2Pz)2]Cu}2(1,5-COD)

The fluorinated bis(pyrazolyl)borate [H2B(3,5-(CF3)2Pz)2]− allows the isolation of thermally stable copper(I) complexes containing phosphorus and nitrogen based donors, alkyne and alkene ligands. [H2B(3,5-(CF3)2Pz)2]Cu(PPh3), [H2B(3,5-(CF3)2Pz)2]Cu(NCCH3) and {[H2B(3,5-(CF3)2Pz)2]Cu}2(1,5-COD) were synthesized by using [H2B(3,5-(CF3)2Pz)2]K, CF3SO3Cu, and the appropriate ligand, PPh3, NCCH3 or 1,5-COD. [H2B(3,5-(CF3)2Pz)2]Cu(HCCPh) and [H2B(3,5-(CF3)2Pz)2]Cu(H2CCHPh) were obtained by treating [H2B(3,5-(CF3)2Pz) 2]Cu(NCCH3) with phenylacetylene and styrene, respectively. X-ray data show that [H2B(3,5-(CF3)2Pz)2]CuL (where L = PPh3, HCCPh, H2CCHPh) and {[H2B(3,5-(CF3)2Pz)2]Cu}2(1,5-COD) have three-coordinate, trigonal planar copper sites. The bis(pyrazolyl)borate moiety adopts the common boat conformation. The νCC stretching band of [H2B(3,5-(CF3)2Pz)2]Cu(PhCCH) was observed at 1927 cm−1. Structural and spectroscopic data of the alkene and alkyne complexes indicate minimal back-bonding from the d10 copper(I) center.

Graphical abstractThe fluorinated bis(pyrazolyl)borate [H2B(3,5-(CF3)2Pz)2]− allows the isolation of thermally stable copper(I) complexes containing phosphorus and nitrogen based donors, and unsaturated hydrocarbon ligands like alkenes and alkynes.Figure optionsDownload full-size imageDownload as PowerPoint slide