Isolable Ethylene Complexes of Copper(I), Silver(I), and Gold(I) Supported by Fluorinated Scorpionates [HB{3‐(CF3),5‐(CH3)Pz}3]– and [HB{3‐(CF3),5‐(Ph)Pz}3

Abstract

The group 11 metal adducts [HB{3‐(CF3),5‐(CH3)Pz}3]M(C2H4) (M = Au, Ag, and Cu; Pz = pyrazolyl) have been synthesized via a metathesis process using [HB{3‐(CF3),5‐(CH3)Pz}3]Na and CF3SO3Cu, CF3SO3Ag, AuCl and ethylene. The related [HB{3‐(CF3),5‐(Ph)Pz}3]Ag(C2H4) has also been synthesized using [HB{3‐(CF3),5‐(Ph)Pz}3]Na(THF), CF3SO3Ag and ethylene. These group 11 metal ethylene complexes are white solids and form colorless crystals. They have been characterized by NMR spectroscopy and X‐ray crystallography. The gold‐ethylene adduct [HB{3‐(CF3),5‐(CH3)Pz}3]Au(C2H4) shows large upfield NMR shifts of the ethylene proton and carbon signals relative to the corresponding peaks of the free ethylene, indicating relatively high Au→ethylene backbonding. NMR chemical shift data suggest that the silver complexes of both the tris(pyrazolyl)borate ligands [HB{3‐(CF3),5‐(CH3)Pz}3]– and [HB{3‐(CF3),5‐(Ph)Pz}3]– exhibit the weakest interaction with ethylene as compared to the respective copper and gold complexes. X‐ray crystal structures reveal that the gold atom in [HB{3‐(CF3),5‐(CH3)Pz}3]Au(C2H4) binds to scorpionate in κ2‐fashion while the related silver adduct features a κ3‐bonded scorpionate. [HB{3‐(CF3),5‐(CH3)Pz}3]Cu(C2H4) has a scorpionate that binds to copper with two short Cu–N bonds and one long Cu–N distance.