Tetrakis(acetonitrile)copper(I) tetrafluoroborate is a complex compound of copper with acetonitrile as the ligand and tetrafluoroborate as the counterion.
Tetrakis(acetonitrile)copper(I) tetrafluoroborate can be prepared starting from nitrosyl tetrafluoroborate, which is obtained from dinitrogen tetroxide and tetrafluoroboric acid. The nitrosyl salt is then reacted with metallic copper in acetonitrile, initially producing a green-blue copper(II) complex. This complex is reduced to the copper(I) complex by further reaction with metallic copper. By boiling with additional copper powder until decolorization, the copper(I) complex is obtained.
Tetrakis(acetonitrile)copper(I) tetrafluoroborate forms colorless crystals in the orthorhombic crystal system in the space group Pna21 with the lattice parameters a = 23.882 Å; b = 8.3285 Å; c = 20.338 Å, and twelve unit cells. The compound is isomorphous with tetrakis(acetonitrile)copper(I) perchlorate and tetrakis(acetonitrile)silver(I) perchlorate.
Tetrakis(acetonitrile)copper(I) tetrafluoroborate can be reacted with methoxyisobutyl isonitrile to produce Tetrakis(methoxyisobutyl isonitrile)copper(I) tetrafluoroborate. This compound is used to produce technetium(99mTc)-sestamibi.