Uncommon behavior of copper(I) tetrafluoroborate and perchlorate in [Cu(DAF)(H2O)]BF4 and [Cu(DAF)(ClO4)] π-complexes (DAF-diallyl formamide)

Crystals of [Cu(DAF)(H2O)]BF4 (I) and [Cu(DAF)(ClO4)] (II) (DAF is diallyl formamide) were synthesized by an alternate-current electrochemical method, and their structures were determined (MoKalpha radiation, 1247 and 859 independent reflections with I greater than or equal to 2 sigma (I), R = 0.043 and 0.032 for I and II, respectively). The complexes crystallize in space croup P2(1)/n, Z = 4. For I, a = 10.782(3) Angstrom, b = 12.096(5) Angstrom, c = 9.185(3) Angstrom, gamma = 103.62(3)degrees, and V= 1164.2(7) Angstrom (3); for II, a = 10.064(3) Angstrom, b = 10.753(6) Angstrom, c = 10.002(3) Angstrom, gamma = 87.52(4)degrees, and V = 1081.4(8) Angstrom (3). The copper atom in structures I and II coordinates both C=C bonds in one DAF molecule and oxygen atom of the amide group of another DAF molecule, as well as an oxygen atom of H2O (in I) or ClO4 (in II) in the axial position. The uncommon behavior of the anions in structures I and II is explained by their different values of Pierson hardness.