Journal of Chemical Crystallography, Vol. 33, No. 1, January 2003 ( C  2003) Copper(II) complexes 1-phenylpropane-1,2-dione- and benzil bis(3-piperidylthiosemicarbazone): A structural study Jerry P. Jasinski, (1) ∗ Heidi E. Exel, (1) Alfonso Casti ˜ neiras, (2) Elena Bermejo, (2) Heloisa Beraldo, (3) and Douglas X. West (4) Received November 29, 2001 The crystal and molecular structure of copper(II) complexes of benzil bis(3-piperidylthio- semicarbazone), [Cu(Bnzpip)] and 1-phenylpropane-1,2-dione bis(3-piperidylthiosemi- carbazone), [Cu(Pmpip)] have been determined. [Cu(Bnzpip)] is monoclinic, space group P 2 1 / n with a = 13.9375(10) ˚ A, b = 11.6621(4) ˚ A, c = 16.4710(10) ˚ A, β = 100.667(2) ◦ , and V = 2630.9(3) ˚ A 3 with Z = 4, for d calc = 1.399 g/cm 3 . [Cu(Pmpip)] is also mon- oclinic, space group P 2 1 / n with a = 11.292(6) ˚ A, b = 10.219(5) ˚ A, c = 20.292(6) ˚ A, β = 101.50(3) ◦ , and V = 2295(2) ˚ A 3 with Z = 4, for d calc = 1.525 g/cm 3 . Both com- plexes involve N 2 S 2 coordination, are relatively planar except for the phenyl rings and have similar bond distances and angles to copper(II) complexes of other 3-piperidylthiosemi- carbazones. KEY WORDS: Benzil; 1-phenyl-1,2-propane; copper(II); bis(thiosemicarbazone); piperidine; crystal structure. Introduction α-ketoaldehyde and α-diketone bis(thio- semicarbazones) and their metal complexes have demonstrated significant antitumor activity. 1 Biological activity has shown a dependence on the thiosemicarbazone’s N(4)-substituent 2 in a range of heterocyclic thiosemicarbazones (i.e., (1) Department of Chemistry, Keene State College, Keene, New Hampshire 03435. (2) Departamento de Qu´ ımica Inorg´ anica, Universidad de Santiago de Compostela, Santiago de Compostela, Spain. (3) Departamento de Qu´ ımica, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. (4) Department of Chemistry, University of Washington, Seattle, Washington. ∗ To whom correspondence should be addressed. E-mail: jjasinski@keene.edu the N(4)- refers to the IUPAC numbering sys- tem for thiosemicarbazones, C==N(1)---N(2)H--- C(3)(S)---N(4)). A series of bis(N(4)-alkyl-, dialkyl-, and 3-azacyclothiosemicarbazones) and their various metal complexes have recently been prepared and characterized spectrally and structurally. 3–12 The antitumor activity of a selec- tion of these substituted bis(thiosemicarbazones) and many of their copper(II) complexes has rece- ntly been evaluated. 13 In order to enhance our un- derstanding of the structure/activity relationship of bis(thiosemicarbazones), we report here the crystal and molecular structures of two additional copper(II) complexes, 1-phenylpropane-1,2- dione bis(3-piperidylthiosemicarbazonato)copper (II), [Cu(Pmpip)], and benzil bis(3-piperidylth- iosemicarbazonato)copper(II), [Cu(Bnzpip)]. 11 1074-1542/03/0100-0011/0 C  2003 Plenum Publishing Corporation