Pol$mhnVol. IO, No. 14,~~. 1625-1629, 1991

Printed in Great Britain

0277-5387/91 $3.00+.00

0 1991 Pergamon Press plc

STRUCTURAL CHARACTERIZATION OF THE S-BENZYLDITHIOCARBAZATE DERIVED FROM

2-FORMYLPYRIDINE N-OXIDE AND ITS DIMERIC COPPER@) NITRATE COMPLEX

ZHENG XU, ELMER C. ALYEA,? GEORGE FERGUSONT and MICHAEL C. JENNINGS

Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada Nl G 2W 1

(Received 12 December 1990 ; accepted 2 1 March 199 1)

Abstract-The thiobenzyl dithiocarbazate of 2-formylpyridine N-oxide, 2-C,H,N(O)- CH=N-NH-C(S)-SCH2C6H5, crystallizes from ethanol as centrosymmetric dimeric units as a consequence of intermolecular N(O). . . H-N bonds [0 . . . N 2.763(4) A]. In the centrosymmetric copper(I1) complex, {Cu(ONO,)[2-C,H,N(O)--CH=N-N=C(S)- SCH2C6H5]}2, the anionic ligand is coordindted via the N-oxide oxygen, the azomethine nitrogen and the thiol sulphur atoms. Including the nitrato group, the coordination geometry is primarily distorted square planar [with Cu-O(l) 1.949(l), Cu-N(9) 1.939(2), Cu-S( 12) 2.254(l), Cu-O(22) 1.963(2) A], but weak axial interactions to a second oxygen atom of the nitrato group [2.682(2) A] an d a neighbouring N-oxide oxygen atom [2.674(2) A] complete an octahedron for the copper atoms in the dimeric units.

Thiosemicarbazones and dithiocarbazates of 2- acetylpyridine have received extensive attention due to their antimalarial, antitumour and antibacterial activity. I Their chelating ability with transition metal ions is found to relate to their medicinal activity.2*3 In investigating the coordinating ability of these ligands with transition metal ions, West and co-workers recently extended their studies to thiosemicarbazones and the related S-methyl- dithiocarbazate of 2-acetylpyridine N-oxide.“‘j Our current interest in sulphur-nitrogen donor ligands for copper complexation’ led us to prepare the new potentially ONS donor ligand derived from 2-for- mylpyridine N-oxide and thiobenzylthiosemicar- bazide, abbreviated as HONS. This paper reports the crystal structure determinations of the ligand and that of a copper(I1) nitrato complex of the deprotonated ligand, Cu(ONO,)(ONS) ; both species occur as dimeric units via bridging N-oxide atoms.

On the basis of IR, electronic and ESR spectral evidence, West and co-workers proposed that

t Authors to whom correspondence should be addressed.

s-c’ \R ‘R

Fig. 1. General structural formula of HONS and its pro- posed bonding in copper(I1) complexes in the depro-

tonated tridentate form (R’ = H, CH3).

thiosemicarbazones of 2-acetylpyridine N-oxide could coordinate to copper(I1) in a planar fashion, as depicted in Fig. 1. Since these earlier studies indicated that such ligands could coordinate as neu- tral, bidentate ligands (R = NHCH,),’ as well as in the deprotonated form utilizing ONS donor atoms [R = N(CH3)2,6 SCHs6 and NCsH,44], the present X-ray crystal structure determinations were under- taken in initiating our complexation studies of HONS (R = SCHzC6H5, R’ = H in Fig. 1).

The structure of the ligand, C14H1 3N3OS2, as

1625

1626 ZHENG XU et al.

Fig. 2. A view of the HONS ligand with the crystallographic numbering scheme; ellipsoids are at the 50% level.

Table 1. Molecular dimensions for HONS

Bond lengths (A)

0(1)---N(2) 1.301(4) C(1 l)-S(12) 1.652(4)

N(2+C(3) 1.353(5) C(ll)--S(13) 1.740(4)

N(2)-C(7) 1.370(4) S(13)--c(l4) 1.822(4)

C(3)---C(4) 1.349(6) C(14)--C(15) 1.484(5)

C(4)_C(5) 1.376(6) C(l5)--c(l6) 1.375(6)

C(5)-C(6) 1.372(6) C(l5)-C(20) 1.377(6)

C(6)--C(7) 1.368(5) C(l6)--c(l7) 1.395(7)

C(7tC(8) 1.452(5) C(l7)-C(l8) 1.351(7)

C(8)-N(9) 1.276(5) C(l8)-C(l9) 1.342(7)

N(9)-N(l0) 1.364(4) C(l9)--c(20) 1.358(7) N(lO)-C(I1) 1.347(4) N(10). ..O(l)* 2.763(4)

Bond angles (“)

G(l)-N(2)--c(3) 119.8(3) N(lO)--C(ll)-S(13) 113.3(3)

G( 1 )-N(2)--c(7) 120.3(3) S(12)---C(ll)-S(13) 126.3(2)

C(3)-N(2)-C(7) 119.9(3) C(ll)-S(l3+C(l4) 102.1(2)

N(2)_C(3)-C(4) 121.5(4) S(l3)--c(l4)-C(l5) 107.6(3)

C(3)--c(4)-C(5) 119.8(4) C(14)--C(15)-C(16) 121.0(4)

C(4)--c(5)--c(6) 118.9(4) C(14)-C(15)-C(20) 121.3(4)

C(5>-c(6)--c(7) 120.9(4) C(16)-C(15)-C(20) 117.6(4)

N(2)_C(7)--C(6) 119.0(3) C(15)-C(16)-C(17) 120.6(4)

N(2)_C(7)-C(8) 115.9(3) C(l6)--c(l7)--c(l8) 119.1(4)

C(6)_C(7)--c(8) 125.0(3) C(l7)--c(l8)--c(l9) 121.0(5)

C(7)--c(8)_N(9) 120.2(3) C(18>--c(19k--C(20) 120.3(5)

C(8)-N(9PN(lO) 114.9(3) C(l5)--c(2O>-c(l9) 121.4(4)

N(9)-N(lO)--C(l l) 121.1(3) G(l)* . ..H(lO)--N(l0) 157.7 N(lO)-C(lI)-S(12) 120.4(3)

The * refers to an atom at equivalent position -x, -y, 1 -z.

Cu(ONO,)(ONS) 1627

023

Fig. 3. A view of the dimeric [Cu(ONO,)(ONS)], complex with the crystallographic numbering scheme ; ellipsoids are at the 50% level.

shown in Fig. 2,t displays bond lengths consistent with the representation in Fig. 1. The 0(1)-N(2) distance of 1.301(4) A is much shorter than 1.39 8, found in Me,NO, where there can be no n- bonding, * and reflects significant double bond character. Similarly, the azomethine C(8)--N(9) distance [ 1.276(5) A] corresponds to a double bond, as does the C( 1 l)-S( 12) bond length [ 1.652(4) A, cf. 1.740(4) A for C(ll)-S(13)]. The O(1) to S(13) portion of the dithiocarbazate ligand is almost planar, with small dihedral angles between

0(1)--C(8)andC(8)-C(11)(8.9”)orN(10)---S(13) (12.8”) moieties. The benzyl group, however, is twisted at right angles relative to the planes con- taining the potential donor atoms ; for example, the dihedral angles between C( 14)-C(20) and C(8 )-X(11) or N(lO)-S(13) planes are 87.1 and 90.8”, respectively (Table 1). An important feature

t Crystal data for C,4H,3N30S2, kf, = 303.4, mono- clinic, space group P2,/a, a = 8.873(3), b = 11.635(2), c = 14.193(2) A, b = 94.28(2)“, F’= 1461(l) A3, Z = 4, 0, = 1.38 g cmp3, p = 3.5 cm-‘, F(OO0) = 632, MO-K, radiation (n = 0.71073 A), T = 21°C. 3635 reflections were measured on a CAD4 diffractometer (20,, = W), 3134 were unique and 1435 had Z > 3a(Z). Lorentz and polarization corrections were applied. The structure was solved using direct methods (SIMPEL). Refinement (with weights derived from the counting statistics) by full- matrix least-squares calculations (with all hydrogen atoms allowed for but not refined) converged with R = 0.046 and wR = 0.057 for the 1435 observed reflec- tions. An extinction correction was also refined. The final cycle of refinement had 182 variables and maximum shift/ error ratio of < 0.005. A final difference map had no chemically significant features. Full details of the analysis are available from the Cambridge Crystallographic Data Centre or from the authors.

of the crystal structure is the intermolecular hydro- gen bond [NO . -. H-NO * * * N 2.763(4) A] between

the N-oxide oxygen atom and the amine hydrogen atom of a neighbouring molecule ; the HONS ligand thus occurs as centrosymmetric dimeric units in the solid state.

Our crystallographic study of the copper com- plex establishes it as a centrosymmetric dimer (Fig. 3)# with the copper(I1) geometry as primarily square planar. The copper atom is bonded to the N-oxide oxygen atom [ 1.949( 1) A], the azomethine nitrogen atom [1.939(2) A] and the thiol sulphur atom [2.254(l) fk] of the deprotonated ligand ; a copper-nitrato bond [Cu-O(22) = 1.963(2) A] completes the distorted square plane. Bond length changes [e.g. longer N(2)-0( l), C(8)-N(9), C(l l)-S(12) and shorter N(lO)---C(l l)] as com-

$ Crystal data for C28H24C~2NsO&, IV, = 855.89, triclinic, space group PI, a = 10.100(2), b = 10.985(2), c = 8.156(2) A, tl = 95.34(2), fi = 107.98(2), y = 81.98(2)“, I/= 851.1(6) A3, Z = 1, DC = 1.67 g crn3, p = 15.5 cn-’ F(OOO) = 434, MO-K, radiation (A= 0.71073 A),’ T = 21°C. 3800 reflections were mea- sured on a CAD4 diffractometer (20,, = 54”), 3703 were unique and 2950 had Z > 3u(Z). Lorentz, polarization and Gaussian absorption corrections were applied. The structure was solved using the Patterson heavy-atom method. Refinement (with weights derived from the counting statistics) by full-matrix least-squares cal- culations (with all hydrogen atoms allowed for but not refined) converged with R = 0.027 and wR = 0.040 for the 2950 observed reflections. The tinal cycle of refine- ment had 226 variables and maximum shift/error ratio of 0.01. A final difference map had no chemically significant features. Full details of the analysis are available from the Cambridge Crystallographic Data Centre or from the authors.

1628 ZHENG XU et al.

Table 2. Molecular dimensions for Cu(ONO,)(ONS)

Cu-o( 1) cu-O( l)* Cu-N(9) cu-S( 12) cu-O(22) Cu-0(23)

0(1)-N(2) N(2)-C(3) N(2)-C(7) C(3VJ4) C(4)-C(5) CW--C(6) C(6)---C(7) C(7)--C(8) C(8)--N(9)

o(l)---Cu-o(l)* 0(1)-&-N(9) 0(1)---Cu-s(12) O( l)-Cu-G(22) 0( l)-Cu-O(23) O(l)*-&-N(9) o(l)*---&-S(12) O( l)*-Cu-o(22) 0( l)*-Cu-O(23) N(9)-Cu-S( 12) N(9)--Cu-0(22) N(9)-Cu-0(23) S( 12)-Cu-o(22) S(12)--Cu-O(23) 0(22)-&-0(23) cu-O( 1)---&l* Cu-0( 1)-N(2) Cu-O( 1)-N(2)

G(1 )-N(2)--c(3) G( 1 )-N(2)--c(7) C(3)-N(2)_C(7) N(2)_C(3)--C(4) C(3)-C(4)-C(5) C(4)_C(5)--c(6) C(5)-C(6)-C(7) N(2)_C(7t-C(6)

1.949(l) 2.674(2) 1.939(2) 2.254( 1) 1.963(2) 2.682(2) 1.344(2) 1.344(3) 1.368(3) 1.372(4) 1.371(4) 1.364(3) 1.397(3) 1.433(3) 1.291(3)

Bond lengths (A)

N(9)-N(l0) N(lO)--C(ll) C(1 I)---S(12) C(ll)-S(13)

S(l3)-C(l4) C(l4)-C(l5) C(l5>-c(l6) C(l5)--c(20) C(l6)-C(l7) C(l7)--c(l8) C(l8)--c(l9) C(l9)--c(20) N(21)--0(22) N(21>--0(23) N(21)--0(24)

1.392(2) 1.306(3) 1.724(2) 1.745(2) 1.825(3) 1.508(3) 1.381(3) 1.364(3) 1.387(4) 1.340(3) 1.364(5) 1.392(5) 1.292(2) 1.232(3) 1.217(3)

Bond angles (“)

78.39(6) N(2)---C(7)--C(8) 91.75(7) C(6)-C(7_(8)

177.36(5) C(7)_C(8)_N(9) 88.79(6) Cu-N(9)-C(8) 86.04(6) Cu-N(9)---N( 10)

104.45(6) C(8)_N(9FN(lO) 100.48(3) N(9)-N(10 jC(11) 76.14(5) N(lO)-C(ll)-S(12)

126.87(5) N(lO)---C(ll)--S(13) 86.21(5) S(12)-C(llFS(13)

179.27(6) cu-s(12)--C(11) 126.72(7) C(1 I)-S(13)-C(14) 93.26(4) S(l3)-C(l4)-C(l5) 96.52(4) C(l4)--c(l5)--c(l6) 52.82(6) C(l4)-C(l5)--c(20)

101.61(6) C(16)--c(15)--c(20) 126.2( 1) C(l5)-C(l6)--c(l7) 108.57(9) C(l6)-+17)-C(l8) 115.7(2) C(l7)--c(l8)-C(l9) 122.7(2) C(l8)-C(l9)-C(20) 121.5(2) C(l5)--c(2O)--c(l9) 120.7(2) 0(22)--N(21)-0(23) 119.7(2) 0(22)-N(21)-0(24) 119.3(2) 0(23)-N(21)-0(24) 121.2(3) Cu-G(22)-N(21) 117.6(2) Cu-O(23)--N(21)

123.7(2) 118.6(2) 126.7(2) 125.5(2) 120.8(l) 113.7(2) 112.3(2) 127.1(2) 118.9(2) 114.0( 1) 93.44(7)

103.8(l) 114.6(2) 121.1(2) 121.1(2) 117.9(2) 120.4(2) 121.2(2) 119.3(2) 120.2(3) 121.0(3) 118.1(2) 117.8(2) 124.1(2) 110.9(l) 78.0( 1)

The * refers to an atom at equivalent position -x, 1 --y, -z.

pared with the uncomplexed HONS ligand are con- sistent with expectations, as represented in Fig. 1. However, the complex crystallizes as a dimer as a consequence of bridging N-oxide oxygencopper interactions [Cu-O(l)* = 2.674(2) A]. In the cen- trosymmetric dimer [CU(C~H~NO)~(NO&~ the bridging pyridine N-oxide 0-Cu distance to the other copper atom is considerably shorter [2.439(6) A], whereas the Cu-0 bond lengths to the two pyridine N-oxide ligands [1.951(5), 1.968(5) A] and

the pyridine N-oxide N-O distances [1.362(7) A] are similar to those found in the present complex (Table 2).

Pseudo-octahedral geometry for each copper(I1) atom in our complex is completed by virtue of another weak axial bond to a second oxygen atom of the nitrato group [Cu-O(23) = 2.682(2) A]. The asymmetric bidentate nature of the nitrato group, which is planar, is reflected in the disparate N-O bond distances [N(21)-0(22) 1.292(2),

Cu(ONO,)(ONS) 1629

N(21)-0(23) 1.232(2), N(21)---0(24) 1.217(3) A]. Whereas the tridentate planar coordinating behav- iour of similar thiosemicarbazone and dithio- carbazate ligands and the tetragonal nature of the copper(I1) geometry was indicated previously by spectroscopic evidence,“6 the specific bonding and unique dimeric interactions are described by this first X-ray analysis of a copper(I1) complex with a dithiocarbazate (or thiosemicarbazone) of a pyridine N-oxide. Complexation studies of HONS with a variety of metal ions are underway.

Acknowledgements-We thank NSERC Canada for Operating and Infrastructure Grants (E.C.A. and G.F.) and for a CIDA award (Z.X.). We are grateful to Gou Shaohua of Nanjing University for the synthesis of the compounds.

REFERENCES

1. D. L. Klayman, J. P. Scovill, J. F. Bartosevich and J. Bruce, J. Med. Chem. 1983, 26, 35 and refs therein;

6.

7.

8.

9.

M. A. Ali and S. E. Livingstone, Coord. Chem. Rev. 1974,13, 101; M. Mohan, M. Kumar, A. Kumar, P. H. Madhuranath and N. K. Jha, J. Inorg. Biochem. 1988,33, 121. J. P. Scovill, D. L. Klayman and C. F. Franchino, J. Med. Chem. 1982,25,1261. J. P. Scovill, D. L. Klayman, C. Lambros, G. E. Childs and J. D. Notsch, J. Med. Chem. 1984, 27, 87. D. X. West, R. M. Makeever, J. P. Scovill and D. L. Klagman, Polyhedron 1984, 3, 947. D. X. West, R. M. Makeever, G. Ertem, J. P. Scovill and L. K. Pannell, Transition Met. Chem. 1986, 11, 131. D. X. West and L. K. Pannell, Transition Met. Chem. 1989,14,457 ; D. X. West and D. L. Huffman, Tran- sition Met. Chem. 1989, 14, 190. E. C. Alyea, S. Liu, B. Li, Z. Xu and X. Z. You, Acta Crust. C 1989, 45, 1566 ; E. C. Alyea, G. Ferguson, M. C. Jennings, B. Li, Z. Xu and X. Z. You, Poly- hedron 1990,9,2463. A. Caron, G. J. Palenik, E. Goldish and J. Donohue, Acta Cryst. 1964, 17, 102. S. SCavniEar and B. Matkovic, Acta Cryst. 1969, B25, 2046.