Coordination compounds in a pentacyclic aromatic system from 2-aminobenzothiazole derivatives and transition metal ions

Polyhedron 25 (2006) 2363–2374 www.elsevier.com/locate/poly

Coordination compounds in a pentacyclic aromatic system from 2-aminobenzothiazole derivatives and transition metal ions Fabiola Te´llez a,b, Adrian Pen˜a-Hueso a, Nora´h Barba-Behrens Rosalinda Contreras a, Angelina Flores-Parra a,* b

b,*

,

a Departamento de Quı´mica, Cinvestav, A. P. 14-740, Me´xico, D.F., 07000, Me´xico Departamento de Quı´mica Inorga´nica, Facultad de Quı´mica, Universidad Nacional Auto´noma de Me´xico, C.U., Coyoaca´n, Me´xico, D.F., 04510, Me´xico

Received 12 January 2006; accepted 3 March 2006 Available online 14 March 2006

Abstract Herein we report the syntheses and structural analyses of coordination compounds derived from 2-(2-benzothiazolylamino)benzothiazole, bis-btz (1), 2-(2-aminobenzothiazolylamino)benzoxazole, btz-boz (2) and 2-(2-benzothiazolylamino) benzimidazole, btz-bz (3). Ligands 1–3 are aromatic heterocycles prepared from 2-aminobenzothiazole that differ by the heteroatom (S, O, N) at position 12. These heterocycles were reacted with cobalt(II), nickel(II), and zinc(II) acetates; in addition, ligand 1 with mercury(II) acetate. The coordination compounds were characterized in the solid state by UV–Vis–NIR reflectance spectra, IR, X-ray diffraction and mass spectrometry. Unusual electronic spectra of Co2+ and Ni2+ compounds, indicated the participation of the metal ion in the ligand electronic delocalization. The N–H group was, in all cases, deprotonated and coordination to the metal ion occurs through the nitrogen atoms N(3) and N(13), forming a six-membered ring in a planar pentacyclic aromatic system. A distorted tetrahedral geometry is stabilized for ML2 complexes (M2+ = Co, Ni, Zn; L = 1–3) and for the (bis-btz)2Hg2+ compound, while nickel in [Ni(btz-boz)2(MeOH)] is square pyramidal and octahedral in [Ni(L)(OAc)(MeOH)2] (L = 1–3). Solid state structures showed 1D and 2D supramolecular arrangements.  2006 Elsevier Ltd. All rights reserved. Keywords: 2-Aminobenzothiazole; Pentacyclic aromatic system; Coordination compounds; Supramolecular arrangements

1. Introduction Polyfunctional ligands based on benzazoles are relevant due to their biological activity as fungicides, antibiotics, pesticides and neuroprotectors [1–7], also by their fluorescent and luminescent properties [8,9] and the possibility to give rise to supramolecular arrangements [10,11]. Compounds with transition metal ions of benzazole derivatives, as 2-aminobenzothiazole, 2-aminothiazole, and 2-aminobenzoxazole, have showed that bonding occurs through the nitrogen atom in a monodentate form, regardless of the metal ion or the heteroatom (S, O) present in the molecule, stabilizing *

Corresponding authors. Tel.: +52 55 5061 3720; fax: +52 55 5061 3389 (A. Flores-Parra). E-mail address: afl[email protected] (A. Flores-Parra). 0277-5387/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2006.03.003

different molecular aggregates based on intermolecular hydrogen bonding [12–16]. While, with the bis-benzothiazolyl methane, a bidentate coordination has been observed and a delocalized system may be stabilized [17,18]. In this context we have been investigating the coordination behavior of benzimidazole and thiazole derivatives towards Lewis acids and transition metal ions [19–33]. Continuing our work in this area, we were interested in ligands with two heterocyclic rings. These ligands are formed by two benzazoles bridged by a NH group, bisbtz: 2-(2-benzothiazolylamino)benzothiazole (1), btz-boz: 2-(2-aminobenzothiazolylamino)benzoxazole (2) and btzbz: 2-(2-benzothiazolylamino)benzimidazole (3), Scheme 1. The studied ligands are in a delocalized planar conformation, which may adopt several conformers and tautomers [19,32]. These aromatic nitrogenated molecules

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(J.T. Baker), were used without further purification. Compounds 1–3 were synthesized according to the reported methods by Mercha´n et al. [35,36].

H 1 8

7

S

6

9 5

2

12

N 11 E

10

N

N

3

13

2.2. Physical measurements

18

15

4

1 E = S,

14 19

16

17

A FT IR spectrometer (Perkin–Elmer 1600) was used for obtaining IR spectra of solid samples in KBr pellets (4000–400 cm1). UV–Vis–NIR spectra (diffuse reflectance, 40 000–4000 cm1) were recorded on a Cary-5E (Varian) spectrometer. Elemental analyses were carried out with a Fisons EA 1180 analyzer. The MS spectra were obtained by DIP (Direct Insertion Probe) at 20 eV in an HP 5989 spectrometer.

bis-btz

2 E = O, btz-boz 3 E = NH, btz-bz Scheme 1. Benzothiazole derived ligands.

posses versatile chemical, structural and tautomeric behavior, that upon coordination to metal ions, may give rise to different structures. Our aim was to study the effect of the heteroatoms (nitrogen, oxygen or sulfur) in their coordination mode; as to investigate the participation of the metal ions, in the formation of six-membered rings with alternating sp2 carbon and nitrogen atoms in an aromatic pentacyclic system [30]. Therefore, herein we report the synthesis and characterization of coordination compounds 4–16 of these benzothiazole ligands 1–3 with Co2+, Ni2+, Zn2+ and Hg2+ ions (Scheme 2), which may form supramolecular arrangements by interaction of the heteroatoms, hydrogen bonds or p stacking. Compounds 4 and 5 have been described in a patent [34] but their structural study was not reported.

2.3. Crystallography Crystal data and information about the data collection and structure refinement details are given in Table 1. Xray diffraction studies were performed with KAPPACCD area detector and CAD4-Enraf-Nonius. The crystal structures were determined and refined with the SHELXTL [x, y] system. Hydrogen atoms of compounds 6, 7, 9 and 12 were systematically placed on idealized positions and refined with a riding model. For compounds 14 and 15 all aromatic hydrogen atoms were found on the difference-Fourier maps and refined with free coordinates and fixed isotropic thermal parameters [37].

2. Experimental

2.4. Syntheses of complexes: general procedure

2.1. Materials

All compounds were synthesized following the same procedure as described for compound 4. Compounds 5–13 from a 2:1 molar ratio (ligand:metal) and 14–16 employing an equimolar ratio.

All chemicals were reagent grade: methanol (J.T. Baker), 2-aminobenzothiazole (Aldrich); Co(OAc)2 Æ 4H2O, Ni(OAc)2 Æ 4H2O, Zn(OAc)2 Æ H2O and Hg(OAc)2

N

S

E

N

N M N N

E N S btz-btz 4 E = S, M = Co 5 E = S, M = Ni 6 E = S, M = Zn 7 E = S, M = Hg N

S N

btz-boz 8 E = O, M = Co 10 E = O, M = Zn

E

N

N

E N S

MeHO

E N

Ni OHMe O

9 E = O, btz-boz 12a E = NH, btz-bz

btz-bz E = NH, M = Co E = NH, M = Ni E = NH, M = Zn

N

S

Ni OHMe N N

11 12 13

O CH3

14 15 16

E = S, btz-btz E = O, btz-boz E = NH, btz-bz

Scheme 2. Obtained coordination compounds from ligands 1–3.

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Table 1 Crystal data Compound 4 6 7 C58H38N12OS9Zn2 C30H22N6OS5Hg Formula C58H38N12OS9Co2 Formula weight 1325.49 1338.37 843.46 Crystal size (mm) 0.40 · 0.25 · 0.20 0.30 · 0.25 · 0.18 0.25 · 0.15 · 0.05 Color orange pale yellow pale yellow Crystal system monoclinic monoclinic monoclinic P121/n1 P121/c1 Space group P21/n ˚) a (A 21.7074(3) 21.7556(4) 15.167(1) ˚) b (A 11.2747(2) 11.2937(3) 12.328(1) ˚) c (A 25.6315(4) 25.5796(5) 16.819(1) a () 90.0 90.0 90.0 b () 112.391(1) 112.546(1) 102.2(1) c () 90.0 90.0 90.0 ˚ 3) V (A 5800.2(2) 5804.6(2) 3074.1675(2) Z 4 4 4 1.518 1.531 1.822 Dcalc Temperature (K) 293(2) 293(2) 298 h () 3.47–27.49 3.449–27.58 3.492–27.515 Reflections collected 24 036 20 915 27 901 13 254 (0.0694) 13 179 (0.033) 5738 (0.04) Independent reflections (Rint, %) Reflections observed 6577 5844 2451 S = goodness-of-fit 1.018 1.024 0.9065 Final R1 factor gt 0.0562 0.0525 0.0635 Final wR2 factor 0.1251 0.0504 0.0733 Diffractometer KAPPA-CCD KAPPA-CCD KAPPA-CCD rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi P 2 2 P P 2 2 2ffi P 2 2 2ffi jF o hF o ij jjF o jjF c jj wðF o F c Þ wðF o F c Þ P 22 ; S¼ Rint ¼ P F 2 ; R1 ¼ P jF j ; wR2 ¼ . mn wðF Þ o

o

9 C29H20N6O3S2Ni 623.34 0.50 · 0.25 · 0.20 red triclinic P 1 8.599(3) 11.788(6) 14.139(7) 82.997(2) 72.755(2) 86.741(2) 1358.4(11) 2 1.524 293(2) 3.04–29.98 12 341 7842 (0.0462)

12 C28H18N8NiS2 589.33 0.20 · 0.10 · 0.10 red triclinic P 1 10.3504(2) 13.7626(2) 19.5850(4) 76.770(1) 84.843(1) 89.732(1) 2704.45(9) 4 1.447 293(2) 3.45–27.87 22 935 12 746 (0.0621)

14 C18H19N3O4S2Ni 464.19 0.55 · 0.30 · 0.05 green monoclinic C12/c1 31.6471(4) 7.2485(1) 20.7356(3) 90.0 121.445(1) 90.0 4058.07(10) 8 1.52 293(2) 3.41–27.88 29 847 4800 (0.0497)

15 C18H19N3O5SNi 448.13 0.30 · 0.10 · 0.10 green triclinic P 1 9.749(3) 9.917(3) 10.849(2) 82.673(16) 74.118(15) 73.44(2) 965.6(15) 2 1.541 293(2) 2.59–26.96 2822 2667 (0.0093)

4129 1.024 0.0744 0.1843 KAPPA-CCD

6115 0.973 0.0494 0.0914 KAPPA-CCD

3635 1.023 0.0337 0.0781 KAPPA-CCD

2664 1.111 0.0368 0.0985 CAD4

o

2.4.1. [Co(bis-btz)2] Æ DMSO (4) Bis-btz (284 mg, 1 mmol) was dissolved in hot methanol (30 mL), and a solution of Co(OAc)2 Æ 4H2O (125 mg, 0.5 mmol) in hot methanol (5 mL) was added. An orange precipitate was obtained by evaporation of the solvent, which was filtered and recrystallized in DMSO, the orange crystals were suitable for X-ray diffraction studies. Yield: 203 mg (65%). Dec. at 380 C. Anal. Calc. for C28H16N6S4Co: C, 53.92; H, 2.58; N; 13.48. Found: C, 53.86; H, 2.61; N, 13.42%. leff = 4.79 BM. MS: m/z 623(72) [M]+. 2.4.2. [Ni(bis-btz)2] (5) The previous procedure was repeated using Ni(OAc)2 Æ 4H2O (125 mg, 0.5 mmol) and bis-btz (284 mg, 1 mmol), yielding a dark red microcrystalline powder. Yield: 153 mg (49%). Dec. at 320 C. . Anal. Calc. for C28H16N6S4Ni: C, 53.94; H, 2.58; N, 13.48. Found: C, 54.02; H, 2.59; N, 13.49%. leff = 2.99 BM. MS: m/z 623(56) [M]+. 2.4.3. [Zn(bis-btz)2] Æ 0.5DMSO (6) Zn(OAc)2 Æ H2O (100 mg, 0.5 mmol) was reacted with bis-btz (284 mg, 1 mmol). A pale yellow powder was isolated which was recrystallized from hot DMSO. The crystals were suitable for X-ray diffraction. Yield: 194 mg (62%). Dec. at 310 C. Anal. Calc. for C29H19N6O0.5S4.5Zn: C, 52.05; H, 2.86; N, 12.56. Found: C, 51.45; H, 2.76; N, 12.23%. MS: m/z 628(98) [M]+. 2.4.4. [Hg(bis-btz)2] Æ DMSO (7) The previous procedure was repeated using Hg(OAc)2 (160 mg, 0.5 mmol) and bis-btz (284 mg, 1 mmol). A pale yellow powder was filtered off and recrystallized from hot DMSO. Yield: 238 mg (63%). Dec. at 260 C. Anal. Calc.

for C30H22N6O1S5Hg: C, 42.72; H, 2.63; N, 9.96. Found: C, 42.68; H, 2.42; N, 10.16%. MS: m/z 283(100) [C14H9N3S2]+. 2.4.5. [Co(btz-boz)2] (8) The same procedure was repeated using Co(OAc)2 Æ 4H2O (125 mg, 0.5 mmol) and btz-boz (267 mg, 1 mmol), yielding a microcrystalline orange powder. Yield: 156 mg (52%). Dec. at 375 C. Anal. Calc. for C28H16N6S2O2Co: C, 56.85; H, 2.72; N, 14.20. Found: C, 56.77; H, 2.66; N, 14.02%. leff = 5.11 BM. MS: m/z 591(100) [M]+. 2.4.6. [Ni(btz-boz)2(MeOH)] (9) Ni(OAc)2 Æ 4H2O (125 mg, 0.5 mmol) was reacted with btz-boz (267 mg, 1 mmol). A dark red powder was isolated and recrystallized from hot DMSO. An X-ray diffraction study was carried out for the obtained crystals. Yield: 144 mg (48%); m.p. 322–326 C. Anal. Calc. for C29H20N6S2O3Ni: C, 55.88; H, 3.23; N, 13.48. Found: C, 55.92; H, 2.61; N, 13.67%. leff = 2.99 BM. MS: m/z 591(100) [M]+. 2.4.7. [Zn(btz-boz)2] Æ 0.5DMSO (10) Zn(OAc)2 Æ H2O (100 mg, 0.5 mmol) was reacted with btz-boz (267 mg, 1 mmol), it was recrystallized from hot DMSO, yielding a microcrystalline pale yellow powder. Yield: 203 mg (68%). Dec. at 300 C. Anal. Calc. for C29H19N6S2.5O2.5Zn: C, 54.67; H, 3.01; N, 13.20. Found: C, 54.33; H, 2.98; N, 12.90%. MS: m/z 593(100) [M]+. 2.4.8. [Co(btz-bz)2] Æ MeOH (11) The previous procedure was repeated using Co(OAc)2 Æ 4H2O (125 mg, 0.5 mmol) and btz-bz (267 mg, 1 mmol).

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An orange powder was filtered off and washed in methanol. Yield: 153 mg (49%). Dec. at 350 C. Anal. Calc. for C29H22N8O1S2Co: C, 55.86; H, 3.17; N, 18.74. Found: C, 56.03; H, 3.57; N, 18.03%. leff = 4.49 BM. MS: m/z 589(100) [M]+.

was not suitable for mass spectrometry, it decomposed without melting.

2.4.9. [Ni(btz-bz)2(MeOH)] (12a) Ni(OAc)2 Æ 4H2O (125 mg, 0.5 mmol) was reacted with btz-bz (267 mg, 1 mmol). A dark red powder was obtained. Yield: 97 mg (31%). Dec. at 390. IR(KBr), m (cm1): 3435.5 (OH). Anal. Calc. for C29H20N8O1S2Ni: C, 56.06; H, 3.57; N, 18.03. Found: C, 56.25; H, 3.15; N, 18.46%. leff = 3.05 BM. MS: m/z 589(100) [M]+. The red crystalline powder was recrystallized from methanol, by standing at r.t. for 2 months, it gave crystals suitable for single X-ray diffraction. During crystallization the MeOH molecule was lost giving compound [Ni(btz-bz)2] (12), which was characterized by X-ray diffraction analysis.

Ligands 1–3 were reacted with cobalt(II), nickel(II) and zinc(II) acetates; ligand 1 was also reacted with mercury(II) acetate; in all coordination compounds the N–H group was deprotonated, as was deduced from the neutral character of the compounds. Cobalt(II) compounds 4, 8, 11 presented an orange color, while zinc(II) 6, 10, 13 and mercury(II) 7 complexes were characterized as pale yellow microcrystalline powders, regardless of the ligand used in the reaction synthesis. While for nickel(II), red compounds were isolated when two ligands are coordinated to the metal center 5, 9, 12, 12a; when only one ligand is present, green complexes 14–16 were obtained.

2.4.10. [Zn(btz-bz)2] (13) A solution of Zn(OAc)2 Æ H2O (100 mg, 0.5 mmol) was added to btz-bz (267 mg, 1 mmol). The product of the reaction was isolated and filtered. A pale yellow powder was obtained. Yield: 150 mg (50%). Dec. at 310 C. Anal. Calc. for C28H18N8S2Zn: C, 56.43; H, 3.04; N, 18.80%. Found: C, 56.29; H, 3.30; N, 18.80%. MS: m/z 594(10) [M]+. The coordination compounds 14–16 were synthesized following the same procedure, as described for compound 14 using an equimolar ratio ligand to metal.

3.1. Mass spectrometry

2.4.11. [Ni(bis-btz)(OAc)(MeOH)2] (14) Bis-btz (284 mg, 1 mmol) was dissolved in hot methanol (30 mL) and a solution of Ni(OAc)2 Æ 4H2O (249 mg, 1 mmol) in hot methanol (5 mL) was added. Green crystals were obtained by partial evaporation of the solvent and isolated by filtration. Yield: 195 mg (42%). Dec. at 370 C. Anal. Calc. for: C18H19N3O4S2Ni: C, 46.57; H, 4.12; N, 9.05. Found: C, 46.53; H, 4.11; N, 8.97%. MS: m/z 464(90) [M]+.

3. Results and discussion

The analyses by mass spectrometry at 20 eV for compounds 4–6, 8 and 10–13, showed the molecular ion peaks. This behavior confirms that both ligands are strongly attached to the metal(II) ion, surrounding the metal atom and preventing further reactions that could lead to fragmentation. Whereas for mercury(II) 7, the molecular ion peak was not observed indicating weaker coordination bonds, only the main peak at m/z 283 due to the ligand [C14H8N3S2]+ was identified. In compound 9, the methanol molecule was lost and the peak at 590 corresponds to the nickel(II) bonded to two ligands. The molecular ion for compound [Ni(bis-btz)(OAc)(MeOH)2] (14) is observed together with another at m/z 622 which corresponds to two ligand molecules attached to the metal ion due to intermolecular rearrangements. Compounds [Ni(btz-boz)- (OAc)(MeOH)2] (15) and [Ni(btz-bz)(OAc)(MeOH)2] (16) decomposed without melting and their mass spectra were not recorded. 3.2. Infrared spectroscopy

2.4.12. [Ni(btz-boz)(OAc)(MeOH)2] (15) The previous procedure was repeated using Ni(OAc)2 Æ 4H2O (249 mg, 1 mmol) and btz-boz (267 mg, 1 mmol). After two weeks, green crystals suitable for X-ray diffraction were obtained by slow evaporation at r.t. Yield: 204 mg (46%). Anal. Calc. for C18H19N3O5SNi: C, 48.25; H, 4.27; N, 9.38. Found: C, 48.26; H, 4.20; N, 9.48%. The obtained compound was not suitable for mass spectrometry, it decomposed without melting. 2.4.13. [Ni(btz-bz)(OAc)(MeOH)2] (16) Complex 16 was synthesized with an analogous procedure to 14. A solution of Ni(OAc)2 Æ 4H2O (249 mg, 1 mmol) in methanol was added to a solution of btz-bz (267 mg, 1 mmol). A green powder was obtained by slow evaporation of the solvent. Yield: 145 g (32%). Anal. Calc. for C18H19N4O4S1Ni: C 48.46; H, 4.29; N, 12.56. Found: C, 47.95; H, 4.47; N, 12.47%. The obtained compound

The symmetric ligand bis-btz 1, exhibits two IR bands assigned to the m(C@N) at 1560 and 1542 cm1, which are shifted (D @ 100 cm1) upon coordination to the metal ions 4–7 to 1479–1462 and 1451–1444 cm1, respectively. Whereas for the non-symmetric ligands, btz-boz and btzbz and their corresponding coordination compounds 8–13, different m(C@N) bands corresponding to the thiazole, oxazole or benzimidazole rings were observed (Table 2), which shifted upon coordination. In all cases a strong bonding of the nitrogen atoms to the metal ions is shown. The m(C@N) bands in complexes 14–16 are in the expected regions. 3.3. Electronic spectra 3.3.1. Cobalt(II) compounds 4, 8 and 11 The orange [Co(bis-btz)2] (4), [Co(btz-boz)2] (8) and [Co(btz-bz)2] (11) compounds, have a magnetic moment

F. Te´llez et al. / Polyhedron 25 (2006) 2363–2374 Table 2 IR spectroscopic data (cm1) for compounds 1–16 m(C@N) bis-btz btz-boz btz-bz [Co(bis-btz)2] Æ DMSO [Ni(bis-btz)2] [Zn(bis-btz)2] Æ 0.5DMSO [Hg(bis-btz)2] Æ DMSO [Co(btz-boz)2] [Ni(btz-boz)2(MeOH)] [Zn(btz-boz)2] Æ 0.5DMSO [Co(btz-bz)2] Æ MeOH [Ni(btz-bz)2(MeOH)] [Zn(btz-bz)2] [Ni(bis-btz)(OAc)(MeOH)2] [Ni(btz-boz)(OAc)(MeOH)2] [Ni(btz-bz)(OAc)(MeOH)2]

1 2 3 4 5 6 7 8 9 10 11 12a 13 14 15 16

1460, 1577, 1629, 1462, 1462, 1479, 1473, 1531, 1529, 1536, 1533, 1534, 1533, 1546, 1549, 1549,

1542 1536(br) 1597 1444 1439 1450 1451 1477, 1464, 1442 1476, 1464, 1442 1479, 1466, 1453 1483, 1452(br) 1482, 1452(br) 1484, 1453(br) 1474, 1446(br) 1490, 1450(br) 1491, 1450(br)

characteristic of a cobalt(II) ion, leff = 4.79, 5.11 and 4.49 BM, respectively. The diffuse reflectance spectra of these tetrahedral compounds are unusual with two CT broad absorption bands in the 28 000–22 500 cm1 region which are extended up 4 to the visible region. The m3 4T1(P) A2(F) transition is observed as a well defined a shoulder at 20 250, 20 768 and 21 818 cm1, for 4, 8 and 11 respectively; while a multicomponent band in the NIR assigned to m2 4T1(P) 4 A2(F), at 9456, 9775 and 9534 cm1 respectively, Table 3. Their electronic spectra show the influence of the high electronic density from the planar conjugated ligands, when coordinated to the cobalt(II) ion, forming a six-membered chelate ring. The electronic delocalization in the system, which is extended to the metal ion, would also explain the shifting of the transitions m2 and m3 to higher energy giving rise to the orange color of the complexes. It is observed

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that when changing the heteroatom in the 12 position, S in 1 (bis-btz), O in 2 (btz-boz) and N in 3 (btz-bz), the electronic transitions are shifted respectively, indicating stronger ligand fields. This is consistent with their mass spectra and IR, which are in agreement with a strong bonding from the ligands towards the metal ions. 3.3.2. Nickel(II) compounds 5, 9 and 12a The electronic spectrum of the crystalline complex [Ni(bis-btz)2] (5) is rather similar to the already discussed tetrahedral cobalt(II) compounds, with two CT broad absorption bands extended up to the visible region (32 500–20 000 cm1) and transitions at 18 900 and 8009 cm1 assigned to m3 3T1(P) 3T1(F) and m2 3A2(F) 3 T1(F) for a nickel(II) ion in a distorted tetrahedral geometry [38,39]. Compounds [Ni(btz-boz)2(MeOH)] (9) and [Ni(btz-bz)2(MeOH)] (12a) showed the corresponding bands for a pentacoordinated nickel(II) in a square pyramidal geometry with absorption bands centered at 20 000, 16 500, 10 826, 9730 and 8190 cm1 for compound 9, whereas for 12a are at 20 720, 16 413, 10 600, 9325 and 7250 cm1. They also present two charge transfer bands in the 30 400–24 000 cm1 region (Table 3). 3.3.3. Nickel(II) compounds 14–16 The reflectance spectra of the green nickel(II) complexes, [Ni(bis-btz)(OAc)(MeOH)2] (14), [Ni(btz-boz)(OAc)(MeOH)2] (15) and [Ni(btz-bz)(OAc)(MeOH)2] (16) showed three absorption bands (Table 3), which may be assigned to a distorted octahedral geometry, as observed in previously reported thiabendazol nickel(II) bis- and tris-chelates [28]; 3 with transitions m1 3T2g(F) 3A2g(F), m2 3T1g(F) A2g(F) 3 3 and m3 T1g(P) A2g(F) in the regions 9300–9800, 14 828– 14 964 and 23 252–25 000 cm1, respectively. Additionally,

Table 3 UV–Vis–NIR electronic spectra data (cm1) for compounds 1–16 Ligands 1 2 3

bis-btz btz-boz btz-bz

27 250 25 300 27 431

Cobalt(II) compounds 4 8 11

[Co(bis-btz)2] Æ DMSO [Co(btz-boz)2] [Co(btz-bz)2] Æ MeOH

28 000, 24 038, 20 250(m3), 9456(m2) 28 000, 25 100, 20 768(m3), 9775(m2) 28 800, 25 328, 21 818(m3), 9534(m2)

Nickel(II) compounds 5 9 12a 14 15 16

[Ni(bis-btz)2] [Ni(btz-boz)2(MeOH)] [Ni(btz-bz)2(MeOH)] [Ni(bis-btz)(OAc)(MeOH)2] [Ni(btz-boz)(OAc)(MeOH)2] [Ni(btz-bz)(OAc)(MeOH)2]

29 820, 25 300, 18 900, 8009 30 400, 24 088, 20 000a, 16 500b, 10 826c, 9730d, 8190e 31 410, 25 470, 20 720a, 16 413b, 10 600c, 9325d, 7250e 26 190(br), 23 252(m3), 14 964(m2), 9299(m1) 31 500, 27 838, 24 378(m3), 14 958(m2), 9797(m1) 29 700, 27 500, 25 000(m3), 14 828(m2), 9655(m1)

Zinc(II) and mercury(II) compounds 6 [Zn(bis-btz)2] Æ 0.5DMSO 10 [Zn(btz-boz)2] Æ 0.5DMSO 13 [Zn(btz-bz)2] 7 [Hg(bis-btz)2] Æ DMSO a–e

Electronic transitions: 3E(P), 3A2, 3E; 3A2; 3B2; 3E.

26 000 27 150 27 390 28 500, 26 000, 24 900

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the spectra presented two broad charge transfer bands in the 31 500–26 000 cm1 region.

defined charge transfer bands at 28 500, 26 000 and 24 900 were observed, Table 3.

3.3.4. Zinc(II) 6, 10, 13 and mercury(II) 7 compounds For [Zn(bis-btz)2] (6), [Zn (btz-boz)2] (10) and [Zn(btzbz)2] (13), the broad absorptions at 26 000, 27 150 and 27 390 cm1 are associated to charge transfer ligand to metal bands, whereas for [Hg(bis-btz)2] (7), three well

3.4. X-ray structure determination 3.4.1. Tetrahedral compounds 4, 6, 7 and 12 X-ray diffraction analyses for the bis-btz isostructural compounds 4, 6, 7 and the btz-bz complex 12 show a metal

Fig. 1. ORTEP view of [Co(bis-btz)2] Æ DMSO (4) with thermal ellipsoids for non-H atoms at the 30% probability level.

˚ , S1  N3 3.32 A ˚ and S1  C9 Fig. 2. View of compound 6 showing the sulfur p allylic interaction with C2–N3–C9 atoms with distances S1  C2 3.44 A ˚ and N1000   H4 0 2.64 A ˚. ˚ , and two N  H bonds N10  H5000 2.71A 3.37 A

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Fig. 3. Crystal packing in compound [Hg(bis-btz)2] Æ DMSO (7).

Fig. 4. ORTEP view of the crystal structure of the [Ni(btz-bz)2] (12) showing the 30% probability thermal ellipsoid.

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atom with two deprotonated ligands chelating through the nitrogen atoms N3 and N13, in a distorted tetrahedral geometry, Figs. 1–5. In these compounds the N–metal(II) bond lengths are very similar and relatively short (Table 4), 4 Co–N ca. ˚ , 6 Zn–N ca. 1.99 A ˚ , 7 Hg–N ca. 2.2 A ˚ and 12 Ni–N 1.98 A ˚ 1.97 A. In addition, the C–N bond lengths of the central six-membered rings have similar values in between double ˚ ) indicatand single bonds of sp2 C and N atoms (ca. 1.33 A ing an electronic delocalized p-system where the metal(II) ion participates in the system, as deduced from the electronic spectra for the cobalt(II) 4, 8, 11 and nickel(II) 5 compounds. The short bond lengths M–N are in agreement with the observation of their molecular ion peaks in mass spectra. The two ligands are in a perpendicular arrangement, with an angle between the planes close to 90. The bite

Table 4 ˚ ) and angles () for compounds 4, 6, 7 and 12 Selected bond lengths (A 4 M1–N3 M1–N13 M1–N3A M1–N13A N3–C2 N10–C11 N10–C2 C11–N13 S12–C11 N3–M1–N13 N3A–M1–N13A N13–M1–N3A N13–M1–N13A N3–M1–N3A

Fig. 5. Hydrogen bonds in compound 12.

6 1.979(3) 1.978(3) 1.987(3) 1.984(3) 1.326(5) 1.320(5) 1.342(5) 1.350(5) 1.755(4)

92.5(1) 92.8(1) 120.7(1) 117.1(1) 117.6(1)

7 1.988(4) 1.993(4) 1.996(4) 1.986(4) 1.328(6) 1.327(7) 1.334(7) 1.333(6) 1.754(5)

93.1(2) 93.1(2) 116.8(2) 117.4(2) 117.2(2)

12 2.24(1) 2.17(1) 2.20(1) 2.20(1) 1.32(2) 1.30(2) 1.35(2) 1.36(2) 1.77(1)

84.8(4) 85.1(5) 123.4(5) 129.7(4) 125.7(4)

1.989(3) 1.950(3) 1.983(3) 1.957(3) 1.334(4) 1.353(4) 1.355(4) 1.346(4) 92.4(1) 92.0(1) 120.8(1) 123.8(1) 107.3(1)

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angles of the ligands are ca. 92 in compounds 4 and 12, ca. 93 in 6 and while for 7 is 85, due to its larger ionic radii. Coordination to the metal atoms gives rise to a quasiplanar pentacyclic arrangement for the aromatic rings, some distortion of the ligand is observed, in the cobalt(II) compound 4 the torsion angle M1–N3–C9–C4 is 12, while in zinc(II) 6 is 14, in the mercury(II) 7 is 5 and for 12 there is no distortion. In compound 6 two molecules are associated through two N  H hydrogen bonds and one sulfur atom has an intermolecular p allylic interaction with three atoms [C2–N3–C9] as is shown in Fig. 2. The crystal packing for compound 7 is shown in Fig. 3. In compound 12, hydrogen bonding between N10 and ˚ (176.64) gives rise to a dimeric arrangement, N13, 2.926 A Fig. 5.

Table 5 ˚ ) and angles () for 9, 14 and 15 Selected bond lengths (A

3.4.2. Square-based pyramidal geometry, compound 9 The nickel(II) compound 9 is pentacoordinated in a square pyramidal geometry, which is consistent with its observed electronic spectrum, with two btz-boz ligands and a methanol molecule, Fig. 6. This complex has a structural angular parameter s value of 0.14, where s = (b  a)/ 60; a = 151.94 and b = 160.15, indicating a square pyramidal geometry with a small trigonal component [40]. The bond lengths between the nickel(II) ion and the nitrogen ˚ , Table 5. The apical position atoms are in the range of 2 A is occupied by N13 of the boz ring, Fig. 6. The Ni–O1 bond ˚ ] is in the range expected for oxygen– length [2.107(3) A nickel(II) bonds. Similar values of the bond lengths in the central ring between N3–C2 1.324(5), N10–C2 1.345(5),

160.1(1) 109.5(2) 92.8(1)

Fig. 6. Dimeric association by short hydrogen bonding between ˚ , in compound N10  H1 0 2.726, N10 0   H1 1.951 and S1 0   H1 2.944 A 9. The upper inset represents the square-based pyramidal geometry of nickel atom 9.

9 M1–N3 M1–N13 M1–N3A M1–N13A M1–O1 M1–O2 M1–O3 M1–O4 N3–C2 N13–C11 N10–C2 N10–C11 N3–M1–N13 N3A–M1–N13A O1–M1–O2 O3–M1–O4 N13A–M1–N3 N3A–M1–N13 N3A–M1–N3

14 2.038(3) 1.988(3) 2.043(4) 2.011(4) 2.107(3)

1.324(5) 1.334(5) 1.345(5) 1.320(5) 88.1(1) 86.0(2)

15

2.032(2) 2.019(2)

2.043(4) 2.011(3)

2.072(2) 2.139(2) 2.091(1) 2.147(1) 1.326(3) 1.324(3) 1.347(3) 1.346(3)

2.111(3) 2.090(3) 2.191(2) 2.061(3) 1.321(4) 1.322(4) 1.341(4) 1.322(5)

88.32(7)

88.8(1)

176.81(7) 61.98(6)

171.9(1) 61.1(1)

C11–N10 1.320(5) indicate the delocalization of the p system. A supramolecular arrangement is formed by hydrogen bonding of the imino nitrogen N10 with the oxygen atom ˚ , Fig. 6. of the coordinated methanol N10  H1–O1 1.951 A 3.4.3. Octahedral compounds 14 and 15 The nickel(II) compounds 14 and 15 have a similar distorted octahedral geometry, with one ligand molecule bonded to the metal ion forming a pentacyclic frame, a bidentate acetate group, and two trans-methanol molecules completing the hexacoordination (Figs. 7–10). The compounds have two slightly different nickel(II)nitrogen bond lengths, Ni–N3 2.032(2) and Ni–N13 ˚ for 15, which 2.019(2) for 14 and 2.043(4) and 2.011(3) A are longer that those observed in the bis-chelate tetrahedral ˚ and Ni–N13 1.950(3) A ˚ ]. compound 12 [Ni–N3 1.989(3) A In both compounds, the trans methanol molecules are per˚ , as pendicular to the main plane and in the range of 2.10 A those of the bidentate chelating carboxylates, Table 5. The main difference between both compounds is that the conformation of the bis-btz ligand in 14 is folded in a butterfly shape, the torsional angle between the two halves of the pentacyclic system is 127, whereas in 15 the btz-boz ligand is planar, Fig. 8. The explanation for this difference is that in 15 there is a double intermolecular p-interaction ˚ ), this dimer between C2 and C11 of two molecules (3.318 A is reinforced by two cooperative intermolecular hydrogen bonding of the coordinated methanol and the imine ˚ ), Fig. 9. In addition, the nitrogen, O1–H1  N10 0 (2.101 A dimers form a mono dimensional polymer by two O2– ˚ ). Whereas in 14 there H2  O3 0 hydrogen bonds (2.018 A is a 2D arrangement formed by intermolecular interactions: ˚ ) and a p-interaction of O–CH proton with C15 (2.892 A 0 ˚ two hydrogen bonds, O1–H1  N10 (1.920 A) and O2– ˚ ), Fig. 10. H2  O400 (1.990 A

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Fig. 7. ORTEP drawing of the molecular structure of 15. Thermal ellipsoids are drawn on the 30% probability level.

Fig. 8. Butterfly shape of the bis-btz ligand in 14 hydrogen atoms are omitted for clarity and a view of compound 15 showing the plane depicted by the pentacyclic framework.

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Fig. 9. Mono dimensional arrangement in compound 15 due to intermolecular hydrogen bonds between O1–H1  N10 0 and O2 0 –H2 0   O300 and p-interactions between C2  C1100 and C11  C2 0 .

Fig. 10. Two dimensional polymer in compound 14 is formed by p and hydrogen bonds cooperative interactions.

4. Summary We have obtained a series of interesting compounds that have in common a six-membered ring, by inclusion of a metal(II) ion in a planar delocalized system, formed by alternating sp2 carbon and nitrogen atoms, integrated in a pentacyclic aromatic framework. Nitrogens N3 and N13 atoms were the binding sites with the metal ions, the nature of the heteroatom (S, O, N) in 12 position, did not affected the coordination behavior of the ligand. The orange cobalt(II) compounds, showed the participation of the metal ions in the electronic delocalization. In the tetrahedral compounds, with exception of the mercury compound 7, the two large polycyclic systems surround the metal ion, protecting it and allowing to observe the molecular ions in their mass spectra. In the studied compounds, supramolecular arrangements were formed by intermolecular hydrogen bonds with

the iminic nitrogen N10 and by p-interactions. In the octahedral nickel(II) compounds, with coordinated acetate and methanol molecules, the oxygen atoms participated into stabilizing 1D and 2D network systems, via intermolecular hydrogen bonds. Acknowledgements F.T. and A. P.-H. thank Conacyt for Ph.D. scholarship and F.T. thanks DGPA-UNAM for postdoctoral scholarship. Financial support by Conacyt (Gant 34714-E) and Cinvestav is acknowledged. Appendix A. Supplementary material Crystallographic data have been deposited with the Cambridge Crystallographic Data Centre CCDC Nos. 257701 (4), 257702 (6), 257703 (7), 257988 (9), 280064 (12), 257705 (14) and 257704 (15). Copies of this information may be

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