Bis(4-hydroxy-3-methoxy­benz­alde­hyde thio­semicarbazonato-N¹,S)nickel(II) tetra­ethanol solvate

The title complex crystallizes as a tetraethanol solvate, [Ni(C₉H₁₀N₃O₂S)₂]·4C₂H₆O, with the metal on a centre of inversion. Two singly deprotonated ligands coordinate the metal atom in a planar fashion. The metal complexes are organized into layers by an extended network of hydrogen bonds involving the NH₂ groups, the phenolic OH groups and the solvent mol­ecules.

S1. Comment

Transition metal complexes with thiosemicarbazones possess important biological activities. Antimalarial, antiviral and antibacterial activities have been proved for various representatives of this class of compounds (West et al., 1991). Nevertheless, structural studies are comparatively rare and predominantly deal with complexes having tridentate thiosemicarbazones. To our knowledge, there is only one report on a transition metal complex with the fairly hydrophilic, bidentate 4-hydroxy-3-methoxybenzaldehyde thiosemicarbazone (vanilline thiosemicarbazone, Hvtsc) (Ortner & Abram, 1998), whereas the coordination chemistry of the isomeric, but potentially tridentate, ligand 2-hydroxy-3-methoxybenzaldehyde thiosemicarbazone is better known (Cui & Hu, 1994a,b; Agarwala & Hingorani, 1997; Offiong et al., 1996). Here we describe the structure of the neutral nickel(II) complex, [Ni(vtsc)₂], (I), which contains two chelate-bonded vanilline thiosemicarbazonato ligands. \sch

The structure consists of [Ni(vtsc)₂] molecules (Fig. 1) with the metal on a centre of inversion and hydrogen-bonded molecules of solvent ethanol. The organic ligands are deprotonated at the azomethine position and bonded to the metal via the sulfur and N3 atoms forming five-membered chelate rings. This results in an almost planar coordination with maximum deviation of 0.161 (1) Å from a least-square plane formed by the atoms Ni, S, C1, N2 and N3 (r.m.s. 0.1189 Å). The hydroxyl group remains protonated and does not contribute to the coordination of the metal. A comparison of the bond lengths found for [Ni(vtsc)₂] with those in the [Au(Hdamp)Cl(vtsc)]⁺ cation [Hdamp is 2-(dimethylammoniummethyl)phenyl], (Ortner & Abram, 1998) indicates a considerably higher degree of delocalization of electron density inside the chelate rings of the nickel compound under study. This is reflected by the C1—S bond length of 1.726 (3) Å (Table 1) which lies between the values of isolated C—S single and double bonds, whereas a C—S bond of 1.76 Å with almost single bond character has been found for the gold compound. The same is true for the C,N-skeletons of the thiosemicarbazone moieties which show nearly equal bonds for [Ni(vtsc)₂], whereas alternating short and long values are observed for the gold complex. An unusually short C—C bond length is observed in one of the solvent molecules which is probably due to thermal motion and/or disorder.

The triclinic unit cell contains four molecules of the solvate ethanol. Hydrogen bridges between the complex molecules and two symmetry-related ethanol molecules form a two-dimensional arrangement. These layers are interconnected by additional hydrogen bonds between H30 and the nitrogen atoms of the thiosemicarbazone backbone of a complex molecule of the neigbouring layer. The hydrogen-bonding parameters are summarized in Table 2.

S2. Experimental

[Ni(vtsc)₂] was prepared as previously reported (Akinchan et al., 1992). Brown, column-shaped single crystals of the sparingly soluble complex have been obtained from slow cooling of a concentrated ethanol solution.

S3. Refinement

Scattering factors, dispersion corrections and absorption coefficients were taken from International Tables for Crystallography, Vol. C. (1992).

Computing details

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: SET4 in SDP (Frenz, 1983); data reduction: SDP; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1997); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. : Ellipsoid diagram (Zsolnai, 1997) of the molecular structure of [Ni(vtsc)2] showing 50% probability displacement ellipsoids. Symmetry operation: (i) -x, -y, -z.

'Bis(vanillin thiosemicarbazonato)nickel(II) ethanol solvate'

Crystal data

[Ni(C9H10N3O2S)2]·4C2H6O	Z = 1
Mr = 691.50	F(000) = 366
Triclinic, P1	Dx = 1.396 Mg m^−3
a = 6.894 (1) Å	Cu Kα radiation, λ = 1.54184 Å
b = 10.675 (1) Å	Cell parameters from 25 reflections
c = 11.878 (2) Å	θ = 18.2–26.7°
α = 73.19 (1)°	µ = 2.50 mm^−1
β = 79.75 (1)°	T = 203 K
γ = 84.91 (1)°	Column, brown
V = 822.8 (2) Å^3	0.30 × 0.25 × 0.25 mm

Data collection

Enraf Nonius CAD4 diffractometer	2695 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.019
Graphite monochromator	θmax = 64.9°, θmin = 6.5°
ω scans	h = −1→8
Absorption correction: ψ scans SDP (Frenz, 1983)	k = −12→12
Tmin = 0.503, Tmax = 0.536	l = −13→13
3560 measured reflections	3 standard reflections every 200 reflections
2792 independent reflections	intensity decay: 1.0%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.052	H-atom parameters constrained
wR(F^2) = 0.152	Calculated w = 1/[σ^2(Fo^2) + (0.094P)^2 + 0.5715P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
2792 reflections	Δρmax = 0.65 e Å^−3
197 parameters	Δρmin = −0.59 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0154 (19)

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ni	0.0000	0.0000	0.0000	0.0358 (3)
S	−0.28664 (9)	0.10377 (6)	−0.00553 (7)	0.0456 (3)
N1	−0.3298 (4)	0.3510 (2)	0.0016 (2)	0.0499 (6)
H1A	−0.2942	0.4211	0.0146	0.060*
H1B	−0.4418	0.3513	−0.0226	0.060*
N2	−0.0440 (3)	0.2462 (2)	0.0556 (2)	0.0408 (5)
N3	0.0624 (3)	0.1260 (2)	0.07254 (19)	0.0384 (5)
C1	−0.2123 (4)	0.2426 (3)	0.0189 (2)	0.0400 (6)
C2	0.1939 (4)	0.1084 (3)	0.1424 (2)	0.0410 (6)
H2	0.2722	0.0310	0.1470	0.049*
C11	0.2413 (4)	0.1870 (3)	0.2145 (2)	0.0424 (6)
C12	0.1361 (5)	0.2972 (3)	0.2372 (3)	0.0566 (8)
H12	0.0252	0.3309	0.2005	0.068*
C13	0.1953 (5)	0.3568 (3)	0.3142 (3)	0.0614 (9)
H13	0.1221	0.4301	0.3301	0.074*
C14	0.3580 (5)	0.3114 (3)	0.3675 (3)	0.0514 (7)
C15	0.4665 (4)	0.2024 (3)	0.3456 (2)	0.0449 (6)
C16	0.4074 (4)	0.1404 (3)	0.2710 (2)	0.0436 (6)
H16	0.4793	0.0656	0.2576	0.052*
C17	0.7436 (5)	0.0548 (4)	0.3817 (3)	0.0606 (8)
H17A	0.8509	0.0374	0.4278	0.091*
H17B	0.7972	0.0741	0.2976	0.091*
H17C	0.6634	−0.0214	0.4047	0.091*
O1	0.6250 (3)	0.1645 (2)	0.4040 (2)	0.0585 (6)
O2	0.4162 (3)	0.3694 (2)	0.4439 (2)	0.0629 (6)
H2A	0.3391	0.4320	0.4507	0.094*
O20	0.2447 (4)	0.5963 (3)	0.4781 (2)	0.0767 (8)
H20	0.3438	0.6349	0.4786	0.115*
C21	0.1401 (9)	0.6738 (5)	0.3870 (6)	0.1128 (19)
H21A	0.2110	0.6670	0.3097	0.135*
H21B	0.0098	0.6377	0.3986	0.135*
C22	0.1159 (10)	0.8033 (5)	0.3840 (5)	0.1125 (18)
H22A	0.0448	0.8498	0.3197	0.169*
H22B	0.2441	0.8404	0.3711	0.169*
H22C	0.0416	0.8114	0.4592	0.169*
O30	0.2661 (3)	0.4154 (2)	0.9294 (2)	0.0552 (5)
H30	0.1766	0.3673	0.9710	0.083*
C31	0.2732 (7)	0.4209 (4)	0.8080 (3)	0.0802 (12)
H31A	0.3771	0.4797	0.7598	0.096*
H31B	0.1475	0.4592	0.7835	0.096*
C32	0.3105 (8)	0.2937 (5)	0.7814 (4)	0.0883 (13)
H32A	0.3136	0.3062	0.6969	0.132*
H32B	0.2062	0.2354	0.8265	0.132*
H32C	0.4363	0.2557	0.8034	0.132*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni	0.0362 (4)	0.0333 (4)	0.0422 (4)	0.0023 (2)	−0.0098 (3)	−0.0163 (3)
S	0.0386 (4)	0.0415 (4)	0.0666 (5)	0.0051 (3)	−0.0156 (3)	−0.0282 (3)
N1	0.0463 (13)	0.0379 (12)	0.0737 (16)	0.0073 (10)	−0.0243 (12)	−0.0221 (11)
N2	0.0429 (12)	0.0341 (11)	0.0502 (13)	0.0057 (9)	−0.0151 (10)	−0.0169 (9)
N3	0.0394 (11)	0.0341 (11)	0.0430 (11)	0.0034 (8)	−0.0094 (9)	−0.0128 (9)
C1	0.0405 (14)	0.0383 (13)	0.0442 (14)	0.0018 (10)	−0.0094 (11)	−0.0156 (11)
C2	0.0415 (14)	0.0385 (13)	0.0474 (14)	0.0050 (11)	−0.0122 (11)	−0.0177 (11)
C11	0.0433 (14)	0.0449 (14)	0.0455 (14)	0.0042 (11)	−0.0134 (11)	−0.0206 (12)
C12	0.0562 (18)	0.0600 (19)	0.071 (2)	0.0170 (15)	−0.0307 (15)	−0.0391 (16)
C13	0.0616 (19)	0.064 (2)	0.079 (2)	0.0217 (16)	−0.0314 (17)	−0.0466 (18)
C14	0.0552 (17)	0.0591 (18)	0.0506 (16)	0.0022 (14)	−0.0151 (13)	−0.0290 (14)
C15	0.0416 (14)	0.0541 (16)	0.0427 (14)	0.0027 (12)	−0.0121 (11)	−0.0174 (12)
C16	0.0429 (14)	0.0450 (14)	0.0462 (14)	0.0048 (11)	−0.0123 (11)	−0.0168 (12)
C17	0.0528 (18)	0.074 (2)	0.0621 (19)	0.0166 (16)	−0.0220 (15)	−0.0275 (16)
O1	0.0510 (12)	0.0744 (15)	0.0633 (13)	0.0143 (10)	−0.0273 (10)	−0.0340 (11)
O2	0.0634 (13)	0.0742 (15)	0.0730 (15)	0.0133 (11)	−0.0290 (11)	−0.0487 (12)
O20	0.0734 (16)	0.0777 (17)	0.0888 (18)	0.0213 (13)	−0.0353 (14)	−0.0321 (14)
C21	0.107 (4)	0.087 (3)	0.157 (5)	0.016 (3)	−0.066 (4)	−0.031 (3)
C22	0.144 (5)	0.082 (3)	0.119 (4)	−0.009 (3)	−0.045 (4)	−0.024 (3)
O30	0.0544 (12)	0.0465 (11)	0.0676 (13)	−0.0068 (9)	−0.0144 (10)	−0.0159 (10)
C31	0.110 (3)	0.062 (2)	0.065 (2)	−0.002 (2)	−0.027 (2)	−0.0051 (18)
C32	0.106 (3)	0.098 (3)	0.061 (2)	0.014 (3)	−0.012 (2)	−0.028 (2)

Geometric parameters (Å, º)

Ni—N3^i	1.908 (2)	C12—C13	1.387 (4)
Ni—N3	1.908 (2)	C13—C14	1.368 (4)
Ni—S^i	2.1799 (7)	C14—O2	1.367 (3)
Ni—S	2.1799 (7)	C14—C15	1.390 (4)
S—C1	1.726 (3)	C15—O1	1.367 (3)
N1—C1	1.340 (3)	C15—C16	1.380 (4)
N2—C1	1.317 (3)	C17—O1	1.429 (4)
N2—N3	1.401 (3)	O20—C21	1.425 (5)
N3—C2	1.301 (3)	C21—C22	1.369 (7)
C2—C11	1.452 (4)	O30—C31	1.419 (4)
C11—C12	1.394 (4)	C31—C32	1.472 (6)
C11—C16	1.410 (4)
N3^i—Ni—N3	180.0	C12—C11—C16	118.0 (2)
N3^i—Ni—S^i	85.42 (7)	C12—C11—C2	127.2 (2)
N3—Ni—S^i	94.58 (7)	C16—C11—C2	114.7 (2)
N3^i—Ni—S	94.58 (7)	C13—C12—C11	119.9 (3)
N3—Ni—S	85.42 (7)	C14—C13—C12	121.5 (3)
S^i—Ni—S	180.0	O2—C14—C13	121.7 (3)
C1—S—Ni	95.44 (9)	O2—C14—C15	118.5 (3)
C1—N2—N3	112.2 (2)	C13—C14—C15	119.9 (3)
C2—N3—N2	115.3 (2)	O1—C15—C16	125.4 (3)
C2—N3—Ni	125.24 (18)	O1—C15—C14	115.2 (3)
N2—N3—Ni	119.40 (16)	C16—C15—C14	119.4 (3)
N2—C1—N1	118.1 (2)	C15—C16—C11	121.3 (3)
N2—C1—S	122.6 (2)	C15—O1—C17	117.0 (2)
N1—C1—S	119.4 (2)	C22—C21—O20	114.1 (5)
N3—C2—C11	131.6 (2)	O30—C31—C32	114.8 (3)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O30^ii	0.87	2.07	2.930 (3)	168
O20—H20···O2^iii	0.83	2.02	2.753 (3)	146
O2—H2A···O20	0.83	1.91	2.705 (3)	160
N1—H1B···O30^iv	0.87	2.19	3.023 (3)	161
O30—H30···N2^v	0.83	2.01	2.838 (3)	174
O30—H30···N3^v	0.83	2.63	3.360 (3)	147

Symmetry codes: (ii) −x, −y+1, −z+1; (iii) −x+1, −y+1, −z+1; (iv) x−1, y, z−1; (v) x, y, z+1.