Crystal structure of fac-aquatricarbonyl[(S)-valin­ato-κ2N,O]­rhenium(I)

Piletska, K.O.; Domasevitch, K.V.; Shtemenko, A.V.

doi:10.1107/S2056989016005235

research communications

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ISSN: 2056-9890

Volume 72| Part 4| April 2016| Pages 590-592

https://doi.org/10.1107/S2056989016005235

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Crystal structure of fac-aquatricarbonyl[(S)-valinato-κ²N,O]rhenium(I)

Kseniia O. Piletska,^a ^* Kostiantyn V. Domasevitch ^b and Alexander V. Shtemenko ^a

^aDepartment of Inorganic Chemistry, Ukrainian State University of Chemical Technology, Gagarin Ave. 8, Dnipropetrovsk 49005, Ukraine, and ^bInorganic Chemistry Department, National Taras Shevchenko University of Kyiv, Volodymyrska Street 64/13, Kyiv 01601, Ukraine
^*Correspondence e-mail: ksenijapiletska@gmail.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 19 March 2016; accepted 28 March 2016; online 31 March 2016)

In the molecule of the title compound, [Re(C₅H₁₀NO₂)(CO)₃(H₂O)], the Re^I atom adopts a distorted octahedral coordination sphere defined by one aqua and three carbonyl ligands as well as one amino N and one carboxylate O atom of the chelating valinate anion. The carbonyl ligands are arranged in a fac-configuration around the Re^I ion. In the crystal, an intricate hydrogen-bonding system under participation of two O—H, two N—H and one C—H donor groups and the carboxylate and carbonyl O atoms as acceptor groups contribute to the formation of a three-dimensional supramolecular network.

Keywords: crystal structure; rhenium carbonyl complex; valine.

CCDC reference: 1469075

1. Chemical context

The syntheses of metal–organic compounds, which are capable of visualization of biomolecules, is receiving growing interest in biocoordination chemistry (Coogan & Fernández-Moreira, 2014 ). For the labeling of biomolecules, octahedral fac-tricarbonyl complexes of Tc and Re are the most promising compounds (Alberto, 2007 ; Coogan et al., 2014 ). The compact M(CO)₃-core (M = Tc, Re) allows labeling of low molecular weight substrates under retention of activity and specificity. In this context, Re(CO)₃⁺ compounds are of interest as the closest non-radioactive analogs of ^99mTc-based systems, which could be particularly important for visualization and immunotherapy. Studies of the cytotoxicity of rhenium carbonyl complexes also suggest their specific anticancer activity (Leonidova & Gasser, 2014 ).

Most of the known Re(CO)₃⁺ complexes with biologically essential substrates comprise tridentate co-ligands, e.g. histidinato-O,N,N′ (Alberto et al., 1999 ), methioninato-N,O,S (He et al., 2005 ), 2,3-diaminopropionato-N,N′,O (Liu et al., 2006 ), completing the coordination octahedra of the central ions. At the same time, coordinatively unsaturated complexes of bidentate aminocarboxylates could be suited for interactions with additional ligands, such as guanine bases (Zobi et al. 2005a ), thus allowing an attractive scenario for the assembly of mixed-ligand systems.

In this communication, we report the synthesis and crystal structure of a novel Re(CO)₃⁺ complex with valine and water as co-ligands. Following the findings of Zobi et al. (2005b ), sufficient reactivity of this compound towards DNA may be anticipated.

2. Structural commentary

In the molecule of the title compound (Fig. 1), the Re¹ ion resides in a slightly distorted octahedral coordination environment, with a facial arrangement of three nearly equidistant carbonyl ligands [Re1—C bond lengths are in the range 1.881 (7)–1.909 (7) Å]. The compound crystallizes in the chiral space group P2₁2₁2₁, with the S-enantiomer of the valinate anion present in the selected crystal. The anion coordinates in a bidentate-chelating fashion through the amino N and one carboxylate O atoms, with Re1—N1 and Re1—O4 bond lengths of 2.195 (5) and 2.122 (4) Å, respectively. The five-membered chelate ring [bite angle N1—Re1—O4 = 74.62 (18)°] has the expected envelope conformation, with the atoms of the Re1—O4—C4—C5 fragment being coplanar within 0.035 (3) Å and the N1 flap atom deviating from the given mean plane by 0.547 (6) Å. The Re1—O6 bond involving the aqua ligand [2.175 (5) Å] is slightly longer than the one with the carboxyl O atom. The CO ligands coordinate in an almost linear fashion, with O—C—Re bond angles spanning a range from 175.5 (7) to 179.9 (8)°, while the corresponding C—Re1—C angles are within 87.1 (3)–89.8 (2)°. All other bond length and angles are comparable to those found for related Re^I complexes (Rajendran et al., 2000 ).

Figure 1
The molecular structure of the title complex, with displacement ellipsoids drawn at the 40% probability level.

3. Supramolecular features

In the crystal, the packing of the molecules is governed by an intricate system of hydrogen bonds, including classical O—H⋯O and N—H⋯O bonds and weaker C—H⋯O interactions (Table 1). Two rather strong and nearly linear O—H⋯O bonds are observed between the aqua ligand and the non-coordinating carboxylate O atoms of two symmetry-related neighbouring molecules. The amino group forms two weaker N—H⋯O bonds to carbonyl O atom acceptor groups of two neighbouring molecules. Each non-coordinating carboxylate O atom accepts two such bonds, yielding hydrogen-bonded chains parallel to the a-axis direction (Fig. 2), whereas the N—H⋯O bonds expand the hydrogen-bonding system into a three-dimensional network. Additional C—H⋯O interactions consolidate this arrangement (Fig. 3). The combination of O—H⋯O and C—H⋯O (involving the chiral C5 atom) bonds may be important for the observed enantioselective packing of the chiral moieties (Petkova et al., 2001 ).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O6—H1W⋯O5ⁱ	0.85	1.85	2.693 (5)	175
O6—H2W⋯O5ⁱⁱ	0.85	1.88	2.723 (5)	175
N1—H1N⋯O3ⁱⁱⁱ	0.90	2.15	2.979 (7)	153
N1—H2N⋯O1^iv	0.90	2.41	3.103 (6)	133
C5—H5⋯O2^v	0.99	2.59	3.527 (7)	158
Symmetry codes: (i) x-1, y, z; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (iii) $[-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) x, y+1, z; (v) x+1, y, z.

Figure 2
Primary supramolecular interactions involving rather strong O—H⋯O bonds that produce chains parallel to the a axis. [Symmetry codes: (i) x − 1, y, z; (ii) x − 0.5, −y + 0.5, −z + 1.]

Figure 3
The crystal structure of the title complex showing all hydrogen-bonding interactions (O—H⋯O, N—H⋯O and C—H⋯O) as dashed lines. The isopropyl CH-hydrogen atoms were omitted for clarity. [Symmetry codes: (i) x − 1, y, z; (iv) x, y + 1, z; (v) x + 1, y, z.]

4. Synthesis and crystallization

To a solution of DL-valine (0.116 g, 0.984 mmol) in 5 ml of water, a solution of triaquatricarbonylrhenium(I) bromide (0.100 g, 0.246 mmol) in 10 ml of methanol was added. The reaction mixture was heated and stirred at 343 K under a steady stream of argon for 4 h. After cooling to room temperature, the solution was left to evaporate in air for a period of a few days. After removal of the methanol co-solvent, a colourless crystalline product formed. The precipitate was collected by suction filtration, washed with water and then with a 50 ml portion of petroleum ether and dried (yield: 0.068 g, 68%). Suitable single crystals were obtained by slow diffusion of hexane vapor into a methanol solution of the complex. IR (KBr, cm⁻¹): ν_as(CO) 2028 (s), ν_s(CO) 1905 (s).

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. C-bound hydrogen atoms were placed geometrically and refined using a riding model, with C—H = 0.97 Å and U_iso(H) = 1.5U_eq(C) for methyl and with C—H = 0.99 Å and U_iso(H) = 1.2U_eq(C) for methine groups. N- and O-bound hydrogen atoms were found from difference maps and refined with N—H = 0.90 Å, O—H = 0.85 Å and U_iso(H) = 1.2U_eq(N,O).

Table 2
Experimental details

Crystal data
Chemical formula	[Re(C₅H₁₀NO₂)(CO)₃(H₂O)]
M_r	404.39
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	213
a, b, c (Å)	7.1229 (5), 7.2913 (7), 22.6098 (18)
V (Å³)	1174.24 (17)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	10.36
Crystal size (mm)	0.16 × 0.12 × 0.12

Data collection
Diffractometer	Stoe Imaging plate diffraction system
Absorption correction	Numerical (X-SHAPE and X-RED; Stoe, 2001 )
T_min, T_max	0.288, 0.370
No. of measured, independent and observed [I > 2σ(I)] reflections	10442, 2809, 2546
R_int	0.040
(sin θ/λ)_max (Å⁻¹)	0.660

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.022, 0.047, 0.99
No. of reflections	2809
No. of parameters	147
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.68, −0.91
Absolute structure	Flack x determined using 990 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 ).
Absolute structure parameter	−0.018 (10)
Computer programs: IPDS Software (Stoe, 2000 ), SHELXS97 (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ), DIAMOND (Brandenburg, 1999 ) and WinGX (Farrugia, 2012 ).

Supporting information

CCDC reference: 1469075

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989016005235/wm5283sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016005235/wm5283Isup2.hkl

checkCIF report

Computing details top

Data collection: IPDS Software (Stoe, 2000); cell refinement: IPDS Software (Stoe, 2000); data reduction: IPDS Software (Stoe, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 2012).

fac-Aquatricarbonyl[(S)-valinato-κ²N,O]rhenium(I) top

Crystal data top

[Re(C₅H₁₀NO₂)(CO)₃(H₂O)]	D_x = 2.287 Mg m⁻³
M_r = 404.39	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 8000 reflections
a = 7.1229 (5) Å	θ = 2.9–28.0°
b = 7.2913 (7) Å	µ = 10.36 mm⁻¹
c = 22.6098 (18) Å	T = 213 K
V = 1174.24 (17) Å³	Prism, colorless
Z = 4	0.16 × 0.12 × 0.12 mm
F(000) = 760

Data collection top

Stoe Imaging plate diffraction system diffractometer	2546 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.040
φ oscillation scans	θ_max = 28.0°, θ_min = 2.9°
Absorption correction: numerical (X-SHAPE and X-RED; Stoe, 2001)	h = −9→9
T_min = 0.288, T_max = 0.370	k = −9→9
10442 measured reflections	l = −29→29
2809 independent reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.022	H-atom parameters constrained
wR(F²) = 0.047	w = 1/[σ²(F_o²) + (0.0254P)²] where P = (F_o² + 2F_c²)/3
S = 0.99	(Δ/σ)_max = 0.002
2809 reflections	Δρ_max = 1.68 e Å⁻³
147 parameters	Δρ_min = −0.91 e Å⁻³
0 restraints	Absolute structure: Flack x determined using 990 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013).
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.018 (10)

Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Re1	0.27215 (3)	0.24317 (4)	0.36414 (2)	0.01911 (8)
O1	0.1402 (9)	−0.1539 (7)	0.3751 (3)	0.0475 (16)
O2	−0.0548 (9)	0.3311 (10)	0.2820 (3)	0.059 (2)
O3	0.4865 (10)	0.1103 (10)	0.2566 (3)	0.0510 (17)
O4	0.4953 (6)	0.2146 (6)	0.42564 (19)	0.0201 (10)
O5	0.7729 (7)	0.3107 (6)	0.4559 (2)	0.0296 (11)
O6	0.1463 (7)	0.3556 (6)	0.4439 (2)	0.0216 (10)
H1W	0.0276	0.3449	0.4455	0.032*
H2W	0.1929	0.3046	0.4744	0.032*
N1	0.4095 (7)	0.5125 (7)	0.3670 (3)	0.0202 (10)
H1N	0.4012	0.5560	0.3298	0.030*
H2N	0.3545	0.5944	0.3913	0.030*
C1	0.1826 (10)	−0.0024 (10)	0.3716 (4)	0.0300 (15)
C2	0.0674 (10)	0.2983 (10)	0.3127 (3)	0.0309 (18)
C3	0.4063 (11)	0.1628 (11)	0.2973 (3)	0.0283 (16)
C4	0.6284 (10)	0.3294 (9)	0.4248 (3)	0.0215 (14)
C5	0.6095 (10)	0.4941 (9)	0.3839 (3)	0.0216 (14)
H5	0.6814	0.4668	0.3475	0.026*
C6	0.6917 (11)	0.6706 (9)	0.4109 (4)	0.0319 (16)
H6	0.8235	0.6446	0.4220	0.038*
C7	0.5880 (13)	0.7280 (13)	0.4668 (4)	0.048 (2)
H7A	0.4638	0.7721	0.4565	0.072*
H7B	0.6574	0.8250	0.4864	0.072*
H7C	0.5768	0.6236	0.4931	0.072*
C8	0.6942 (12)	0.8254 (9)	0.3654 (5)	0.0424 (19)
H8A	0.5664	0.8610	0.3561	0.064*
H8B	0.7566	0.7837	0.3298	0.064*
H8C	0.7613	0.9298	0.3816	0.064*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Re1	0.01711 (11)	0.02296 (11)	0.01726 (10)	0.00198 (16)	−0.00083 (9)	−0.00125 (15)
O1	0.035 (3)	0.027 (3)	0.081 (5)	−0.005 (2)	−0.001 (3)	0.002 (3)
O2	0.038 (4)	0.091 (5)	0.048 (4)	0.017 (3)	−0.016 (3)	−0.006 (3)
O3	0.060 (5)	0.061 (4)	0.032 (3)	0.016 (3)	0.012 (3)	−0.006 (3)
O4	0.018 (2)	0.020 (3)	0.023 (2)	−0.0010 (17)	−0.0010 (17)	0.0027 (17)
O5	0.015 (2)	0.043 (2)	0.030 (2)	0.0011 (19)	−0.005 (2)	0.0118 (19)
O6	0.019 (2)	0.024 (2)	0.022 (2)	0.0027 (18)	0.0015 (19)	0.0026 (18)
N1	0.020 (3)	0.020 (2)	0.020 (3)	0.0023 (19)	−0.002 (3)	0.003 (2)
C1	0.020 (4)	0.037 (4)	0.032 (4)	−0.002 (3)	−0.004 (3)	0.000 (3)
C2	0.023 (4)	0.043 (5)	0.026 (4)	0.011 (3)	−0.010 (3)	−0.010 (3)
C3	0.027 (4)	0.041 (4)	0.016 (3)	0.006 (3)	0.005 (3)	−0.001 (3)
C4	0.017 (4)	0.028 (3)	0.019 (3)	0.005 (3)	0.003 (3)	0.002 (2)
C5	0.017 (3)	0.025 (3)	0.023 (3)	0.002 (2)	0.000 (2)	0.000 (2)
C6	0.024 (4)	0.031 (3)	0.041 (4)	0.000 (3)	−0.005 (3)	−0.001 (3)
C7	0.055 (5)	0.039 (5)	0.050 (5)	0.005 (5)	−0.006 (4)	−0.022 (4)
C8	0.033 (5)	0.027 (3)	0.066 (6)	−0.007 (3)	−0.002 (5)	0.004 (4)

Geometric parameters (Å, º) top

Re1—C3	1.881 (7)	N1—H1N	0.9004
Re1—C2	1.908 (7)	N1—H2N	0.9004
Re1—C1	1.909 (7)	C4—C5	1.520 (9)
Re1—O4	2.122 (4)	C5—C6	1.539 (9)
Re1—O6	2.175 (5)	C5—H5	0.9900
Re1—N1	2.195 (5)	C6—C7	1.523 (11)
O1—C1	1.148 (9)	C6—C8	1.526 (11)
O2—C2	1.139 (9)	C6—H6	0.9900
O3—C3	1.148 (9)	C7—H7A	0.9700
O4—C4	1.265 (8)	C7—H7B	0.9700
O5—C4	1.255 (8)	C7—H7C	0.9700
O6—H1W	0.8498	C8—H8A	0.9700
O6—H2W	0.8503	C8—H8B	0.9700
N1—C5	1.482 (8)	C8—H8C	0.9700

C3—Re1—C2	88.0 (3)	O5—C4—O4	122.3 (6)
C3—Re1—C1	87.1 (3)	O5—C4—C5	119.9 (6)
C2—Re1—C1	89.8 (3)	O4—C4—C5	117.8 (6)
C3—Re1—O4	96.6 (3)	N1—C5—C4	108.3 (5)
C2—Re1—O4	173.0 (2)	N1—C5—C6	113.1 (5)
C1—Re1—O4	95.8 (3)	C4—C5—C6	112.8 (6)
C3—Re1—O6	173.2 (3)	N1—C5—H5	107.5
C2—Re1—O6	96.4 (3)	C4—C5—H5	107.5
C1—Re1—O6	98.2 (3)	C6—C5—H5	107.5
O4—Re1—O6	78.61 (18)	C7—C6—C8	111.2 (7)
C3—Re1—N1	94.4 (3)	C7—C6—C5	111.9 (6)
C2—Re1—N1	99.8 (3)	C8—C6—C5	110.9 (7)
C1—Re1—N1	170.4 (3)	C7—C6—H6	107.5
O4—Re1—N1	74.62 (18)	C8—C6—H6	107.5
O6—Re1—N1	79.7 (2)	C5—C6—H6	107.5
C4—O4—Re1	119.1 (4)	C6—C7—H7A	109.5
Re1—O6—H1W	114.3	C6—C7—H7B	109.5
Re1—O6—H2W	110.2	H7A—C7—H7B	109.5
H1W—O6—H2W	108.2	C6—C7—H7C	109.5
C5—N1—Re1	110.8 (4)	H7A—C7—H7C	109.5
C5—N1—H1N	109.6	H7B—C7—H7C	109.5
Re1—N1—H1N	105.0	C6—C8—H8A	109.5
C5—N1—H2N	108.7	C6—C8—H8B	109.5
Re1—N1—H2N	114.7	H8A—C8—H8B	109.5
H1N—N1—H2N	107.9	C6—C8—H8C	109.5
O1—C1—Re1	175.5 (7)	H8A—C8—H8C	109.5
O2—C2—Re1	179.9 (8)	H8B—C8—H8C	109.5
O3—C3—Re1	178.6 (7)

Re1—O4—C4—O5	−173.0 (5)	O5—C4—C5—C6	−37.3 (9)
Re1—O4—C4—C5	6.6 (7)	O4—C4—C5—C6	143.1 (6)
Re1—N1—C5—C4	−31.1 (6)	N1—C5—C6—C7	60.3 (8)
Re1—N1—C5—C6	−156.7 (5)	C4—C5—C6—C7	−63.0 (8)
O5—C4—C5—N1	−163.1 (6)	N1—C5—C6—C8	−64.5 (8)
O4—C4—C5—N1	17.2 (8)	C4—C5—C6—C8	172.2 (6)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O6—H1W···O5ⁱ	0.85	1.85	2.693 (5)	175
O6—H2W···O5ⁱⁱ	0.85	1.88	2.723 (5)	175
N1—H1N···O3ⁱⁱⁱ	0.90	2.15	2.979 (7)	153
N1—H2N···O1^iv	0.90	2.41	3.103 (6)	133
C5—H5···O2^v	0.99	2.59	3.527 (7)	158

Symmetry codes: (i) x−1, y, z; (ii) x−1/2, −y+1/2, −z+1; (iii) −x+1, y+1/2, −z+1/2; (iv) x, y+1, z; (v) x+1, y, z.

Acknowledgements

This work was supported by the fund Grant for Science Research (No. 0111U000111) from the Ministry of Education and Science of Ukraine. We also thank EU COST Action CM 1105 for supporting this study.

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