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The title compound, [Re2O3(C19H20N2O2)2], is a hexacoordinate complex containing an [Re2O3]4+ core with a linear O=Re-O-Re=O bridge. The distorted octahedral coordination of the ReV atom is achieved by an N2O2 donor set from the tetradentate imine-phenol ligand. The overall charge of the compound is neutral due to deprotonation of the phenol groups, and the terminating and bridging O atoms. The Re=O and Re-O bond distances of the [Re2O3]4+ core are 1.699 (4) and 1.911 (1) Å, respectively. The Re-O and Re-N bond distances of the equatorial plane are in the ranges 2.024 (4)-2.013 (4) and 2.128 (5)-2.120 (5) Å, respectively.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100004455/qa0249sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100004455/qa0249Isup2.hkl
Contains datablock I

CCDC reference: 145624

Comment top

Rhenium, being a congener to technetium in Group VIIa, might be expected to form complexes that have structural and biological similarities to the corresponding technetium complexes. With the characters of β emitters, both 188Re and 186Re have potential utility in radiotherapy. Recent focus has been on the design and preparation of new rhenium complexes in order to optimize the biodistribution of the potential radiopharmaceuticals. Interest is aroused in exploring the coordination chemistry of the rhenium complexes with tetradentate N2O2 ligands (Luo et al., 1995; Tisato et al., 1990; Mazzi et al., 1986). We describe here the synthesis and characterization of the title compound, (I).

The title compound forms a dinuclear complex, the Re atom being hexacoordinated to two imine N, two phenol O and two axial O atoms. The dinuclear structure, with a linear ORe—O—ReO bridge, is very similar to those of the µ-oxo-dioxotechnetium(V) or µ-oxo-dioxorhenium(V) complexes reported in the literature (Middleton et al., 1979; Bandoli & Nicolini, 1984; Pietzsch et al., 1995; Pillai et al., 1990, 1994). The compound consists of two independent ReO–dmpn(sal) [dmpn(sal) is N,N'-2,2-dimethylpropane-1,3-diylbis(salicylideneimine) or 2,2'-[2,2-dimethylpropane-1,3-diylbis(nitrilomethylidyne)]diphenolate] units bridged by an O atom and the tetradentate Schiff base occupies the four planar coordination sites of an octahedron. The structure of ReO–dmpn(sal), with an N2O2 donor set in the same plane perpendicular to the ReO bond, is different from the configuration of chloro{1,3-[N,N'-bis(salicylidene)diamino]-2,2-dimethylpropyl}oxorhenium(V) [(II); Herrmann, Rauch & Artus, 1996]. It was reported that substitution reactions on the MO3+ (M = Tc, Re) core with N2O2 Schiff base ligands might lead to three types of complex, [MOX(N2O2)] (X = Cl, Br), {[MO(N2O2)]2O} and [MO(OH2)(N2O2)]+ (Herrmann, Rauch & Artus, 1996; Herrmann, Rauch & Roesky, 1996; Bandoli & Nicolini, 1984). The title compound, {[MO(N2O2)]2O}, was facile to form in the solution containing water. The other two types of the compound were presumably formed but the product isolated was the most stable (Bandoli & Nicolini, 1984).

The ReO bond length [1.699 (4) Å] is similar to the mean value (1.691 Å, σ = 0.025 Å) for a large sample of monooxo ReV (Mayer, 1988). The Re—N(imine) distance [2.128 (5) Å] observed is similar to that of (II) (Herrmann, Rauch & Artus, 1996). The O2—Re1—N1 and O2—Re1—N2 angles deviate by less than 2.0° from the ideal value of 90°. The trans-O3—Re1—N2 and trans-O4—Re1—N1 angles are 171.5 (2) and 169.7 (2)°, respectively. The compression of both trans-O—Re—N angles from 180° indicates a marked level of tetrahedral distortion from square-planar geometry around the ReV atom. The least-square-planes data shows that the Re atom is approximately 0.14 Å out of the plane defined by the coordinated atoms of tetradentate ligand toward the terminal O atoms.

Experimental top

N,N'-2,2-Dimethylpropane-1,3-diylbis(salicylideneimine) was prepared by condensation of salicylaldehyde (50 mmol) and 1,3-diamino-2,2-dimethylpropane (25 mmol) in absolute ethanol (100 ml). Refluxing was continued for 6 h and the resultant product was placed in a freezer for 24 h. The yellow precipitate which appeared was collected by filtration and washed with cold ethanol (95%). After recrystallization, yellow crystals were harvested and dried in vacuo. Bu4NReOCl4 was synthesized following the previous report of Cotton & Lippert (1966). Bu4NCl (2 M, 20 ml) was added to NH4ReO4 (20 mmol) in distilled water. The white precipitate, Bu4NReO4, were collected and dried. Bu4NReO4 was purged with dry HCl in dry ethanol (100 ml). The brown precipitate were collected and dried. N,N'-2,2-Dimethylpropane-1,3-diylbis(salicylideneimine) (0.84 mmol) was added to solid Bu4NReOCl4 (0.42 mmol) in dry ethanol. The reaction mixture was refluxed for 3 h and then stirred for 24 h at room temperature. The green solution was concentrated until dark-green crystals of the Re complex formed. The crystals were then dissolved in 95% ethanol at 348 K and the resulting solution was allowed to stand at room temperature for a few days whereupon crystals suitable for X-ray analysis were formed.

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SHELXTL (Sheldrick, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

µ-oxo-bis-{oxo[N,N'-2,2-dimethylpropane-1,3- diylbis(salicylideneiminato)]rhenium (V)} top
Crystal data top
[Re2O3(C19H20N2O2)2]F(000) = 1004
Mr = 1037.14Dx = 1.929 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 11.2427 (2) ÅCell parameters from 6635 reflections
b = 13.3736 (2) Åθ = 2.5–25°
c = 12.4932 (2) ŵ = 6.83 mm1
β = 108.109 (1)°T = 293 K
V = 1785.38 (5) Å3Tabular, green
Z = 20.21 × 0.20 × 0.06 mm
Data collection top
CCD area-detector
diffractometer
4225 independent reflections
Radiation source: fine-focus sealed tube3266 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.056
ϕ and ω scansθmax = 28.8°, θmin = 1.9°
Absorption correction: empirical (using intensity measurements) from equivalent data (sheldrick, 1991)
?
h = 1414
Tmin = 0.274, Tmax = 0.664k = 1717
10934 measured reflectionsl = 1610
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.084H-atom parameters constrained
S = 1.01 w = 1/[σ2(Fo2) + (0.0352P)2]
where P = (Fo2 + 2Fc2)/3
4225 reflections(Δ/σ)max < 0.001
232 parametersΔρmax = 1.19 e Å3
0 restraintsΔρmin = 1.79 e Å3
Crystal data top
[Re2O3(C19H20N2O2)2]V = 1785.38 (5) Å3
Mr = 1037.14Z = 2
Monoclinic, P21/cMo Kα radiation
a = 11.2427 (2) ŵ = 6.83 mm1
b = 13.3736 (2) ÅT = 293 K
c = 12.4932 (2) Å0.21 × 0.20 × 0.06 mm
β = 108.109 (1)°
Data collection top
CCD area-detector
diffractometer
4225 independent reflections
Absorption correction: empirical (using intensity measurements) from equivalent data (sheldrick, 1991)
?
3266 reflections with I > 2σ(I)
Tmin = 0.274, Tmax = 0.664Rint = 0.056
10934 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0380 restraints
wR(F2) = 0.084H-atom parameters constrained
S = 1.01Δρmax = 1.19 e Å3
4225 reflectionsΔρmin = 1.79 e Å3
232 parameters
Special details top

Experimental. The data collection nominally covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle for the crystal and each exposure cover 0.3° in ω. The crystal-to-detector distance was 5.89 cm. Converge of the unique set is over 90.8% complete to at least 28.79° in θ. Repeating the initial frames at the end of data collection and analyzing the duplicate reflections monitored, crystal decay was monitored and found to be negligible.

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 (Å2) top
xyzUiso*/Ueq
Re10.048078 (19)0.134220 (15)0.546208 (17)0.03092 (8)
O10.00000.00000.50000.0340 (12)
O20.1108 (4)0.2492 (3)0.5846 (4)0.0454 (10)
O30.0324 (4)0.1010 (3)0.6994 (3)0.0420 (9)
O40.1335 (3)0.1715 (3)0.5121 (3)0.0398 (9)
N10.2294 (4)0.0692 (3)0.5884 (4)0.0392 (11)
N20.0395 (4)0.1571 (3)0.3758 (4)0.0319 (10)
C10.1201 (6)0.0645 (4)0.7872 (5)0.0392 (14)
C20.0928 (7)0.0562 (5)0.8884 (5)0.0563 (18)
H2A0.01470.07640.89120.068*
C30.1783 (8)0.0189 (6)0.9844 (6)0.071 (2)
H3A0.15750.01461.05070.085*
C40.2949 (8)0.0123 (6)0.9829 (6)0.074 (2)
H4A0.35250.03781.04770.088*
C50.3247 (7)0.0053 (5)0.8853 (6)0.066 (2)
H5A0.40340.02660.88530.079*
C60.2409 (6)0.0332 (4)0.7839 (5)0.0454 (15)
C70.2841 (5)0.0344 (4)0.6881 (5)0.0432 (15)
H7A0.36250.00630.69880.052*
C80.2910 (5)0.0462 (4)0.5034 (5)0.0438 (14)
H8A0.26190.01890.47150.053*
H8B0.38020.04070.54130.053*
C90.2710 (5)0.1206 (4)0.4063 (6)0.0422 (14)
C100.1345 (5)0.1171 (4)0.3289 (5)0.0426 (14)
H10A0.12930.15400.26070.051*
H10B0.11350.04800.30740.051*
C110.0533 (5)0.2009 (4)0.3054 (5)0.0386 (13)
H11A0.04490.21390.23500.046*
C120.1692 (5)0.2328 (4)0.3209 (5)0.0343 (12)
C130.2541 (6)0.2796 (5)0.2279 (5)0.0506 (16)
H13A0.22850.29570.16600.061*
C140.3740 (6)0.3025 (5)0.2253 (6)0.0579 (19)
H14A0.42880.33370.16280.070*
C150.4115 (6)0.2786 (5)0.3164 (6)0.0509 (17)
H15A0.49300.29260.31480.061*
C160.3309 (5)0.2345 (4)0.4098 (5)0.0419 (14)
H16A0.35900.21840.47020.050*
C170.2063 (5)0.2129 (4)0.4161 (5)0.0331 (12)
C180.3132 (6)0.2254 (5)0.4461 (6)0.0533 (17)
H18A0.39840.22370.49420.080*
H18B0.26080.25170.48720.080*
H18C0.30710.26730.38230.080*
C190.3479 (6)0.0816 (5)0.3330 (6)0.0588 (18)
H19A0.43510.08160.37590.088*
H19B0.33470.12400.26830.088*
H19C0.32200.01470.30880.088*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Re10.03185 (13)0.03354 (13)0.02764 (12)0.00291 (9)0.00967 (9)0.00108 (9)
O10.033 (3)0.040 (3)0.026 (3)0.001 (2)0.006 (2)0.002 (2)
O20.056 (3)0.036 (2)0.042 (2)0.0019 (19)0.012 (2)0.0040 (19)
O30.046 (2)0.053 (2)0.026 (2)0.003 (2)0.0090 (19)0.0048 (18)
O40.040 (2)0.050 (2)0.033 (2)0.0133 (18)0.0176 (19)0.0078 (18)
N10.037 (3)0.037 (3)0.043 (3)0.001 (2)0.009 (2)0.001 (2)
N20.032 (2)0.037 (3)0.030 (2)0.0008 (19)0.014 (2)0.0050 (19)
C10.049 (3)0.038 (3)0.027 (3)0.005 (3)0.007 (3)0.004 (2)
C20.072 (5)0.062 (4)0.033 (3)0.012 (4)0.015 (3)0.004 (3)
C30.100 (6)0.074 (5)0.033 (4)0.018 (5)0.012 (4)0.015 (4)
C40.082 (6)0.081 (6)0.039 (4)0.000 (5)0.009 (4)0.021 (4)
C50.061 (4)0.067 (5)0.054 (4)0.005 (4)0.004 (4)0.017 (4)
C60.047 (4)0.041 (3)0.038 (3)0.005 (3)0.001 (3)0.004 (3)
C70.034 (3)0.042 (3)0.048 (4)0.006 (2)0.005 (3)0.001 (3)
C80.035 (3)0.047 (4)0.051 (4)0.006 (3)0.016 (3)0.005 (3)
C90.033 (3)0.040 (3)0.058 (4)0.001 (2)0.021 (3)0.003 (3)
C100.040 (3)0.055 (4)0.041 (3)0.000 (3)0.024 (3)0.002 (3)
C110.040 (3)0.050 (4)0.027 (3)0.001 (3)0.013 (3)0.006 (3)
C120.033 (3)0.040 (3)0.031 (3)0.003 (2)0.011 (2)0.004 (2)
C130.041 (3)0.072 (4)0.038 (3)0.010 (3)0.010 (3)0.019 (3)
C140.046 (4)0.070 (5)0.050 (4)0.009 (3)0.003 (3)0.021 (4)
C150.031 (3)0.056 (4)0.064 (4)0.012 (3)0.012 (3)0.004 (3)
C160.034 (3)0.051 (4)0.046 (4)0.008 (3)0.019 (3)0.005 (3)
C170.029 (3)0.031 (3)0.036 (3)0.000 (2)0.007 (2)0.004 (2)
C180.042 (3)0.049 (4)0.074 (5)0.001 (3)0.025 (4)0.003 (3)
C190.048 (4)0.059 (4)0.080 (5)0.008 (3)0.036 (4)0.011 (4)
Geometric parameters (Å, º) top
Re1—O21.697 (4)C3—C41.381 (12)
Re1—O11.9114 (2)C4—C51.364 (12)
Re1—O42.015 (4)C5—C61.420 (8)
Re1—O32.025 (4)C6—C71.425 (9)
Re1—N22.123 (5)C8—C91.530 (8)
Re1—N12.126 (5)C9—C181.514 (8)
O3—C11.320 (6)C9—C191.534 (9)
O4—C171.343 (6)C9—C101.540 (8)
N1—C71.292 (7)C11—C121.439 (7)
N1—C81.470 (8)C12—C131.401 (7)
N2—C111.279 (7)C12—C171.404 (8)
N2—C101.469 (7)C13—C141.377 (9)
C1—C21.395 (9)C14—C151.368 (10)
C1—C61.434 (9)C15—C161.369 (8)
C2—C31.376 (9)C16—C171.407 (7)
O2—Re1—O1171.76 (14)C3—C2—C1121.8 (7)
O2—Re1—O498.06 (18)C2—C3—C4120.4 (8)
O1—Re1—O489.75 (12)C5—C4—C3119.3 (7)
O2—Re1—O394.71 (19)C4—C5—C6122.9 (7)
O1—Re1—O388.86 (12)C5—C6—C7116.7 (6)
O4—Re1—O382.77 (15)C5—C6—C1116.9 (6)
O2—Re1—N292.19 (19)C7—C6—C1126.4 (5)
O1—Re1—N284.94 (12)N1—C7—C6129.0 (6)
O4—Re1—N291.43 (16)N1—C8—C9116.7 (5)
O3—Re1—N2171.54 (15)C18—C9—C8112.9 (6)
O2—Re1—N191.05 (18)C18—C9—C19109.5 (5)
O1—Re1—N181.39 (12)C8—C9—C19106.3 (5)
O4—Re1—N1169.80 (16)C18—C9—C10112.6 (5)
O3—Re1—N191.95 (18)C8—C9—C10110.5 (5)
N2—Re1—N192.80 (18)C19—C9—C10104.5 (5)
Re1i—O1—Re1180.0N2—C10—C9116.4 (5)
C1—O3—Re1127.3 (4)N2—C11—C12128.5 (5)
C17—O4—Re1126.0 (3)C13—C12—C17118.8 (5)
C7—N1—C8115.5 (5)C13—C12—C11115.7 (5)
C7—N1—Re1121.2 (4)C17—C12—C11125.3 (5)
C8—N1—Re1122.5 (4)C14—C13—C12122.1 (6)
C11—N2—C10115.6 (5)C15—C14—C13118.8 (6)
C11—N2—Re1121.9 (4)C14—C15—C16121.1 (6)
C10—N2—Re1122.4 (3)C15—C16—C17121.4 (6)
O3—C1—C2117.7 (6)O4—C17—C12125.1 (5)
O3—C1—C6123.6 (5)O4—C17—C16117.0 (5)
C2—C1—C6118.7 (6)C12—C17—C16117.8 (5)
Symmetry code: (i) x, y, z+1.

Experimental details

Crystal data
Chemical formula[Re2O3(C19H20N2O2)2]
Mr1037.14
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)11.2427 (2), 13.3736 (2), 12.4932 (2)
β (°) 108.109 (1)
V3)1785.38 (5)
Z2
Radiation typeMo Kα
µ (mm1)6.83
Crystal size (mm)0.21 × 0.20 × 0.06
Data collection
DiffractometerCCD area-detector
diffractometer
Absorption correctionEmpirical (using intensity measurements) from equivalent data (Sheldrick, 1991)
Tmin, Tmax0.274, 0.664
No. of measured, independent and
observed [I > 2σ(I)] reflections
10934, 4225, 3266
Rint0.056
(sin θ/λ)max1)0.678
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.084, 1.01
No. of reflections4225
No. of parameters232
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.19, 1.79

Computer programs: SMART (Bruker, 1998), SMART, SHELXTL (Sheldrick, 1991), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL.

Selected geometric parameters (Å, º) top
Re1—O21.697 (4)Re1—N22.123 (5)
Re1—O11.9114 (2)Re1—N12.126 (5)
Re1—O42.015 (4)N1—C71.292 (7)
Re1—O32.025 (4)N2—C111.279 (7)
O2—Re1—O1171.76 (14)O4—Re1—N291.43 (16)
O2—Re1—O498.06 (18)O3—Re1—N2171.54 (15)
O1—Re1—O489.75 (12)O2—Re1—N191.05 (18)
O2—Re1—O394.71 (19)O1—Re1—N181.39 (12)
O1—Re1—O388.86 (12)O4—Re1—N1169.80 (16)
O4—Re1—O382.77 (15)O3—Re1—N191.95 (18)
O2—Re1—N292.19 (19)N2—Re1—N192.80 (18)
O1—Re1—N284.94 (12)Re1i—O1—Re1180.0
Symmetry code: (i) x, y, z+1.
 

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