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Acta Cryst. (2009). E65, m1533-m1534    [ doi:10.1107/S1600536809045930 ]

trans-Bis(1-cyclohexylpyrrolidin-2-one)dinitratopalladium(II)

Y. Takahashi and Y. Ikeda

Abstract top

In the title compound, [Pd(NO3)2(C10H17NO)2], the PdII centre is located on an inversion center and is coordinated in a square-planar geometry by two O atoms of the monodentate nitrate groups and two carbonyl O atoms of the 1-cyclohexylpyrrolidin-2-one ligands.

Comment top

Ambidentate ligands are known as ligands with two different coordination cites, such as thiocyanate ion (N and S), cyanate ion (N and O), dimethyl sulfoxide (DMSO, O and S), and N,N-dimethylformamide (DMF, N and O) (Fairlie et al., 1985; Rack et al., 2003; Sigel et al., 1982). For amide complexes of metal ions classified as hard Lewis acids, such as [M(NH3)5(amide)]3+ (M = Co, Cr) (Anget et al., 1990; Curtis et al., 1983), the O-bonded form is thermodynamically and kinetically more favored than the N-bonded form. On the other hand, PdII classified as a soft Lewis acid usually exhibits a weak affinity to O-donor ligands. Hence, amide compounds should coordinate to PdII through a nitrogen atom more preferably. In fact, it has been known that the PdII complex with 2-pyrrolidone is N-bonded form, i.e., cis-PdCl2(pyrroline-2-ol)2 (Pankratov et al., 2004). However, PdII complexes with O-bonded amides have been also reported, e.g., PdCl2(L)2, Pd(L)4.(ClO4)2 (L = DMF, N,N-dimethylacetamide, N-methyl-acetamide, and N-methylformamide) (Wayland et al., 1969), and Pd(DMF)2(o-(N-methylliminomethyl)phenyl).BF4 (Rheingold et al., 1988). In a similar manner to amides, PdII complexes with S– and O-bonded DMSO have been reported, such as trans-PdCl2(DMSO)2 with two S-bonded DMSO, and Pd(DMSO)4(BF4)2.DMSO with two S– and O-bonded DMSO and a solvated DMSO (Johansson et al., 1981; Johansson et al., 2001; Langs et al., 1967). In PdII nitrate complexes, some crystal structures with S–, P–, N–, or O-donor ligand have been reported, e.g., cis-Pd(NO3)2(DMSO)2, (Bennett et al., 1967) Pd(NO3)2(dppm).3CDCl3 (dppm = bis(diphenylphosphino)methane), (Adrian et al., 2006; Rath et al., 1999) enPd(NO3)2 (en = ethylenediamine), (Bray et al.,2005; Cerdà et al., 2006) and trans-Pd(NO3)2(H2O)2 (Gromilov et al., 2008; Khranenko et al., 2007; Laligant et al., 1991). In all of these complexes, nitrate coordinates to PdII as the oxygen donor unidentate ligand. So far as we know, trans-Pd(NO3)2(L)2 (L: oxygen donor unidenntate ligand) is only trans-Pd(NO3)2(H2O)2 and Pd(NO3)2(O-bonded amide)2 has not been reported. We prepared PdII nitrate complex with the O-bonded amide, trans-Pd(NO3)2(NCP)2 (NCP = N-cycrohexyl-2-pyrrolidone), and analyzed its crystal structure using the single-crystal X-ray analytical method. An ORTEP view of trans-Pd(NO3)2(NCP)2 is shown in Fig. 1. In this complex, the configuration around Pd atom is square planar. The nitrate and NCP coordinate to PdII through their oxygen atoms. The cyclohexyl group of NCP is torsional to pyrrolidone ring. Fig. 2 shows the configuration of coordinated nitrate in trans-Pd(NO3)2(NCP)2. From this figure, it is found that the nitrate is planar with O—N—O angles close to 120°, and that the distance of Pd···O(3)is longer than Pd···O(2), and almost same as that of trans-Pd(NO3)2(H2O)2 (2.926 Å; Khranenko et al. (2007). This reflects the fact that in the trans-Pd(NO3)2(NCP)2 complex nitrate coordinates to PdII as the unidentate ligand. As mentioned above, the skeletal structure of trans-Pd(NO3)2(NCP)2 is almost same as that of trans-Pd(NO3)2(H2O)2. However, the Pd—O(NO3) distance in trans-Pd(NO3)2(NCP)2 is slightly longer than that in trans-Pd(NO3)2(H2O)2 (1.999 (5) Å) (Khranenko et al.(2007)), and the Pd—O(NCP) distance is 0.02 Å shorter than the Pd—O(water) distance (2.030 (5) Å). The differences in Pd—O(L) (L = H2O or NCP) distances are considered to be due to those in electron donicity of L, that is, the donor number (28.6) of NCP is larger than that (18.0) of water (Gutmann, 1967, Gutmann,1968, Koshino et al., 2005). Thus, the NCP molecules should more strongly coordinate to the Pd(NO3)2 moiety than water. This may result in a slightly longer distance of Pd—O(NO3) in trans-Pd(NO3)2(NCP)2 than in trans-Pd(NO3)2(H2O)2. Infrared spectrum of trans-Pd(NO3)2(NCP)2 in the solid state was measured as a CaF2 pellet by Shimadzu FT—IR-8400S spectrophotometer. The carbonyl stretching band of NCP was observed at 1593 cm-1, which is lower frequency than that (1670 cm-1) of free NCP. The lower shift value (Δ ν = 77 cm-1) is comparable to those (68–107 cm-1) for other PdII amide complexes(Wayland et al., 1969). This supports the result of single-crystal analysis that NCP coordinates to the Pd(NO3)2 moiety through carbonyl oxygen atom. 1H and 13C NMR spectra of solution prepared by dissolving trans-Pd(NO3)2(NCP)2 and (CH3)4Si into CDCl3 were also measured using Jeol ECX-400 NMR spectrometer (1H: 399.8 MHz). The 1H and 13C NMR signals corresponding to free NCP were not observed. Most of 1H and 13C NMR signals due to coordinated NCP were found to be shifted to lower field compared with those of free NCP. In 1H NMR spectrum, the signals of methyne (CH) proton in cyclohexyl group and the methylene protons (N—CH2) in pyrrolidone ring were observed as a broad multiplet at 3.78 p.p.m. (0.14 p.p.m. high field shift compared with that of free NCP) and triplet at 3.58 and 3.50 p.p.m. (0.02 and 0.10 p.p.m. low field shift compared with those of free NCP), respectively. In the 13C NMR spectrum, carbonyl carbon and methylene carbon (N—CH2) in pyrrolidone ring were observed at 180.49 p.p.m. (6.44 p.p.m. low field shift compared with that of free NCP) and 46.09 p.p.m. (3.22 p.p.m. low field shift compared with that of free NCP). These results suggest that even in CDCl3 solution two NCP molecules coordinate to PdII. It is worth noting that in spite of the soft Lewis acid all coordination sites of PdII are occupied by oxygen donor ligands. The present result should be first example for the crystal analysis of trans-Pd(NO3)2(L)2 complex, in which L is the ambidentate ligand with O– and N-bonding sites.

Related literature top

For general background to ambidentate ligands, see: Fairlie et al. (1985); Rack et al. (2003); Sigel et al. (1982). For amide complexes of metal ions, see: Anget et al. (1990); Curtis et al. (1983). Pankratov et al. (2004); Wayland et al. (1969); Rheingold et al. (1988); Johnson et al. (1981; Johansson et al. (2001); Langs et al. (1967); Bennett et al. (1967); Adrian et al. (2006); Rath et al. (1999); Bray et al. (2005); Cerdà et al. (2006); Gromilov et al. (2008); Khranenko et al. (2007); Laligant et al. (1991). For bond-length data, see: Gutmann (1967, 1968); Koshino et al. (2005).

Experimental top

The crystal of trans-Pd(NO3)2(NCP)2 was prepared by adding Pd(NO3)2.2H2O (0.8218 g, 3.084 mmol, Kojima Chemicals Co., Inc., 38.85wt% in Pd) to CH2Cl2 solution of NCP (1.035 g, 6.186 mmol, Aldrich, 99%). The mixture was refluxed for 30 min with stirring and filtered off any undissolved PdII nitrate. The resulting solution was concentrated to approximately 5 ml, and then diethyl ether was added to form bilayer and to precipitate the complexes. Brown crystals were formed (yield 1.065 g, 59%). Elemental analyses were carried out by LECO CHNS-932 elemental analyzer. Cacl. for H34C20N4O8Pd: C, 42.52; H, 6.07; N, 9.92. Found: C, 42.25; H, 5.80; N, 9.88%.

Refinement top

The H atoms of methylene and methyne were placed in calculated positions with C—H = 0.99 and 1.00, respectively. All H atoms were refined as riding on their parent atoms with Uiso(H) = 1.2Ueq(C)

Computing details top

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2006); program(s) used to solve structure: SIR92 (Altomare et al., 1994) and DIRDIF99 (Beurskens et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2006).

Figures top
[Figure 1] Fig. 1. The ORTEP view of trans-Pd(NO3)2(NCP)2 complex with the atomic numbering. The thermal ellipsoids are drawn at 50% probability.
[Figure 2] Fig. 2. The configuration of coordinated nitrate in trans-Pd(NO3)2(NCP)2.
[Figure 3] Fig. 3. The packing view of trans-Pd(NO3)2(NCP)2 complex. The thermal ellipsoids are drawn at 50% probability.
trans-Bis(1-cyclohexylpyrrolidin-2-one)dinitratopalladium(II) top
Crystal data top
[Pd(NO3)2(C10H17NO)2]Z = 1
Mr = 564.91F(000) = 292.00
Triclinic, P1Dx = 1.571 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71075 Å
a = 7.6431 (5) ÅCell parameters from 5845 reflections
b = 9.8892 (8) Åθ = 3.3–27.5°
c = 10.1118 (7) ŵ = 0.83 mm−1
α = 60.8650 (19)°T = 173 K
β = 66.057 (2)°Platelet, brown
γ = 68.845 (2)°0.78 × 0.41 × 0.07 mm
V = 597.24 (7) Å3
Data collection top
Rigaku R-AXIS RAPID
diffractometer		2662 reflections with F2 > 2σ(F2)
Detector resolution: 10.00 pixels mm-1Rint = 0.021
ω scansθmax = 27.5°
Absorption correction: numerical
(ABSCOR; Higashi, 1999)		h = −9→9
Tmin = 0.754, Tmax = 0.943k = −12→12
5836 measured reflectionsl = −11→13
2696 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.052H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0294P)2 + 0.1351P]
where P = (Fo2 + 2Fc2)/3
2696 reflections(Δ/σ)max = 0.001
152 parametersΔρmax = 0.32 e Å−3
Primary atom site location: structure-invariant direct methodsΔρmin = −0.93 e Å−3
Crystal data top
[Pd(NO3)2(C10H17NO)2]γ = 68.845 (2)°
Mr = 564.91V = 597.24 (7) Å3
Triclinic, P1Z = 1
a = 7.6431 (5) ÅMo Kα radiation
b = 9.8892 (8) ŵ = 0.83 mm−1
c = 10.1118 (7) ÅT = 173 K
α = 60.8650 (19)°0.78 × 0.41 × 0.07 mm
β = 66.057 (2)°
Data collection top
Rigaku R-AXIS RAPID
diffractometer		2696 independent reflections
Absorption correction: numerical
(ABSCOR; Higashi, 1999)		2662 reflections with F2 > 2σ(F2)
Tmin = 0.754, Tmax = 0.943Rint = 0.021
5836 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.020H-atom parameters constrained
wR(F2) = 0.052Δρmax = 0.32 e Å−3
S = 1.07Δρmin = −0.93 e Å−3
2696 reflectionsAbsolute structure: ?
152 parametersFlack parameter: ?
? restraintsRogers parameter: ?
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Pd(1)1.00001.00000.00000.02155 (5)
O(1)0.92669 (15)0.93354 (13)0.23446 (12)0.0268 (2)
O(2)1.18410 (17)1.12278 (13)−0.03171 (13)0.0308 (2)
O(3)0.98979 (19)1.33981 (14)−0.14453 (18)0.0454 (3)
O(4)1.25913 (19)1.34980 (16)−0.12849 (17)0.0447 (3)
N(1)1.14168 (19)1.27768 (16)−0.10479 (15)0.0289 (2)
N(2)0.99744 (17)0.78446 (13)0.46810 (13)0.0201 (2)
C(1)1.04947 (19)0.84244 (15)0.31243 (15)0.0200 (2)
C(2)1.2637 (2)0.78476 (17)0.24741 (16)0.0246 (2)
C(3)1.3405 (2)0.70029 (19)0.39282 (17)0.0283 (3)
C(4)1.1591 (2)0.6721 (2)0.53523 (17)0.0308 (3)
C(5)0.79357 (19)0.80910 (15)0.56480 (15)0.0197 (2)
C(6)0.7016 (2)0.67022 (18)0.61976 (19)0.0284 (3)
C(7)0.4882 (2)0.6965 (2)0.7192 (2)0.0320 (3)
C(8)0.4713 (2)0.7307 (2)0.85611 (18)0.0331 (3)
C(9)0.5632 (2)0.8697 (2)0.79808 (19)0.0329 (3)
C(10)0.7782 (2)0.8389 (2)0.70401 (18)0.0288 (3)
H(1)1.43090.59870.39430.034*
H(2)1.41060.76710.39300.034*
H(3)0.71850.90560.49660.024*
H(4)1.14270.56170.58140.037*
H(5)1.16700.69470.61760.037*
H(6)0.83530.93140.66500.035*
H(7)0.85270.74580.77330.035*
H(8)0.55430.88690.88940.040*
H(9)0.49070.96660.73040.040*
H(10)0.33160.75440.91340.040*
H(11)0.53710.63590.93070.040*
H(12)0.40910.78650.65150.038*
H(13)0.43530.60110.76120.038*
H(14)1.32860.87420.16650.030*
H(15)1.28470.71080.20030.030*
H(16)0.77720.57180.68330.034*
H(17)0.70680.65780.52680.034*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pd(1)0.02369 (9)0.02268 (9)0.01332 (8)−0.00108 (5)−0.00923 (5)−0.00290 (6)
O(1)0.0252 (5)0.0317 (5)0.0153 (4)0.0013 (4)−0.0097 (3)−0.0052 (4)
O(2)0.0337 (5)0.0282 (5)0.0285 (5)−0.0043 (4)−0.0169 (4)−0.0047 (4)
O(3)0.0352 (6)0.0284 (5)0.0613 (8)−0.0068 (4)−0.0266 (6)0.0010 (5)
O(4)0.0404 (7)0.0437 (7)0.0463 (7)−0.0220 (5)−0.0156 (5)−0.0031 (6)
N(1)0.0270 (6)0.0299 (6)0.0209 (5)−0.0104 (4)−0.0063 (4)−0.0008 (4)
N(2)0.0224 (5)0.0203 (5)0.0152 (5)−0.0035 (4)−0.0084 (4)−0.0035 (4)
C(1)0.0242 (6)0.0195 (5)0.0162 (5)−0.0047 (4)−0.0083 (4)−0.0049 (4)
C(2)0.0229 (6)0.0275 (6)0.0181 (6)−0.0022 (5)−0.0075 (5)−0.0059 (5)
C(3)0.0241 (7)0.0327 (7)0.0221 (6)−0.0021 (5)−0.0110 (5)−0.0055 (5)
C(4)0.0262 (7)0.0367 (7)0.0188 (6)−0.0018 (5)−0.0123 (5)−0.0017 (5)
C(5)0.0228 (6)0.0197 (5)0.0151 (5)−0.0050 (4)−0.0067 (4)−0.0042 (4)
C(6)0.0278 (7)0.0286 (7)0.0356 (8)−0.0083 (5)−0.0092 (5)−0.0160 (6)
C(7)0.0262 (7)0.0341 (7)0.0388 (8)−0.0127 (5)−0.0082 (6)−0.0132 (6)
C(8)0.0292 (7)0.0403 (8)0.0232 (7)−0.0150 (6)−0.0022 (5)−0.0064 (6)
C(9)0.0331 (8)0.0436 (8)0.0268 (7)−0.0137 (6)−0.0004 (6)−0.0199 (7)
C(10)0.0311 (7)0.0397 (8)0.0242 (7)−0.0169 (6)−0.0014 (5)−0.0174 (6)
Geometric parameters (Å, °) top
Pd(1)—O(1)2.0092 (11)C(9)—C(10)1.533 (2)
Pd(1)—O(1)i2.0092 (11)C(2)—H(14)0.990
Pd(1)—O(2)2.0112 (15)C(2)—H(15)0.990
Pd(1)—O(2)i2.0112 (15)C(3)—H(1)0.990
O(1)—C(1)1.2699 (17)C(3)—H(2)0.990
O(2)—N(1)1.3158 (16)C(4)—H(4)0.990
O(3)—N(1)1.229 (2)C(4)—H(5)0.990
O(4)—N(1)1.222 (2)C(5)—H(3)1.000
N(2)—C(1)1.3200 (17)C(6)—H(16)0.990
N(2)—C(4)1.4754 (19)C(6)—H(17)0.990
N(2)—C(5)1.4713 (15)C(7)—H(12)0.990
C(1)—C(2)1.5020 (17)C(7)—H(13)0.990
C(2)—C(3)1.535 (2)C(8)—H(10)0.990
C(3)—C(4)1.5304 (18)C(8)—H(11)0.990
C(5)—C(6)1.525 (2)C(9)—H(8)0.990
C(5)—C(10)1.525 (2)C(9)—H(9)0.990
C(6)—C(7)1.5351 (19)C(10)—H(6)0.990
C(7)—C(8)1.525 (3)C(10)—H(7)0.990
C(8)—C(9)1.518 (3)
O(1)—Pd(1)—O(1)i180.00 (7)C(4)—C(3)—H(2)110.7
O(1)—Pd(1)—O(2)89.93 (5)H(1)—C(3)—H(2)108.8
O(1)—Pd(1)—O(2)i90.07 (5)N(2)—C(4)—H(4)111.1
O(1)i—Pd(1)—O(2)90.07 (5)N(2)—C(4)—H(5)111.1
O(1)i—Pd(1)—O(2)i89.93 (5)C(3)—C(4)—H(4)111.1
O(2)—Pd(1)—O(2)i180.00 (6)C(3)—C(4)—H(5)111.1
Pd(1)—O(1)—C(1)121.33 (8)H(4)—C(4)—H(5)109.0
Pd(1)—O(2)—N(1)117.47 (11)N(2)—C(5)—H(3)107.6
O(2)—N(1)—O(3)118.89 (17)C(6)—C(5)—H(3)107.7
O(2)—N(1)—O(4)116.54 (14)C(10)—C(5)—H(3)107.6
O(3)—N(1)—O(4)124.58 (13)C(5)—C(6)—H(16)109.5
C(1)—N(2)—C(4)112.87 (10)C(5)—C(6)—H(17)109.5
C(1)—N(2)—C(5)123.33 (12)C(7)—C(6)—H(16)109.5
C(4)—N(2)—C(5)123.11 (10)C(7)—C(6)—H(17)109.5
O(1)—C(1)—N(2)121.72 (11)H(16)—C(6)—H(17)108.1
O(1)—C(1)—C(2)127.06 (11)C(6)—C(7)—H(12)109.4
N(2)—C(1)—C(2)111.21 (11)C(6)—C(7)—H(13)109.4
C(1)—C(2)—C(3)103.45 (11)C(8)—C(7)—H(12)109.4
C(2)—C(3)—C(4)105.44 (12)C(8)—C(7)—H(13)109.4
N(2)—C(4)—C(3)103.45 (10)H(12)—C(7)—H(13)108.0
N(2)—C(5)—C(6)110.78 (12)C(7)—C(8)—H(10)109.4
N(2)—C(5)—C(10)111.59 (14)C(7)—C(8)—H(11)109.4
C(6)—C(5)—C(10)111.32 (11)C(9)—C(8)—H(10)109.4
C(5)—C(6)—C(7)110.86 (14)C(9)—C(8)—H(11)109.4
C(6)—C(7)—C(8)111.34 (17)H(10)—C(8)—H(11)108.0
C(7)—C(8)—C(9)111.23 (12)C(8)—C(9)—H(8)109.5
C(8)—C(9)—C(10)110.64 (16)C(8)—C(9)—H(9)109.5
C(5)—C(10)—C(9)109.88 (17)C(10)—C(9)—H(8)109.5
C(1)—C(2)—H(14)111.1C(10)—C(9)—H(9)109.5
C(1)—C(2)—H(15)111.1H(8)—C(9)—H(9)108.1
C(3)—C(2)—H(14)111.1C(5)—C(10)—H(6)109.7
C(3)—C(2)—H(15)111.1C(5)—C(10)—H(7)109.7
H(14)—C(2)—H(15)109.0C(9)—C(10)—H(6)109.7
C(2)—C(3)—H(1)110.7C(9)—C(10)—H(7)109.7
C(2)—C(3)—H(2)110.7H(6)—C(10)—H(7)108.2
C(4)—C(3)—H(1)110.7
O(1)—Pd(1)—O(2)—N(1)−113.91 (10)C(5)—N(2)—C(1)—O(1)4.9 (2)
O(2)—Pd(1)—O(1)—C(1)−66.76 (14)C(5)—N(2)—C(1)—C(2)−174.43 (15)
O(1)—Pd(1)—O(2)i—N(1)i−66.09 (10)C(4)—N(2)—C(5)—C(6)−74.5 (2)
O(2)i—Pd(1)—O(1)—C(1)113.24 (14)C(4)—N(2)—C(5)—C(10)50.2 (2)
O(1)i—Pd(1)—O(2)—N(1)66.09 (10)C(5)—N(2)—C(4)—C(3)−174.89 (17)
O(2)—Pd(1)—O(1)i—C(1)i−113.24 (14)O(1)—C(1)—C(2)—C(3)172.09 (18)
O(1)i—Pd(1)—O(2)i—N(1)i113.91 (10)N(2)—C(1)—C(2)—C(3)−8.6 (2)
O(2)i—Pd(1)—O(1)i—C(1)i66.76 (14)C(1)—C(2)—C(3)—C(4)16.71 (19)
Pd(1)—O(1)—C(1)—N(2)−172.54 (13)C(2)—C(3)—C(4)—N(2)−18.6 (2)
Pd(1)—O(1)—C(1)—C(2)6.7 (2)N(2)—C(5)—C(6)—C(7)−179.40 (13)
Pd(1)—O(2)—N(1)—O(3)2.66 (19)N(2)—C(5)—C(10)—C(9)178.01 (11)
Pd(1)—O(2)—N(1)—O(4)−177.21 (12)C(6)—C(5)—C(10)—C(9)−57.65 (14)
C(1)—N(2)—C(4)—C(3)14.4 (2)C(10)—C(5)—C(6)—C(7)55.81 (17)
C(4)—N(2)—C(1)—O(1)175.65 (17)C(5)—C(6)—C(7)—C(8)−54.16 (16)
C(4)—N(2)—C(1)—C(2)−3.7 (2)C(6)—C(7)—C(8)—C(9)55.18 (16)
C(1)—N(2)—C(5)—C(6)95.31 (17)C(7)—C(8)—C(9)—C(10)−57.20 (18)
C(1)—N(2)—C(5)—C(10)−140.05 (16)C(8)—C(9)—C(10)—C(5)58.08 (16)
Symmetry codes: (i) −x+2, −y+2, −z.
Table 1
Selected geometric parameters (Å) top
Pd(1)—O(1)2.0092 (11)Pd(1)—O(2)2.0112 (15)
Acknowledgements top

The authors would like to thank Takeshi Kawasaki for his useful comments.

references
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