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In the title compound, (C2H8NO)2[PdCl4], 2-hy­droxy­ethanaminium cations and tetra­chloridopalladate(II) dianions crystallize in a 2:1 ratio with the anion residing on a crystallographic inversion center. The cations and anions are linked in a complex three-dimensional framework by three types of strong hydrogen bonds (N—H...O, N—H...Cl, and O—H...Cl), which form various ring and chain patterns of up to the ternary graph-set level.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536810045435/nk2068sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536810045435/nk2068Isup2.hkl
Contains datablock I

CCDC reference: 802977

Key indicators

  • Single-crystal X-ray study
  • T = 100 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.012
  • wR factor = 0.028
  • Data-to-parameter ratio = 29.9

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) ..... 1 PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L= 0.600 13 PLAT153_ALERT_1_C The su's on the Cell Axes are Equal (x 100000) 40 Ang. PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L= 0.600 4
Alert level G PLAT794_ALERT_5_G Note: Tentative Bond Valency for Pd1 ....... 1.98
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

Comment top

Hydrolysis of imines in Schiff base first row transition metal complexes is now common (Chattopadhyay et al. 2007, Czaun et al., 2010; Guzei et al., 2010; Lee et al., 1948) These metal complexes have been used to protect amines by first converting them to imines followed by metal assisted hydrolysis back to the amine (Deng et al., 2002; Kurita, 2001; Shelley et al., 1999). However, hydrolysis of imines by second row transition metal complexes is very rare. In an attempt to use 2,4-di-tert-butyl-6-{(2-hydroxyethylimino)methyl}phenol to prepare a palladium complex, we isolated the ammonium chloride salt of tetrachloropalladate, [C2H8NO]2+[PdCl4]2-, a result of the hydrolysis of the imine ligand.

The ionic title compound (I) consists of bis(2-hydroxyethanaminium) cations and tetrachloro-palladium(II) dianions in a 2:1 ratio. The tetrachloro-palladium(II) dianion resides on a crystallographic inversion center. The geometrical parameters of (I) are typical as confirmed by a Mogul geometrical check (Bruno et al., 2004). Three types of hydrogen bonds, N1—H1A···O1,(a), N1—H1C···Cl2,(b), and O1—H1···Cl1,(c) form a three dimensional framework. The most easily visualized graph set motifs in the network include the primary ring pattern R22(10) a->a->, three different secondary patterns formed by bonds b and c, the chain C22(9) b c, the chain C44(18) bcc and the ring R44(18) bcbc, and the ternary chain pattern C33(8) acb (Bernstein et al., 1995).

The R-factor of the structural determination of (I) is a mere 1.18%. Data mining of the Cambridge Structural Database (Cambridge Structural Database, CSD, version 1.12, August 2010 update; Allen, 2002) found only 113 reported structural determinations with lower R-factors. This extremely low R-factor along with the unusually low standard uncertainties on the bond distances (fourth decimal place) and angles (third decimal place) are indicative of the high precision of this structure.

Related literature top

For the hydrolysis of imines in Schiff base first-row transition metal complexes, see: Chattopadhyay et al. (2007); Czaun et al. (2010); Guzei et al. (2010); Lee et al. (1948). For the use of Schiff base first-row transition metal complexes as amine protecting groups, see: Deng et al. (2002); Kurita (2001); Shelley et al. (1999). For geometrical parameter checks, see: Bruno et al. (2004). For R factor comparisons, see: Allen (2002). For graph-set notation, see: Bernstein et al. (1995).

Experimental top

A solution of [PdCl2(NCMe)2] (0.11 g, 0.429 mmol) in dichloromethane (5 ml) was added to a solution of 2,4-di-tert-butyl-6-[(2-hydroxy-ethylimino)methyl]-phenol (0.12 g, 0.429 mmol) in dichloromethane (5 ml). The mixture was stirred at room temperature for 16 h, filtered, and the filtrate evaporated to dryness. Recrystallization of the residue from dichloromethane-hexane gave brown crystals over several days. Yield: 0.10 g (58%).

Refinement top

All H-atoms were placed in idealized locations with an O—H distance of 0.84 Å, N—H distances of 0.91 Å, and C—H distances of 0.99 Å. All H-atoms were refined as riding with appropriate thermal displacement coefficients Uiso(H) = 1.5 times Ueq(bearing atom) for the hydrogen atoms attached to oxygen atoms or 1.2 times Ueq(bearing atom) for all hydrogen atoms attached to nitrogen or carbon atoms.

Structure description top

Hydrolysis of imines in Schiff base first row transition metal complexes is now common (Chattopadhyay et al. 2007, Czaun et al., 2010; Guzei et al., 2010; Lee et al., 1948) These metal complexes have been used to protect amines by first converting them to imines followed by metal assisted hydrolysis back to the amine (Deng et al., 2002; Kurita, 2001; Shelley et al., 1999). However, hydrolysis of imines by second row transition metal complexes is very rare. In an attempt to use 2,4-di-tert-butyl-6-{(2-hydroxyethylimino)methyl}phenol to prepare a palladium complex, we isolated the ammonium chloride salt of tetrachloropalladate, [C2H8NO]2+[PdCl4]2-, a result of the hydrolysis of the imine ligand.

The ionic title compound (I) consists of bis(2-hydroxyethanaminium) cations and tetrachloro-palladium(II) dianions in a 2:1 ratio. The tetrachloro-palladium(II) dianion resides on a crystallographic inversion center. The geometrical parameters of (I) are typical as confirmed by a Mogul geometrical check (Bruno et al., 2004). Three types of hydrogen bonds, N1—H1A···O1,(a), N1—H1C···Cl2,(b), and O1—H1···Cl1,(c) form a three dimensional framework. The most easily visualized graph set motifs in the network include the primary ring pattern R22(10) a->a->, three different secondary patterns formed by bonds b and c, the chain C22(9) b c, the chain C44(18) bcc and the ring R44(18) bcbc, and the ternary chain pattern C33(8) acb (Bernstein et al., 1995).

The R-factor of the structural determination of (I) is a mere 1.18%. Data mining of the Cambridge Structural Database (Cambridge Structural Database, CSD, version 1.12, August 2010 update; Allen, 2002) found only 113 reported structural determinations with lower R-factors. This extremely low R-factor along with the unusually low standard uncertainties on the bond distances (fourth decimal place) and angles (third decimal place) are indicative of the high precision of this structure.

For the hydrolysis of imines in Schiff base first-row transition metal complexes, see: Chattopadhyay et al. (2007); Czaun et al. (2010); Guzei et al. (2010); Lee et al. (1948). For the use of Schiff base first-row transition metal complexes as amine protecting groups, see: Deng et al. (2002); Kurita (2001); Shelley et al. (1999). For geometrical parameter checks, see: Bruno et al. (2004). For R factor comparisons, see: Allen (2002). For graph-set notation, see: Bernstein et al. (1995).

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009) and FCF_filter (Guzei 2007); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2009); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), publCIF (Westrip, 2010) and modiCIFer (Guzei, 2007).

Figures top
[Figure 1] Fig. 1. Molecular structure of (I). The thermal ellipsoids are shown at 50% probability level. Hydrogen bonds are shown with dashed lines. Symmetry transformations used to generate equivalent atoms: (i) -x + 2,-y + 2,-z + 1.
Bis(2-hydroxyethanaminium) tetrachloridopalladate(II) top
Crystal data top
(C2H8NO)2[PdCl4]F(000) = 368
Mr = 372.39Dx = 2.028 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 9951 reflections
a = 8.9401 (4) Åθ = 3.4–30.6°
b = 8.1621 (4) ŵ = 2.37 mm1
c = 8.5921 (4) ÅT = 100 K
β = 103.445 (2)°Block, orange
V = 609.78 (5) Å30.30 × 0.10 × 0.06 mm
Z = 2
Data collection top
Bruker SMART APEXII area-detector
diffractometer
1769 reflections with I > 2σ(I)
Mirror optics monochromatorRint = 0.024
0.60° ω and 0.6° φ scansθmax = 30.6°, θmin = 3.4°
Absorption correction: analytical
(SADABS; Bruker, 2001)
h = 1212
Tmin = 0.536, Tmax = 0.871k = 1111
14744 measured reflectionsl = 1212
1851 independent reflections
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)] = 0.012Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.028H-atom parameters constrained
S = 0.98 w = 1/[σ2(Fo2) + (0.0111P)2 + 0.3119P]
where P = (Fo2 + 2Fc2)/3
1851 reflections(Δ/σ)max = 0.001
62 parametersΔρmax = 0.43 e Å3
0 restraintsΔρmin = 0.50 e Å3
Crystal data top
(C2H8NO)2[PdCl4]V = 609.78 (5) Å3
Mr = 372.39Z = 2
Monoclinic, P21/cMo Kα radiation
a = 8.9401 (4) ŵ = 2.37 mm1
b = 8.1621 (4) ÅT = 100 K
c = 8.5921 (4) Å0.30 × 0.10 × 0.06 mm
β = 103.445 (2)°
Data collection top
Bruker SMART APEXII area-detector
diffractometer
1851 independent reflections
Absorption correction: analytical
(SADABS; Bruker, 2001)
1769 reflections with I > 2σ(I)
Tmin = 0.536, Tmax = 0.871Rint = 0.024
14744 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0120 restraints
wR(F2) = 0.028H-atom parameters constrained
S = 0.98Δρmax = 0.43 e Å3
1851 reflectionsΔρmin = 0.50 e Å3
62 parameters
Special details top

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
Pd11.00001.00000.50000.00979 (3)
Cl10.73683 (3)0.96899 (3)0.46100 (3)0.01355 (5)
Cl21.04022 (3)0.81392 (3)0.70777 (3)0.01331 (5)
O10.57008 (9)0.31533 (9)0.44982 (9)0.01677 (15)
H10.61470.22450.45270.025*
N10.74116 (10)0.59194 (11)0.58009 (10)0.01328 (16)
H1A0.64910.64490.55700.016*
H1C0.81770.66500.61850.016*
H1B0.74040.51350.65520.016*
C10.62509 (12)0.42371 (14)0.34444 (12)0.01645 (19)
H1E0.54380.50410.29870.020*
H1D0.64870.36000.25510.020*
C20.76792 (13)0.51374 (13)0.43181 (13)0.01585 (19)
H2A0.85490.43590.46040.019*
H2B0.79510.59880.36100.019*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pd10.00874 (5)0.00986 (5)0.01049 (5)0.00005 (3)0.00164 (3)0.00051 (3)
Cl10.01008 (10)0.01379 (10)0.01650 (11)0.00018 (8)0.00250 (8)0.00104 (8)
Cl20.01270 (10)0.01301 (10)0.01342 (10)0.00109 (8)0.00143 (8)0.00129 (7)
O10.0146 (3)0.0126 (3)0.0239 (4)0.0011 (3)0.0062 (3)0.0002 (3)
N10.0124 (4)0.0126 (4)0.0146 (4)0.0007 (3)0.0028 (3)0.0006 (3)
C10.0148 (4)0.0202 (5)0.0141 (4)0.0002 (4)0.0029 (4)0.0009 (4)
C20.0136 (4)0.0199 (5)0.0153 (4)0.0011 (4)0.0059 (4)0.0009 (4)
Geometric parameters (Å, º) top
Pd1—Cl22.3074 (2)N1—H1B0.9100
Pd1—Cl12.3119 (3)C1—C21.5127 (15)
O1—C11.4322 (13)C1—H1E0.9900
O1—H10.8400C1—H1D0.9900
N1—C21.4932 (13)C2—H2A0.9900
N1—H1A0.9100C2—H2B0.9900
N1—H1C0.9100
Cl2i—Pd1—Cl189.409 (8)C2—C1—H1E109.4
Cl2—Pd1—Cl190.591 (9)O1—C1—H1D109.4
C1—O1—H1109.5C2—C1—H1D109.4
C2—N1—H1A109.5H1E—C1—H1D108.0
C2—N1—H1C109.5N1—C2—C1110.29 (8)
H1A—N1—H1C109.5N1—C2—H2A109.6
C2—N1—H1B109.5C1—C2—H2A109.6
H1A—N1—H1B109.5N1—C2—H2B109.6
H1C—N1—H1B109.5C1—C2—H2B109.6
O1—C1—C2111.14 (8)H2A—C2—H2B108.1
O1—C1—H1E109.4
O1—C1—C2—N151.28 (11)
Symmetry code: (i) x+2, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O1ii0.911.972.8370 (12)158
O1—H1···Cl1iii0.842.353.1869 (8)179
N1—H1C···Cl20.912.303.2048 (9)170
Symmetry codes: (ii) x+1, y+1, z+1; (iii) x, y1, z.

Experimental details

Crystal data
Chemical formula(C2H8NO)2[PdCl4]
Mr372.39
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)8.9401 (4), 8.1621 (4), 8.5921 (4)
β (°) 103.445 (2)
V3)609.78 (5)
Z2
Radiation typeMo Kα
µ (mm1)2.37
Crystal size (mm)0.30 × 0.10 × 0.06
Data collection
DiffractometerBruker SMART APEXII area-detector
Absorption correctionAnalytical
(SADABS; Bruker, 2001)
Tmin, Tmax0.536, 0.871
No. of measured, independent and
observed [I > 2σ(I)] reflections
14744, 1851, 1769
Rint0.024
(sin θ/λ)max1)0.715
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.012, 0.028, 0.98
No. of reflections1851
No. of parameters62
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.43, 0.50

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXTL (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009) and FCF_filter (Guzei 2007), SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2009), publCIF (Westrip, 2010) and modiCIFer (Guzei, 2007).

Selected geometric parameters (Å, º) top
Pd1—Cl22.3074 (2)Pd1—Cl12.3119 (3)
Cl2i—Pd1—Cl189.409 (8)Cl2—Pd1—Cl190.591 (9)
Symmetry code: (i) x+2, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O1ii0.911.972.8370 (12)157.8
O1—H1···Cl1iii0.842.353.1869 (8)179.3
N1—H1C···Cl20.912.303.2048 (9)169.9
Symmetry codes: (ii) x+1, y+1, z+1; (iii) x, y1, z.
 

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