Complexes from a Biphasic Solvent - ACS Publications - American

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One-step preparation and crystallization of almost insoluble palladium(II) and platinum(II/IV) complexes from a biphasic solvent system Matthias Boege, and Juergen Heck Cryst. Growth Des., Just Accepted Manuscript • Publication Date (Web): 22 Sep 2015 Downloaded from http://pubs.acs.org on September 22, 2015

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Crystal Growth & Design

One-step preparation and crystallization of almost insoluble palladium(II) and platinum(II/IV) complexes from a biphasic solvent system Matthias Böge†, Jürgen Heck*† †Institute of Inorganic and Applied Chemistry, Department of Chemistry, Hamburg University, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany Palladium; platinum; coordination compounds; N,N-ligand; crystallization

ABSTRACT: Scarcely soluble palladium(II) and platinum(II/IV) halido complexes with diamino ligands were prepared via a biphasic solvent system. Metal precursors like tetrachloridopalladate salts were dissolved in oxygen-free water, whereas the organic diamino ligands were dissolved in dry and oxygen-free dichloromethane. The dichloromethane layer was carefully covered with the aqueous layer under nitrogen atmosphere at room temperature. The desired products crystallized within a few weeks at the phase boundary. In the case of dihalidopalladium complexes with diamino-binaphthalene and diamino-carbohydrate ligands crystals were obtained without further manipulation, which were suitable for X-ray structure analysis.

INTRODUCTION Halidopalladium(II) and platinum(II) complexes with chelating N,N-ligands are usually prepared by solvation of the metal halide in the liquid ligand (Scheme 1a),1 by substitution of halido ligands in metallate complexes with the nitrogen ligands in polar-protic2 or polar-aprotic3 solution (Scheme 1b) or by substitution of weaker neutral ligands like nitriles4 or dimethylsulfoxide5 in neutral complex precursors (Scheme 1c). Scheme 1: Preparation of dichloridopalladium(II) and platinum(II) complexes by conventional methods.1-5

The first method (Scheme 1a) is limited to liquid or fusible ligands. The second method (Scheme 1b) is appropriate for complexes, which are poorly soluble in the polar-protic solvents, but the ligand might not be well soluble in water or alcohols. Furthermore, higher alcohols can reduce the metal precursor. The modified method using polar-aprotic solvents like dmf causes problems within the purification, since the reaction products except alkali halides are often soluble in the chosen solvent and residues of the solvent are not easily re-

moved. The third method (Scheme 1c, L' = nitrile) is merely appropriate for complexes with aprotic nitrogen ligands because of the risk of reactions between the nitriles, which behave like electrophiles, and amines.6-8 The dmso ligand is a nucleophile and does not react with amino ligands. But as already described, residues of polar aprotic solvents like dmso are not easily removed from the reaction product. Another problem is the structural analysis of neutral palladium(II) and platinum(II) complexes. Halidoplatinum complexes with diaminocarbohydrate ligands are often barely soluble in common solvents like alcohols, chlorinated hydrocarbons etc. These diaminocarbohydrate complexes containing hydroxyl groups usually are soluble in water.9.10 For the recording of nmr spectra of halidoplatinum complexes with diaminocarbohydrate ligands without hydroxyl groups dmso-d6 or dmf-d7 are the solvents of choice.11,12 It also concerns the halidoplatinum complexes with nitrogen ligands containing large aromatic systems.3,13 The suitable solvents dmso and dmf do not well mix with nonpolar organic solvents and display the tendency to form oils with the complexes. Therefore, these barely soluble complexes are hardly able to crystallize with conventional methods from polar, aprotic solvents. Complex preparation by interface diffusion applying ligand and metal precursor in different solvents are well known for biphasic14-16 and multiphasic17 layering. Since the diffusion of the solvents provided the complex formation, miscible liquids have always been used, yet. In this publication we present a new method of preparation of neutral palladium(II) and platinum(II/IV) complexes using a biphasic solvent system with two immiscible liquids, which allows the subsequent crystallization of the desired product. Some of the obtained crystals were directly suitable for elemental analysis and X-ray structure determination without further manipulation. By application of the new diffusion

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method formerly unknown halidopalladium(II) and platinum(II/IV) complexes of two different diaminomonosaccharides and halidopalladium(II) complexes of (R)- and (S)-2,2'diamino-1,1'-binaphthalene were prepared. The synthesis of the diaminomonosaccharide ligands has recently been described.18

RESULTS AND DISCUSSION Synthesis and characterization. The dibromido- and dichlorido-{(R)and (S)-2,2'-diamino-1,1'binaphthalene}palladium(II) complexes 5-7, the dibromido(methyl 2,3-diamino-4,6-O-benzylidene-2,3dideoxy-α-D-glucopyranoside)palladium(II) complex 8, and the halido(methyl 2,3-diamino-4,6-O-benzylidene-2,3dideoxy-α-D-gulopyranoside)platinum(II/IV) complexes 9 and 10 were prepared by the following method: under nitrogen atmosphere a solution of the ligand in dichloromethane was carefully layered with an aqueous solution of the appropriate halidometallate (Scheme 2). In order not to create too many nuclei of crystals by the emulsification of the liquids a syringe was used for the deposition of the aqueous layer. Kept in the dark the product crystallized at the phase boundary within a few weeks depending on the concentration of the reactants. A Schlenk tube was used as experimental setup (Figure 1). The yields were not optimized, because they were obtained mostly between 70-90 %.

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to a small distortion of the unit cell resulting from different cocrystallization of solvents. Furthermore, some additional signals occur, which indicates a minor phase impurity (Table in supp. inf.). Compound 8 is slightly soluble in common solvents in contrast to other compounds described here. Thus, proton nmr spectra from complex 8, which was obtained through the biphasic diffusion method, could be recorded. These nmr spectra were identical to these recorded from complex 8, obtained by the conventional method.

Scheme 2: Preparation of dichloridopalladium(II) and platinum(II/IV) complexes using a biphasic solvent system.

The crystals of the palladium complexes 5-8 were suitable for X-ray structure analysis. Crystals of the diaminobinaphthalene complexes 5-7 were shaped as needles with a size of about 0.3-0.5 mm length, while the diaminocarbohydrate complex 8 yielded bi-pyramidal crystals with an edge length up to 0.5 mm. The platinum complexes 9 and 10 were obtained as powders. When complex 8 was synthesized following a conventional route (Scheme 1c), the same compound was obtained as by the biphasic method. Nevertheless, it might be crystallized in a polymorphic modification, since polymorphs have already been described for platinum complexes.19-23 Thus, a powder diffractogram was measured from the sample obtained by a synthetic strategy involving ligand substitution. This was compared to a calculated powder diffractogram related to the X-ray structure of 8 (supp. inf.). Both do mainly coincide except a slight shift of a number of signals, which may regard

Figure 1. Schematic drawing of the experimental setup of the preparation method using a biphasic system. A Schlenk tube containing two liquid layers is displayed. The upper layer is an aqueous solution of the appropriate halidometallate. The lower layer is a solution of the ligand in dichloromethane. The desired product crystallizes at the phase boundary.


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Table 1. Ir data of the metal-halide and metal-nitrogen vibrational bands of the complexes 5-10a) and corresponding data derived from DFT calculations in parenthesis.b) compound

central metal

halido ligand

ν{M-Hal} (DFT) [cm-1]

5

Pd(II)

Br

217, 207 (scissoring: 241; stretching: 216, 208)b)

6

Pd(II)

Br

218, 207

Cl

338, 311 (stretching: 335, 331, 305; 290)b)

7

Pd(II)

8

Pd(II)

Br

230, 183 (scissoring: 249; stretching: 239, 222, 216, 177)b)

9 10

Pt(II) Pt(IV)

Cl Br

336, 321 233, 226

ν{M-N} (DFT) [cm-1] 481, 474 (ring vibration: 572, 554, 474, 411, 357, 320, 295; stretching: 529, 526, 421, 411; rocking: 513; scissoring: 444, 423; wagging: 318; twisting: 207)b) 481, 474 483, 479 (ring vibration: 573, 555, 475, 411, 221; stretching: 527, 423, 290; rocking: 428, 220; scissoring: 357)b) 543, 449, 434 (ring vibration: 522, 376, 344, 311; stretching: 501, 436; scissoring: 483, 434, 421; wagging: 239, 222, 205)b) 494, 489 511, 501, 463

a) Measured in a polyethylene matrix. b) Derived from DFTcalculations using Orca 2.8 and BP86/def-2tzvp.30-37

Table 2. Raman data of the metal-halide and metalnitrogen vibrational bands of the complexes 5-10. compound

central metal

halido ligand

5a

Pd(II)

Br

6b

Pd(II)

Br

7b 8b 9a 10a

Pd(II) Pd(II) Pt(II) Pt(IV)

Cl Br Cl Br

ν{M-Hal} [cm-1] 250, 231, 216, 198 249, 231, 215, 198 333, 315

495, 451, 422

229, 182 348 234, 193

497, 452, 436 498, 485, 438 511

ν{M-N} [cm-1] 493, 448 492, 447

a) Measured in a polyethylene matrix. b) Measured as a powder.

The energies of the vibrational modes of the metal-halide and the metal-nitrogen bonds in complexes 5-10 are found in the expected range (Tables 1 and 2):24,25 The bands of the metal-bromine and -chlorine stretching modes appear between 233-182 cm-1 and between 338-311 cm-1, respectively. The bands of the metal-nitrogen stretching modes fall in the range of 511-434 cm-1. In some cases and especially regarding to the diamino-binaphthalene complexes 5-7 some bands are only ir active and some only raman active. The vibration bands found

in raman spectra obtained from pure powders and from powders in polyethylene matrices appeared to be congruent (compare experimental part). The recorded absorption and emission assigned to metal ligand vibrations are comparable to these from corresponding ethylenediamine (en) complexes: dichlorido(en)platinum(II) and tetrabromido(en)platinum(IV) bear stretching bands of the metal-halide bonds at 331, 309 and 282 cm-1 (ir) and 308 and 286 cm-1 (raman), and at 237 and 198 cm-1 (ir) and 225, 210, 199 and 191 cm-1 (raman), respectively.26 The metal-nitrogen stretching bands are observed at 545 and 464 cm-1 (ir) and 566 and 549 cm-1 (raman), and. at 540 and 457 cm-1 (raman), respectively.26 For dichlorido(en)palladium(II) and dibromido(en)palladium(II) stretching bands of the metal-halide bonds are recorded at 343, 307 and 272 cm-1 (ir)27 and 344, 309, 272 cm-1 (raman),28 and at 228, 207 and 195 cm-1 (ir), respectively.27 Their metal-nitrogen stretching bands are found at 516, 508 and 445 cm-1 (ir)27 and 534, 537 and 452 cm-1 (raman),28 and at 520, 503 and 441 cm-1 (ir), respectively.27 Another comparable cis-dichloridopalladium complex displayed ir stretching bands of the metal-chlorine bonds at 309 and 284 cm-1.29 For a better assignment of the vibrational bands, the structures and ir vibrational frequencies of the palladium compounds 5, 7 and 8 were calculated by DFT methods (Orca 2.8; BP86/def2-tzvp).30-37 The results (Tables 1 and 2) demonstrate, that an assignment of metal-ligand bands either to metal-halide or to metal-nitrogen vibrations by particular ranges is simplistic, since the bands of the rocking, twisting and wagging modes of vibration of the amino groups are partly located at the same range like the stretching bands of the metal-halide bonds (Table 1). Thus, the calculations reveal the rather complex vibrational modes of the palladium nitrogen bonds including the ring vibration of the five or seven-membered ring derived from the chelation of the metal. Especially in the case of the binaphthalene complexes 5 and 7 the calculated ir data regarding the vibrational modes of the palladium-halide bonds fit the measured spectra quite well. Stretching bands of the palladium-bromine and chlorine bonds were predicted to 216 and 208 cm-1 and 335, 331 and 305 cm-1, respectively, and actually found in the measured ir spectra of 5 at 217 and 207 cm-1 and of 7 at 338 and 311 cm-1. The DFT calculation of 8 was performed for its dimeric superstructure, which was revealed by X-ray structure determination. Stretching bands at 239, 222, 216 and 177 cm-1 were predicted and found in the ir spectrum of 8 at 230 and 183 cm-1. Structural discussion. Diaminobinaphthalene complexes 5-7 crystallize in the space group C2 with R1 = 0.0240 (5), R1 = 0.0194 (6), and R1 = 0.0219 (7) (Table 3). The distances and the angles between the atoms at the metal center of the dibromide-palladium complexes 5 and 6 are very similar. The palladium-bromine distances amount about 243 pm and the palladium-ntrogen distances about 207 pm. The distances between the palladium and the chlorine atoms in dichloridopalladium complex 7 (about 230 pm) are slightly smaller than the distances between the palladium and the bromine atoms in 5 and 6, while the Hal-Pd-Hal bond angles lie in the same range: 94.8-95.1°. In consequence, the N-Pd-N bond angles and the torsion angles between the planes of the naphthalene rings are significantly different contrasting the dibromido(90.0-90.1°) and the dichloridopalladium complexes (90.5°). While the distances between the palladium and the two



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Table 3. Crystallographic data and structural refinement of the compounds 5-8.a)

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empirical formula formula weight /g mol-1 temperature /K crystal size [mm] crystal system space group a /pm b /pm c /pm β /° V /nm3 Z ρ (calc.) /g cm-3 µ /mm F(000) θ range /° index ranges

reflections collected independent reflections Flack parameter R1, ωR2 (2σ) R1, ωR2 (all data) data / restraints / parameters GOOF on F2

5

6

7

8

C20H16Br2N2Pd

C20H16Br2N2Pd

C20H16Cl2N2Pd

C59H86Br8Cl6N8O16Pd4

550.57 100(2) 0.30·0.06·0.02 monoclinic C2 1936.6(2) 753.62(8) 1277.37(13) 97.8540(10) 1.8468(3) 4 1.980 5.337 1064 2.5 - 28.2 -24 ≤ h ≤ 20 -9 ≤ k ≤ 9 -16 ≤ l ≤ 14 6310 3890 [Rint = 0.0250] 0.009(7) 0.0240, 0.0523 0.0269, 0.0539 3560 / 1 / 226

550.57 100(2) 0.30·0.07·0.02 monoclinic C2 1933.63(7) 753.75(3) 1276.58(5) 97.8410(10) 1.84319(12) 4 1.984 5.347 1064 2.5 - 32.2 -27 ≤ h ≤ 27 -10 ≤ k ≤ 10 -18 ≤ l ≤ 18 20789 10870 [Rint = 0.0289] 0.024(4) 0.0194, 0.0370 0.0222, 0.0378 5415 / 1 / 226

461.65 100(2) 0.41·0.22·0.02 monoclinic C2 1932.8(3) 744.78(13) 1257.7(2) 97.270(2) 1.7960(5) 4 1.707 1.335 920 2.5 - 28.1 -24 ≤ h ≤ 24 -9 ≤ k ≤ 9 -16 ≤ l ≤ 16 9675 5829 [Rint = 0.0234] -0.01(2) 0.0219, 0.0512 0.0238, 0.0525 3953 / 1 / 226

2440.92 100(2) 0.12·0.12·0.10 tetragonal P43212 1576.790(10) 1576.790(10) 3272.15(5) 8.13544(14) 16 1.993 5.060 4760 2.2 - 30.5 -23 ≤ h ≤ 23 -23 ≤ k ≤ 23 -48 ≤ l ≤ 48 217705 48640 [Rint = 0. 0442] 0.012(4) 0.0298, 0.0642 0.0362, 0.0666 14551 / 6 / 492

0.752

0.898

1.074

1.045

a) Hydrogen atoms were refined using the riding model. Measured using a Bruker AXS with Mo-Kα radiation, programs used: SAINT [Bruker AXS, 1998], SADABS [Bruker AXS, 1998], SHELXS-97 [Sheldrick, 1990], SHELXL-97 [Sheldrick, 1997].

Figure 2. Molecular structures of 2,2'-diamino-1,1'-binaphthalene palladium(II) complexes 5-7 and diaminoglucopyranoside palladium(II) complex 8 obtained from X-ray structure determination. The atoms of the cocrystallized dichloromethane molecules from the structure of 8 and the hydrogen atoms are omitted for clarity.


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Crystal Growth & Design Table 4. Selected structural data of complexes 5-8 and corresponding data for 5, 7 and 8 derived from DFT calculations in parenthesis.c) compound

5

distance Pd-N1 {DFT}[pm]

207.3(3) {216.7}c)

distance Pd-N2 {DFT} [pm]

207.5(3) {216.7}c)

torsion and dihedral angles {DFT} [°] non-bonding N-N distance {DFT} [pm] distance Pd-Hal (trans-N1) {DFT} [pm] distance Pd-Hal (trans-N2) {DFT} [pm] bond angle N1-Pd-N2 {DFT} [°]

6 207.3(2)

207.4(2)

7 207.9(2) {215}c)

206.8(2) {215}c)

64.1(2)a) {68.6}a),c)

64.0(2)a)

64.8(2)a) {68.3}a),c)

293.5(5) {307}c)

293.4(3)

294.8(4) {307}c)

242.92(5) {245.7}c)

242.54(3)

230.29(8) {232}c)

242.81(5) {245.7}c)

242.78(3)

230.22(8) {232}c)

90.1(1) {90.3}c)

90.02(7)

90.52(9) {91.1}c)

bond angle Hal-Pd-Hal {DFT} [°]

94.79(2) {96.5}c)

94.82(1)

95.07(3) {97.5}c)

intermolecular distances N-Hal {DFT} [pm]

334.1(4) 351.6(4)

333.7(2) 351.4(2)

339.3(3) 320.6(3)

8 206.2(2) 206.3(3) {211212}c) 203.9(2) 203.9(2) {211212}c) 54.7(3)b) 55.1(3)b) {56.7}b),c) 274.2(4) 275.6(4) {280}c) 242.10(3) 243.61(4) {248}c) 242.46(4) 242.81(4) {248}c) 83.9(1) 84.4(1) {82.6}c) 96.24(1) 96.58(2) {97.597.6}c) 353.5(2) 338.0(3) 361.2(2) 348.9(3) {334341}c)

a) Torsion angle defined by the planes of atoms N1-C2-C1 and N2-C12-C11. b) Dihedral angle defined by the planes of atoms N1-C2-C3 and N2-C3-C2. c) Derived from DFT-calculations using Orca 2.8 and BP86/def-2tzvp.30-37 Figure 3. One half of the asymmetric unit of the crystal packing of 8 obtained from X-ray structure determination viewed from two directions. The dimeric structure is almost C2-symmetric and the benzylidene groups of the sugar ligands build a cavity. The atoms of the cocrystallized dichloromethane molecules and the hydrogen atoms except the bridging hydrogen atoms are omitted for clarity.

coordinating nitrogen atoms are nearly equal in 5 and 6 (207.3-207.5 pm), these distances significantly differ in 7 from 206.8-207.9 pm (Table 4). Dichloridopalladium(II) complexes with en,19,38 1,2diamino-cyclohexane39 and 3,4-diamino-carbohydrate40 ligands show comparable structures at the metal center: their palladium-nitrogen distances are found in the range of 192 to 207 pm and their palladium-chlorine distances are found in the range of 229 to 232 pm. Their Cl-Pd-Cl and N-Pd-N bond angles are in the range of 93.0-95.3° and 83.0-86.0°, respectively. Due to the backbone with four carbon atoms between the amino groups of the diamino-binaphthalene ligands the palladium-nitrogen distances and the N-Pd-N bond angles of 90.0-90.5° in 5-7 are larger than the corresponding bond length and angles of the ligands with two carbon atoms between the amino groups as found in 8.

The molecular structures of complexes 5-7 are depicted in Figure 2. Short intermolecular distances between the nitrogen and halide atoms in their crystal structures suggest the presence of hydrogen bridge bonds (Table 4). The dft-optimized structures of 5 and 7 display larger bond length and angles than actually found in the X-ray structure. But only the calculated palladium-nitrogen distances (215-217 pm) are much larger than the observed values (Table 4). Dibromido-diaminoglucopyranoside complex 8 crystallizes in the space group P43212 with R1 = 0.0298 (Figure 2, Table 3). There are four molecules of 8 and three molecules of co-crystallized dichloromethane found in the asymmetric unit (Figure 3), which do not significantly differ from each other (Table 4). The distances between the palladium and the bromine atoms (about 243 pm) are similar to these found for complexes 5 and 6, while the palladium-nitrogen distances are significantly smaller (from 204 to 206 pm). Due to the small dihedral angles defined by the planes of the atoms N1-C2-C3 and N2-C3-C2 the N-Pd-N bond angle (about 84°) is rather small compared to the corresponding data of 5 and 6. In contrast, the Br-Pd-Br bond angle is rather large (96.2-96.6°). As illustrated by the non-bonding distances between the nitrogen



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atoms the steric demand of the coordinating groups of the monosaccharide ligand 1 is less than the steric demand of the coordinating groups of the binaphthalene ligands 3 and 4 (Table 4). The dichloridopalladium(II) complexes with en,19,38 1,2diamino-cyclohexane39 and 3,4-diamino-carbohydrate40 ligands show quite similar coordination geometries, except the distance and the Cl-Pd-Cl bond angles. The reason is the larger atomic radius of bromine compared to chlorine.41 The dihedral angle defined by the planes of the atoms N1-C2-C3 and N2-C3-C2 in 8 is significantly smaller than in halfsandwich complexes containing the same ligand.18 The dimeric structure of two molecules of 8 has been optimized by DFT methods.30-37 In particular the lengths of the palladium-nitrogen bonds are predicted longer (211-212 pm) than actually found. The calculated palladium-halogen distances and the bond angles better agree with those derived from X-ray structure determination. Two molecules of 8 form an almost C2-symmetric dimer, which constitutes one half of the asymmetric unit in the crystal structure (Figure 3). The square-planar complexes are parallely arranged and the benzylidene groups of the sugar ligands build a cavity. The short intermolecular distances between the nitrogen and the bromine suggest the presence of hydrogen bridge bonds (Table 4), which stabilize the dimeric structure. A comparable structure stabilized by hydrogen-bridges between the hydrogen atoms of the coordinating amino groups and the bromide ligands was obtained by DFToptimization.30-37 The DFT-calculated bond lengths at the metal center are slightly longer than these obtained from X-ray structure determination, while the intermolecular distances between Br1 and N4, Br2 and N3, Br3 and N2 and Br4 and N1, which are part of the hydrogen bridge bonds, are calculated slightly smaller (Table 4). The non-bonding distance between the palladium atoms in the X-ray determined molecular structure is about 334 pm. In the DFT-optimized structure a distance of 327 pm is found. Both distances are larger than two times the van-der-Waals radius of palladium, which amounts 326 pm.41 Following the DFT-calculations the dimer of 8 is 182 kJ/mol more stable than two monomers of 8. Thus, every hydrogen bridge bond would contribute about 46 kJ/mol to the stability of the dimer. Similar dimeric structures of dichloridopalladium(II) complexes with diamino-carbohydrate ligands have been described by Priebe and coworkers. They partly found sub-van-derWaals distances of the palladium atoms with distances from 324 to 333 pm.40 Conclusion and outlook. The new diffusion method of preparation with subsequent crystallization demonstrated the suitability for the preparation of insoluble, neutral palladium(II) and platinum(II,IV) complexes, which do not undergo fast hydrolysis of the metal halide bond. For all of the palladium complexes under study crystals were obtained, which were suitable for X-ray structure analysis. This diffusion method using biphasic solvent system with two immiscible layers allows the steering of the rates of crystallization by the grade of concentration of the ligand and metal precursor solutions. For the insoluble platinum complexes the concentrations might have been too high to obtain single crystals suitable for X-ray structure analysis. In order to prevent from hydrolysis and other possible side reactions modifications of the applied solvent system might be appropriate. The use of an ionic, non-aqueous layer for the

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metal precursor and an etheric layer for the ligand should provide inert conditions.

EXPERIMENTAL SECTION General Considerations. All the manipulations of air-sensitive compounds were carried out under a nitrogen atmosphere using the standard Schlenk techniques.43 The solvents were dried and distilled prior to use by literature methods.44,45 1H NMR spectra (DEPTQ/APT) were recorded on a Bruker Fourier 300 (1H: 300 MHz) and on a Bruker Avance 400 (1H: 400 MHz) at room temperature and the chemical shift values refer to acetone-d6 (δ(1H), 2.05 ppm).46 For the assignment of the proton signals various 2Dnmr-methods were carried out (1H-1H-COSY). Elemental analyses were carried out by the central elemental analysis section of the department of chemistry at the University of Hamburg. Air-sensitive compounds were analyzed on a Vario EL III of the company Elementar, non-sensitive compounds were analyzed on an EA 1108 CHNS-O of the company Carlo Erba. FAB-MS were carried out by the MS section of the institute of organic chemistry of the University of Hamburg with a VG Analytical 70-250 S using xenon. The far IR spectra were carried out using a PE matrix on a Vertex 70 of Bruker and the Raman spectra on a SENTERRA Dispersive Raman Microscope of Bruker. All chemical reagents were purchased from commercial sources and used as received except bis(benzonitril)dibromidopalladium(II), which was prepared by common methods.1 X-ray crystallographic studies. The powder diffractogram of 8 was measured on a Panalytical MPD X'Pert Pro with a copper source from a sample obtained by a synthetic strategy involving ligand substitution. Related to the cif-file of 8 a powder diffractogram was calculated using Mercury 1.4.2 assuming a copper source with 0.154056 nm. Red crystals were grown from 5, 6, 7 and 8 at normal pressure and room temperature from the presented biphasic system. The crystallographic and refinement data of the compounds 5-8 are shown in Table 3. The X-ray single crystal structures were determined on a Bruker SMART CCD diffractometer with Mo Kα radiation (λ = 71.073 pm); programs used: SAINT [Bruker AXS, 1998],47 SADABS [Bruker AXS, 1998],48 XPREP [Sheldrick, 1997],49 SHELXS-97 [Sheldrick, 1997],50 SHELXL-97 [Sheldrick, 1997].51 The weighting scheme is zero in the solution of the data sets of the crystals of 5 and 6. Due to the high number of significant reflections wR2(all) and wR2(2σ) are very similar. Thus, the GOOF's are unusually small. Attempts for 5 and 6 to set the weighting scheme to '0.001, 1' slightly lowered R1 and increased the difference between wR2(all) and wR2(2sigma), but further lowered the GOOF's. DFT calculations. Orca 2.830 has been used for DFT calculations. The functional BP8631,32 was applied for structure optimization of the structures with basis set DefBas-4 (basis sets: H: Ahlrichs-TZV, main group elements: Ahlrichs-TZV(2d2p), second row transition elements: Ahlrichs-TZV(2d2fg,3p2df))33-35 was taken. Usually some constraints were put for optimization as (commands) TightSCF, SlowConv, Grid6, NoFinalGrid, Decontract and when problems with negative frequencies arose additional constraints were added like (commands) Grid7, VerySlowConv, VerytightSCF as needed. All minima from BP86 were verified to have no negative frequencies. For the optimization of the crowded organometallic structures a van-derWaals correction (VDW06) was used.36 The explanation of the used commands is given in the user manual of Orca 2.9 (OrcaManual 2.9).37 General procedure of synthesis of palladium(II) and platinum(II/IV) complexes by means of a biphasic system. Palladium chloride (68 mg, 0.38 mmol) was dissolved in a warm solution of potassium bromide (456 mg, 3.8 mmol) in degassed water (10 mL). A solution of ligand 3 (109 mg, 0.38 mmol) in dichloromethane (10 mL) was carefully overlayed with the aqueous solution. The biphasic batch was kept in the dark for several weeks, until the aqueous solution had become almost colorless. The aqueoussolution was carefully removed, the organic solution filtered and the obtained crystals washed with cold dichloromethane and


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diethyl ether. cis-Dibromido{(S)-2,2’-diamino-1,1’binaphthalene}palladium(II) (5) was yielded as red crystals (175 mg, 0.32 mmol, 84 % yield). Found: C, 43.62; H, 2.94; N, 5.06. Calcd for C20H16Br2N2Pd: C, 43.63; H, 2.93; N, 5.09. IR (PE): ṽ = 481 (s, ṽ{PdN}), 474 (s, ṽ{Pd-N}), 328 (s), 298 (m), 217 (s, ṽ{Pd-Br}), 207 (s, ṽ{Pd-Br}) cm-1. Raman (PE): ṽ = 493 (m, ṽ{Pd-N}), 448 (s, ν{PdN}), 331 (m), 250 (w, ṽ{Pd-Br}), 231 (s, ṽ{Pd-Br}), 216 (m, ṽ{PdBr}), 198 (w, ṽ{Pd-Br}) cm-1. cis-Dibromido{(R)-2,2’-diamino-1,1’-binaphthalene}palladium(II) (6; 186 mg, 0.34 mmol, 86 % yield): red crystals. Found: C, 43.66; H, 2.91; N, 5.09. Calcd for C20H16Br2N2Pd: C, 43.63; H, 2.93; N, 5.09. IR (PE): ṽ = 481 (s, ṽ{Pd-N}), 474 (s, ṽ{Pd-N}), 329 (s), 298 (m), 218 (s, ṽ{Pd-Br}), 207 (s, ṽ{Pd-Br}) cm-1. Raman (powder): ṽ = 492 (m, ṽ{Pd-N}), 447 (m, ṽ{Pd-N}), 331 (m), 249 (w, ṽ{Pd-Br}), 231 (s, ṽ{Pd-Br}), 215 (m, ṽ{Pd-Br}), 198 (m, ṽ{Pd-Br}) cm-1. cis-Dichlorido{(S)-2,2’-diamino-1,1’-binaphthalene}palladium(II) (7; 103 mg, 0.22 mmol, 74 % yield): red crystals. Found: C, 51.65; H, 3.41; N, 5.93. Calcd for C20H16Cl2N2Pd: C, 52.03; H, 3.49; N, 5.93. IR (PE): ṽ = 483 (s, ṽ{Pd-N}), 479 (s, ṽ{Pd-N}), 338 (s, ṽ{Pd-Cl}), 320 (w), 311 (m, ṽ{Pd-Cl}), 298 (w), 237 (w) cm-1. Raman (powder): ṽ = 589 (w), 555 (w), 541 (m), 536 (m), 522 (w), 495 (m, ṽ{Pd-N}), 451 (m, ṽ{Pd-N}), 422 (w, ṽ{Pd-N}), 359 (w), 333 (m, ṽ{Pd-Cl}), 315 (w, ṽ{Pd-Cl}), 252 (w), 233 (s), 215 (m) cm-1. Raman (PE): ṽ = 588 (w), 554 (w), 541 (m), 535 (m), 521 (w), 495 (m, ṽ{Pd-N}), 451 (m, ṽ{Pd-N}), 425 (w, ṽ{Pd-N}), 358 (w), 333 (m, ṽ{Pd-Cl}), 315 (w, ṽ{Pd-Cl}), 252 (w), 233 (s), 218 (m) cm-1. cis-Dibromido(methyl 2,3-diamino-4,6-O-benzylidene-2,3dideoxy-α-D-glucopyranoside)palladium(II) (8; 103 mg, 0.22 mmol, 74 % yield): red crystals. Found: C, 29.41; H, 3.61; N, 4.86. Calcd for C44H64Br6Cl4N6O12Pd3 (3[C14H20Br2N2O4Pd] + 2CH2Cl2): C, 29.21; H, 3.56; N, 4.64. According to X-ray crystallography and nmr spectra the product contains two-thirds of an equivalent dichloromethane. 1H NMR (CD2Cl2, 400 MHz): δ = 7.84-7.66 (m, 2 H, H-2'), 7.58-7.43 (m, 3 H, H-3', H-4'), 5.63 (s, 1 H, H-7), 4.69 (d, 3J1,2 = 3.2 Hz, 1 H, H1), 4.43 (m, 1 H, H-3), 4.24 (dd, 2J6a,6b = 10.5 Hz, 3J6a,5 = 4.9 Hz, 1 H, Ha-6), 4.10 (m, 1 H, H-N), 3.85 (m, 1 H, H-2), 3.73 (m, 2J6a,6b = 10.4 Hz, 3J6a,5 = 10.4 Hz, 2 H, Hb-6, H-N), 3.59 (dd, 3J4,3 = 3J4,5 = 9.6 Hz, 1 H, H-4), 3.49-3.36 (m, 1 H, H-5), 3.44 (s, 3 H, OMe) 3.05, 2.43 (m, 2 H, H-N) ppm. 1H NMR (acetone-d6, 300 MHz): δ = 7.55-7.48 (m, 2 H, H-2'), 7.40-7.34 (m, 3 H, H-3', H-4'), 5.64 (s, 1 H, H-7), 4.98 (d, 3 J1,2 = 3.1 Hz, 1 H, H-1), 4.92, 4.57, 4.43 (m, 3 H, H-N), 4.27 (dd, 2 J6a,6b = 10.2 Hz, 3J6a,5 = 4.8 Hz, 1 H, Ha-6), 4.05 (m, 1 H, H-N), 3.85 (m, 1 H, H-2), 3.87-3.77 (m, 2 H, H-4, Hb-6), 3.61 (dd, 3J = 5.0 Hz, 9.4 Hz, 1 H, H-5), 3.55-3.37 (m, 2 H, H-2, H-3), 3.48 (s, 3 H, OMe) ppm. MS (fab): m/z = 467.0 (100 %, [M-Br]+), 385.1 (62 %, [M2Br]+). IR (PE): ṽ = 543 (m), 449 (m, ṽ{Pd-N}), 434 (s, ṽ{Pd-N}), 263 (m), 230 (s, ṽ{Pd-Br}), 183 (m, ṽ{Pd-Br}) cm-1. Raman (powder): ṽ = 546 (w), 532 (m), 497 (m, ṽ{Pd-N}), 452 (w, ṽ{PdN}), 436 (w, ṽ{Pd-N}), 385 (w), 288 (w), 262 (w), 229 (m, ṽ{PdBr}), 182 (s, ṽ{Pd-Br}) cm-1. Raman (PE): ṽ = 546 (w), 533 (m), 496 (m, ṽ{Pd-N}), 451 (w, ṽ{Pd-N}), 434 (w, ṽ{Pd-N}), 384 (w), 288 (w), 262 (w), 229 (m, ṽ{Pd-Br}), 182 (s, ṽ{Pd-Br}) cm-1. cis-Dichlorido(methyl 2,3-diamino-4,6-O-benzylidene-2,3dideoxy-α-D-gulopyranoside)platinum(II) (9; 162 mg, 0.30 mmol, 72 % yield): yellow crystals. Found: C, 30.74; H, 3.69; N, 5.03. Calcd for C14H20Cl2N2O4Pt: C, 30.78; H, 3.69; N, 5.13. IR (PE): ṽ = 564 (w), 494 (s, ṽ{Pt-N}), 489 (m, ṽ{Pt-N}), 336 (s, ṽ{Pt-Cl}), 321 (s, ṽ{Pt-Cl}), cm-1. Raman (PE): ṽ = 583 (w), 498 (m, ṽ{Pt-N}), 485 (m, ṽ{Pt-N}), 438 (w, ṽ{Pt-N}), 348 (m, ṽ{Pt-Cl}), 202 (m) cm-1. Tetrabromido(methyl 2,3-diamino-4,6-O-benzylidene-2,3-dideoxyα-D-gulopyranoside)platinum(IV) (10; 117 mg, 0.15 mmol), 43 % yield): red crystals. Found: C, 21.25; H, 2.67; N, 3.44. Calcd for C14H20Br4N2O4Pt: C, 21.15; H, 2.54; N, 3.52. IR (PE): ṽ = 571 (w), 511 (w, ṽ{Pt-N}), 501 (w, ṽ{Pt-N}), 463 (m, ṽ{Pt-N}), 334 (w), 313 (w), 233 (s, ṽcis{Pt-Br}), 226 (ṽcis{Pt-Br}) cm-1. Raman (PE): ṽ = 579 (w), 511 (w, ṽ{Pt-N}), 337 (w), 234 (m, ṽcis{Pt-Br}), 193 (s, ṽtrans{PtBr}) cm-1. Preparation of cis-dibromido(methyl 2,3-diamino-4,6-Obenzylidene-2,3-dideoxy-α-D-glucopyranoside)palladium(II) (8) by ligand substitution. Bis(benzonitril)dibromidopalladium(II) (202 mg, 0.428 mmol) and ligand 1 (120 mg, 0.428 mmol) were heated to

reflux in 1,2-dichloroethane (10 mL) for four hours. Then the solvent was removed in vacuum, the residue was suspended with dichloromethane and treated with diethyl ether. Compound 8 was yielded as an orange-red powder (220 mg, 0.390 mmol, 91 % yield). Found: C, 29.42; H, 3.59; N, 4.72. Calcd for C44H64Br6Cl4N6O12Pd3 (3[C14H20Br2N2O4Pd] + 2CH2Cl2): C, 29.21; H, 3.56; N, 4.64.

ASSOCIATED CONTENT Supporting Information. Cif-files of complexes 5-8. Calculated powder diffractogram of 8 related to its X-ray structure. Measured powder diffractogram of 8 obtained from ligand substitution. Molecular structures and data of 5-8 from DFT calculations. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author * E-mail: [email protected].

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT We thank Prof. Dr. Ulrich Behrens for supporting the solution of the crystallographic data sets, the X-ray section of Dr. Frank Hoffmann and the nmr spectroscopy section of Dr. Eckhardt Haupt for the measurements.

REFERENCES (1) Kharasch, M. S.; Seyler, R. C.; Mayo, F. R. J. Am. Chem. Soc. 1938, 60, 882-884. (2) Fanizzi, F. P.; Maresca, L.; Natile, G.; Lanfranchi, M.; ManottiLanfredi, A. M.; Tiripicchio, A. Inorg. Chem. 1988, 27, 2422-2431. (3) Bombard; S.; Gariboldi, M. B.; Monti, E.; Gabano, E. L. Gaviglio, E.; Ravera, M.; Osella, D. J. Biol. Inorg. Chem. 2010, 15, 841-850. (4) Carr, J. D.; Coles, S. J.; Hursthouse, M. B.; Light, M. E.; Munro, E. L.; Tucker, J. H. R.; Westwood, J. Organometallics 2000, 19, 3312-3315. (5) Peters, A.; Wild, U.; Hübner, O.; Kaifer, E.; Himmel, H.-J. Chem. Eur. J. 2008, 14, 7813-7821. (6) Belluco, U.; Benetollo, F.; Bertani, R.; Bombieri, G.; Michelin, R. A.; Mozzon, M.; Pombeiro, A. J. L.; Guedes da Silva, F. C. Inorg. Chim. Acta 2002, 330, 229-239. (7) Bacchi, A.; Belli Dell’ Amico, D.; Calderazzo, F.; Labella, L.; Pelizzi, G.; Manchetti, F.; Samaritani, S. Inorg. Chim. Acta 2010, 363, 2467-2473. (8) Kuznetsov, M. L.; Bokach, N. A.; Kharlampidi, D. D.; Medvedev, Yu. N.; Kukushkin, V. Yu.; Dementiev, A. I. Russ. J. General Chem. 2010, 80, 458-467. (9) Tsubomura, T.; Ogawa, M.; Kobayashi, K.; Sakurai, T.; Yoshikawa, S. Inorg. Chem. 1990, 29, 2622-2626. (10) Berger, I.; Nazarov, A. A.; Hartinger, C. G.; Groessl, M.; Valiahdi, S.-M.; Jakupec, M. A.; Keppler, B. K. Chem. Med. Chem. 2007, 2, 505-514. (11) Sachinvala, N. D.; Chen, H.; Niemczura, W. P.; Furusawa, E.; Cramer, R. E.; Rupp, J. J.; Ganijan, I. J. Med. Chem. 1993, 36, 17911795. (12) Hanessian, S.; Wang, J. Can. J. Chem. 1993, 71, 886-895. (13) Fisher, D. M.; Bednarski, P. J.; Grünert, R.; Turner, P.; Fenton, R. R.; Aldrich-Wright, J. R. Chem. Med. Chem. 2007, 2, 488495. (14) Mitzi, D. B. J. Solid State Chem. 1999, 145, 694-704. (15) Jin, J.-Ch.; Wang, Y.-Y., Zhang, W.-H.; Lermontov, A. S.; Lermontova, E. Kh.; Shi, Q.-Z. Dalton Trans. 2009, 10181-10191. (16) Pan, M.; Zhou, W.-X.; Ma, W. Y.; Niu, J.; Li, J. J. Coord. Chem. 2014, 67, 3176-3187. (17) Bujak, M. Cryst. Growth Des. 2015, 15, 1295-1302.



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(18) Böge, M.; Fowelin, Ch.; Heck, J.; Bednarski, P. Organometallics 2015, 34, 1507-1521. (19) Iball, J.; MacDougall, M.; Scrimgeour, S. Acta Cryst. 1975, B31, 1672-1674. (20) Ellis, L. T.; Hambley, T. W. Acta Cryst. 1994, C50, 18881889. (21) Textor, M.; Oswald, H. R. Z. Anorg. Allg. Chem. 1974, 407, 244-256. (22) Grzesiak, A. L.; Matzger, A. J. Inorg. Chem. 2007, 46, 453457. (23) Barone, C. R.; Maresca, L.; Natile, G.; Pacifico, C. Inorg. Chim. Acta 2011, 366, 384-387. (24) Adams, D. M.: Metal-Ligand and Related Vibrations, Hodder & Stoughton Educ., London, 1967. (25) Hartley, F. R.: The Chemistry of Platinum and Palladium, Wiley, New York 1973. (26) Campbell, J. R.; Clark, R. J. H.; Turtle, P. C. Inorg Chem. 1978, 17, 3622-3628. (27) Berg, R. W.; Rasmussen, K. Spectrochim. Acta 1973, 29A, 319-327. (28) Berg, R. W. Spectrochim. Acta 1975, 31A, 1409-1419. (29) Schmidt, M; Heck, J. Z. Allg. Anorg. Chem. 2012, 638, 11511158. (30) DFT calculations by Orca Version 2.8 (ORCA – an ab initio, Density Functional and Semiempirical program package), by Frank Neese, Max-Planck-Institut für chemische Energiekonversion, Mühlheim/Ruhr, homepage: http://www.mpibac.mpg.de/bac/mitarbeiter/neese/neese_en.php, 10.06.13; source: Orca 2.9, http://www.mpibac.mpg.de/bac/logins/neese/description.php, 10.06.13. (31) Perdew, J. P. Phys. Rev. 1986, B33, 8822-8824. (32) Becke, A. D. Phys. Rev. 1988, A38, 3098-3100. (33) Schafer, A.; Horn, H.; Ahlrichs, R. J. Chem. Phys. 1992, 97, 2571-2577. (34) Weigend, F.; Ahlrichs, R. Phys. Chem. Chem. Phys. 2005, 7, 3297-3305. (35) Wachters, A. J. H. J. Chem. Phys. 1970, 52, 1033-1036. (36) van-der-Waals correction: Grimme, S. J. Comput. Chem. 2006, 27, 1787-1799. (37) OrcaManual 2.9: http://www.mpibac.mpg.de/bac/logins/neese /downloads/OrcaManual_2_9.pdf, 10.06.13. (38) Ito, T.; Marumo, F.; Saito, Y. Acta Cryst. 1971, B27, 16951701. (39) Rafii, E.; Dassonneville, B.; Heumann, A. Chem. Comm. 2007, 583-585. (40) Samochocka, K.; Fokt, I.; Anulewicz-Ostrowska, R.; Przewloka, T.; Mazurek, A. P.; Fuks, L.; Lewandowski, W.; Kozerski, L.; Bocian, W.; Lewandowska, H.; Sitkowski, J.; Priebe, W. Dalton Trans. 2003, 2177-2183. (42) Bondi, A. J. Phys. Chem. 1964, 68, 441-451. (43) Shriver, D. F. ; Drezdzon, M. A.: The Manipulation of AirSensitive Compounds, second edition, John Wiley & Sons, New York 1986. (44) Brauer, G.: Handbuch der Präparativen Anorganischen Chemie, volume III, third edition, Ferdinand Enke Verlag, Stuttgart 1981. (45) Organikum, 22. edition, Wiley-VCH, Weinheim 2004. (46) Gottlieb, H. E.; Kotlyar, V.; Nudelmann, A. J. Org. Chem. 1997, 62, 7512-7515. (47) Saint 6.02, Program for data reduction. Bruker Industrial Automatation, 2000. (48) SADABS, Program for area detector absorption corrections. Siemens Analytical X-ray Instruments. (49) Sheldrick, G.: SHELXTL-NT V 5.1. Bruker Crystallographic Research Systems, Bruker Analytical X-ray Instruments Inc., Madison, Wisconsin, USA, 1997. (50) Sheldrick, G.: SHELXS-97, Program for crystal structure refinement. Universität Göttingen, 1997. (51) Sheldrick, G.: SHELXL-97, Program for crystal structure refinement. Universität Göttingen, 1997.


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For Table of Contents Use Only One-step preparation and crystallization of almost insoluble palladium(II) and platinum(II/IV) complexes from a biphasic solvent system Matthias Böge, Jürgen Heck

Scarcely soluble palladium(II) and platinum(II/IV) halido complexes with diamino ligands were prepared via a biphasic solvent system. Metal precursors like tetrachloridopalladate salts were dissolved in oxygen-free water, whereas the organic diamino ligands were dissolved in dry and oxygen-free dichloromethane. The dichloromethane layer was carefully covered with the aqueous layer under nitrogen atmosphere at room temperature. The desired products crystallized within a few weeks at the phase boundary. In the case of dihalidopalladium complexes with diamino-binaphthalene and diamino-carbohydrate ligands crystals were obtained without further manipulation, which were suitable for X-ray structure analysis. Thus, this new diffusion method of preparation with subsequent crystallization demonstrates the suitability for the preparation of insoluble, neutral palladium(II) and platinum(II,IV) complexes, which do not undergo fast hydrolysis of the metal halide bond.

9 ACS Paragon Plus Environment


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Scarcely soluble palladium(II) and platinum(II/IV) halido complexes with diamino ligands were prepared via a biphasic solvent system. Metal precursors like tetrachloridopalladate salts were dissolved in oxygen-free water, whereas the organic diamino ligands were dissolved in dry and oxygen-free dichloromethane. The dichloromethane layer was carefully covered with the aqueous layer under nitrogen atmosphere at room temperature. The desired products crystallized within a few weeks at the phase boundary. In the case of the palladium complexes crystals were obtained without further manipulation, which were suitable for X-ray structure analysis. 133x112mm (96 x 96 DPI)


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Figure 1. Depiction of the experimental setup of the preparation method using a biphasic system. A Schlenk tube containing two liquid layers is displayed. The upper layer is an aqueous solution of the appropriate halidometallate. The lower layer is a solution of the ligand in dichloro-methane. The product crystallizes at the phase boundary. 143x342mm (96 x 96 DPI)



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Molecular structures of 2,2'-diamino-1,1'-binaphthalene palladium(II) complexes 5-7 and diaminoglucopyranoside palladium(II) complex 8 obtained from X-ray structure determination. The atoms of the cocrystallized dichloromethane molecules from the structure of 8 and the hydrogen atoms are omitted for clarity. 696x569mm (96 x 96 DPI)


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One half of the asymmetric unit of the crystal packing of 8 obtained from X-ray structure determination viewed from two directions. The dimeric structure is almost C2-symmetric and the benzylidene groups of the sugar ligands build a cavity. The atoms of the cocrystallized dichloromethane molecules and the hydrogen atoms except the bridging hydrogen atoms are omitted for clarity. 296x529mm (96 x 96 DPI)



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Scheme 1: Preparation of dichloridopalladium(II) and platinum(II) complexes by conventional methods. 71x59mm (300 x 300 DPI)


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Preparation of dichloridopalladium(II) and plati-num(II/IV) complexes using a biphasic solvent system. 104x72mm (300 x 300 DPI)


Complexes from a Biphasic Solvent - ACS Publications - American

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