Two-Step Mechanochemical Synthesis of Carbene Complexes of

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Two-step mechanochemical synthesis of carbene complexes of palladium(II) and platinum(II) Christopher J. Adams, Matteo Lusi, Emily M Mutambi, and A. Guy Orpen Cryst. Growth Des., Just Accepted Manuscript • Publication Date (Web): 08 May 2017 Downloaded from http://pubs.acs.org on May 12, 2017

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Crystal Growth & Design

Two-step mechanochemical synthesis of carbene complexes of palladium(II) and platinum(II) Christopher J. Adams, Matteo Lusi†*, Emily M. Mutambi, and A. Guy Orpen. School of Chemistry, University of Bristol, Bristol BS8 1TS, U. K.

KEYWORDS: NHC_synthesis, mechanochemical_reactions, topochemical_control, carbene_complexes.

Abstract:

A mechanochemical strategy for the synthesis of N-heterocyclic carbene complexes is described, in which 1,3-dibenzylimidazole complexes of palladium and platinum are produced in a two-step process by grinding together the reactants with a mortar and pestle. Crystallographic characterization reveals that unlike the solution syntheses, which produces a mixture of products, the solid-state reactions occur under topochemical conditions affording isomerically and polymorphically pure products.

Introduction:

ACS Paragon Plus Environment

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N-heterocyclic carbene (NHC) ligands have progressively evolved from being an academic curiosity in the 1960s to their present role as ligand of choice for the design of catalysts for many organic reactions.1-3 In particular, NHC complexes of palladium and platinum are often preferred alternatives to tertiary phosphine complexes - for example in alkene metathesis.4-6 Synthetic procedures that lead to precursor imidazolium salts have been developed alongside many routes that allow the introduction of an NHC ligand to a metal centre2 and new methods are still regularly reported.7 Apart from a solvent-free, metal-vapour synthetic procedure,8 carbene complexes are generally obtained by traditional solution chemistry.1,9-13 Nevertheless, the formation and reaction of carbene intermediates in the solid state has been known for over two decades,14,15 but until recently such potential was not exploited for the preparation of carbene complexes.16-18 Despite such efforts, it has been argued that the development of NHC catalysts would benefit from an improved synthetic control.6 In chemistry, each alternative synthetic route increases the possibility of obtaining the desired product under the most convenient conditions, and the long interest of molecular chemists towards solid state reactions is therefore unsuprising.19-21 Solid-state methods of synthesis such as solid-gas22 or photo-,23,24 thermal-24 and mechanochemical25,26 reactions represent an opportunity for “greener” organic and organometallic chemistry, and may afford a desired product in essentially quantitative yield without using solvent and eliminating purification and separation steps,27-29 making them of particular relevance for industrial-scale application. The literature on mechanochemical synthesis of organometallic compounds has been recently reviewed by Rightmire and Hanusa.30 It is important to note that the limited mobility of the reacting molecules in the solid state (i.e. as crystals) enable reactions under topochemical conditions for increased isomeric and polymorphic purity.22,31 As demonstrated in Schmidt’s


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seminal paper, topochemical reactions become particularly useful when coupled with the ability to control the structures of molecular crystals.31 Nowadays the combination of supramolecular knowledge and chemical ingenuity allows the rational arrangement of molecules or ions into pre-defined crystalline structures.32-35 The existence of a large number of chemical species with similar charges and shapes, which can interact through the same weak supramolecular forces, offers a chance for finely modulating those structures and their properties. Then, the interplay of crystal engineering and solid-state reactions represents a powerful tool for chemical synthesis.36-38 It has been shown that strong and directional charged assisted hydrogen bonding between anionic metal halide and protonated organic cations is critical in the structure of these salts.39-41 The robustness of this interaction supports the formation of the desired product either in solution or in the solid state. Moreover new chemical bonds can be reversibly formed by elimination/absorption of hydrochloric and hydrobromic acid from those salt precursors.42-47 We have recently applied such a two-step solid-state strategy to the synthesis of platinum and palladium complexes with mixed pyridine/carbene ligands.48 This work extends that study to dicarbene complexes.

Experimental detail: Syntheses were carried out in air using standard glassware. All reagents were purchased from Sigma-Aldrich and used without further purification. The 1,3-dibenzylimidazolium chloride (IBz·HCl) ligand was prepared in solution by modifications of published methods, and oven-


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dried in vacuo at 60 ˚C.49,50 Grinding was carried out by hand using an agate mortar and pestle. The time required for grinding varied depending on the metal, and it was noted that grinding of platinum salts required more time than palladium salts. Synthesis of [HIBz] 2[PdCl4] (1Pd): 0.037 g (0.1 mmol) of K2PdCl4 and 0.057 g (0.2 mmol) of 1,3-dibenzylimidazolium chloride were ground in an agate motor and pestle for ca. 10-15 minutes. Microanalytical data (%) for C34H34Cl4N4Pd + 2KCl; Calculated: C, 45.58; H, 3.82; N, 6.25. Found: C, 45.36; H, 4.30; N, 5.95. Single crystals were obtained by dissolving a small amount of the powder product in acetone and water (1:1), and allowing the mixture of solvents to slowly evaporate. Crystals grew in 14 days, after which they were extracted from the mother liquors and allowed to dry in air. Microanalytical data (%) for C34H34Cl4N4Pd - Calculated: C, 54.68; H, 4.59; N, 7.50. Found: C, 54.99; H, 4.69; N, 7.51. Synthesis of [PdCl2(IBz)2] (2Pd): 0.094 g (0.1 mmol) of 1Pd was ground with 0.011g (0.2 mmol) of KOH in an agate mortar and pestle for ca. 10 minutes. Single crystals of the coordination compound suitable for X-ray diffraction were grown in a mini H-tube by diffusing dichloromethane from one side, into a acetonitrile:water (4:1) solution of the product on the other side. Crystals of cis-2Pd grew after 5 days and were extracted from the mother liquor and dried in air and the KCl remained in solution. Microanalytical data (%) for C34H32Cl2N4Pd Calculated: C, 61.70; H, 5.70; N, 14.39. Found: C, 61.94; H, 5.52; N, 14.37. Single crystals of trans-2Pd were grown in a mini H-tube from acetonitrile solution by allowing slow inward diffusion of dichloromethane. Crystals grew after 5 days, after which they were extracted from the mother liquor and dried in air. Microanalytical data (%) for C34H32Cl2N4Pd1 - Calculated: C, 60.59; H, 4.79; N, 8.31. Found: C, 59.91; H, 4.96; N, 7.94. 1H NMR: ppm (δ) 5.30 (s, 8 H) 6.93 (s, 4 H) 7.18 - 7.29 (m, 8 H) 7.31 - 7.45 (m, 12 H).


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Synthesis of [HIBz] 2[PtCl4] (1Pt): 0.042 g (0.1 mmol) of K2PtCl4 and 0.057 g (0.2 mmol) of 1,3-dibenzylimidazolium chloride were ground in an agate pestle and mortar for ca. 10 minutes. Microanalytical data (%) for C34H34Cl4N4Pt + 2KCl; Calculated: C, 41.47; H, 3.48; N, 5.69. Found: C, 41.07; H, 3.00; N, 5.32. Single crystals of the α form (α-1Pt) were obtained by dissolving a small amount of the product in ethanol and water (1:1) and allowing the solvents to slowly evaporate. Crystals grew after 8 days, after which they were extracted from the mother liquors and allowed to dry in air. Microanalytical data (%) for C34H34Cl4N4Pt, Calculated: C, 48.87; H, 4.10; N, 6.71. Found: C, 49.20; H, 4.45; N, 7.07. Single crystals of the β polymorph (β1Pt) were obtained by dissolving a small amount of the product in dichloromethane and allowing the solvent to slowly evaporate. Crystals grew after 1 day, were extracted from the mother liquor and allowed to dry in air. Microanalytical data (%) for C34H34Cl4N4Pt - Calculated: C, 48.87; H, 4.10; N, 6.71. Found: C, 48.31; H, 3.95; N, 6.96. Synthesis of [PtCl2(IBz)2] (2Pt): 0.099 g (0.1 mmol) of 1Pt + 2KCl mixture was ground with 0.011g (0.2 mmol) of KOH in an agate mortar and pestle for ca. 10 minutes. The resulting crystalline material was dried at 40 oC to remove any traces of water. Microanalytical data (%) for C34H34Cl2N4Pt + 4KCl - Calculated: C, 38.49; H, 3.04; N, 5.28. Found: C, 38.53; H, 2.78; N, 3.78. 1H NMR (CDCl3): ppm (δ) 5.72 (s, 8 H) 6.65 (s, 4 H) 7.27 - 7.33 (m, 12 H) 7.45 (dd, J = 7.98, 1.56 Hz, 8 H) Single crystal X-ray diffraction: X-ray data were collected at 100 K on a Bruker APEX II diffractometer using Mo-Kα X-ray radiation. Data were corrected for absorption using empirical methods

(SADABS)51

based

upon

symmetry-equivalent

reflections

combined

with

measurements at different azimuthal angles. Crystal structures were solved and refined against all F2 values using the SHELXTL51 interfaced with X-Seed52 suite of programs. Non-hydrogen


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atoms were refined anisotropically. Hydrogen atoms were placed in calculated positions, refined using idealized geometries (riding model) and assigned fixed isotropic displacement parameters. X-ray Powder diffraction: All crystalline phases were analysed at room temperature by powder X-ray diffraction on a Bruker D8 diffractometer using Cu-Kα X-radiation. The powder patterns of the products of mechanochemical eliminations showed an extra peak at 2θ = 28° due to the presence of KCl.

Results and discussion: The two-step syntheses of compounds are summarized in Scheme 1. The first step of the strategy, reaction (i), consists of the formation of the desired hydrogen-bonded salt between a N,N′-dibenzylimidazolium cation and a tetrachlorometallate anion: 1M (M = Pd, Pt;). In the second step, reaction (ii), the formation of the organometallic compounds 2M is achieved by dehydrochlorination of the salts in the solid state. The precursor salts 1M are obtained by co-grinding potassium tetrachloropalladate or tetrachloroplatinate with the imidazolium salt N,N′-dibenzylimidazolium chloride (Bz·HCl). Grinding the H-bonded salts with two equivalents of KOH affords the carbene complexes 2M. The imidazolium salt 1Pd (CCDC ref. code ZAZHAL53) forms straightforwardly by manually grinding IBz·HCl with K2PdCl4 in a 2:1 ratio. Recrystallization of the powder from acetone and water (1:1) affords quality single crystals suitable for X-ray structure determination (Figure 1a). The PdCl4 cation is on a center of inversion and the two independent chlorine atoms are 2.70 and 2.99 Å from the hydrogen atom of the C-H group (Figure 1). The identical nature of the


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mechanochemically synthesized powder and the single crystal is confirmed by X-ray powder diffraction (PXRD) (Figure. 2). The powder diffractogram shows a diffraction peak at 2θ = 28° characteristic of the KCl side product. Notably, 1Pd presents a significant anisotropic thermal expansion between 100 and 303 K (Table 1), with expansion coefficients of 206 × 10-6, -7 × 10-6 and 34 × 10-6 K-1 for the a, b and c crystallographic axes respectively. The coordination compound 2Pd is formed by co-grinding pure 1Pd with two equivalents of KOH. The occurrence of dehydrochlorination is confirmed by elemental analysis, which indicated the loss (to evaporation) of two equivalents of H2O, and by inspection of the X-ray powder diffraction pattern that shows the formation of KCl (Figure 3). Recrystallization of the product from acetonitrile / dichloromethane produced a mixture of trans-2Pd and cis-2Pd (CCDC ref. code MUSRAU54 and EHOQAU0155 respectively) whose structures were determined by XRD (Figure 1) suggesting an equilibrium between the two species in that solution. A qualitative PXRD analysis reveals that the mechanochemical synthesis produces only the trans-2Pd polymorph (Figure 3), and thus that the mechanochemical elimination occurs under topochemical control in which the symmetry of the metal complex is preserved. Presumably, in solution, cis-2Pd is formed by isomerization of the trans isomer. Interestingly, it became evident during the course of this study that when 1Pd + 2KCl (i.e. the direct product of reaction (i)) is ground with two equivalents of KOH, a new phase is formed (Figure 3). Any attempt of structure determination from powder resulted vain. trans-2Pd is formed only when “clean” 1Pd (in which KCl has been washed away) is used as reagent. At this stage the role of salt and water in the reaction are not clear but the diffractogram shows the absence of the expected KCl.56


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A crystal structure for 1Pt has been reported in the literature (CSD refcode: LIVGED);1 PXRD shows that mechanochemical synthesis (i) of 1Pt affords a new polymorph, henceforth referred to as the β-phase, isomorphous with 1Pd (Figure 4). The two polymorphs can be isolated by recrystallization of the ground powder from two different solvent systems. Dichloromethane produces the previously known phase (α-1Pt), whilst a solution of ethanol and water (1:1) gives β-1Pt (Table 1). The main difference between the polymorphs is on the relative orientation of the organic and inorganic ions, which affects the H-bond distances between the carbon and chlorine atoms (about 3.44 and 3.66 for α and 3.44 and 3.82 for β). The structural match between the bulk mechanochemical product and the single crystal model of β-1Pt is again confirmed by PXRD. The attempted synthesis of 2Pt through reaction (ii), upon grinding of either forms of 1Pt with a base (K2CO3 and KOH), resulted in an amorphous powder that could not be characterized by PXRD. Moreover, unlike previously reported cases involving nitrogen functionalized ligands44-46 any attempt to achieve the coordination compounds by thermal elimination of HCl from the salts were unsuccessful. In fact thermogravimetric analysis revealed that the salts decompose above 200 °C without clean loss of HCl (see ESI). The recrystallization of the amorphous product in common solvents was unsuccessful, nonetheless NMR suggests that the coordination compound 2Pt is formed.

Conclusions: The direct reaction of a basic metal salt and an acidic ligand offers a low temperature and solvent-free approach to the preparation of hydrogen-bonded salts of N,N′-substituted imidazolium cations. The hydrogen-bonded salts can be converted to the respective carbene


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complexes by mechanochemical dehydrochlorination. As evidenced by the X-ray powder diffraction patterns a high yield of the desired product is possible in minutes under ambient conditions, and in this respect topochemical control is likely to be critical. This work proves that the two-step synthetic strategy originally described for pyridine systems can be generalized to wider organometallic chemistry. In contrast to most reactions involving carbenes, all the reactions herein were performed without the benefit of a protective air- and moisture free environment, and without the use of specialized bases, which increases the chances in the quest for new catalysts. At the same time, the absence of solvents and the high yield observed for the products make the reported synthesis environmentally friendly when applied to large scale industrial applications.


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Scheme 1: Reaction scheme for the synthesis of 1 and 2.

Table 1: Crystal structure details 1Pd (100 K)

1Pd (rt)

β -1Pt

trans-2Pd

cis-2Pd

Formula

C34H34Cl4N4Pd

C34H34Cl4N4Pd

C34H34Cl4N4Pt

C34H32Cl2N4Pd

C34H32Cl2N4Pd

Formula weight

746.85

746.85

835.54

673.94

673.94

T/K

100(2)

298(2)

100(2)

100(2)

100(2)

Crystal system

Monoclinic

Monoclinic

Monoclinic

Monoclinic

Monoclinic

Space group

P21/c

P21/c

P21/c

P21/c

P21/c

a/Å b/Å

11.945(5) 8.6715(4)

12.432(2) 8.6584(15)

12.0527(2) 8.6160(2)

10.8500(2) 12.4691(3)

7.5255(5) 33.734(2)

c/Å

17.182(8)

17.298(8)

17.298(2)

13.2312(2)

12.2030(10)

α/°

90.00

90.00

90

90.00

90.00

β/°

114.256(3)

107.549(10)

115.71(3)

125.0980(5)

95.782(5)

γ/°

90.00

90.00

90

90.00

90.00

V/Å3

1630.81(13) 2

1677.6(5) 2

1620.55(14) 2

1464.56(5) 2

3082.2(4) 4

1.530

1.478

1.710

1.528

1.452

0.933

0.902

1.052

0.847

0.805

16733 4262 (0.0512) 0.0413 0.1022

16733 4262 (0.0512) 0.0419 0.1036

30899 4031 (0.0438) 0.0218 0.0518

35627 4870 (0.0556) 0.0330 0.0747

23456 9389 (0.0777) 0.0796 0.1352

Z ρ Mg/m3 µ/mm-1 Total reflect. Indep. reflect. (Rint) R1, wR2 [I>2σ(I)]


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Figure 1: structures of (A) 1Pd; (B) trans-2Pd; (C) cis-2Pd. Selected H atoms are omitted for clarity; H-bonds are indicated with a dashed line

Figure 2: comparison of PXRD patterns measured (top) and calculated (bottom) for 1Pd. The peak of KCl is indicated.

Figure 3: comparison of PXRD patterns (from top to bottom): calculated for cis-2Pd; measured for reaction (ii) of 1Pd + 2KCl with KOH (the product obtained without washing the salt); measured for reaction (ii) of 1Pd (the salt having been washed with water before grinding; calculated for trans-2Pd.


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Figure 4: Comparison of PXRD patterns: calculated for α-1Pt (top); measured (center) and calculated (bottom) for β-1Pt. The peak due to KCl is indicated.

ASSOCIATED CONTENT: Supporting Information. The thermograms for 1Pd and 1Pt are available free of charge. CCDC 1043579, 1043580, 1043583, 1043585 and 1043586 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre (CCDC) via www.ccdc.cam.ac.uk/data_request/cif

AUTHOR INFORMATION Corresponding Author *Matteo Lusi † Phone: +353 (0)612 0 2143; e-mail: [email protected] Present Addresses † Department of Chemical and Environmental Science, University of Limerick, Limerick, Ireland.


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Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ACKNOWLEDGMENT: We thank ESPRC and the University of Bristol for support of this work.

REFERENCES (1)

Newman, C. P.; Deeth, R. J.; Clarkson, G. J.; Rourke, J. P. Synthesis of Mixed NHC/L Platinum(II) Complexes: Restricted Rotation of the NHC Group. Organomet. 2007, 26, 6225-6233. (2) Newman, C. P.; Clarkson, G. J.; Rourke, J. P. Silver(I) N-heterocyclic carbene halide complexes: A new bonding motif. J. Organomet. Chem. 2007, 692, 4962-4968. (3) Hopkinson, M. N.; Richter, C.; Schedler, M.; Glorius, F. An overview of N-heterocyclic carbenes. Nature 2014, 510, 485-496. (4) Wei, W.; Qin, Y. C.; Luo, M. M.; Xia, P. F.; Wong, M. S. Synthesis, structure, and catalytic activity of palladium(II) complexes of new CNC pincer-type N-heterocyclic carbene ligands. Organomet. 2008, 27, 2268-2272. (5) Wilson, D. J. D.; Couchman, S. A.; Dutton, J. L. Are N-Heterocyclic Carbenes “Better” Ligands than Phosphines in Main Group Chemistry? A Theoretical Case Study of LigandStabilized E2 Molecules, L-E-E-L (L = NHC, phosphine; E = C, Si, Ge, Sn, Pb, N, P, As, Sb, Bi). Inorg. Chem. 2012, 51, 7657-7668. (6) Crabtree, R. H. NHC ligands versus cyclopentadienyls and phosphines as spectator ligands in organometallic catalysis. J. Organomet. Chem. 2005, 690, 5451-5457. (7) Moss, R. A.; Wang, L.; Weintraub, E.; Krogh-Jespersen, K. The solvation of carbenes: π and O-ylidic complexes of p-nitrophenylehlorocarbene. J. Phys. Chem. A 2008, 112, 46514659. (8) Arnold, P. L.; Cloke, F. G. N.; Geldbach, T.; Hitchcock, P. B. Metal Vapor Synthesis as a Straightforward Route to Group 10 Homoleptic Carbene Complexes. Organometallics 1999, 18, 3228-3233. (9) Liu, Q.-X.; Song, H.-B.; Xu, F.-B.; Li, Q.-S.; Zeng, X.-S.; Leng, X.-B.; Zhang, Z.-Z. Synthesis, crystal structure and photophysical properties of N-heterocyclic carbene Pd(II), Pt(II) complexes and iodine adduct. Polyhedron 2003, 22, 1515-1521. (10) Yagyu, T.; Yano, K.; Kimata, T.; Jitsukawa, K. Synthesis and Characterization of a Manganese(III) Complex with a Tetradentate N-Heterocyclic Carbene Ligand. Organomet. 2009, 28, 2342-2344. (11) Yagyu, T.; Oya, S.; Maeda, M.; Jitsukawa, K. Syntheses and Characterization of Palladium(II) Complexes with Tridentate N-Heterocyclic Carbene Ligands Containing Aryloxy Groups and Their Application to Heck Reaction. Chem. Lett. 2006, 35, 154-155.


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(12) Danopoulos, A. A.; Winston, S.; Gelbrich, T.; Hursthouse, M. B.; Tooze, R. P. Synthesis and structural characterisation of stable pyridine- and phosphine-functionalised Nheterocyclic carbenes. Chem. Commun. 2002, 482-483. (13) Hahn, F. E.; Jahnke, M. C. Heterocyclic carbenes: Synthesis and coordination chemistry. Angew. Chem. Int. Ed. 2008, 47, 3122-3172. (14) Garcia-Garibay, M. A. Engineering Carbene Rearrangements in Crystals: From Molecular Information to Solid-State Reactivity. Acc. Chem. Res. 2003, 36, 491-498. (15) Kupfer, R.; Poliks, M. D.; Brinker, U. H. Carbene rearrangements. 43. Carbenes in Constrained Systems. 2. First Carbene Reactions within Zeolites: Solid-State Photolysis of Adamantane-2-spiro-3'-diazirine. J. Am. Chem. Soc. 1994, 116, 7393-7398. (16) Mutambi, E. M., PhD Thesis, Universtiy of Bristol, Bristol, UK, 2011. (17) Juribasic, M.; Uzarevic, K.; Gracin, D.; Curic, M. Mechanochemical C-H bond activation: rapid and regioselective double cyclopalladation monitored by in situ Raman spectroscopy. Chem. Commun. 2014, 50, 10287-10290. (18) Beillard, A.; Bantreil, X.; Metro, T.-X.; Martinez, J.; Lamaty, F. Mechanochemistry for facilitated access to N,N-diaryl NHC metal complexes. New J. Chem. 2017, 41, 10571063. (19) Schmitt, A. Ueber die Einwirkung des Broms auf Zimmtsäure. Justus Liebigs Ann. Chem. 1863, 127, 13. (20) Pellizzari, G. Gazz. Chim. Ital. 1884, 14, 1. (21) Ling, A. R.; Baker, J. L. XCVI.-Halogen derivatives of quinone. Part III. Derivatives of quinhydrone. J. Chem. Soc. Trans. 1893, 63, 1314-1327. (22) Paul, I. C.; Curtin, D. Y. Reactions of Organ Crystals with Gases. Science 1975, 187, 1926. (23) Friščić, T.; MacGillivray, L. R. Single-crystal-to-single-crystal [2 + 2] photodimerizations: from discovery to design. Z. Kristallogr. - Crystal. Mat. 2005, 220, 351-363. (24) Toda, F. In Organic Solid State Reactions; Toda, F., Ed.; Springer Berlin Heidelberg: 2005; Vol. 254, p 1-40. (25) James, S. L.; Adams, C. J.; Bolm, C.; Braga, D.; Collier, P.; Friščić, T.; Grepioni, F.; Harris, K. D. M.; Hyett, G.; Jones, W.; Krebs, A.; Mack, J.; Maini, L.; Orpen, A. G.; Parkin, I. P.; Shearouse, W. C.; Steed, J. W.; Waddell, D. C. Mechanochemistry: opportunities for new and cleaner synthesis. Chem. Soc. Rev. 2012, 41, 413-447. (26) Mottillo, C.; Friščić, T. Advances in Solid-State Transformations of Coordination Bonds: From the Ball Mill to the Aging Chamber. Molecules 2017, 22, 144. (27) Kaupp, G. In Organic Solid State Reactions; Toda, F., Ed.; Springer Berlin / Heidelberg: 2005; Vol. 254, p 130-131. (28) Kaupp, G. Waste-free large-scale syntheses without auxiliaries for sustainable production omitting purifying workup. CrystEngComm 2006, 8, 794-804. (29) Cliffe, M. J.; Mottillo, C.; Stein, R. S.; Bucar, D.-K.; Friščić, T. Accelerated aging: a low energy, solvent-free alternative to solvothermal and mechanochemical synthesis of metalorganic materials. Chemical Science 2012, 3, 2495-2500. (30) Rightmire, N. R.; Hanusa, T. P. Advances in organometallic synthesis with mechanochemical methods. Dalton Trans. 2016, 45, 2352-2362. (31) Schmidt, G. M. J. Photodimerization in the solid state. Pure Appl. Chem. 1971, 27, 647678.


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Page 15 of 17

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(32) Hosseini, M. W. Molecular Tectonics: From Simple Tectons to Complex Molecular Networks. Acc. Chem. Res. 2005, 38, 313-323. (33) Wuest, J. D. Engineering crystals by the strategy of molecular tectonics. Chem. Commun. 2005, 5830-5837. (34) Aakeroy, C. B.; Champness, N. R.; Janiak, C. Recent advances in crystal engineering. CrystEngComm 2010, 12, 22-43. (35) Tiekink, E. R. T.; Vittal, J.; Zaworotko, M. Organic Crystal Engineering: Frontiers in Crystal Engineering; Wiley, Chippenham, UK, 2010. (36) Kaupp, G.; Naimi-Jamal, M. R.; Maini, L.; Grepioni, F.; Braga, D. Mechanistic studies of heterophase protonation and deprotonation reactions of solid [CoIII(η5-C5H4COOH)(η5C5H4COO)] using supermicroscopy. CrystEngComm 2003, 5, 474-479. (37) Braga, D.; Grepioni, F. Reactions Between or Within Molecular Crystals. Angew. Chem. Int. Ed. Engl. 2004, 43, 4002-4011. (38) Braga, D.; Grepioni, F.; Polito, M.; Chierotti, M. R.; Ellena, S.; Gobetto, R. A Solid−Gas Route to Polymorph Conversion in Crystalline [FeII(η5-C5H4COOH)2]. A Diffraction and Solid-State NMR Study. Organometallics 2006, 25, 4627-4633. (39) Lewis, G. R.; Orpen, A. G. A metal-containing synthon for crystal engineering: synthesis of the hydrogen bond ribbon polymer [4,4'-H2bipy][MCl4] (M = Pd, Pt). Chem. Commun. 1998, 1873-1874. (40) Dolling, B.; Gillon, A. L.; Orpen, A. G.; Starbuck, J.; Wang, X.-M. Homologous families of chloride-rich 4,4'-bipyridinium salt structures . Chem. Commun. 2001, 567-568. (41) Brammer, L.; Swearingen, J. K.; Bruton, E. A.; Sherwood, P. Hydrogen bonding and perhalometallate ions: A supramolecular synthetic strategy for new inorganic materials. Proc. Natl. Acad. Sci. U. S. A., 2002, 99, 4956. (42) Mínguez Espallargas, G.; Hippler, M.; Florence, A. J.; Fernandes, P.; van de Streek, J.; Brunelli, M.; David, W. I. F.; Shankland, K.; Brammer, L. Reversible Gas Uptake by a Nonporous Crystalline Solid Involving Multiple Changes in Covalent Bonding. J. Am. Chem. Soc. 2007, 129, 15606-15614. (43) Mínguez Espallargas, G.; van de Streek, J.; Fernandes, P.; Florence, A. J.; Brunelli, M.; Shankland, K.; Brammer, L. Mechanistic Insights into a Gas–Solid Reaction in Molecular Crystals: The Role of Hydrogen Bonding. Angew. Chem. Int. Ed. Engl. 2010, 49, 88928896. (44) Adams, C. J.; Colquhoun, H. M.; Crawford, P. C.; Lusi, M.; Orpen, A. G. Solid-State Interconversions of Coordination Networks and Hydrogen-Bonded Salts. Angew. Chem. Int. Ed. Engl. 2007, 46, 1124-1128. (45) Adams, C. J.; Kurawa, M. A.; Lusi, M.; Orpen, A. G. Solid state synthesis of coordination compounds from basic metal salts. CrystEngComm 2008, 10, 1790-1795. (46) Adams, C. J.; Haddow, M. F.; Lusi, M.; Orpen, A. G. Crystal synthesis of 1,4phenylenediamine salts and coordination networks. CrystEngComm 2011, 13, 8. (47) Adams, C. J.; Haddow, M. F.; Lusi, M.; Orpen, A. G. Crystal engineering of lattice metrics of perhalometallate salts and MOFs. Proc. Natl. Acad. Sci. USA 2010, 107, 16033-16038. (48) Adams, C. J.; Lusi, M.; Mutambi, E. M.; Guy Orpen, A. Two-step solid-state synthesis of PEPPSI-type compounds. Chem. Commun. 2015, 51, 9632-9635. (49) Milgrom, L. R.; Dempsey, P. J. F.; Yahioglu, G. 5,10,15,20-tetrakis(N-protected-imidazol2-yl)porphyrins. Tetrahedron 1996, 52, 9877-9890.


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Page 16 of 17

(50) Montgomery, J. A.; Thomas, H. J. The Use of the Allyl Group as a Blocking Group for the Synthesis of N-Substituted Purines1. J. Org. Chem. 1965, 30, 3235-3236. (51) Sheldrick, G. M. A short history of SHELX. Acta Cryst. Sect. A 2008, 64, 112-122. (52) Barbour, L. J. X-Seed — A Software Tool for Supramolecular Crystallography. J. Supramol. Chem. 2001, 1, 189-191. (53) Song, H.; Yan, N.; Fei, Z.; Kilpin, K. J.; Scopelliti, R.; Li, X.; Dyson, P. J. Evaluation of ionic liquid soluble imidazolium tetrachloropalladate pre-catalysts in Suzuki coupling reactions. Catal. Today 2012, 183, 172-177. (54) Bettucci, L.; Bianchini, C.; Oberhauser, W.; Hsiao, T.-H.; Lee, H. M. Chemoselective aerobic oxidation of unprotected diols catalyzed by Pd–(NHC) (NHC = N-heterocyclic carbene) complexes. J. Mol. Catal. A: Chem. 2010, 322, 63-72. (55) Chan, K.-T.; Tsai, Y.-H.; Lin, W.-S.; Wu, J.-R.; Chen, S.-J.; Liao, F.-X.; Hu, C.-H.; Lee, H. M. Palladium Complexes with Carbene and Phosphine Ligands: Synthesis, Structural Characterization, and Direct Arylation Reactions between Aryl Halides and Alkynes. Organometallics 2010, 29, 463-472. (56) Note: one of the reviewer as correctly suggested that such new phase coould be an ionic cocrystal.


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For Table of Contents Use Only,

Two-step mechanochemical synthesis of carbene complexes of palladium(II) and platinum(II) Christopher J. Adams, Matteo Lusi†*, Emily M. Mutambi, and A. Guy Orpen.

TOC graphic:

SYNOPSIS: Complexes of palladium and platinum are prepared by two consecutive mechanochemical reactions which afford topochemical control.


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Two-Step Mechanochemical Synthesis of Carbene Complexes of

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