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Two new polymorphic forms of Ph2Te2–1,4-C6F4I2 cocrystals feature an unusual packing of Ph2Te2 molecules, which is typical for native Ph2Se2 but not Ph2Te2. This suggests the existence the yet unknown, Ph2Se2-like polymorph of Ph2Te2.

The investigation of the coordination chemistry of heterometallic transition-metal complexes of palladium (Pd) and rhenium (Re) led to the isolation and crystallographic characterization of tetra­kis­(1,3-di­methyl­imidazolium-2-yl­idene)palladium(II) hexa­deca­carbonyl­tetra­rhenium diethyl ether disolvate, [Pd(C5H8N2)4][Re4(CO)16]·2C4H10O or [Pd(IMe)4][Re4(CO)16]·2C4H10O, (1), and di­carbonyl­octa-μ-carbonyl-tetra­kis­(tri­phenyl­phosphane)palladiumdirhenium, [Pd4Re2(C18H15P)4(CO)10] or Pd4Re2(PPh3)4(μ-CO)8(CO)2, (2), from the reaction of Pd(PPh3)4 with 1,3-di­methyl­imidazolium-2-carboxyl­ate and Re2(CO)10 in a toluene–aceto­nitrile mixture., The investigation of the coordination chemistry of heterometallic transition-metal complexes of palladium (Pd) and rhenium (Re) led to the isolation and crystallographic characterization of tetra­kis­(1,3-di­methyl­imidazolium-2-yl­idene)palladium(II) hexa­deca­carbonyl­tetra­rhenium diethyl ether disolvate, [Pd(C5H8N2)4][Re4(CO)16]·2C4H10O or [Pd(IMe)4][Re4(CO)16]·2C4H10O, (1), and octa-μ-carbonyl-di­carbonyl­tetra­kis­(tri­phenyl­phosphane)palladium­dirhenium, [Pd4Re2(C18H15P)4(CO)10] or Pd4Re2(PPh3)4(μ-CO)8(CO)2, (2), from the reaction of Pd(PPh3)4 with 1,3-di­methyl­imidazolium-2-carboxyl­ate and Re2(CO)10 in a toluene–aceto­nitrile mixture. In complex 1 the Re—Re bond lengths [2.9767 (3)–3.0133 (2) Å] are close to double the covalent Re radii (1.51 Å). The palladium–rhenium carbonyl cluster 2 has not been structurally characterized previously; the Pd—Re bond lengths [2.7582 (2)–2.7796 (2) Å] are about 0.1 Å shorter than the sum of the covalent Pd and Re radii (1.39 + 1.51 = 2.90 Å). One carbene ligand and a diethyl ether mol­ecule are disordered over two positions with occupancy ratios of 0.5:0.5 and 0.625 (15):0.375 (15) in 1. An unidentified solvent is present in compound 2. The given chemical formula and other crystal data do not take into account the unknown solvent mol­ecule(s). The SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9–18] in PLATON was used to remove the contribution of the electron density in the solvent region from the intensity data and the solvent-free model was employed for the final refinement. The cavity with a volume of ca 311 Å3 contains approximately 98 electrons.

Almost equal molecular sizes of diiodoacetylene (C2I2) and the [Br3]− anion result in isomorphic neutral cocrystal (DMFc–C2I2) and [DMFc]+Br3− salt. This isomorphic pair of neutral and ionic crystals provides a unique example for the analysis of different types of bonding resulting in isotypic solid-state structures. Their energy frameworks visualize the obvious difference between their energetic structures: the lattice of DMFc–C2I2 is built upon the chains stabilized by I···(η5-C5Me5) halogen bonds; at the same time, [DMFc]+Br3− consists of electrostatically assembled layers associated by Br···π(Cp*) XBs interactions.

Cocrystallization of the palladium acetate cluster Pd3(OAc)6 (abbreviated as [Pd3]) with electron-deficient iodine(I)-based perfluoroarenes (ArFI: iodopentafluorobenzene, 4-iodoheptafluorotoluene, 1,4-diiodotetrafluorobenzene, 1,2-diiodotetrafluorobenzene, and octafluoro-4,4′-diiodo-1,1-biphenyl) and iodine-free octafluoronaphthalene gave a series of six cocrystals [Pd3]·(arene) studied by single-crystal X-ray diffractometry. Significant intermolecular noncovalent interactions were verified by a density functional theory study, molecular electrostatic potential and Hirshfeld surface analyses, a combined QTAIM/NCPlot approach, and NBO and energy framework calculations. In five out of six structures, the aromatic rings coupled with cluster [Pd3] via lone pair–π-(ArF)-hole interactions. The iodine-containing arenes, ArFI, were additionally involved in halogen bonding with carboxylate O centers, but inorganic–organic stacking still remained the structure-determining interaction. In the stacking, the electron-rich PdO4 plane behaved as a five-center nucleophile providing oxygen lone pairs in addition to the dz2-PdII orbital; this plane complemented the π-acidic surface of the arenes, affording highly polar circular stacking, where organics wrapped inorganics.

1,2-trans-diiodo-ethene (C2H2I2) – is an overlooked halogen bond donor, which demonstrate the distinct similarity of the geometry and directionality of I···I halogen bonds around the iodine atoms in its native and CpMn(CO)2(C2H2I2) π-complex crystals. Distortion of the planar geometry of C2H2I2 upon the π-coordination result the distortion of the native planar layered geometry of C2H2I2, so that [CpMn(CO)2](π-C2H2I2) features more complex I···I XB assisted 3D network. Unusual structural parallels between the native C2H2I2 crystals and solid iodine are discussed.

In the cocrystalline salts [(Me5C5)2Fe]+I3−/(4-XC6H4OH) (X = Cl, I), the directionality of X ⋯ I − I 2 halogen bonds is a significant packing factor notwithstanding their relatively low energies (∼10 kcal mol−1), as compared to the fivefold stronger ionic bonding between [(Me5C5)2Fe+] and [I3]− (∼50 kcal mol−1). This adds significant details to the structural landscape of [(Me5C5)2Fe+]I3 and offers an illustrative example of the stronger structure-defining effect of halogen bonding over the hydrogen one.

A carboxylate⋯iodine supramolecular heterosynthon can be reliably applied in cocrystal engineering, using metal carboxylates as building blocks. Analysis of the energy framework of the exemplary paddlewheel crystal [Cu(OAc)2MeOH]2 indicates a robust 1D chain and even 2D layer long-range synthon modules, which can be intactly transferred into cocrystals. However, this approach allows the identification of a “weak link” – i.e. layers where the C–H⋯OC hydrogen bonds between ([Cu(OAc)2(MeOH)]2)n polymeric chains will be subject to substitution by I⋯OC halogen bonds during interaction with halogen bond donor co-formers. In contrast to the O–H⋯OC/C–H⋯OC catemeric crystals of pure acetic acid, the crystal design exercise based on the I⋯OC(carboxyl) supramolecular synthon afforded a 1 : 1 cocrystal of 1,4-C6F4I2 and CH3COOH, where the discrete centrosymmetric dimers of acetic acid are stabilized by I⋯OC(carboxyl) halogen bonds.

o-Ferrocenylcarbonylbenzoic acid (η5-C5H5)Fe(η5-C5H4C(O)C6H4COOH) (I) and o-cymantrenylcarbonylbenzoic acid (II) were obtained from ferrocene or (η5-C5H5)Mn(CO)3, respectively, by the Friedel–Crafts reaction with phthalic anhydride. Methyl o-ferrocenylcarbonylbenzoate (η5-C5H5)Fe(η5-C5H4C(O)C6H4COOMe (III) and methyl o-cymantrenylcarbonylbenzoate (CO)3Mn(η5-C5H4C(O)C6H4COOMe) (IV) were synthesized from I and II, respectively using dimethyl carbonate (DMC) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to promote the methylation reaction. 4-Ferrocenylphthalazin-1(2H)-one (V) and 4-cymantrenylphthalazin-1(2H)-one (VI) were obtained by the interaction of hydrazine hydrate with I and II, respectively, by the prolonged reflux or convenient solvothermal synthesis. Cyclic voltammetry measurements showed that compounds III and V undergo reversible one-electron oxidation, localized presumably at the ferrocene unit. For III the irreversible one-electron oxidation is apparently associated with the oxidation of the benzoate fragment. All new compounds were characterized by spectroscopic methods and the molecular structures of II and III were determined by X-ray diffraction analysis.

By the reaction of tetramer [Me3Pt(μ3-Cl)]4 with RhCl3 and [PPN]Cl (PPN = Ph3P = N=PPh3+) in a acetone-DCM mixture under the influence of ultrasound a heterometallic ionic complex [PPN][Me3Pt(μ-Cl)3Rh(μ-Cl)3PtMe3] (I) have been prepared. Tetranuclear complex [PPN]2 [(Me3Pt)2Ru2(μ-O)(μ-Cl)6Cl4]2- (II) have been obtained in a small yield starting from RuCl3 in similar conditions. Complex II has also been prepared purposefully in higher yield by the action of Me3Pt(Me2CO)3][PF6] on [PPN]4[Ru2OCl10]. Both complexes were characterized by elemental analysis, 1H, 13C, and 195Pt NMR spectroscopy, and their structures were determined by single crystal X-ray diffraction.

The crystal structures of PhMeTeI2 (1), FcMeTeI2 (2) and [FcMe2Te]+I− (3), which are the products of iodomethylation of R2Te2 (R = Ph, ferrocenyl (Fc)) by MeI, are reported. Analysis of secondary interactions and packing patterns in 1–3 revealed Te⋯πPh chalcogen bonding in 1, unusual structural parallels between 2 and 3, and unprecedented isomorphic substitution in the crystals of 3 with an admixture of Te–I ionized molecules 2 [FcMeTeI+]I−. In summary, we are discussing the 3c-4e bonding model as a general, seamless scheme for the geometry and electronic structure of hypervalent tellurium atom coordination in both the isolated molecules and crystals, which overcomes the confusing division between the molecular and supramolecular geometry.

In the co-crystals of diphenyl dichalcogenides Ph2E2 (E = Se, Te), the E–E and E–π(Ph) chalcogen bonds assemble Ph2E2 molecules into the chains, which imitate the typical packing patterns of the parent Ph2E2 crystals. These co-crystals consist of quite stable tectonic 1D and 2D Ph2E2 chain architectures, which are repeated in the crystals of pure Ph2E2 as well as in their co-crystals with the halogen bond donor molecules. These chains can be clearly visualized as separate parallel 1D and 2D structures in the energy framework diagrams in CrystalExplorer. From this point of view, the supramolecular reaction of Ph2E2 with the halogen bond donor 1,4-diiodotetrafluorobenzene (p-DITFB) can be considered as the insertion of p-DITFB molecules between the Ph2E2 chains in such a way that I–E and I–π(Ph) halogen bonds come in place of E–E and Te–π(Ph) chalcogen bonds, which are responsible for the close packing of these chains in the parent crystal form. Persistent packing patterns found in parent and binary crystals can provide insight into the mechanism of the crystallization process.

The supramolecular arrangement of 4-cyanopyridine (4CNpy) in its native crystal form and its co-crystals with halogen bond (XB) donors is discussed in terms of long-range synthon aufbau modules (LSAMs) and energy frameworks. Dissociations of 2D zigzag chains of parent 4CNpy into 1D dimers observed in its co-crystals are in good agreement with the aufbau model. Its co-formers, XB donors 1,4-I2(CF2)4, C2I2, 1,3- and 1,4-I2C6F4 (m- and p-DITFB), provide equal energy of I⋯N XBs, but perfluorinated iodo-alkane 1,4-I2(CF2)4 and diiodoacetylene C2I2 cannot achieve the same strength of homomolecular aggregation as π–π stacking in columnar DITFB modules. As a result, DITFBs form I⋯N XBs with both Npy and NCN nitrogen atoms of 4CNpy, while 1,4-I2(CF2)4 and C2I2 only with the Npy atom. This is not a particular case of 4CNpy co-crystals, but in general, DITFB appears to be a more effective XB donor co-former than C2I2, 1,4-I2(CF2)n and other iodo-XB donors, which has similar potential to an iodine atom but lacks homomolecular aggregation. In supramolecular reactions of p-DITFB with (η6-Ar)RuX2(4CNpy) (Ar = p-cymene, X = Cl, I) bearing Npy-coordinated 4CNpy, the former gives definite preference to the XBs with the halogen atoms, but not to the CN group of the 4CNpy ligand.

Claisen condensation of acetylferrocene (η5-C5H5)Fe(η5-C5H4COCH3) and methyl ether of cymantrenecarboxylic acid (CO)3Mn(η5-C5H4COOMe) results in β-diketone (η5-C5H5)Fe(η5-C5H4)-C(O)CH2C(O)-(η5-C5H4)Mn(CO)3 (I) which reacts with hydrazine to form a heterometallic pyrazole (η5-C5H5)Fe(η5-C5H4)-N2C3H3-(η5-C5H4)Mn(CO)3 (II) or reacts with diiodo(p-cymene)ruthenium(II) dimer giving chelate β-ketoenolate complexes of ruthenium, (p-cymene)RuI[(η5-C5H5)Fe(η5-C5H4)-C(O)CHC(O)-(η5-C5H4)Mn(CO)3] (III). The structures of complexes I–III were determined by single crystal X-ray diffraction. Electrochemical properties were studied too.

Halogen bond (HaB) assisted co-crystallization strategy was used to explore the structural landscape of ferrocenic polychalcogenides varying from a rather compact ferrocenophane triselenide (1,1’-FcSe3) to bulky diferrocenyl ditelluride (Fc2Te2) and its mixed-valent derivative (FcTeTeI2Fc). Comparison of the supramolecular organization in their native crystals and respective cocrystals with the iconic halogen bond donor, 1,4-diiodotetrafluorobenzene (p-DITFB), demonstrate three different patterns: 1) conservation of the chain structures for FcTeTeI2Fc, 2) transformation of single Se···Se intermolecular interaction to double for FcSe3, and 3) for Fc2Te2, in the absence of specific and directed intermolecular interactions, the cocrystal packing of Fc2Te2 is governed only by p-DITFB HaBs directionality. This allows a rough glimpse of ferrocenic polychalcogenides structural landscape and shows the directions and methods for its further detailization.

Formal substitution of aryl group on to the ferrocenyl in [CpFe(CO)(μ-TeR)]2 (R = Ar, Fc) complex dramatically changes its Fe2Te2 core structure and chemical properties. Introduction of electron-rich and bulky ferrocenyl moiety instead of Ph in [CpFe(CO)TePh]2 provide flattening of Fe2Te2 core in [CpFe(CO)(μ-TeFc)]2 (1), further photochemical decarbonylation resulting unusual [(CpFe)3(μ-TeFc)3(μ-CO)(CO)] cluster (2). The electrochemical oxidation of 1 shows two reversible one-electron oxidation waves attributed to oxidation of Fe2Te2 core. Chemical oxidation of 1 is accompanied by isomerization of its core and results in dicationic salt cis-[CpFe(CO)(μ-TeFc)]2 (PF6)2 (3). This study also provides an illustrative example of the increasing nuclearity in Fe1 → Fe2 → Fe3 row, upon the stepwise electron-compensating decarbonylation of iron-carbonyl complexes and (apart from this) insight into the distribution of toluene molecules inclusion inside the channels of crystals of compound 2.

The reaction of Re(CO)3(THF)2Cl with (Cymen)RuCl2 (Cymen = p-methyl-iso-propylbenzene) in benzene gave the known heterometallic complex (Cymen)Ru(μ-Cl)3Re(CO)3 (I), which was converted to the heterometallic complex (Cymen)Ru(μ-S-tert-Bu)3Re(CO)3 (II) on treatment with tert-butylmercaptan and triethylamine. Treatment of I with sodium tellurophenolate in THF results in the formation of the ionic complex [(Cymen)Ru(μ-TePh)3Ru(Cymen)]+[(CO)3Re(μ-TePh)3Re(CO)3]− (III) with homobinuclear cation and anion. The structures of II and III were determined by X-ray diffraction (CIF files CCDC nos. 1022559 (II) and 1022560 (III)).

A new chelating metalloligand (dppe)Pt(TeFc)2 (Fc = ferrocenyl) (1) was synthesized and used to prepare a mixed-metal tellurate-brigded complex (dppe)Pt(μ-TeFc)2Re(CO)3Cl (2). Both compounds were structurally and electrochemically investigated. Details of their molecular structure and CVA are discussed.

Interaction of [Cp2Cr2(CO)4[μ-SC5H4Mn(CO)3]2 with sulphur gave binuclear complex Cp2Cr2[μ-SC5H4Mn(CO)3]2(μ-S) (I) (Cp = π-C5H5) and triangular cluster Cp3Cr3[μ-SC5H4Mn(CO)3](μ-S)2(μ3-S) (II). I was also synthesized from Cp2Cr2(μ-SCMe3)2(μ-S) and (CO)3Mn(C5H4SH). Interaction between I and Co2(CO)8 resulted in triangular mixed-metal cluster Cp2Cr2[μ-SC5H4Mn(CO)3](μ3-S)2Co(CO)2 (III). The molecular structures of I–III were determined by means of single-crystal X-ray diffraction analysis.

The interaction of cymantrenylcarboxylic acid (C5H4CO2H)Mn(CO)3 (CymCOOH) or its potassium salts with salts of Cu (II) in alcohol or water with subsequent treatment with ligands L gives binuclear complexes LCu(CymCOO)4CuL where L = THF (I), Et2O (II), CymCOOH (III) or PPh3 (IV). The structures of I–III were solved by X-ray analyses. The frame of all complexes is constructed as “paddle-wheel” with four carboxylate bridges. At thermal decomposition of I and II in Ar the loss of L ligands took place, then the decarboxylation of all CymCOO groups was observed followed by decarbonylation with elimination of nine CO groups only. Finally the loss of cyclopentadienyl ligands results the solid product which according to powder XRD data contains metallic copper and Mn1.5Cu1.5O4 phase probably due to the splitting of the retaining CO groups.

The structure and dynamic behavior of complex [(η 5 -C 5 H 4 CH 3 )Cr(CO) 2 (μ-SBu)Pt(PPh 3 ) 2 ] in solution was studied by multinuclear ( 1 H, 13 C, 31 P) NMR spectroscopy including a phase-sensitive NOESY experiment. Increasing temperature causes rupture of the Cr–Pt bond in the three-membered ring of the complex and rotation of the S–Pt(PPh 3 ) 2 unit around the Cr–S bond line, followed by formation of a new Cr–Pt bond to close the ring. All activation parameters for this dynamic process have been determined.

Thermal reaction between PhC Cl and powdered Te afforded a mixture of (E)-4-iodo-2-(iodo(phenyl)-5-phenyl-1,3-ditellurofulvene (1) and (Z)-4-iodo-2-(iodo(phenyl)-5-phenyl-1-(diiodo),3-ditellurofulvene (2), which was subsequently reduced to (Z)-4-iodo-2-(iodo(pheny1)-5-phenyl-1,3-ditellurofulvene (3). Formation of 1 and 3 as the thermodynamically most stable products has been rationalized using density functional theory (DFT) calculations. Molecular structures of 1-3 were established crystallographically. In the solid state the coordination sphere of both tellurium atoms in 2 is extended by weak intermolecular Te center dot center dot center dot pi interactions with the solvate molecule of toluene which completes the pseudo-trigonal bipyramidal coordination geometry around each Te atom and assembles 2 into the chains along the crystallographic c-axis. (c) 2010 Elsevier B.V. All rights reserved.