Hydrogen versus fluorine: effects on molecular structure and intermolecular interactions in a platinum isocyanate complex

At the molecular level, the enantiomerically pure square‐planar organoplatinum complex (SP‐4‐4)‐(R)‐[2‐(1‐aminoethyl)‐5‐fluorophenyl‐κ²C¹,N][(R)‐1‐(4‐fluorophenyl)ethylamine‐κN](isocyanato‐κN)platinum(II), [Pt(C₈H₉FN)(NCO)(C₈H₁₀FN)], and its congener without fluorine substituents on the aryl rings adopt the same structure within error. The similarities between the compounds extend to the most relevant intermolecular interactions, i.e. N—H…O and N—H…N hydrogen bonds link neighbouring molecules into chains along the shortest lattice parameter in each structure. Differences between the crystal structures of the fluoro‐substituted and parent complex become obvious with respect to secondary interactions perpendicular to the classical hydrogen bonds; the fluorinated compound features short C—H…F contacts with an F…H distance of ca 2.6 Å. The fluorine substitution is also reflected in reduced backbonding from the metal cation to the isocyanate ligand.     

Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one, 3‐hydroxypyridine and 3‐hydroxypyridin‐2‐one ligands: molecular structures and hydrogen‐bonded networks

Copper(II) bis(4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dionate) complexes with pyridin‐2‐one (pyon), 3‐hydroxypyridine (hpy) and 3‐hydroxypyridin‐2‐one (hpyon) were prepared and the solid‐state structures of (pyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)] or [Cu(tfpb‐κ²O ,O ′)₂(pyon‐κO )], (I), bis(pyridin‐3‐ol‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)₂] or [Cu(tfpb‐κ²O ,O ′)₂(hpy‐κO )₂], (II), and bis(3‐hydroxypyridin‐2‐one‐κO )bis(4,4,4‐trifluoro‐3‐oxo‐1‐phenylbutan‐1‐olato‐κ²O ,O ′)copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO₂)₂] or [Cu(tfpb‐κ²O ,O ′)₂(hpyon‐κO )₂], (III), were determined by single‐crystal X‐ray analysis. The coordination of the metal centre is square pyramidal and displays a rare example of a mutual cis arrangement of the β‐diketonate ligands in (I) and a trans‐octahedral arrangement in (II) and (III). Complex (II) presents the first crystallographic evidence of κO‐monodentate hpy ligation to the transition metal enabling the pyridine N atom to participate in a two‐dimensional hydrogen‐bonded network through O—H…N interactions, forming a graph‐set motif R ₂²(7) through a C—H…O interaction. Complex (III) presents the first crystallographic evidence of monodentate coordination of the neutral hpyon ligand to a metal centre and a two‐dimensional hydrogen‐bonded network is formed through N—H…O interactions facilitated by C—H…O interactions, forming the graph‐set motifs R ₂²(8) and R ₂²(7).     

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η2‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC1)platinum(II)]

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)platinum(II)], [Pt₂(C₁₅H₁₉O₄)₂Cl₂], containing a derivative of the natural compound eugenol as ligand, have been performed. Using five different sets of crystallization conditions resulted in four different complexes which can be further used as starting compounds for the synthesis of Pt complexes with promising anticancer activities. In the case of vapour diffusion with the binary chloroform–diethyl ether or methylene chloride–diethyl ether systems, no change of the molecular structure was observed. Using evaporation from acetonitrile (at room temperature), dimethylformamide (DMF, at 313 K) or dimethyl sulfoxide (DMSO, at 313 K), however, resulted in the displacement of a chloride ligand by the solvent, giving, respectively, the mononuclear complexes (acetonitrile‐κN)(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chloridoplatinum(II) monohydrate, [Pt(C₁₅H₁₉O₄)Cl(CH₃CN)]·H₂O, (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethylformamide‐κO)platinum(II), [Pt(C₁₅H₁₉O₄)Cl(C₂H₇NO)], and (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethyl sulfoxide‐κS)platinum(II), determined as the analogue {η²‐2‐allyl‐4‐methoxy‐5‐[(ethoxycarbonyl)methoxy]phenyl‐κC¹}chlorido(dimethyl sulfoxide‐κS)platinum(II), [Pt(C₁₄H₁₇O₄)Cl(C₂H₆OS)]. The crystal structures confirm that acetonitrile interacts with the Pt^II atom via its N atom, while for DMSO, the S atom is the coordinating atom. For the replacement, the longest of the two Pt—Cl bonds is cleaved, leading to a cis position of the solvent ligand with respect to the allyl group. The crystal packing of the complexes is characterized by dimer formation via C—H…O and C—H…π interactions, but no π–π interactions are observed despite the presence of the aromatic ring.     

Platinum complexes of oxopurines: cis‐bis(theophyllinato‐N7)bis(triphenylphosphine)platinum(II) and cis‐chloro(theobrominato‐N1)bis(triphenylphosphine)platinum(II) ethanol hemisolvate

The syntheses and structures of two mixed‐ligand complexes of platinum(II) with deprotonated oxopurine bases and tri­phenyl­phosphine are reported, namely the theophyllinate complex cis‐bis(1,2,3,6‐tetra­hydro‐1,3‐di­methyl­purine‐2,6‐dionato‐κN⁷)­bis(tri­phenyl­phosphine‐κP)­platinum(II), [Pt(C₇H₇N₄O₂)₂(C₁₈H₁₅P)₂], (I), and the theobrominate complex cis‐chloro(1,2,3,6‐tetrahydro‐3,7‐dimethylpurine‐2,6‐dionato‐κN¹)­bis(tri­phenyl­phosphine‐κP)­platinum(II) ethanol hemisolvate, [PtCl(C₇H₇N₄O₂)(C₁₈H₁₅P)₂]·0.5C₂H₅OH, (II). In (I), the coordination geometry of Pt is square planar, formed by the two coordinating N atoms of the theophyl­linate anions in a cis arrangement and two P atoms from the tri­phenyl­phosphine groups. In (II), there are two crystallographically independent mol­ecules. They both exhibit a square‐planar coordination geometry around Pt involving one Cl atom, the coordinating N atom of the theobrominate anion and two P atoms from the tri­phenyl­phosphine groups. The two tri­phenyl­phosphine groups are arranged in a cis configuration in both structures. The heterocyclic rings are rotated with respect to the coordination plane of the metal by 82.99 (8) and 88.09 (8)° in complex (I), and by 85.91 (16) and 88.14 (18)° in complex (II). Both structures are stabilized by intramolecular stacking interactions involving the purine rings and the phenyl rings of adjacent tri­phenyl­phosphine moieties.     

Three zinc(II) and cadmium(II) complexes containing 4‐amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole and polynitrile ligands: synthesis,molecular and supramolecular structures,and photoluminescence properties

Three photoluminescent complexes containing either Zn^II or Cd^II have been synthesized and their structures determined. Bis[4‐amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole‐κ²N ¹,N ⁵]bis(dicyanamido‐κN ¹)zinc(II), [Zn(C₁₂H₁₀N₆)₂(C₂N₃)₂], (I), bis[4‐amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole‐κ²N ¹,N ⁵]bis(dicyanamido‐κN ¹)cadmium(II), [Cd(C₁₂H₁₀N₆)₂(C₂N₃)₂], (II), and bis[4‐amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole‐κ²N ¹,N ⁵]bis(tricyanomethanido‐κN ¹)cadmium(II), [Cd(C₁₂H₁₀N₆)₂(C₄N₃)₂], (III), all crystallize in the space group P , with the metal centres lying on centres of inversion, but neither analogues (I) and (II) nor Cd^II complexes (II) and (III) are isomorphous. A combination of N—H…N and C—H…N hydrogen bonds and π–π stacking interactions generates three‐dimensional framework structures in (I) and (II), and a sheet structure in (III). The photoluminescence spectra of (I)–(III) indicate that the energies of the π–π* transitions in the coordinated triazole ligand are modified by minor changes of the ligand geometry associated with coordination to the metal centres.     

Hydrogen bonding and π–π interactions in the cocrystal salt [Fe(bpe)2(H2O)4](TCEP)2·2(bpe) [bpe is trans‐1,2‐bis(pyridin‐4‐yl)ethene and TCEP is 1,1,3,3‐tetracyano‐2‐ethoxypropenide]

The cocrystal salt tetraaquabis[trans‐1,2‐bis(pyridin‐4‐yl)ethene‐κN]iron(II) bis(1,1,3,3‐tetracyano‐2‐ethoxypropenide)–trans‐1,2‐bis(pyridin‐4‐yl)ethene (1/2), [Fe(C₁₂H₁₀N₂)₂(H₂O)₄](C₉H₅N₄O)₂·2C₁₂H₁₀N₂, is a rare example of a mononuclear Fe^II compound with trans‐1,2‐bis(pyridin‐4‐yl)ethane (bpe) ligands. The complex cation resides on a crystallographically imposed inversion center and exhibits a tetragonally distorted octahedral coordination geometry. Both the symmetry‐independent bpe ligand and the cocrystallized bpe molecule are essentially planar. The 1,1,3,3‐tetracyano‐2‐ethoxypropenide counter‐ion is nonplanar and the bond lengths are consistant with significant electron delocalization. The extended structure exhibits an extensive O—H…N hydrogen‐bonding network with layers of complex cations joined by the cocrystallized bpe. Both the coordinated and the cocrystallized bpe are involved in π–π interactions. Hirshfeld and fingerprint plots reveal the important intermolecular interactions. Density functional theory was used to estimate the strengths of the hydrogen‐bonding and π–π interactions, and suggest that the O—H…N hydrogen bonds enhance the strength of the π‐interactions by increasing the polarization of the pyridine rings.     

Co‐crystallized cis and trans isomers of dichloro­bis(2‐picolylamine)iron(II)

The octa­hedral cis and trans isomers of dichloro­bis(2‐picolyl­amine)iron(II), [FeCl₂(C₆H₈N₂)₂], co‐crystallize in a 1:1 ratio. The cis isomer lies on a twofold axis, whereas the trans isomer lies on an inversion centre. The structure is fully ordered, with both Fe atoms in a pure high‐spin state. The Fe, Cl and N(H₂) atoms of both isomers lie in the same plane, allowing all Cl and amine H atoms to be engaged in extensive two‐dimensional hydrogen bonding. The hydrogen‐bonded layers are inter­connected through π–π inter­actions between the pyridine rings. Searches in the Cambridge Structural Database uncover very few examples of such isomer co‐existence.     

Highly Efficient Deep‐Blue Emitters Based on cis and trans N‐Heterocyclic Carbene PtII Acetylide Complexes: Synthesis,Photophysical Properties,and Mechanistic Studies

We have synthesized cis and trans N‐heterocyclic carbene (NHC) platinum(II) complexes bearing σ‐alkynyl ancillary ligands, namely [Pt(dbim)₂(C?CR)₂] [DBIM=N,N′‐didodecylbenzimidazoline‐2‐ylidene; R=C₆H₄F ( 4 ), C₆H₅ ( 5 ), C₆H₂(OMe)₃ ( 6 ), C₄H₃S ( 7 ), and C₆H₄C?CC₆H₅ ( 8 )] and [Pt(ibim)₂(C?CC₆H₅)₂] ( 9 ) (ibim=N,N′‐diisopropylbenzimidazoline‐2‐ylidene), starting from [Pt(cod)(C?CR)₂] (COD=cyclooctadiene) and 2 equivalents of [dbimH]Br ([ibimH]Br for complexes 9 ) in the presence of tBuOK and THF. Mechanistic investigations aimed at uncovering the cis to trans isomerization reaction have been performed on the representative cis complex 5 a [Pt(dbim)₂(C?CC₆H₅)₂] and revealed the isomerization to progress smoothly in good yield when 5 a was treated with catalytic amounts of [Pt(cod)(C?CR)₂] at 75 °C in THF or when 5 a was heated at 200 °C in the solid state under an inert atmosphere. Detailed examination of the reactions points to the possible involvement, in a catalytic fashion, of a solvent‐stabilized Pt^II dialkyne complex in the former case and a Pt⁰ NHC complex in the latter case, for the transformation of the cis isomer to the corresponding trans complex. Thermal stability and the isomerization process in the solid state have been further investigated on the basis of TGA and DSC measurements. X‐ray diffraction studies have been carried out to confirm the solid‐state structures of 4 b , 5 a , 5 b , and 9 b . All of the synthesized dialkyne complexes 4 – 9 exhibit phosphorescence in solution, in the solid state at room temperature (RT), and also in frozen solvent glasses at 77 K. The emission wavelengths and quantum yields have been found to be highly tunable as a function of the alkynyl ligand. In particular, the trans isomer of complex 9 in a spin‐coated film (10 wt % in poly(methyl methacrylate), PMMA) exhibits a high phosphorescence quantum yield of 80 %, which is the highest reported for Pt^II‐based deep‐blue emitters. Experimental observations and time‐dependent density functional theory (TD‐DFT) calculations are strongly indicative of the emission being mainly governed by metal‐perturbed interligand (³IL) charge transfer.     

Complexes of nickel(II) and copper(II) with 1,2,4‐triazole‐3‐carboxylic acid and of cobalt(III) with 3‐amino‐1,2,4‐triazole‐5‐carboxylic acid

Because of their versatile coordination modes and strong coordination ability for metals, triazole ligands can provide a wide range of possibilities for the construction of metal–organic frameworks. Three transition‐metal complexes, namely bis(μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato)‐κ³N ²,O :N ¹;κ³N ¹:N ²,O‐bis[triamminenickel(II)] tetrahydrate, [Ni₂(C₃HN₃O₂)₂(NH₃)₆]·4H₂O, (I), catena‐poly[[[diamminediaquacopper(II)]‐μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato‐κ³N ¹:N ⁴,O‐[diamminecopper(II)]‐μ‐1,2,4‐triazol‐4‐ide‐3‐carboxylato‐κ³N ⁴,O :N ¹] dihydrate], {[Cu₂(C₃HN₃O₂)₂(NH₃)₄(H₂O)₂]·2H₂O}_n , (II), (μ‐5‐amino‐1,2,4‐triazol‐1‐ide‐3‐carboxylato‐κ²N ¹:N ²)di‐μ‐hydroxido‐κ⁴O :O‐bis[triamminecobalt(III)] nitrate hydroxide trihydrate, [Co₂(C₃H₂N₄O₂)(OH)₂(NH₃)₆](NO₃)(OH)·3H₂O, (III), with different structural forms have been prepared by the reaction of transition metal salts, i.e. NiCl₂, CuCl₂ and Co(NO₃)₂, with 1,2,4‐triazole‐3‐carboxylic acid or 3‐amino‐1,2,4‐triazole‐5‐carboxylic acid hemihydrate in aqueous ammonia at room temperature. Compound (I) is a dinuclear complex. Extensive O—H…O, O—H…N and N—H…O hydrogen bonds and π–π stacking interactions between the centroids of the triazole rings contribute to the formation of the three‐dimensional supramolecular structure. Compound (II) exhibits a one‐dimensional chain structure, with O—H…O hydrogen bonds and weak O—H…N, N—H…O and C—H…O hydrogen bonds linking anions and lattice water molecules into the three‐dimensional supramolecular structure. Compared with compound (I), compound (III) is a structurally different dinuclear complex. Extensive N—H…O, N—H…N, O—H…N and O—H…O hydrogen bonding occurs in the structure, leading to the formation of the three‐dimensional supramolecular structure.     

Hydrogen‐bonded chains in three cis‐dichloridoplatinum(II) complexes bearing piperidine and amine ligands

The crystal structures of cis‐dichlorido(ethylamine‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₂H₇N)(C₅H₁₁N)], (I), cis‐dichlorido(3‐methoxyaniline‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₇H₉NO)], (II), and cis‐dichlorido(piperidine‐κN)(quinoline‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₉H₇N)], (III), have been determined at 100 K in order to verify the influence of the nonpiperidine ligand on the geometry and crystal packing. The crystal packing is characterized by N—H...Cl hydrogen bonding, resulting in the formation of chains of molecules connected in a head‐to‐tail fashion. Hydrogen‐bonding interactions play a major role in the packing of (I), where the chains further aggregate into planes, but less so in the case of (II) and (III), where π–π stacking interactions are of greater importance.     

One‐pot concomitant preparation of two copper(II) coordination polymers with different configurations of bridging bithiophene ligands

By employing the conjugated bithiophene ligand 5,5′‐bis(1H‐imidazol‐1‐yl)‐2,2′‐bithiophene (bibp), which can exhibit trans and cis conformations, two different Cu^II coordination polymers, namely, poly[[μ‐5,5′‐bis(1H‐imidazol‐1‐yl)‐2,2′‐bithiophene‐κ²N:N′](μ₂‐4,4′‐oxydibenzoato‐κ²O:O′)copper(II)], [Cu(C₁₄H₈O₅)(C₁₄H₁₀N₄S₂)]_n or [Cu(bibp)(oba)]_n, (I), and catena‐poly[μ‐aqua‐bis[μ‐5,5′‐bis(1H‐imidazol‐1‐yl)‐2,2′‐bithiophene‐κ²N:N′]bis(μ₃‐4,4′‐oxydibenzoato)‐κ³O:O′:O′′;κ⁴O:O′,O′′:O′‐dicopper(II)], [Cu₂(C₁₄H₈O₅)₂(C₁₄H₁₀N₄S₂)(H₂O)]_n or [Cu₂(bibp)(oba)₂(H₂O)]_n, (II), have been prepared through one‐pot concomitant crystallization and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis, powder X‐ray diffraction (PXRD) and thermogravimetric (TG) analysis. Single‐crystal X‐ray diffraction indicates that the most interesting aspect of the structure is the existence of sole trans and cis conformations of the bibp ligand in a single net of (I) and (II), respectively. Compound (I) displays a threefold interpenetrating three‐dimensional framework with a 4‐connected {6⁵.8} cds topology, whereas (II) features a one‐dimensional chain structure. In the crystal of (II), the polymeric chains are further extended through C—H…O hydrogen bonds and C—H…π interactions into a three‐dimensional supramolecular architecture. In addition, strong intramolecular O—H…O hydrogen bonds formed between the bridging water molecules and the carboxylate O atoms improve the stability of the framework of (II). Furthermore, solid‐state UV–Vis spectroscopy experiments show that compounds (I) and (II) exhibit optical band gaps which are characteristic for optical semiconductors, with values of 2.70 and 2.26 eV, respectively.     

Novel Octahedral Bis[2‐(1‐aziridinyl)ethanol‐κ2N,O] Complexes of Cobalt(II)

The synthesis and molecular structure of trans‐{bis[(acetato‐κO)‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) ( 4 ) and cis‐{bis[chlorido‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) ( 5 ) is reported. Both neutral chelate complexes are prepared from the corresponding Co^II salt [CoX₂; X = OAc ( 1 ), Cl ( 2 )] and 2‐(1‐aziridinyl)ethanol (azolH, 3 ) in dry dichloromethane. A third, ionic complex, cis‐{bis[aqua‐(2‐(1‐aziridinyl)ethanol‐κ²N,O)]}cobalt(II) diacetate ( 6 ) is formed from 4 in the presence of water and could be crystallized from aqueous dichloromethane. In all cases, 2‐(1‐aziridinyl)ethanol is coordinating as bidentate chelate ligand by the nitrogen and oxygen atom of the aziridinyl and hydroxy moiety. After purification, the compounds have been fully characterized using IR spectroscopy and FAB⁺‐MS. The single‐crystal X‐ray structure analysis revealed a distorted octahedral geometry for all complexes with either trans ( 4 ) or cis ( 5 , 6 ) configuration.     

The coordination complex structures and hydrogen bonding in the three‐dimensional alkaline earth metal salts (Mg,Ca, Sr and Ba) of (4‐aminophenyl)arsonic acid

(4‐Aminophenyl)arsonic acid (p‐arsanilic acid) is used as an antihelminth in veterinary applications and was earlier used in the monosodium salt dihydrate form as the antisyphilitic drug atoxyl. Examples of complexes with this acid are rare. The structures of the alkaline earth metal (Mg, Ca, Sr and Ba) complexes with (4‐aminophenyl)arsonic acid (p‐arsanilic acid) have been determined, viz. hexaaquamagnesium bis[hydrogen (4‐aminophenyl)arsonate] tetrahydrate, [Mg(H₂O)₆](C₆H₇AsNO₃)·4H₂O, (I), catena‐poly[[[diaquacalcium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]‐[diaquacalcium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ]] dihydrate], {[Ca(C₆H₇AsNO₃)₂(H₂O)₂]·2H₂O}_n , (II), catena‐poly[[triaquastrontium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]], [Sr(C₆H₇AsNO₃)₂(H₂O)₃]_n , (III), and catena‐poly[[triaquabarium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]], [Ba(C₆H₇AsNO₃)₂(H₂O)₃]_n , (IV). In the structure of magnesium salt (I), the centrosymmetric octahedral [Mg(H₂O)₆]²⁺ cation, the two hydrogen p‐arsanilate anions and the four water molecules of solvation form a three‐dimensional network structure through inter‐species O—H and N—H hydrogen‐bonding interactions with water and arsonate O‐atom and amine N‐atom acceptors. In one‐dimensional coordination polymer (II), the distorted octahedral CaO₆ coordination polyhedron comprises two trans‐related water molecules and four arsonate O‐atom donors from bridging hydrogen arsanilate ligands. One bridging extension is four‐membered via a single O atom and the other is eight‐membered via O :O ′‐bridging, both across inversion centres, giving a chain coordination polymer extending along the [100] direction. Extensive hydrogen‐bonding involving O—H…O, O—H…N and N—H…O interactions gives an overall three‐dimensional structure. The structures of the polymeric Sr and Ba complexes (III) and (IV), respectively, are isotypic and are based on irregular M O₇ coordination polyhedra about the M ²⁺ centres, which lie on twofold rotation axes along with one of the coordinated water molecules. The coordination centres are linked through inversion‐related arsonate O :O ′‐bridges, giving eight‐membered ring motifs and forming coordination polymeric chains extending along the [100] direction. Inter‐chain N—H…O and O—H…O hydrogen‐bonding interactions extend the structures into three dimensions and the crystal packing includes π–π ring interactions [minimum ring centroid separations = 3.4666 (17) Å for (III) and 3.4855 (8) Å for (IV)].     

Supramolecular architectures in metal(II) (Cd/Zn) halide/nitrate complexes of cytosine/5‐fluorocytosine

Three new metal(II)–cytosine (Cy)/5‐fluorocytosine (5FC) complexes, namely bis(4‐amino‐1,2‐dihydropyrimidin‐2‐one‐κN³)diiodidocadmium(II) or bis(cytosine)diiodidocadmium(II), [CdI₂(C₄H₅N₃O)₂], ( I ), bis(4‐amino‐1,2‐dihydropyrimidin‐2‐one‐κN³)bis(nitrato‐κ²O,O′)cadmium(II) or bis(cytosine)bis(nitrato)cadmium(II), [Cd(NO₃)₂(C₄H₅N₃O)₂], ( II ), and (6‐amino‐5‐fluoro‐1,2‐dihydropyrimidin‐2‐one‐κN³)aquadibromidozinc(II)–6‐amino‐5‐fluoro‐1,2‐dihydropyrimidin‐2‐one (1/1) or (6‐amino‐5‐fluorocytosine)aquadibromidozinc(II)–4‐amino‐5‐fluorocytosine (1/1), [ZnBr₂(C₄H₅FN₃O)(H₂O)]·C₄H₅FN₃O, ( III ), have been synthesized and characterized by single‐crystal X‐ray diffraction. In complex ( I ), the Cd^II ion is coordinated to two iodide ions and the endocyclic N atoms of the two cytosine molecules, leading to a distorted tetrahedral geometry. The structure is isotypic with [CdBr₂(C₄H₅N₃O)₂] [Muthiah et al. (2001). Acta Cryst. E 57 , m558–m560]. In compound ( II ), each of the two cytosine molecules coordinates to the Cd^II ion in a bidentate chelating mode via the endocyclic N atom and the O atom. Each of the two nitrate ions also coordinates in a bidentate chelating mode, forming a bicapped distorted octahedral geometry around cadmium. The typical interligand N—H…O hydrogen bond involving two cytosine molecules is also present. In compound ( III ), one zinc‐coordinated 5FC ligand is cocrystallized with another uncoordinated 5FC molecule. The Zn^II atom coordinates to the N(1) atom (systematic numbering) of 5FC, displacing the proton to the N(3) position. This N(3)—H tautomer of 5FC mimics N(3)‐protonated cytosine in forming a base pair (via three hydrogen bonds) with 5FC in the lattice, generating two fused R₂²(8) motifs. The distorted tetrahedral geometry around zinc is completed by two bromide ions and a water molecule. The coordinated and nonccordinated 5FCs are stacked over one another along the a‐axis direction, forming the rungs of a ladder motif, whereas Zn—Br bonds and N—H…Br hydrogen bonds form the rails of the ladder. The coordinated water molecules bridge the two types of 5FC molecules via O—H…O hydrogen bonds. The cytosine molecules are coordinated directly to the metal ion in each of the complexes and are hydrogen bonded to the bromide, iodide or nitrate ions. In compound ( III ), the uncoordinated 5FC molecule pairs with the coordinated 5FC ligand through three hydrogen bonds. The crystal structures are further stabilized by N—H…O, N—H…N, O—H…O, N—H…I and N—H…Br hydrogen bonds, and stacking interactions.     

A triangular palladium(II) supramolecular coordination complex based on 1,4‐bis(1H‐imidazol‐1‐yl)benzene and (2,2′‐bipyridyl)palladium(II) nitrate: synthesis and crystal structure

The self‐assembly of ditopic bis(1H‐imidazol‐1‐yl)benzene ligands ( L ^H) and the complex (2,2′‐bipyridyl‐κ²N,N′)bis(nitrato‐κO)palladium(II) affords the supramolecular coordination complex tris[μ‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]‐triangulo‐tris[(2,2′‐bipyridyl‐κ²N,N′)palladium(II)] hexakis(hexafluoridophosphate) acetonitrile heptasolvate, [Pd₃(C₁₀H₈N₂)₃(C₁₂H₁₀N₄)₃](PF₆)₆·7CH₃CN, 2 . The structure of 2 was characterized in acetonitrile‐d₃ by ¹H/¹³C NMR spectroscopy and a DOSY experiment. The trimeric nature of supramolecular coordination complex 2 in solution was ascertained by cold spray ionization mass spectrometry (CSI–MS) and confirmed in the solid state by X‐ray structure analysis. The asymmetric unit of 2 comprises the trimetallic Pd complex, six PF₆^? counter‐ions and seven acetonitrile solvent molecules. Moreover, there is one cavity within the unit cell which could contain diethyl ether solvent molecules, as suggested by the crystallization process. The packing is stabilized by weak inter‐ and intramolecular C—H…N and C—H…F interactions. Interestingly, the crystal structure displays two distinct conformations for the L ^H ligand (i.e. syn and anti), with an all‐syn‐[Pd] coordination mode. This result is in contrast to the solution behaviour, where multiple structures with syn/anti‐ L ^H and syn/anti‐[Pd] are a priori possible and expected to be in rapid equilibrium.     

Mono‐ and dinuclear CuII complexes of the benzyldipicolylamine (BDPA) ligand: crystal structure,synthesis and characterization

The crystal structures of mono‐ and dinuclear Cu^II trifluoromethanesulfonate (triflate) complexes with benzyldipicolylamine (BDPA) are described. From equimolar amounts of Cu(triflate)₂ and BDPA, a water‐bound Cu^II mononuclear complex, aqua(benzyldipicolylamine‐κ³N ,N′ ,N ′′)bis(trifluoromethanesulfonato‐κO )copper(II) tetrahydrofuran monosolvate, [Cu(CF₃SO₃)₂(C₁₉H₁₉N₃)(H₂O)]·C₄H₈O, (I), and a triflate‐bridged Cu^II dinuclear complex, bis(μ‐trifluoromethanesulfonato‐κ²O :O ′)bis[(benzyldipicolylamine‐κ³N ,N′ ,N ′′)(trifluoromethanesulfonato‐κO )copper(II)], [Cu₂(CF₃SO₃)₄(C₁₉H₁₉N₃)₂], were synthesized. The presence of residual moisture in the reaction medium afforded water‐bound complex (I), whereas dinuclear complex (II) was synthesized from an anhydrous reaction medium. Single‐crystal X‐ray structure analysis reveals that the Cu^II centres adopt slightly distorted octahedral geometries in both complexes. The metal‐bound water molecule in (I) is involved in intermolecular O—H…O hydrogen bonds with triflate ligands and tetrahydrofuran solvent molecules. In (II), weak intermolecular C—H…F(triflate) and C—H…O(triflate) hydrogen bonds stabilize the crystal lattice. Complexes (I) and (II) were also characterized fully using FT–IR and UV–Vis spectroscopy, cyclic voltammetry and elemental analysis.     

Cis‐ and trans‐bis(2‐cyano­ethyl­sulfan­yl)(decane‐1,10‐diyldithio)tetra­thia­fulvalene

The isomeric title compounds, 2,7‐bis(2‐cyanoethylsulfanyl)‐3,6‐(decane‐1,10‐diyldithio)tetrathiafulvalene and 2,6‐bis­(2‐cyanoethylsulfanyl)‐3,7‐(decane‐1,10‐diyldithio)­tetra­thiafulvalene, both C₂₂H₂₈N₂S₈, comprise bis­(2‐cyano­ethyl­sulfan­yl)tetra­thia­fulvalene units tethered by a saturated deca­methyl­enedithio linker attached in either a cis or a trans manner. The tetra­thia­fulvalene (TTF) group is planar in the cis isomer, but distorted significantly from planarity and twisted about its long axis in the trans isomer. In both structures, inter­molecular inter­actions are segregated into regions in which TTF units are brought into close contact and regions where the polymethyl­ene chains are brought into close contact. In the cis isomer, TTF units exhibit π–π stacking inter­actions, while in the trans isomer they do not.     

Synthesis and anticancer activity of chalcogenide derivatives and platinum(II) and palladium(II) complexes derived from a polar ferrocene phosphanyl–carboxamide

The polar phosphanyl‐carboxamide, 1′‐(diphenylphosphanyl)‐1‐[N‐(2‐hydroxyethyl)carbamoyl]ferrocene ( 1 ), reacts readily with hydrogen peroxide and elemental sulfur to give the corresponding phosphane‐oxide and phosphane‐sulfide, respectively, and with platinum(II) and palladium(II) precursors to afford various bis(phosphane) complexes [MCl₂( 1 ‐κP)₂] (M = trans‐Pd, trans‐Pt and cis‐Pt). The anticancer activity of the compounds was evaluated in vitro with the complexes showing moderate cytotoxicities towards human ovarian cancer cells. Moreover, the biological activity was found to be strongly influenced by the stereochemistry, with trans‐[PtCl₂( 1 ‐κP)₂] being an order of magnitude more active than the corresponding cis isomer. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and Spectroscopic Characterization of Potassium Polyfluoroalken‐1‐yltrifluoroborates

The potassium fluoroborates K[RCF=CFBF₃] (R = F, Cl (cis‐/trans‐mixture), trans‐C₄F₉, cis‐C₂F₅, cis‐C₆F₁₃, trans‐C₄H₉, trans‐C₆H₅) were prepared by fluoridation (methoxide‐fluoride substitution with K[HF₂]) of RCF=CFB(OMe)₂ and Li[RCF=CFB(OMe)₃] which were obtained from RCF=CFLi and B(OMe)₃. The K[RCF=CFBF₃] salts were characterized by their ¹H, ¹¹B, ¹⁹F NMR and IR spectra.     

A one‐dimensional platinum mixed‐valence complex with bridging thiocyanate S atoms: [[PtII(en)2](μ‐SCN)[PtIV(en)2](μ‐SCN)](ClO4)4 (en is ethane‐1,2‐diamine)

A new one‐dimensional platinum mixed‐valence complex with nonhalogen bridging ligands, namely catena‐poly[[[bis(ethane‐1,2‐diamine‐κ²N,N′)platinum(II)]‐μ‐thiocyanato‐κ²S:S‐[bis(ethane‐1,2‐diamine‐κ²N,N′)platinum(IV)]‐μ‐thiocyanato‐κ²S:S] tetrakis(perchlorate)], {[Pt₂(SCN)₂(C₂H₈N₂)₄](ClO₄)₄}_n, has been isolated. The Pt^II and Pt^IV atoms are located on centres of inversion and are stacked alternately, linked by the S atoms of the thiocyanate ligands, forming an infinite one‐dimensional chain. The Pt^IV—S and Pt^II...S distances are 2.3933 (10) and 3.4705 (10) Å, respectively, and the Pt^IV—S...Pt^II angle is 171.97 (4)°. The introduction of nonhalogen atoms as bridging ligands in this complex extends the chemical modifications possible for controlling the amplitude of the charge‐density wave (CDW) state in one‐dimensional mixed‐valence complexes. The structure of a discrete Pt^IV thiocyanate compound, bis(ethane‐1,2‐diamine‐κ²N,N′)bis(thiocyanato‐κS)platinum(IV) bis(perchlorate) 1.5‐hydrate, [Pt(SCN)₂(C₄H₈N₂)₂](ClO₄)₂·1.5H₂O, has monoclinic (C2) symmetry. Two S‐bound thiocyanate ligands are located in trans positions, with an S—Pt—S angle of 177.56 (3)°.