Three Polymorphic CdII Coordination Polymers Obtained from the Solution and Mechanochemical Reactions of 3‐Cyanopentane‐2,4‐dione with CdII Acetate

We previously reported that monomeric and polymeric metal complexes are obtained from solution and mechanochemical reactions of 3‐cyano‐pentane‐2,4‐dione (CNacacH) with 3d metal acetates (M=Mn^II, Fe^II, Co^II, Ni^II, Cu^II, and Zn^II). A common feature found in all complexes was that their structural base is trans‐[M(CNacac)₂]. Here, we report that the reactions of CNacacH with Cd^II acetate in the solution and solid states afford different coordination polymers composed of trans‐[Cd(CNacac)₂] and cis‐[Cd(CNacac)₂] units, respectively. From a methanol solution containing CNacacH (L) and Cd(OAc)₂ ? 2 H₂O (M), a coordination polymer ( Cd‐1 ) in which trans‐[Cd(CNacac)₂] units are three‐dimensionally linked was obtained. In contrast, two different coordination polymers, Cd‐2 and Cd‐3 , were obtained from mechanochemical reactions of CNacacH with Cd(OAc)₂ ? 2 H₂O at M/L ratios of 1:1 and 1:2, respectively. In Cd‐2 , cis‐[Cd(CNacac)₂] units are two‐dimensionally linked, whereas the units are linked three‐dimensionally in Cd‐3 . Furthermore, Cd‐1 and Cd‐2 converted to Cd‐3 by applying an annealing treatment and grinding with a small amount of liquid, respectively, in spite of the polymeric structures. These phenomena, 1) different structures are formed from solution and mechanochemical reactions, 2) two polymorphs are formed depending on the M/L ratio, and 3) structural transformation of resulting polymeric structures, indicate the usability of mechanochemical method in the syntheses of coordination polymers as well as the peculiar structural flexibility of cadmium‐CNacac polymers.     

Dual zinc catalysts for L‐lactide polymerization and reaction of CO2 with cyclohexene oxide

A series of zinc complexes, [ L ^X ZnEt] ( 1–5 ) and [ L ^X Zn ₂ (OAc) ₃ ] (6–9) , associated with NNO‐tridentate Schiff base ligands (2‐(((2‐((cyclohexyl[methyl]amino)methyl)phenyl)imino)methyl)phenolate (CAP) derivatives), were synthesized, and their activity toward ring‐opening polymerization (ROP) of L‐lactide (LA) and the reaction of CO₂ with cyclohexene oxide were also investigated. All of [ L ^X ZnEt] revealed excellent catalytic activity to ring‐opening polymerization (ROP) of LA in the presence of benzyl alcohol. Among them, [ L ^H ZnEt] (1) showed the highest activity with 82% conversation within 45 s. In contrast, [L ^X Zn ₂ (OAc) ₃ ] (6–9) were inactive in ROP of L‐lactide. In addition, all of these Zn complexes demonstrated moderate activity in the reaction of CO₂ with cyclohexene oxide in the presence of Bu₄NCl.     

Metal‐catalyzed reversible conversion between chemical and electrical energy designed towards a sustainable society

Proton dissociation of an aqua‐Ru‐quinone complex, [Ru(trpy)(q)(OH₂)]²⁺ (trpy = 2,2′ : 6′,2″‐terpyridine, q = 3,5‐di‐t‐butylquinone) proceeded in two steps (pK_a = 5.5 and ca. 10.5). The first step simply produced [Ru(trpy)(q)(OH)]⁺, while the second one gave an unusual oxyl radical complex, [Ru(trpy)(sq)(O^?.)]⁰ (sq = 3,5‐di‐t‐butylsemiquinone), owing to an intramolecular electron transfer from the resultant O^2? to q. A dinuclear Ru complex bridged by an anthracene framework, [Ru₂(btpyan)(q)₂(OH)₂]²⁺ (btpyan = 1,8‐bis(2,2′‐terpyridyl)anthracene), was prepared to place two Ru(trpy)(q)(OH) groups at a close distance. Deprotonation of the two hydroxy protons of [Ru₂(btpyan)(q)₂(OH)₂]²⁺ generated two oxyl radical Ru‐O^?. groups, which worked as a precursor for O₂ evolution in the oxidation of water. The [Ru₂(btpyan)(q)₂(OH)₂](SbF₆)₂ modified ITO electrode effectively catalyzed four‐electron oxidation of water to evolve O₂ (TON = 33500) under electrolysis at +1.70 V in H₂O (pH 4.0). Various physical measurements and DFT calculations indicated that a radical coupling between two Ru(sq)(O^?.) groups forms a (cat)Ru‐O‐O‐Ru(sq) (cat = 3,5‐di‐t‐butylcathechol) framework with a μ‐superoxo bond. Successive removal of four electrons from the cat, sq, and superoxo groups of [Ru₂(btpyan)(cat)(sq)(μ‐O₂^?)]⁰ assisted with an attack of two water (or OH^?) to Ru centers, which causes smooth O₂ evolution with regeneration of [Ru₂(btpyan)(q)₂(OH)₂]²⁺. Deprotonation of an Ru‐quinone‐ammonia complex also gave the corresponding Ru‐semiquinone‐aminyl radical. The oxidized form of the latter showed a high catalytic activity towards the oxidation of methanol in the presence of base. Three complexes, [Ru(bpy)₂(CO)₂]²⁺, [Ru(bpy)₂(CO)(C(O)OH)]⁺, and [Ru(bpy)₂(CO)(CO₂)]⁰ exist as an equilibrium mixture in water. Treatment of [Ru(bpy)₂(CO)₂]²⁺ with BH₄^? gave [Ru(bpy)₂(CO)(C(O)H)]⁺, [Ru(bpy)₂(CO)(CH₂OH)]⁺, and [Ru(bpy)₂(CO)(OH₂)]²⁺ with generation of CH₃OH in aqueous conditions. Based on these results, a reasonable catalytic pathway from CO₂ to CH₃OH in electro‐ and photochemical CO₂ reduction is proposed. A new pbn (pbn = 2‐pyridylbenzo[b]‐1,5‐naphthyridine) ligand was designed as a renewable hydride donor for the six‐electron reduction of CO₂. A series of [Ru(bpy)_3‐n(pbn)_n]²⁺ (n = 1, 2, 3) complexes undergoes photochemical two‐ (n = 1), four‐ (n = 2), and six‐electron reductions (n = 3) under irradiation of visible light in the presence of N(CH₂CH₂OH)₃. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 169–186; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200800039     

Formation of the Distinct Redox‐Interrelated Forms of Nitric Oxide from Reaction of Dinitrosyl Iron Complexes (DNICs) and Substitution Ligands

Release of the distinct NO redox‐interrelated forms (NO⁺, ^.NO, and HNO/NO^?), derived from reaction of the dinitrosyl iron complex (DNIC) [(NO)₂Fe(C₁₂H₈N)₂]^? ( 1 ) (C₁₂H₈N=carbazolate) and the substitution ligands (S₂CNMe₂)₂, [SC₆H₄‐o‐NHC(O)(C₅H₄N)]₂ ((PyPepS)₂), and P(C₆H₃‐3‐SiMe₃‐2‐SH)₃ ([P(SH)₃]), respectively, was demonstrated. In contrast to the reaction of (PyPepS)₂ and DNIC 1 in a 1:1 stoichiometry that induces the release of an NO radical and the formation of complex [PPN][Fe(PyPepS)₂] ( 4 ), the incoming substitution ligand (S₂CNMe₂)₂ triggered the transformation of DNIC 1 into complex [(NO)Fe(S₂CNMe₂)₂] ( 2 ) along with N‐nitrosocarbazole ( 3 ). The subsequent nitrosation of N‐acetylpenicillamine (NAP) by N‐nitrosocarbazole ( 3 ) to produce S‐nitroso‐N‐acetylpenicillamine (SNAP) may signify the possible formation pathway of S‐nitrosothiols from DNICs by means of transnitrosation of N‐nitrosamines. Protonation of DNIC 1 by [P(SH)₃] triggers the release of HNO and the generation of complex [PPN][Fe(NO)P(C₆H₃‐3‐SiMe₃‐2‐S)₃] ( 5 ). In a similar fashion, the nucleophilic attack of the chelating ligand P(C₆H₃‐3‐SiMe₃‐2‐SNa)₃ ([P(SNa)₃]) on DNIC 1 resulted in the direct release of [NO]^? captured by [(¹⁵NO)Fe(SPh)₃]^?, thus leading to [(¹⁵NO)(¹⁴NO)Fe(SPh)₂]^?. These results illustrate one aspect of how the incoming substitution ligands ((S₂CNMe₂)₂ vs. (PyPepS)₂ vs. [P(SH)₃]/[P(SNa)₃]) in cooperation with the carbazolate‐coordinated ligands of DNIC 1 function to control the release of NO⁺, ^.NO, or [NO]^? from DNIC 1 upon reaction of complex 1 and the substitution ligands. Also, these results signify that DNICs may act as an intermediary of NO in the redox signaling processes by providing the distinct redox‐interrelated forms of NO to interact with different NO‐responsive targets in biological systems.     

Molecular and Silica‐Supported Mo and W d0 Imido‐Methoxybenzylidene Complexes: Structure and Metathesis Activity

5‐Coordinated methoxybenzylidene complexes M(=NAr)(=CH?C₆H₄?o‐OMe)(O^tBu_F3)₂ (Ar=2,6‐ⁱPr₂C₆H₃; ^tBu_F3=CMe₂(CF₃)) of Mo ( 1m_Mo ) and W ( 1m_W ) were synthesized by cross‐metathesis from the corresponding neophylidene/neopentylidene precursors and o‐methoxystyrene. 1m_Mo and 1m_W were grafted onto the surface of silica partially dehydroxylated at 700 °C to give well‐defined silica‐supported alkylidenes (≡SiO)M(=NAr)(=CH?C₆H₄?o‐OMe)(O^tBu_F3) (M=Mo ( 1_Mo ), W ( 1_W )). Supported methoxybenzylidene complexes were tested in metathesis of cis‐4‐nonene, 1‐nonene, and ethyl oleate, and compared to their molecular precursors and supported classical analogs (≡SiO)M(=NAr)(=CHCMe₂R)(O^tBu_F3) (M=Mo, R=Ph ( 2_Mo ), M=W, R=Me ( 2_W )). Both grafted complexes 1_Mo and 1_W show significantly better performance as compared to their molecular precursors 1m_Mo and 1m_W but are less efficient than the classical 4‐coordinated alkylidenes 2_Mo and 2_W . Noteworthy, both 1_Mo and 1_W can reach equilibrium conversion in metathesis of cis‐4‐nonene at catalyst loadings as low as 50 ppm.     

Phthalocyaninate und Tetraphenylporphyrinate von hochkoordiniertem ZrIV/HfIV mit Hydroxo‐, Chloro‐, (Di)Phenolato‐, (Hydrogen)Carbonato‐ sowie (Amino)Carboxylato‐Liganden

Phthalocyaninates and Tetraphenylporphyrinates of High Co‐ordinated Zr^IV/Hf^IV with Hydroxo, Chloro, (Di)Phenolato, (Hydrogen)Carbonato, and (Amino)Carboxylato Ligands Crystals of tetra(n‐butyl)ammonium cis‐tri(phenolato)phthalocyaninato(2‐)zirconate(IV) ( 2 ) and ‐hafnate(IV) ( 1 ), di(tetra(n‐butyl)ammonium) cis‐di(tetrachlorocatecholato(O, O')phthalocyaninato(2‐)zirconate(IV) ( 3 ), and cis‐(di(μ‐alaninato(O, O')di(μ‐hydroxo))di(phthalocyaninato(2‐)zirconium(IV)) ( 12 ) have been isolated from tetra(n‐butyl)ammonium hydroxide solutions of cis‐di(chloro)phthalocyaninato(2‐)zirconium(IV) and ‐hafnium(IV), respectively, and the corresponding acid in polar organic solvents. Similarly, with cis‐di(chloro)tetraphenylporphyrinato(2‐)zirconium(IV), ^cis[Zr(Cl)₂tpp] as precursor crystalline tetra(n‐butyl)ammoniumcis‐tetrachlorocatecholato(O, O')hydrogentetrachlorocatecholato(O)tetraphenylporphyrinato(2‐)zirconate(IV) ( 4 ), cis‐hydrogencarbonato(O, O')phenolatotetraphenylporphyrinato(2‐)zirconium(IV) ( 6 ), cis‐di(benzoato(O, O'))tetraphenylporphyrinato(2‐)zirconium(IV) ( 11 ), and cis‐tetra(μ‐hydroxo)di(tetraphenylporphyrinato(2‐)zirconium(IV)) ( 13 ) with a cis‐arrangement of the symmetry equivalent μ‐hydroxo ligands, and from di(acetato)tetraphenylporphyrinato(2‐)zirconium(IV) the corresponding trans‐isomer ( 14 ) have been prepared. The endothermic dehydration at 215 °C of 13/14 yields μ‐oxodi(μ‐hydroxo)di(tetraphenylporphyrinato(2‐)zirconium(IV)) ( 15 ). 15 also precipitates on dilution of a solution of ^cis[Zr(X)₂tpp] (X = Cl, OAc) in dmf/(ⁿBu₄N)OH with water, while on prolonged standing of this solution on air tri(tetra(n‐butyl)ammonium) cis‐(^nido〈di(carbonato(O, O'))undecaaquamethoxide〉tetraphenylporphyrinato(2‐)zirconate(IV) ( 7 ) crystallizes, in which Zr^IV coordinates a supramolecular nestlike ^nido〈(O₂CO)₂(H₂O)₁₁OCH₃〉^5— cluster anion stabilised by hydrogen bonding in a nanocage of surrounding (ⁿBu₄N)⁺ cations. On the other hand, ^cis[Zr(Cl)₂pc] forms with (Et₄N)₂CO₃ in dichloromethane di(tetraethylammonium) cis‐di(carbonato(O, O')phthalocyaninato(2‐)zirconate(IV) ( 5 ). ^cis[Zr(Cl)₂tpp] dissolves in various O‐donor solvents, from which cis‐di(chloro)dimethylformamidetetraphenylporphyrinato(2‐)zirconium(IV) ( 8 ), cis‐di(chloro)dimethylsulfoxidetetraphenylporphyrinato(2‐)zirconium(IV) ( 9 ), and a 1:1 mixture ( 10 ) of cis‐di(chloro)dimethylsulfoxidetetraphenylporphyrinato(2‐)zirconium(IV) ( 10a ) and cis‐chlorodi(dimethylsulfoxide)tetraphenylporphyrinato(2‐)zirconium(IV) chloride ( 10b ) crystallize. All complexes contain solvate molecules in the solid state, except 3 . Zr^IV/Hf^IV is directed by ∼1Å out of the plane of the tetrapyrrolic ligand (pc, tpp) towards the mutually cis‐coordinated axial ligands. In the more concavely distorted phthalocyaninates, Zr^IV is mainly eight‐coordinated and in the tetraphenylporphyrinates seven‐coordinated. The octa‐coordinated Zr atom is in a distorted quadratic antiprism, and the hepta‐coordinated one is in a square‐base‐trigonal‐cap cooordination polyhedron. In most tpp complexes, the Zr atom is displaced by up to 0.3Å out of the centre of the coordination polyhedron towards the tetrapyrrolic ligand. In 13/14 , both antiprisms are face shared by an O₄ plane, and in 12 they are shared by an O₂ edge and the O atoms of the bridging aminocarboxylates, the dihedral angle between the O₄ planes of both antiprisms being 50.1(1)°. The mean Zr‐N_p distance is 0.05Å longer in the pc complexes than in the tpp complexes (d(Zr‐N_p)_pc = 2.31Å). In the monophenolato complexes, the mean Zr‐O distance (∼2.00Å) is shorter than in the complexes with other O‐donor ligands (d(Zr‐O)_pc = 2.18Å; d(Zr‐O)_tpp = 2.21Å); the Zr‐Cl distances vary between 2.473(1) and 2.559(2)Å (d(Zr‐Cl)_tpp = 2.51Å). d(C‐O_exo) = 1.494(4)Å in the bidentate hydrogencarbonato ligand in 6 is 0.26Å longer than in the bidentate carbonato ligands in 5 and 7 . 9 and 10a are rotamers slightly differing by the orientation of the axial ligands with respect to the tpp ligand. In 1—4, 6 , and 11 the phenolato, catecholato, and benzoato ligands, respectively, are in syn‐ and/or anti‐conformations with respect to the plane of the macrocycle. π‐Dimers with modest overlap of the neighbouring macrocyclic rings are observed in 5, 6, 8, 9, 10b, 12 , and 14 . The common UV/Vis spectroscopical and vibrational properties of the new phthalocyaninates and tetraphenylporphyrinates scarcely reflect their rich structural diversity.     

The Evolution Aspect in the Crystallization Process of [5,5′‐(HCF2CF2CH2OCH2)2‐2,2′‐bpy]MX2 (M = Pt,Pd; X = I,Br): Role of the Intramolecular CF2─H…X(─M) Hydrogen Bonds

The general species (2,2′‐bpy)MX₂ (M = Pd, Pt; X = Br, I) in a crystallization process results in an isomorphous convergence in P2₁/c. Yet, with polyfluorinated side chains, the general [5,5′‐(HCF₂CF₂CH₂OCH₂)₂‐2,2′‐bpy]MX₂ species proceeds to crystallize the isomorphous structures of 5 (M = Pt; X = I) and 6 (M = Pd; X = I) in P2₁/c only; structure 7 (M = Pt; X = Br) crystallizes in P2₁/c but is not isomorphous with 5 and 6 , and structure 8 (M = Pd; X = Br) forms differently in P–1. The causes making the system nonlinear are (1) the intramolecular CF₂─H^…X(─M) hydrogen bonds found in 5–7 but not in 8, and (2) in response to the transition from I to Br, bifurcated [C─H^…]₂ F ─C hydrogen bonds that are formed in 5 and 6 and bifurcated C─ H [^…F─C]₂ hydrogen bonds in 7 . Additionally, the intramolecular CF₂─H^…X(─M) hydrogen bonding from compounds 5–7 could be affirmed by the IR studies.     

Electrochemical Synthesis of MII Complexes with a Schiff Base containing an Amido Group. Crystal Structure of a Cobalt(II) Complex with a Reorganised Ligand

M(HL)(H₂O)_n complexes have been obtained by the electrochemical reaction of Fe, Co, Ni, Cu, Zn and Cd anodes with the potentially pentadentate and trianionic asymmetrical Schiff base 3‐aza‐N‐{2‐[1‐aza‐2‐(5‐nitro‐2‐hydroxylphenyl)‐vinyl]phenyl}‐4‐(5‐nitro‐2‐hydroxyphenyl)but‐3‐enamide (H₃L), containing a hard amido donor atom. The complexes have been characterized by elemental analysis, mass spectrometry, IR and ¹H NMR spectroscopies, magnetic measurements and molar conductivities. Co(HL)(H₂O) ( 2 ) has been found to rearrange in DMF solution into a crystallographically solved octahedral complex, CoL¹(H₂O)₂ ( 7 ) [where H₂L¹ is the symmetrical Schiff base ligand N,N′‐(1,2‐phenylene)‐bis(5‐nitro‐3‐hydroxysalicylidenimine)]. A hydrolysis mechanism is discussed to explain this rearrangement.     

An Approach to Mixed PnAsm Ligand Complexes

The reaction of a P₄ butterfly complex with yellow arsenic yields the largest mixed P_nAs_m ligand complexes synthesized to date. [{Cp′′′Fe(CO)₂}₂(μ,η^1:1‐P₄)] reacts with As₄ to yield [{Cp′′′Fe}₂(μ,η^4:4‐P_nAs_4‐n)] and [Cp′′′Fe(η⁵‐P_nAs_5‐n)]. Mass spectrometry together with NMR spectroscopy and X‐ray crystallography give clear evidence about the arrangement of the E positions within the cyclo‐E₅ and E₄ moieties of the products. Moreover, the results of DFT calculations agree well with the experimental determined outcomes. By coordinating the E₄ complex [{Cp′′′Fe}₂(μ,η^4:4‐P_nAs_4‐n)] with CuCl, a rearrangement of the E positions occurs in favor with a preferred phosphorus coordination towards copper atoms in the resulting 1D polymeric chain.     

Unraveling the Mechanism of Water Oxidation Catalyzed by Nonheme Iron Complexes

Density functional theory (DFT) is employed to: 1) propose a viable catalytic cycle consistent with our experimental results for the mechanism of chemically driven (Ce^IV) O₂ generation from water, mediated by nonheme iron complexes; and 2) to unravel the role of the ligand on the nonheme iron catalyst in the water oxidation reaction activity. To this end, the key features of the water oxidation catalytic cycle for the highly active complexes [Fe(OTf)₂(Pytacn)] (Pytacn: 1‐(2′‐pyridylmethyl)‐4,7‐dimethyl‐1,4,7‐triazacyclononane; OTf: CF₃SO₃^?) ( 1 ) and [Fe(OTf)₂(mep)] (mep: N,N′‐bis(2‐pyridylmethyl)‐N,N′‐dimethyl ethane‐1,2‐diamine) ( 2 ) as well as for the catalytically inactive [Fe(OTf)₂(tmc)] (tmc: N,N′,N′′,N′′′‐tetramethylcyclam) ( 3 ) and [Fe(NCCH₃)(^MePy₂CH‐tacn)](OTf)₂ (^MePy₂CH‐tacn: N‐(dipyridin‐2‐yl)methyl)‐N′,N′′‐dimethyl‐1,4,7‐triazacyclononane) ( 4 ) were analyzed. The DFT computed catalytic cycle establishes that the resting state under catalytic conditions is a [Fe^IV(O)(OH₂)(LN₄)]²⁺ species (in which LN₄=Pytacn or mep) and the rate‐determining step is the O?O bond‐formation event. This is nicely supported by the remarkable agreement between the experimental (ΔG^≠=17.6±1.6 kcal mol^?1) and theoretical (ΔG^≠=18.9 kcal mol^?1) activation parameters obtained for complex 1 . The O?O bond formation is performed by an iron(V) intermediate [Fe^V(O)(OH)(LN₄)]²⁺ containing a cis‐Fe^V(O)(OH) unit. Under catalytic conditions (Ce^IV, pH 0.8) the high oxidation state Fe^V is only thermodynamically accessible through a proton‐coupled electron‐transfer (PCET) process from the cis‐[Fe^IV(O)(OH₂)(LN₄)]²⁺ resting state. Formation of the [Fe^V(O)(LN₄)]³⁺ species is thermodynamically inaccessible for complexes 3 and 4 . Our results also show that the cis‐labile coordinative sites in iron complexes have a beneficial key role in the O?O bond‐formation process. This is due to the cis‐OH ligand in the cis‐Fe^V(O)(OH) intermediate that can act as internal base, accepting a proton concomitant to the O?O bond‐formation reaction. Interplay between redox potentials to achieve the high oxidation state (Fe^V?O) and the activation energy barrier for the following O?O bond formation appears to be feasible through manipulation of the coordination environment of the iron site. This control may have a crucial role in the future development of water oxidation catalysts based on iron.     

Simple Preparation of Sulfate Anion‐Doped Polyaniline‐Clay Nanocomposites by an Environmentally Friendly Mechanochemical Synthesis Route

Summary: Conducting polyaniline (PANI) and montmorillonite (MMT) nanocomposites were prepared from aniline sulfate and MMT by a mechanochemical synthesis route. X‐Ray diffraction analysis confirmed that, by controlling the aniline sulfate content, mechanochemical synthesis led to two types of different formations. After polymerization, the mechanochemical route synthesized much more PANI between the clay layers compared to a solution method. The electrical conductivities of the synthesized PANI‐MMT nanocomposites in pressed pellets ranged in the order of between 10⁻⁴ and 10⁻³ S · cm⁻¹.

X‐ray powder diffraction patterns of the intercalation products prepared by grinding montmorillonite with various amounts of Ani‐SO₄ in a mortar.     

PtII Coordination to N1 of 9‐Methylguanine: Why it Facilitates Binding of Additional Metal Ions to the Purine Ring

The preparation and X‐ray crystal structure analysis of {trans‐[Pt(MeNH₂)₂(9‐MeG‐N1)₂]} ? {3 K₂[Pt(CN)₄]} ? 6 H₂O ( 3 a ) (with 9‐MeG being the anion of 9‐methylguanine, 9‐MeGH) are reported. The title compound was obtained by treating [Pt(dien)(9‐MeGH‐N7)]²⁺ ( 1 ; dien=diethylenetriamine) with trans‐[Pt(MeNH₂)₂(H₂O)₂]²⁺ at pH 9.6, 60 °C, and subsequent removal of the [(dien)Pt^II] entities by treatment with an excess amount of KCN, which converts the latter to [Pt(CN)₄]^2?. Cocrystallization of K₂[Pt(CN)₄] with trans‐[Pt(MeNH₂)₂(9‐MeG‐N1)₂] is a consequence of the increase in basicity of the guanine ligand following its deprotonation and Pt coordination at N1. This increase in basicity is reflected in the pK_a values of trans‐[Pt(MeNH₂)₂(9‐MeGH‐N1)₂]²⁺ (4.4±0.1 and 3.3±0.4). The crystal structure of 3 a reveals rare (N7,O6 chelate) and unconventional (N2,C2,N3) binding patterns of K⁺ to the guaninato ligands. DFT calculations confirm that K⁺ binding to the sugar edge of guanine for a N1‐platinated guanine anion is a realistic option, thus ruling against a simple packing effect in the solid‐state structure of 3 a . The linkage isomer of 3 a , trans‐[Pt(MeNH₂)₂(9‐MeG‐N7)₂] ( 6 a ) has likewise been isolated, and its acid–base properties determined. Compound 6 a is more basic than 3 a by more than 4 log units. Binding of metal entities to the N7 positions of 9‐MeG in 3 a has been studied in detail for [(NH₃)₃Pt^II], trans‐[(NH₃)₂Pt^II], and [(en)Pd^II] (en=ethylenediamine) by using ¹H NMR spectroscopy. Without exception, binding of the second metal takes place at N7, but formation of a molecular guanine square with trans‐[(Me₂NH₂)Pt^II] cross‐linking N1 positions and trans‐[(NH₃)₂Pt^II] cross‐linking N7 positions could not be confirmed unambiguously, despite the fact that calculations are fully consistent with its existence.     

[RuCl3ind3] and [RuCl2ind4]: Two New Ruthenium Complexes derived from the Tumor‐inhibiting RuIII Compound HInd (OC‐6‐11)‐[RuCl4ind2] (ind = indazole)

Indazolium (OC‐6‐11)‐tetrachlorobis(indazole) ruthenate(III), HInd (OC‐6‐11)‐[RuCl₄ind₂], exhibits excellent results in different tumor models in vitro and in vivo. Substitution reactions of this ruthenium(III) complex are of special interest for a deeper understanding of its interactions with biologically occurring targets and its mode of action. The indazolium complex salt can be transformed to the neutral, meridionally configurated trisindazole complex (OC‐6‐21)‐[RuCl₃ind₃] in solvents like tetrahydrofuran. The X‐ray crystal structure of this complex could be solved (monoclinic space group P2(1)/n, a = 12.441(3), b = 10.415(3), c = 21.635(4) Å, β = 105.02(1)°). In spite of the paramagnetic Ru^III atom most of the coordinated indazole protons could be assigned with the help of two‐dimensional NMR experiments. Additionally, a reduced reaction product of HInd (OC‐6‐11)‐[RuCl₄ind₂] in the physiological solubilizer 2‐pyrrolidone could be isolated and the X‐ray crystal structure of this Ru^II complex, (OC‐6‐12)‐[RuCl₂ind₄], crystallized with two 2‐pyrrolidones, could be solved (monoclinic space group P2(1)/n, a = 12.139(2), b = 10.426(2), c = 14.426(3) Å, β = 100.06(3)°).     

β,β‐(1,4‐Dithiino)subporphyrin Dimers Capturing Fullerenes with Large Association Constants

β,β‐(1,4‐Dithiino)subporphyrin dimers 7‐syn and 7‐anti were synthesized by the nucleophilic aromatic substitution reaction of 2‐bromo‐3‐(4‐methoxyphenylsulfonyl)subporphyrin 4 with 2,3‐dimercaptosubporphyrin 5 under basic conditions followed by axial arylation. Additions of C₆₀ or C₇₀ to a dilute solution of 7‐anti (ca. 10^?6 m ) in toluene did not cause appreciable UV/Vis spectral changes, while similar additions to a concentrated solution (ca. 10^?3 m ) resulted in precipitation of complexes. In contrast, dimer 7‐syn captured C₆₀ and C₇₀ in different complexation stoichiometries in toluene; a 1:1 manner and a 2:1 manner, respectively, with large association constants; K_a=(1.9±0.2)×10⁶ m ^?1 for C₆₀@ 7‐syn , and K₁=(1.6±0.5)×10⁶ and K₂=(1.8±0.9)×10⁵ m ^?1 for C₇₀@( 7‐syn )₂. These association constants are the largest for fullerenes‐capture by bowl‐shaped molecules reported so far. The structures of C₆₀@ 7‐anti , C₇₀@ 7‐anti , C₆₀@ 7‐syn , and C₇₀@ 7‐syn have been determined by single‐crystal X‐ray diffraction analysis.     

Polysulfonylamine. CLIV [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 7 [2] Ein dreidimensionales Koordinationspolymer aus Schichten und Pfeilern: Kristallstruktur von Ba[(CH3SO2)2N]2·2H2O

Polysulfonylamines. CLIV. Crystal Structures of Metal Di(methanesulfonyl)amides. 7. A Three‐Dimensional Coordination Polymer Built up from Layers and Pillars: Crystal Structure of Ba[(CH₃SO₂)₂N]₂·2H₂O The barium compound BaA₂·2H₂O, derived from HA = di(methanesulfonyl)amine, has been characterized by single crystal X‐ray diffraction at —95 °C (monoclinic, space group P2₁/n, Z = 4). Despite numerous metal‐ligand bonds, the independent anions A^— and A′^— retain the pseudo‐C₂ symmetric conformation that commonly occurs in organic onium salts BH⁺A^—. The large cation attains ninefold coordination via interactions with one (O, N)‐chelating A^—, three κ¹O‐bonding A^—, two κ¹O‐bonding A′^— and two monodentate water molecules; if a distinctly longer barium‐water distance is included, the coordination number may alternatively be viewed as 9 + 1 and one water molecule regarded as an asymmetrically μ₂‐bridging ligand. In contrast to the previously reported layer structures of SrA₂ and PbA₂, the present crystal displays a three‐dimensional coordination assembly consisting of layers formed by the cations, the water molecules and the pentadentate A^— ligands, and of interlayer pillars provided by the bidentate A′^— ligands; however, the Ba²⁺/A^— substructure turns out to be topologically and crystallographically congruent with the corresponding M²⁺/A^— substructures in SrA₂ and PbA₂. The crystal cohesion of the barium complex is reinforced by four O(W)—H···O=S hydrogen bonds and several non‐classical C—H···O=S hydrogen bonds.     

Microwave‐Assisted Synthesis and Transformations of Cationic CpRu(II)(naphthalene) and CpRu(II)(naphthoquinone) Complexes

Details of the direct synthesis of cationic Ru(II)(η⁵‐Cp)(η⁶‐arene) complexes from ruthenocene using microwave heating are reported. Developed for the important catalyst precursor [Ru(II)(η⁵‐Cp)(η⁶‐1‐4,4a,8a‐naphthalene)][PF₆] reaction time could be shortened from three days to 15 min. The method was extended to [Ru(II)(η⁶‐benzene)(η⁵‐Cp)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐toluene)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐mesitylene)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐hexamethylbenzene)][PF₆], [Ru(II)(η⁵Cp)(η⁶‐indane)][PF₆], [Ru(II)(η⁵‐Cp)(η⁶‐2,6‐dimethylnaphthalene)][PF₆], and [Ru(II)(η⁵‐Cp)(η⁶‐pyrene)][PF₆]. 1‐methylnaphthalene and 2,3‐dimethylnaphthalene afforded mixtures of regioisomeric complexes. [Ru(Cp)(CH₃CN)₃][PF₆], derived from the naphthalene precursor provided access to the cationic RuCp complexes of naphthoquinone, tetralindione, 1,4‐dihydroxynaphthalene, and 1,4‐dimethoxynaphthalene. Reduction of the tetralindione complex afforded selectively the endo,endo diol derivative. X‐Ray structures of five complexes are reported.     

Multifunctional Tricarbazolo Triazolophane Macrocycles: One‐Pot Preparation,Anion Binding,and Hierarchical Self‐Organization of Multilayers

Programming the synthesis and self‐assembly of molecules is a compelling strategy for the bottom‐up fabrication of ordered materials. To this end, shape‐persistent macrocycles were designed with alternating carbazoles and triazoles to program a one‐pot synthesis and to bind large anions. The macrocycles bind anions that were once considered too weak to be coordinated, such as PF₆^?, with surprisingly high affinities (β₂=10¹¹ M ^?2 in 80:20 chloroform/methanol) and positive cooperativity, α=(4 K₂/K₁)=1200. We also discovered that the macrocycles assemble into ultrathin films of hierarchically ordered tubes on graphite surfaces. The remarkable surface‐templated self‐assembly properties, as was observed by using scanning tunneling microscopy, are attributed to the complementary pairing of alternating triazoles and carbazoles inscribed into both the co‐facial and edge‐sharing seams that exist between shape‐persistent macrocycles. The multilayer assembly is also consistent with the high degree of molecular self‐association observed in solution, with self‐association constants of K=300 000 M ^?1 (chloroform/methanol 80:20). Scanning tunneling microscopy data also showed that surface assemblies readily sequester iodide anions from solution, modulating their assembly. This multifunctional macrocycle provides a foundation for materials composed of hierarchically organized and nanotubular self‐assemblies.     

H2 Formation on Cosmic Grain Siliceous Surfaces Grafted with Fe+: A Silsesquioxanes‐Based Computational Model

Cosmic siliceous dust grains are involved in the synthesis of H₂ in the inter‐stellar medium. In this work, the dust grain siliceous surface is represented by a hydrogen Fe‐metalla‐silsesquioxane model of general formula: [Fe(H₇Si₇O_12?n)(OH)_n]⁺ (n=0,1,2) where Fe⁺ behaves like a single‐site heterogeneous catalyst grafted on a siliceous surface synthesizing H₂ from H. A computational analysis is performed using two levels of theory (B3LYP‐D3BJ and MP2‐F12) to quantify the thermodynamic driving force of the reaction: [Fe‐T7H₇]⁺+4H→[Fe‐T7H₇(OH)₂]⁺+H₂. The general outcomes are: 1) H₂ synthesis is thermodynamically strongly favored; 2) Fe‐H / Fe‐H₂ barrier‐less formation potential; 3) chemisorbed H‐Fe leads to facile H₂ synthesis at 20≤T≤100 K; 4) relative spin energetics and thermodynamic quantities between the B3LYP‐D3BJ and MP2‐F12 levels of theory are in qualitative agreement. The metalla‐silsesquioxane model shows how Fe⁺ fixed on a siliceous surface can potentially catalyze H₂ formation in space.     

Calix[4]arene‐Phosphine Dimers: Precursors of Flexible Metallo‐Capsules and Self‐Compacting Molecules

The first diphosphines based on a double calixarene, namely 1,4 (or 1,3)‐bis‐(5‐diphenylphosphino‐25,26,27,28‐tetrapropoxycalix[4]aren‐17‐yl)benzene ( L² , L³ ) were each prepared in four steps starting from 5,17‐dibromo‐25,26,27,28‐tetrapropoxycalix[4]arene. Upon reaction of L² with [Au(tht)(thf)]BF₄, (tht=C₄H₈S) a rigid metallo‐capsule was quantitatively formed, which adopts an oblique form owing to the distinct nature of the spacers linking the two calixarene half‐spheres. In the solid state, the 1,4‐substituted phenylene linker is turned towards the gold ion, suggesting the existence of weak bonding interactions between two aromatic CH protons of this ring and the metal centre (Au???H=2.67 Å). In contrast to this gold complex, the related silver complex shows dynamic behaviour in solution, the exchange between two enantiomeric oblique forms being facilitated by the greater stereochemical flexibility of Ag^I vs. Au^I. A heteronuclear ¹⁰⁹Ag{¹H} HMQC experiment established strong correlations between the CH protons of the phenylene linker and the ¹⁰⁹Ag ion. Dynamic behaviour similar to that observed for the silver complex was further observed in trans‐[PtCl₂? L² ], a chelate complex that could be obtained quantitatively from L² and [PtCl₂(PhCN)₂]. The intended formation of a chelate complex leading to a capsule with an endo‐oriented metal centre was achieved by reacting L³ with [Pd(allyl)(thf)₂]BF₄. The complex thus formed constitutes the first organometallic transition metal complex embedded in a cavity with large portals. Binding of [RuCl₂(p‐cymene)] to L² and L³ resulted in self‐compacting bimetallic complexes in which each calixarene basket entraps a Ru(p‐cymene) unit, thereby forming molecules occupying a minimal volume.     

Three‐Dimensional Antiferromagnetic Order of Single‐Chain Magnets: A New Approach to Design Molecule‐Based Magnets

Two one‐dimensional compounds composed of a 1:1 ratio of Mn^III salen‐type complex and Ni^II oximato moiety with different counter anions, PF₆^? and BPh₄^?, were synthesized: [Mn(3,5‐Cl₂saltmen)Ni(pao)₂(phen)]PF₆ ( 1 ) and [Mn(5‐Clsaltmen)Ni(pao)₂(phen)]BPh₄ ( 2 ), where 3,5‐Cl₂saltmen^2?=N,N′‐(1,1,2,2‐tetramethylethylene)bis(3,5‐dichlorosalicylideneiminate); 5‐Clsaltmen^2?=N,N′‐(1,1,2,2‐tetramethylethylene)bis(5‐chlorosalicylideneiminate); pao^?=pyridine‐2‐aldoximate; and phen=1,10‐phenanthroline. Single‐crystal X‐ray diffraction study was carried out for both compounds. In 1 and 2 , the chain topology is very similar forming an alternating linear chain with a [‐Mn^III‐ON‐Ni^II‐NO‐] repeating motif (where ‐ON‐ is the oximate bridge). The use of a bulky counteranion, such as BPh₄^?, located between the chains in 2 rather than PF₆^? in 1 , successfully led to the magnetic isolation of the chains in 2 . This minimization of the interchain interactions allows the study of the intrinsic magnetic properties of the chains present in 1 and 2 . While 1 and 2 possess, as expected, very similar paramagnetic properties above 15 K, their ground state is antiferromagnetic below 9.4 K and paramagnetic down to 1.8 K, respectively. Nevertheless, both compounds exhibit a magnet‐type behavior at temperatures below 6 K. While for 2 , the observed magnetism is well explained by a Single‐Chain Magnet (SCM) behavior, the magnet properties for 1 are induced by the presence in the material of SCM building units that order antiferromagnetically. By controlling both intra‐ and interchain magnetic interactions in this new [Mn^IIINi^II] SCM system, a remarkable AF phase with a magnet‐type behavior has been stabilized in relation with the intrinsic SCM properties of the chains present in 1 . This result suggests that the simultaneous enhancement of both intrachain (J) and interchain (J′) magnetic interactions (with keeping J ? J′), independently of the presence of AF phase might be an efficient route to design high temperature SCM‐based magnets.