Controlling aggregation of copper(II)-based coordination compounds: From mononuclear to dinuclear, tetranuclear, and polymeric copper complexes

The use of a strategy combining ligand design and changes of reaction conditions has been investigated with the goal of directing the assembly of mononuclear, dinuclear, tetranuclear, and polymeric copper(II) complexes. As a result, closely related copper monomers, alkoxo dimers, and hydroxo cubanes, along with a carbonate-bridged polymeric species, have been synthesized using the rigid, aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and the glutaryl-linked derivative glutaric acid bis-(cis-3,5-diaminocyclohexyl) ester (GADACE). The composition of the monomeric complex has been determined by X-ray crystallography as [Cu(DAHC)2](ClO4)2 (1), the two dimers as [{Cu(DAHC)(OMe)}2](ClO4)2.MeOH (2) and [{Cu(DAMC)(OMe)(ClO4)}2] (3), the three Cu4O4 cubanes as [{Cu(DAHC)(OH)}4](ClO4)(4).2.5MeOH (4), [{Cu(DAMC)(OH)}4](ClO4)4.H2O (5), and [{Cu2(OH)2(GADACE)}2]Cl4.2MeOH.6H2O (6), and an infinite-chain structure as [{Cu(DAHC)(CO3)}n] (7). Furthermore, the cubane structures 4 and 5 have been investigated magnetically. Our studies indicate that formation of the monomeric, dimeric, and tetranuclear DAHC and DAMC complexes can be controlled by small changes in reaction conditions and that further preorganization of the ligand moiety by linking the DAHC cores (GADACE) allows more effective direction of the self-assembly of the Cu4O4 cubane core.     

Different nuclearity silver(I) complexes with novel tetracyano pendant-armed hexaazamacrocyclic ligands

A new series of different nuclearity silver(I) complexes with a variety of tetracyano pendant-armed hexaazamacrocyclic ligands containing pyridine rings (Ln) has been prepared starting from the nitrate and perchlorate Ag(I) salts in acetonitrile solutions. The ligands and complexes were characterized by microanalysis, conductivity measurements, IR, Raman, electronic absorption and emission spectroscopy, and L-SIMS spectrometry. (1)H NMR titrations were employed to investigate silver complexation by ligands L3 and L.(4) The compounds [Ag2L2(NO3)2] (2), ([Ag2L2](ClO4)2.2CH3CN)(infinity) (4), [AgL3](ClO(4)).CH3CN (5), and [Ag4(L4)2(NO3)2](NO3)2.4CH3CN.2H2O (7) were also characterized by single-crystal X-ray diffraction. The complexes have different nuclearities. Complex 2 is dinuclear with an {AgN3O2} core and a significant intermetallic interaction, whereas complex 4 has a polymeric structure formed by dinuclear distorted {AgN4} units joined by nitrile pendant arms. Compound 5 is mononuclear with a distorted {AgN2} linear geometry, and complex 7 consists of discrete units of a tetranuclear array of silver atoms with {AgN3O} and {AgN4} cores in distorted square planar environments. Complexes 2 and 4 were found to be fluorescent in the solid state at room temperature because of the Ag-Ag interactions.     

Ring-opening polymerisation of coordination compounds: a silver(I) network with both ring and polymer components

The terpyridyl ligand 2,6-C5H3N{C(=O)N(Me)-4-C5H4N}2, 1, combined with silver(I) salts to give the complexes [Ag2(1)2][BF4]2, 2, and [{Ag3(1)2}n][CF3SO3]3n, 3; the network structure of complex contains both macrocyclic units [Ag2(mu-1)2]2+ and ring-opened polymeric units [{Ag(mu-1)}n]n+.     

Solid state coordination chemistry of metal oxides: structural consequences of fluoride incorporation into the oxovanadium-copper-bisterpy-{O3P(CH2)nPO3}4- system, n= 1-5 (bisterpy = 2,2':4',4":2",2"'-quaterpyridyl-6', 6"-di-2-pyridine)

Hydrothermal reactions of a vanadate source, an appropriate Cu(II) source, bisterpy and an organodiphosphonate, H2O3P(CH2)nPO3H2(n= 1-5), in the presence of HF, yielded a family of materials of the type oxyfluorovanadium/copper-bisterpy/organodiphosphonate. Under similar reaction conditions, variations in diphosphonate tether length n provided the one-dimensional [{Cu2(bisterpy)}V2F2O2{HO3PCH2PO3}{O3PCH2PO3}](1) and [{Cu2(bisterpy)}V2F4O4{HO3P(CH2)2PO3H}](3), the two-dimensional [{Cu2(bisterpy)}V2F2O2(H2O)2{HO3P(CH2)2PO3}2] x 2H2O (2 x 2H2O), [{Cu2(bisterpy)(H2O2}V2F2O2{O3P(CH2)3PO3}{HO3P(CH2)3PO3H}(4) and [{Cu2(bisterpy)}V4F4O4(OH)(H2O){HO3P(CH2)5PO3}{O3P(CH2)5PO3}] x H2O (9 x H2O) and the three-dimensional [{Cu2(bisterpy)}3V8F6O17{HO3P(CH2)3PO3}4]0.8H2O (5 x 0.8H2O), [{Cu2(bisterpy)}V4F2O6{O3P(CH2)4PO3}2](8) and [{Cu2(bisterpy)(H2O)}2V8F4O8(OH)4{HO3P(CH2)5PO3H}2{O3P(CH2)5PO)}3] x 4.8H2O (10 x 4.8H2O). In addition, two members of the oxovanadium/Cu2(bisterpy)/organodiphosphonate family [{Cu2(bisterpy)}V2O4{HO3P(CH2)3PO3}2](6) and [{Cu2(bisterpy)}3V4O8(OH)2{O3P(CH2)3PO3}2{HO3P(CH2)3PO3}2] x 5H2O (7 x 5H2O) cocrystallized from the reaction mixture which provided 5. The overall architectures reveal embedded substructures based on V/P/O(F) clusters, chains, networks, and frameworks. In contrast to the oxovanadium/Cu2(bisterpy)/ organodiphosphonate family, several of the materials of this study also exhibit the direct condensation of vanadium polyhedra to produce binuclear and/or tetranuclear building units.     

Toluene-sandwiched trinuclear copper(I) and silver(I) triazolates and phosphine adducts of dinuclear copper(I) and silver(I) triazolates

Cu (I) and Ag (I) complexes of the fluorinated triazolate ligand [3,5-(C3F7)2Tz](-) have been synthesized using the corresponding metal(I) oxides and the triazole. They form pi-acid/base adducts with toluene, leading to [Tol][M3][Tol] ([Tol]=toluene; [M3]={[3,5-(C3F7)2Tz]Cu}3 or {[3,5-(C3F7)2Tz]Ag}3) type structures. Packing diagrams show the presence of extended chains of the type {[Tol][M3][Tol]}infinity, but the intertoluene ring distances are too long for significant pi-arene/pi-arene contacts. These copper and silver triazolates react with PPh3 (at a 1:1 metal ion/P molar ratio), leading to dinuclear {[3,5-(C3F7)2Tz]Cu(PPh3)}2 and {[3,5-(C3F7) 2Tz]Ag(PPh3)}2. They feature a six-membered Cu(mu-N-N) 2Cu or Ag(mu-N-N)2Ag core with a boat conformation.     

Isolation of a pentadentate ligand and stepwise synthesis, structures, and magnetic properties of a new family of homo- and heterotrinuclear complexes

A neutral pentadentate ligand, di(pyrazolecarbimido)amine (Hdcadpz), and its adduct with HClO4, [H2dcadpz]+[ClO4]-, were for the first time isolated from our previously reported [Cu3(dcadpz)2(Hpz)2(ClO4)2](ClO4)2.H2O by the use of (NH4)2S to remove the CuII ions and characterized by IR, EA, UV, NMR, MS, and X-ray crystallography. Reactions of copper(II) or nickel(II) nitrate with Hdcadpz in a 1:2 molar ratio generated two mononuclear precursors of [Cu(dcadpz)2] (1) and [Ni(dcadpz)2].2/3DMF (2). Furthermore, three new linear homo- and heterotrinuclear complexes of the same motif [M{M'(dcadpz)2}M] (M=CoII, NiII, M'=CuII, NiII), [{Co(pdm)}2{Cu(dcadpz)2}](NO3)4 (3), [{Ni(pdm)}2{Cu(dcadpz)2}](NO3)4 (4), and [{Ni(MeOH)(H2O)2}2{Ni(dcadpz)2}](NO3)4 (5), were synthesized from these two precursors (pdm=2,6-pyridinedimethanol) and characterized by X-ray crystallography. Magnetic studies show that the central Cu(dcadpz)2 motif is antiferromagnetically coupled with both the terminal Co(II) atoms via the dcadpz- ligand in 3 with a J value of -5.27 cm(-1) and ferromagnetically coupled with both the terminal Ni(II) atoms in 4 with a J value of 2.50 cm(-1), while 5 behaves only as a Curie paramagnet between 2 and 300 K due to the diamagnetic character of the central square-planar Ni(II) atom.     

The cyclic "silver-diphos" motif [Ag2(mu-diphosphine)2]2+ as a synthon for building up larger structures

The dinuclear, cyclic structural motif [Ag2(diphosphine)2](2+), here termed the "silver-diphos" motif, previously observed in many diphosphine-silver complexes, has been investigated as a synthon for building up larger structures such as coordination cages and polymers. A series of ligands containing one to four meta-substituted diphosphine groups, attached via a central core, has been synthesized from the corresponding fluoroarenes by reaction with KPPh2. Upon reaction with silver salts, the target synthon is adopted by meta-substituted diphosphines 1,3-bis(diphenylphosphino)benzene (L1), 2,6-bis(diphenylphosphino)benzonitrile (L2), and 3,5-bis(diphenylphosphino)benzamide (L3), each of which gives a single species in solution consistent with the expected dimeric complexes [Ag2L2(anion)2]. X-ray crystal structures of [Ag2(L1)2(OTf)2] and [Ag2(L2)2(SbF6)2] confirm the adoption of the silver-diphos motif in the solid state. Amide-functionalized diphosphine L3 forms a hydrogen-bonded chain structure in the solid state via the amide group. A discrete boxlike cage [Ag4(L4)2][SbF6]4 based on two silver-diphos synthons is formed when the tetraphosphine Ph2Sn{3,5-bis(diphenylphosphino)benzene}2 (L4) reacts with silver(I). Its single-crystal X-ray structure reveals a central cavity of minimum diameter, ca. 5.0 A, which contains a single SbF6(-) counterion disordered over two sites. In contrast to the highly selective behavior of the di- and tetra-phosphines L1-L4, the heptaphosphine P{3,5-bis(diphenylphosphino)benzene}3 L5 and the hexaphosphine PhSn{3,5-bis(diphenylphosphino)benzene}3 L6 give dynamic mixtures upon reaction with silver salts in solution. This nonspecific behavior is rationalized by the fact that their diphosphine groups are not appropriately disposed to form stable discrete structures based on the silver-diphos synthon. By contrast, the octaphosphine Sn{3,5-bis(diphenylphosphino)benzene}4 L7 does selectively form a single, discrete, highly symmetrical product in solution, [Ag4(L7)(OTf)4]. In this case, the ligand unexpectedly adopts an interarm tetra-chelating coordination mode, resulting in a continuous 24-membered ring around the periphery of the molecule. To understand the adoption of this unusual coordination mode, the alternative diphosphine Ph2Sn(3-diphenylphosphinobenzene)2 L8, which models a single interarm chelating site of L7, was also investigated. By contrast to L7, its coordination was nonspecific, giving mixtures of silver complexes upon reaction with AgOTf. The selective interarm chelation by L7 may therefore be stabilized by the continuous coordination ring in [Ag4(L7)(OTf)4]; that is, the four chelating sites can be thought of as acting in a cooperative manner. Alternatively, interarm steric repulsions between phenyl groups may favor interarm chelation. Overall, we conclude that, if the diphosphine groups are appropriately articulated to act independently (i. e., they are adequately separated and oriented), the silver-diphos synthon can be a useful tool for the coordination-based self-assembly of larger structures.     

The nature of the AgI...AgI interaction in different Ag(NH3)2 dimers embedded in supramolecular solids

An isolated silver(I) ammonia monomer, a dimer, and a novel dimer containing an intercalated water molecule have been embedded as guests in supramolecular frameworks, [Ag(NH3)2][(H2thpe)(H3thpe)].MeCN (1), [{Ag(NH3)2}2][(H2thpe)2]4.25 H2O (2), and [{Ag(NH3)2}-H2O-{Ag(NH3)2}][(H2thpe)(2)]benzene (3) (H3THPE=tris(hydroxyphenyl)ethane). The [{Ag(NH3)2}2]2+ dimer is not stable as an isolated entity, but is stabilized by hydrogen bonding in the supramolecular framework. The water-intercalated silver(I) ammonia dimer, which constitutes a novel species, is also subject by hydrogen bonding in concentrated solutions. The destabilization energy of the dimer relative to isolated monomers is calculated to be approximately 300 kJ mol(-1) by both perturbation methods and DFT theory. For the water-intercalated dimer it is calculated to be approximately 200 kJ mol(-1) according to the BSSE-corrected MP2 calculation. The different aggregate states show a dramatic variation of absorption and emission properties, in accordance with the concentration dependent red-shift observed in solutions. Natural-bond-orbital analysis shows that the disilver-ammonium-aquo "sandwich" cation in 3 is stabilized by interaction between the pi lone pair orbital on the oxygen atom of the water molecule and Ag(I)--N sigma antibonding molecular orbital.     

Topological variations of the PDP ligand and its prospects in molybdenum(0) dearomatization agents

The compounds fac-(κ(3)-PDP)Mo(CO)(3) {1; PDP = 2-[[2-(1-(pyridin-2-ylmethyl)pyrrolidin-2-yl)pyrrolidin-1-yl]methyl]pyridine}, [(cis-β-PDP)Mo(NO)(CO)]PF(6) ([cis-β-3]PF(6)), [(cis-α-PDP)Mo(NO)(CO)]PF(6) ([cis-α-3]PF(6)), [(cis-α-PDP)Mo(NO)Br]PF(6) ([4]PF(6)), [(trans-PDP)Cu](BF(4))(2)·CH(3)CN ([5](BF(4))(2)·CH(3)CN), and [(trans-PDP)Cu](OSO(2)CF(3))(2) ([5](OSO(2)CF(3))(2)) have been synthesized and structurally characterized by single-crystal X-ray diffraction. These are the first reported complexes of PDP on metal centers other than iron(II). The observed configurations indicate a broader range of accessible PDP topologies than has been reported. The {(cis-α-PDP)Mo(NO)}(+) fragment is found to be less π-basic than the dearomatizing {Tp(MeIm)Mo(NO)} fragment [Tp = hydridotris(1-pyrazolyl)borato; MeIm = 1-methylimidazole].     

Discrete, solvent-free alkaline-earth metal cations: metal···fluorine interactions and ROP catalytic activity

Efficient protocols for the syntheses of well-defined, solvent-free cations of the large alkaline-earth (Ae) metals (Ca, Sr, Ba) and their smaller Zn and Mg analogues have been designed. The reaction of 2,4-di-tert-butyl-6-(morpholinomethyl)phenol ({LO(1)}H), 2-{[bis(2-methoxyethyl)amino]methyl}-4,6-di-tert-butylphenol ({LO(2)}H), 2-[(1,4,7,10-tetraoxa-13-azacyclopentadecan-13-yl)methyl]-4,6-di-tert-butylphenol ({LO(3)}H), and 2-[(1,4,7,10-tetraoxa-13-azacyclo-pentadecan-13-yl)methyl]-1,1,1,3,3,3-hexafluoropropan-2-ol ({RO(3)}H) with [H(OEt(2))(2)](+)[H(2)N{B(C(6)F(5))(3)}(2)](-) readily afforded the doubly acidic pro-ligands [{LO(1)}HH](+)[X](-) (1), [{LO(2)}HH](+)[X](-) (2), [{LO(3)}HH](+)[X](-) (3), and [{RO(3)}HH](+)[X](-) (4) ([X](-) = [H(2)N{B(C(6)F(5))(3)}(2)](-)). The addition of 2 to Ca[N(SiMe(3))(2)](2)(THF)(2) and Sr[N(SiMe(3))(2)](2)(THF)(2) yielded [{LO(2)}Ca(THF)(0.5)](+)[X](-) (5) and [{LO(2)}Sr(THF)](+)[X](-) (6), respectively. Alternatively, 5 could also be prepared upon treatment of {LO(2)}CaN(SiMe(3))(2) (7) with [H(OEt(2))(2)](+)[X](-). Complexes [{LO(3)}M](+)[X](-) (M = Zn, 8; Mg, 9; Ca, 10; Sr, 11; Ba, 12) and [{RO(3)}M](+)[X](-) (M = Zn, 13; Mg, 14; Ca, 15; Sr, 16; Ba, 17) were synthesized in high yields (70-90%) by reaction of 3 or 4 with the neutral precursors M[N(SiMe(3))(2)](2)(THF)(x) (M = Zn, Mg, x = 0; M = Ca, Sr, Ba, x = 2). All compounds were fully characterized by spectroscopic methods, and the solid-sate structures of compounds 1, 3, 7, 8, 13, 14, {15}(4)·3CD(2)Cl(2), {16}(4)·3CD(2)Cl(2), and {{17}(4)·EtOH}·3CD(2)Cl(2) were determined by X-ray diffraction crystallography. Whereas the complexes are monomeric in the case of Zn and Mg, they form bimetallic cations in the case of Ca, Sr and Ba; there is no contact between the metal and the weakly coordinating anion. In all metal complexes, the multidentate ligand is κ(6)-coordinated to the metal. Strong intramolecular M···F secondary interactions between the metal and F atoms from the ancillary ligands are observed in the structures of {15}(4)·3CD(2)Cl(2), {16}(4)·3CD(2)Cl(2), and {{17}(4)·EtOH}·3CD(2)Cl(2). VT (19)F{(1)H} NMR provided no direct evidence that these interactions are maintained in solution; nevertheless, significant Ae···F energies of stabilization of 25-26 (Ca, Ba) and 40 kcal·mol(-1) (Sr) were calculated by NBO analysis on DFT-optimized structures. The identity and integrity of the cationic complexes are preserved in solution in the presence of an excess of alcohol (BnOH, (i)PrOH) or L-lactide (L-LA). Efficient binary catalytic systems for the immortal ring-opening polymerization of L-LA (up to 3,000 equiv) are produced upon addition of an excess (5-50 equiv) of external protic nucleophilic agents (BnOH, (i)PrOH) to 8-12 or 13-17. PLLAs with M(n) up to 35,000 g·mol(-1) were produced in a very controlled fashion (M(w)/M(n) ≈ 1.10-1.20) and without epimerization. In each series of catalysts, the following order of catalytic activity was established: Mg ? Zn < Ca < Sr ≈ Ba; also, Ae complexes supported by the aryloxide ligand are more active than their parents supported by the fluorinated alkoxide ancillary, possibly owing to the presence of Ae···F interactions in the latter case. The rate law -d[L-LA]/dt = k(p)·[L-LA](1.0)·[16](1.0)·[BnOH](1.0) was established by NMR kinetic investigations, with the corresponding activation parameters ΔH(++) = 14.8(5) kcal·mol(-1) and ΔS(++) = -7.6(2.0) cal·K(-1)·mol(-1). DFT calculations indicated that the observed order of catalytic activity matches an increase of the L-LA coordination energy onto the cationic metal centers with parallel decrease of the positive metal charge.     

Structural and magnetic diversity in cyano-bridged bi- and trimetallic complexes assembled from cyanometalates and [M(rac-CTH)]n+ building blocks (CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)

Seven new cyano-bridged heterometallic systems have been prepared by assembling [M'(rac-CTH)]n+ complexes (M' = CrIII, NiII, CuII), which have two cis available coordination positions, and [M(CN)6]3- (M = FeIII, CrIII) and [Fe(CN)2(bpy)2]+ cyanometalate building blocks. The assembled systems, which have been characterized by X-ray crystallography and magnetic investigations, are the molecular squares (meso-CTH-H2)[{Ni(rac-CTH)}2{Fe(CN)6)}2].5H2O (2) and [{Ni(rac-CTH)}2{Fe(CN)2(bpy)2}2](ClO4)4.H2O (5), the bimetallic chain [{Ni(rac-CTH)}2{Cr(CN)6)}2Ni(meso-CTH)].4H2O (3), the trimetallic chain [{Ni(rac-CTH)}2{Fe(CN)6)}2Cu(cyclam)]6H2O (4), the pentanuclear complexes [{Cu(rac-CTH}3{Fe(CN)6}2].2H2O (6) and [{Cu(rac-CTH)}3{Cr(CN)6)}2].2H2O (7), and the dinuclear complex [Cr(rac-CTH)(H2O)Fe(CN)6].2H2O (8). With the exception of 5, all compounds exhibit ferromagnetic interaction between the metal ions (JFeNi = 12.8(2) cm-1 for 2; J1FeCu= 13.8(2) cm-1 and J2FeCu= 3.9(4) cm-1 for 6; J1CrCu= 6.95(3) cm-1 and J2CrCu= 1.9(2)cm-1 for 7; JCrFe = 28.87(3) cm-1 for 8). Compound 5 exhibits the end of a transition from the high-spin to the low-spin state of the octahedral FeII ions. The bimetallic chain 3 behaves as a metamagnet with a critical field Hc = 300 G, which is associated with the occurrence of week antiferromagnetic interactions between the chains. Although the trimetallic chain 4 shows some degree of spin correlation along the chain, magnetic ordering does not occur. The sign and magnitude of the magnetic exchange interaction between CrIII and FeIII in compound 8 have been justified by DFT type calculations.     

Binuclear iron-sulfur complexes with bidentate phosphine ligands as active site models of Fe-hydrogenase and their catalytic proton reduction

The displacement of CO in a few simple Fe(I)-Fe(I) hydrogenase model complexes by bisphosphine ligands Ph2P-(CH2)n-PPh2 [with n = 1 (dppm) or n = 2 (dppe)] is described. The reaction of [{mu-(SCH2)2CH2}Fe2(CO)6] (1) and [{mu-(SCH2)2N(CH2CH2CH3)}Fe2(CO)6] (2) with dppe gave double butterfly complexes [{mu-(SCH2)2CH2}Fe2(CO)5(Ph2PCH2)]2 (3) and [{mu-(SCH2)2N(CH2CH2CH3)}Fe2(CO)5(Ph2PCH2)]2 (4), where two Fe2S2 units are linked by the bisphosphine. In addition, an unexpected byproduct, [{mu-(SCH2)2N(CH2CH2CH3)}Fe2(CO)5{Ph2PCH2CH2(Ph2PS)}] (5), was isolated when 2 was used as a substrate, where only one phosphorus atom of dppe is coordinated, while the other has been converted to P=S, presumably by nucleophilic attack on bridging sulfur. By contrast, the reaction of 1 and 2 with dppm under mild conditions gave only complexes [{mu-(SCH2)2CH2}Fe2(CO)5(Ph2PCH2PPh2)] (6) and [{mu-(SCH2)2N(CH2CH2CH3)}Fe2(CO)5(Ph2PCH2PPh2)] (8), where one ligand coordinated in a monodentate fashion to one Fe2S2 unit. Furthermore, under forcing conditions, the complexes [{mu-(SCH2)2CH2}Fe2(CO)4{mu-(Ph2P)2CH2}] (7) and [{mu-(SCH2)2N(CH2CH2CH3)}Fe2(CO)4{mu-(Ph2P)2CH2}] (9) were formed, where the phosphine acts as a bidentate ligand, binding to both the iron atoms in the same molecular unit. Electrochemical studies show that the complexes 3, 4, and 9 catalyze the reduction of protons to molecular hydrogen, with 4 electrolyzed already at -1.40 V versus Ag/AgNO3 (-1.0 V vs NHE).     

Secondary coordination sphere controlled reversible geometry reorganisations in copper(II) complexes

Reversible geometry reorganisations are demonstrated by cis-3,5-diamino-trans-hydroxycyclohexane (cis,trans-DAHC) copper(ii) fluoride complexes, with the concentration of water in the mother liquor controlling interconversion between blue crystals of 5-coordinate syn-[Cu(DAHC)(2)F](F).2CH(3)OH.H(2)O and red crystals of 4-coordinate anti-[Cu(DAHC)(2)](F)(2).2H(2)O.     

Ag4L2 nanocage as a building unit toward the construction of silver metal strings

Self-assembly of AgNO 3 with the semirigid tetratopic ligands 1,2,4,5-tetrakis(benzoimidazol-1-ylmethyl)benzene (TBim) and 1,2,4,5-tetrakis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (TDMBim) afforded compounds [Ag 4(mu 4-TBim) 2(mu 2-eta (2)-NO 3) 2](NO 3) 2. (1)/ 2CH 2Cl 2.2CH 3OH ( 1mu (1)/ 2CH 2Cl 2.2CH 3OH) and [(NO 3 (-)) subset{Ag 4(mu 4-TDMBim) 2}][Ag(NO 3) 2](NO 3) 2.CH 2Cl 2.CH 3OH.4H 2O ( 2.CH 2Cl 2.CH 3OH.4H 2O), respectively. The structures of 1 and 2 were characterized by single-crystal X-ray diffraction analysis. Both compounds adopt a M 4L 2-type tetragonal metalloprismatic cage structure, [Ag 4(mu 4-L) 2] (4+), with strong intramolecular silver-silver contacts. Compound 1 is a discrete species, while compound 2 is a novel infinite chainlike supramolecular array involving silver metal strings assembled from a [Ag 4(mu 4-L) 2] (4+) nanocage and silver linkages. Thermogravimetric analyses of 1. (1)/ 2CH 2Cl 2.2CH 3OH and 2.CH 3OH.4H 2O indicate that the Ag 4L 2-cage structures of 1 and 2 both are thermally stable up to 330 degrees C. Results from an in situ (1)H NMR study of AgNO 3 and TDMBim in different molar ratios unambiguously revealed the successive self-organization process, in which self-organization of the molecular cage takes place initially followed by crystallization of the corresponding supramolecular arrays with silver metal strings.     

Unusual reactions of [{micro-(phthalazine-N2:N3)}Fe2(micro-CO)(CO)6] with organolithium reagents. A novel coordination mode of 1,2-diazane diiron carbonyl compounds

[{Micro-(phthalazine-N2:N3)}Fe2(micro-CO)(CO)6](1) reacts with organolithium reagents, RLi (R = CH3, C6H5, p-CH3C6H4, p-CH3OC6H4, p-CF3C6H4, p-C6H5C6H4), followed by treatment with Me3SiCl to give the novel diiron carbonyl complexes with a saturated N-N six-membered diazane ring ligand, [{C6H4CH(R)NNCH2}Fe2(C=O)(CO)6](2, R = CH3; 3, R = C6H5; 4, R =p-CH3C6H4; 5, R =p-CH3OC6H4; 6, R =p-CF3C6H4; 7, R =p-C6H5C6H4). Compounds 4 and 5 were treated with [(NH4)2Ce(NO3)6] to afford the aryl-substituted phthalazine-coordinated diiron carbonyl compounds [(micro-{1-(p-CH3C6H4)-phthalazine-N2:N3})Fe2(micro-CO)(CO)6](8) and [(micro-{1-(p-CH3OC6H4)-phthalazine-N2:N3})Fe2(micro-CO)(CO)6](9), respectively. The structures of complexes 4 and 9 have been established by X-ray diffraction studies.     

Tetranuclear copper(II) complexes bridged by alpha-D-glucose-1-phosphate and incorporation of sugar acids through the Cu4 core structural changes

Tetranuclear copper(II) complexes containing alpha-D-glucose-1-phosphate (alpha-D-Glc-1P), [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(bpy)4(H2O)2]X3 [X = NO3 (1a), Cl (1b), Br (1c)], and [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(phen)4(H2O)2](NO3)3 (2) were prepared by reacting the copper(II) salt with Na2[alpha-D-Glc-1P] in the presence of diimine ancillary ligands, and the structure of 2 was characterized by X-ray crystallography to comprise four {Cu(phen)}2+ fragments connected by the two sugar phosphate dianions in 1,3-O,O' and 1,1-O mu4-bridging fashion as well as a mu-hydroxo anion. The crystal structure of 2 involves two chemically independent complex cations in which the C2 enantiomeric structure for the trapezoidal tetracopper(II) framework is switched according to the orientation of the alpha-D-glucopyranosyl moieties. Temperature-dependent magnetic susceptibility data of 1a indicated that antiferromagnetic spin coupling is operative between the two metal ions joined by the hydroxo bridge (J = -52 cm(-1)) while antiferromagnetic interaction through the Cu-O-Cu sugar phosphate bridges is weak (J = -13 cm(-1)). Complex 1a readily reacted with carboxylic acids to afford the tetranuclear copper(II) complexes, [Cu4{mu-(alpha-D-Glc-1P)}2(mu-CA)2(bpy)4](NO3)2 [CA = CH3COO (3), o-C6H4(COO)(COOH) (4)]. Reactions with m-phenylenediacetic acid [m-C6H4(CH2COOH)2] also gave the discrete tetracopper(II) cationic complex [Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)(CH2COOH))2(bpy)4](NO3)2 (5a) as well as the cluster polymer formulated as {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)2)(bpy)4](NO3)2}n (5b). The tetracopper structure of 1a is converted into a symmetrical rectangular core in complexes 3, 4, and 5b, where the hydroxo bridge is dissociated and, instead, two carboxylate anions bridge another pair of Cu(II) ions in a 1,1-O monodentate fashion. The similar reactions were applied to incorporate sugar acids onto the tetranuclear copper(II) centers. Reactions of 1a with delta-D-gluconolactone, D-glucuronic acid, or D-glucaric acid in dimethylformamide resulted in the formation of discrete tetracopper complexes with sugar acids, [Cu4{mu-(alpha-D-Glc-1P)}2(mu-SA)2(bpy)4](NO3)2 [SA = D-gluconate (6), D-glucuronate (7), D-glucarateH (8a)]. The structures of 6 and 7 were determined by X-ray crystallography to be almost identical with that of 3 with additional chelating coordination of the C-2 hydroxyl group of D-gluconate moieties (6) or the C-5 cyclic O atom of D-glucuronate units (7). Those with D-glucaric acid and D-lactobionic acid afforded chiral one-dimensional polymers, {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-D-glucarate)(bpy)4](NO3)2}n (8b) and {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-D-lactobionate)(bpy)4(H2O)2](NO3)3}n (9), respectively, in which the D-Glc-1P-bridged tetracopper(II) units are connected by sugar acid moieties through the C-1 and C-6 carboxylate O atoms in 8b and the C-1 carboxylate and C-6 alkoxy O atoms of the gluconate chain in 9. When complex 7 containing d-glucuronate moieties was heated in water, the mononuclear copper(II) complex with 2-dihydroxy malonate, [Cu(mu-O2CC(OH)2CO2)(bpy)] (10), and the dicopper(II) complex with oxalate, [Cu2(mu-C2O4)(bpy)2(H2O)2](NO3)2 (11), were obtained as a result of oxidative degradation of the carbohydrates through C-C bond cleavage reactions.     

Photoinduced magnetization with a high curie temperature and a large coercive field in a cyano-bridged cobalt-tungstate bimetallic assembly

A three-dimensional magnetic material [{CoII(pyrimidine)(H2O)}2{CoII(H2O)2}{WV(CN)8}2](pyrimidine)2. 2H2O is prepared. This compound exhibits a charge-transfer-induced spin transition with a large thermal hysteresis loop of 90 K. Irradiating with light causes the low-temperature phase to exhibit a spontaneous magnetization with a Curie temperature of 40 K and a magnetic hysteresis loop with a coercive field of 12 000 G, which is the highest value reported for a photomagnet. The observed photoinduced magnetization is due to the charge-transfer phase transition from the {CoIIhs(S = 3/2)}{CoIIIls(S = 0)}2-NC-{WIV(S = 0)}2 phase to the {CoIIhs(S = 3/2)}3-NC-{WV(S = 1/2)}2 phase by the irradiation.     

Copper-complex-linked polytungsto-bismuthate (-antimonite) chain containing sandwich Cu(II) ions partially modified with imidazole ligand

Two sandwich-type complexes Na9n(Cu(im)4(H2O)2)1.5n(Cu(im)4(H2O))n[{Cu(im)4}{Na(H2O)2}3{Cu3(im)2(H2O)}(XW9O33)2]2n .(xH2O)n (im=imidazole, X=Bi (1), Sb(2), x=42.5 (1), 40 (2)) have been synthesized and structurally characterized. Basic frameworks of 1 and 2 are built from sandwich-type [{Na(H2O) 2} 3{Cu3(im)2(H2O)}(XW9O33)2](9-) (X=Bi or Sb) anions and [Cu(im) 4](2+) cations. The Cu(2+) and Na(+) ions in the central belt are coordinated by alpha-[XW9O33](9-) units, im, and water molecules to form {CuO4(im)}, {CuO4(H2O)}, and {NaO4(H2O)2} groups in which Cu (2+) ions are partially modified with im ligands. These groups connect alternately forming a six-membered ring including six alpha-[XW9O 33](9-) units. Neighboring anions are further linked by [Cu(im) 4](2+) cations to display an unprecedented anionic chain, which is first observed in sandwich-type tungsto-bismuthate (-antimonite) system. Two kinds of isolated copper complexes and sodium ions are located as counterions, which cause three-dimensional packings of 1 and 2 to present interesting cage structures. The magnetic properties for 1 and 2 both indicate dominant antiferromagnetic interactions among trinuclear Cu(II) clusters.     

The preparation and characterisation of hetero- and homobimetallic complexes containing bridging naphthalene-1,8-dithiolato ligands

Homo- and heterobimetallic complexes of the form [(PPh(3))(2)(mu(2)-1,8-S(2)-nap){ML(n)}] (in which (1,8-S(2)-nap)=naphtho-1,8-dithiolate and {ML(n)}={PtCl(2)} (1), {PtClMe} (2), {PtClPh} (3), {PtMe(2)} (4), {PtIMe(3)} (5) and {Mo(CO)(4)} (6)) were obtained by the addition of [PtCl(2)(NCPh)(2)], [PtClMe(cod)] (cod=1,5-cyclooctadiene), [PtClPh(cod)], [PtMe(2)(cod)], [{PtIMe(3)}(4)] and [Mo(CO)(4)(nbd)] (nbd=norbornadiene), respectively, to [Pt(PPh(3))(2)(1,8-S(2)-nap)]. Synthesis of cationic complexes was achieved by the addition of one or two equivalents of a halide abstractor, Ag[BF(4)] or Ag[ClO(4)], to [{Pt(mu-Cl)(mu-eta(2):eta(1)-C(3)H(5))}(4)], [{Pd(mu-Cl)(eta(3)-C(3)H(5))}(2)], [{IrCl(mu-Cl)(eta(5)-C(5)Me(5))}(2)] (in which C(5)Me(5)=Cp*=1,2,3,4,5-pentamethylcyclopentadienyl), [{RhCl(mu-Cl)(eta(5)-C(5)Me(5))}(2)], [PtCl(2)(PMe(2)Ph)(2)] and [{Rh(mu-Cl)(cod)}(2)] to give the appropriate coordinatively unsaturated species that, upon treatment with [(PPh(3))(2)Pt(1,8-S(2)-nap)], gave complexes of the form [(PPh(3))(2)(mu(2)-1,8-S(2)-nap){ML(n)}][X] (in which {ML(n)}[X]={Pt(eta(3)-C(3)H(5))}[ClO(4)] (7), {Pd(eta(3)-C(3)H(5))}[ClO(4)] (8), {IrCl(eta(5)-C(5)Me(5))}[ClO(4)] (9), {RhCl(eta(5)-C(5)Me(5))}[BF(4)] (10), {Pt(PMe(2)Ph)(2)}[ClO(4)](2) (11), {Rh(cod)}[ClO(4)] (12); the carbonyl complex {Rh(CO)(2)}[ClO(4)] (13) was formed by bubbling gaseous CO through a solution of 12. In all cases the naphtho-1,8-dithiolate ligand acts as a bridge between two metal centres to give a four-membered PtMS(2) ring (M=transition metal). All compounds were characterised spectroscopically. The X-ray structures of 5, 6, 7, 8, 10 and 12 reveal a binuclear PtMS(2) core with PtM distances ranging from 2.9630(8)-3.438(1) A for 8 and 5, respectively. The napS(2) mean plane is tilted with respect to the PtP(2)S(2) coordination plane, with dihedral angles in the range 49.7-76.1 degrees and the degree of tilting being related to the PtM distance and the coordination number of M. The sum of the Pt(1)coordination plane/napS(2) angle, a, and the Pt(1)coordination plane/M(2)coordination plane angle, b, a+b, is close to 120 degrees in nearly all cases. This suggests that electronic effects play a significant role in these binuclear systems.     

Group 13 organoderivatives supported on a metallic oxide model

The [{TiCp*(micro-O)}3(mu3-CH)] (1) metalloligand, (Cp* = eta5-C5Me5), coordinates in a 1:1 ratio to [AlMe3] or 9-BBN to give [{Me3Al}{(mu3-O)(mu-O)2(TiCp)2(TiCp)3(mu3-CH)}](2) or [{(C8H14)B}(mu-H) {(mu3-O)(mu-O)2(TiCp*)3(mu3-CH)}](4), respectively, partial hydrolysis of 2 leads to the new hydroxo-aluminium derivative [{MeAl} {(mu-OH)(mu3-O)}2{(mu-O)2(TiCp*)3-(mu3-CH)}2](3).