Synthesis, structures, and magnetism of copper(II) and manganese(II) coordination polymers with azide and pyridylbenzoates

Three transition-metal coordination polymers with azide and/or carboxylate bridges have been synthesized from 4-(3-pyridyl)benzoic acid (4,3-Hpybz) and 4-(4-pyridyl)benzoic acid (4,4-Hpybz) and characterized by X-ray crystallography and magnetic measurements. Compound 1, [Cu(4,3-pybz)(N(3))](n), consists of 2D coordination networks in which the uniform chains with (μ-EO-N(3))(μ-COO) double bridges are cross-linked by the 4,3-pybz ligands. Compound 2, [Cu(2)(4,4-pybz)(3)(N(3))](n)·3nH(2)O, consists of 2-fold interpenetrated 3D coordination networks with the α-Po topology, in which the six-connected dinuclear motifs with mixed (μ-EO-N(3))(μ-COO)(2) (EO = end-on) triple bridges are linked by the 4,4-pybz spacers. Compound 3, [Mn(4,4-pybz)(N(3))(H(2)O)(2)](n), contains 2D manganese(II) coordination networks in which the chains with single μ-EE-N(3) bridges (EE = end-to-end) are interlinked by the 4,4-pybz ligands, and the structure also features a 2D hydrogen-bonded network in which Mn(II) ions are linked by double triatomic bridges, (μ-EE-N(3))(O-H···N) and (O-H···O)(2). Magnetic studies indicated that the mixed azide and carboxylate bridges in 1 and 2 induce ferromagnetic coupling between Cu(II) ions and that 3 features antiferromagnetic coupling through the EE-azide bridge. In addition, compound 1 exhibits antiferromagnetic ordering below 6.2 K and behaves as a field-induced metamagnet. A magnetostructural survey indicates a general trend that the ferromagnetic coupling through the mixed bridges decreases as the Cu-N-Cu angle increases.     

The chemistry of cadmium-thiocarboxylate derivatives: synthesis, structural features, and application as single source precursors for ternary sulfides

Novel heterobimetallic complexes [(PPh(3))(2)Cu(μ-SCOPh)(2)Cd(SCOPh)] (2a), [(PPh(3))(2)Cu(μ-SCOth)(2)Cd(SCOth)] (2b), [(PPh(3))(2)Ag(μ-SCOth)(2)Cd(SCOth)] (3a), [(PPh(3))(2)Ag(μ-SCOth)(2)Cd(H(2)O)(SCOth)] (3b), [(PPh(3))(2)Ag(μ-SCOPh)(2)Cd(SCOPh)] (3c), and a bimetallic complex [PPh(3)Cd(μ-SCOth)SCOth](2)·CH(2)Cl(2) (5) (th = thiophene) were prepared and characterized by single crystal X-ray diffraction analysis. A coordination polymer [Cd(SCOPh)(2)](n) (4) has also been characterized structurally that exhibited metal-like electrical conductivity. The heterobimetallic complexes on pyrolyzing under controlled conditions yielded ternary sulfides of composition CuCd(7)S(8), CuCd(10)S(11), Ag(2)Cd(8)S(9), and Ag(2)Cd(5)S(6), which have been characterized by SEM-EDX and X-ray diffractometry. Photophysical properties and electrical conductivities of the sulfides have also been studied.     

Dinuclear silver(I) complexes for the design of metal-ligand networks based on triazolopyrimidines

Silver(I) coordination complexes with the versatile and biomimetic ligands 1,2,4-triazolo[1,5-a]pyrimidine (tp), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) and 7-amine-1,2,4-triazolo[1,5-a]pyrimidine (7atp) all feature dinuclear [Ag(2)(μ-tp)(2)](2+) building units (where tp is a triazolopyrimidine derivative), which are the preferred motif, independently of the counter-anion used. According to AIM (atoms in molecules) and ELF (electron localization function) analyses, this fact is due to the great stability of these dinuclear species. The complexes structures range from the dinuclear entities [Ag(2)(μ-tp)(2)(CH(3)CN)(4)](BF(4))(2) (1), [Ag(2)(μ-tp)(2)(CH(3)CN)(4)](ClO(4))(2) (2), [Ag(2)(μ-7atp)(2)](ClO(4))(2) (3) and [Ag(2)(μ-dmtp)(2)(CH(3)CN)](PF(6))(ClO(4)) (4) over the 1D polymer chain [Ag(2)(μ-CF(3)SO(3))(2)(μ-dmtp)(2)](n) (5) to the 3D net {[Ag(2)(μ(3)-tp)(2)](PF(6))(2)·～6H(2)O}(n) (6) with NbO topology.     

Variations of structures and gas sorption properties of three coordination polymers induced by fluorine atom positions in azamacrocyclic ligands

Three coordination polymers of [(NiL(1))(3)(TCBA)(2)] (1), [(NiL(2))(3)(TCBA)(2)] (2), and [(NiL(3))(3)(TCBA)(2)] (3) have been constructed using azamacrocyclic Ni(II) complexes [NiL(1)](ClO(4))(2)/[NiL(2)](ClO(4))(2)/[NiL(3)](ClO(4))(2) and TCBA(3-) as building blocks (L(1) = 3,10-bis(2-fluorobenzyl)-1,3,5,8,10,12-hexaazacyclotetradecane; L(2) = 3,10-bis(3-fluorobenzyl)-1,3,5,8,10,12-hexaazacyclotetradecane; L(3) = 3,10-bis(4-fluorobenzyl)-1,3,5,8,10,12- hexaazacyclotetradecane; TCBA(3-) = tri(4-carboxy-benzyl)amine). The results of X-ray diffraction analyses reveal that 1 shows a 2D Borromean structure, while 2 and 3 form 2D layer structures, and the 2D layers are further connected by the interlayer F···F interactions in 2 and C-H···F interactions in 3 to generate two 3D porous structures with 1D fluorine atoms interspersed channels. Gas sorption measurements illustrate that the desolvated 2 and 3can adsorb N(2), H(2), and CO(2) molecules. The different structures and gas sorption properties of 1 and 2/3 are mainly induced by the different positions of F atoms in azamacrocycle ligands.     

Reactions of cadmium(II) nitrate with 4-(trimethylammonio)benzenethiolate in the presence of N-donor ligands

Reactions of Cd(NO(3))(2)·4H(2)O with TabHPF(6) (TabH = 4-(trimethylammonio)benzenethiol) and Et(3)N in the presence of NH(4)SCN and five other N-donor ligands such as 2,2'-bipyridine (2,2'-bipy), phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (2,9-dmphen), 2,6-bis(pyrazd-3-yl)pyridine (bppy) and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (bdmppy) gave rise to a family of Cd(II)/thiolate complexes of N-donor ligands, {[Cd(2)(μ-Tab)(4)(NCS)(2)](NO(3))(2)·MeOH}(n) (1), [Cd(2)(μ-Tab)(2)(L)(4)](PF(6))(4) (2: L = 2,2'-bipy; 3: L = phen), [Cd(Tab)(2)(L)](PF(6))(2) (4: L = 2,9-dmphen; 5: L = bppy), and [Cd(2)(μ-Tab)(2)(Tab)(2)(bdmppy)](2)(PF(6))(8)·H(2)O (6·H(2)O). These compounds were characterized by elemental analysis, IR spectra, UV-Vis spectra, (1)H NMR, electrospray ionization (ESI) mass spectra and single-crystal X-ray diffraction. For 1, each [Cd(NCS)](+) fragment is connected to its equivalents via a pair of Tab bridges to a one-dimensional chain. For 2 and 3, two [Cd(2,2'-bipy)(2)](2+) or [Cd(phen)(2)](2+) units are linked by a pair of Tab bridges to form a cationic dimeric structure. The Cd atom in [Cd(Tab)(2)(L)](2+) dication of 4 or 5 is coordinated by two Tab ligands and chelated by two N atoms from 2,9-dmphen (4) or three N atoms from bppy (5), forming a distorted tetrahedral (4) or trigonal bipyramidal (5) coordination geometry. For 6, each of two [Cd(Tab)(bdmppy)] fragments is linked to one [(Tab)Cd(μ-Tab)(2)Cd(Tab)] fragment via two Tab bridges to generate a unique cationic zigzag tetrameric structure where the Cd centers take a tetrahedral or a trigonal bipyramidal coordination geometry. The results may provide an interesting insight into mimicking the coordination spheres of the Cd(II) sites of metallothioneins and their interactions with various N-donor ligands encountered in nature.     

Formation of a strandlike polycatenane of icosahedral cages for reversible one-dimensional encapsulation of guests

Self-assembly of ZnCl(2) and the ligand 2,4,6-tris(4-pyridyl)pyridine (pytpy) in solution yields [(ZnCl(2))(12)(pytpy)(8)](n)·xCHCl(3), a polycatenane consisting of a strand of mechanically interlocking icosahedral cages with an inner volume of more than 2700 ?(3). This can be used to encapsulate guest molecules of appropriate size and polarity, forming a precisely defined three-dimensional array of solvent nanodroplets within the crystalline framework. The dynamic composition of these droplets was studied using quantitative solid-state NMR spectroscopy.     

Coordination induced fluorescence enhancement and construction of a Zn3 constellation through hydrolysis of ligand imine arms

The phenoxido and alkoxido bridged neutral Zn(3) complex [Zn(3)(μ-H(2)bemp)(2)(μ(3)-emp)(2)] (1), with an angular Zn(3)(μ-OPh)(2)(μ-OEt)(2) core and capping nitrogen donors, was synthesized via simultaneous chelation-cum-bridging of the parent and hydrolysed ligands. Zinc(II) coordination triggered the solution phase imine (C=N) bond hydrolysis of H(3)bemp (2,6-bis-[(2-hydroxyethylimino)methyl]-4-methylphenol) and yielded the unexpected angular trinuclear Zn(II) complex 1, having structural similarity with the Zn(3) active site of P1 nuclease. H(3)bemp also displays a zinc(II) selective chelation-enhanced fluorescence response from strong metal ion coordination. Complexation of zinc(II) with H(3)bpmp (2,6-bis-[(3-hydroxypropylimino)methyl]-4-methylphenol), a close analogue of H(3)bemp, instead provides only mononuclear [Zn(H(2)bpmpH(N))(2)](ClO(4))(2)·2H(2)O (2·2H(2)O) (H(N) is the proton attached to an imine nitrogen atom) of two zwitterionic ligands, generated through a kind of coordination driven acid-base reaction, without showing any aggregation reaction. As the sole metal-organic precursor, both the complexes under pyrolytic conditions give ZnO nano structures of two morphologies.     

A new class of thermo- and solvatochromic metal-organic frameworks based on 4-(pyridin-4-yl)benzoic acid

Using 4-(pyridin-4-yl)benzoic acid, 44pba (1) as a ligand, two new metal-coordination networks [Co(4)(44pba)(8)](n)·[(DMF)(3)·(EtOH)(0.25)·(H(2)O)(4)](n) (2) and [Ni(4)(44pba)(8)](n)·[(DMF)(3.5)·(EtOH)·(H(2)O)(1.5)](n) (3) were synthesized by solvothermal methods and structurally characterized. Compounds 2 and 3 are isostructural but differ in their solvent content. Each is a 2D-network which forms a spiral parallel to [001], giving rise to three distinct large channels, accounting for some 47% of the unit cell volume. Both 2 and 3 display water-induced phase transformations with chromotropism, which has been confirmed by TGA and XRPD analysis. Solvatochromism in 2 is also evident with crystals exhibiting a range of colours depending on the solvent included. This phenomenon has been characterized using TGA, XRPD and UV-vis spectrophotometry.     

New family of silver(I) complexes based on hydroxyl and carboxyl groups decorated arenesulfonic acid: syntheses, structures, and luminescent properties

Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates, (NH(4))·[Ag(HL1)(NH(3))(H(2)O)] (1), {(NH(4))·[Ag(3)(HL1)(2)(NH(3))(H(2)O)]}(n) (2), [Ag(2)(HL1)(H(2)O)(2)](n) (3), [Ag(2)(HL2)(NH(3))(2)]·H(2)O (4), [Ag(H(2)L2)(H(2)O)](n) (5), [Ag(2)(HL2)](n) (6), [Ag(3)(L3)(NH(3))(3)](n) (7), [Ag(2)(HL3)](n) (8), and [Ag(6)(L3)(2)(H(2)O)(3)](n) (9) (H(3)L1 = 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid, H(3)L2 = 2-hydroxyl-4-carboxylbenzenesulfonic acid, H(3)L3 = 2-hydroxyl-5-carboxylbenzenesulfonic acid), which are characterized by elemental analysis, IR, TGA, PL, and single-crystal X-ray diffraction. Complex 1 is 3-D supramolecular network extended by [Ag(HL1)(NH(3))(H(2)O)](-) anions and NH(4)(+) cations. Complex 2 exhibits 3-D host-guest framework which encapsulates ammonium cations as guests. Complex 3 presents 2-D layer structure constructed from 1-D tape of sulfonate-bridged Ag1 dimers linked by [(Ag2)(2)(COO)(2)] binuclear units. Complex 4 exhibits 3-D hydrogen-bonding host-guest network which encapsulates water molecules as guests. Complex 5 shows 3-D hybrid framework constructed from organic linker bridged 1-D Ag-O-S chains while complex 6 is 3-D pillared layered framework with the inorganic substructure constructing from the Ag2 polyhedral chains interlinked by Ag1 dimers and sulfonate tetrahedra. The hybrid 3-D framework of complex 7 is formed by L3(-) trianions bridging short trisilver(I) sticks and silver(I) chains. Complex 8 also presents 3-D pillared layered framework, and the inorganic layer substructure is formed by the sulfonate tetrahedrons bridging [(Ag1O(4))(2)(Ag2O(5))(2)](∞) motifs. Complex 9 represents the first silver-based metal-polyhedral framework containing four kinds of coordination spheres with low coordination numbers. The structural diversities and evolutions can be attributed to the synthetic methods, different ligands and coordination modes of the three functional groups, that is, sulfonate, hydroxyl and carboxyl groups. The luminescent properties of the nine complexes have also been investigated at room temperature, especially, complex 1 presents excellent blue luminescence and can sensitize Tb(III) ion to exhibit characteristic green emission.     

Different effects of a cotemplate and [(transition-metal)(1,10-phenanthroline)(m)]2+ (m = 1-3) complex cations on the self-assembly of a series of hybrid selenidostannates showing combined optical properties of organic and inorganic components

1,10-Phenanthroline (phen) and monoprotonated methylamine molecules were used as a novel cotemplate to direct the formation of a new inorganic-organic hybrid selenidostannate, (CH(3)NH(3))(4)(Sn(2)Se(6))·6phen (1); while the utilization of three types of transition-metal (TM) phen complex cations with the TM/phen ration of 1:1, 1:2, and 1:3 as structure directors affords {[Mn(phen)(2)](2)(μ(2)-Sn(2)Se(6))}·H(2)O (2a), {[Fe(phen)(2)](2)(μ(2)-Sn(2)Se(6))} (2b), {[Mn(phen)](2)(μ(4)-Sn(2)Se(6))}(n) (3), {[Mn(phen)(2)](Sn(2)Se(5))}(n) (4), and [Fe(phen)(3)](n)(Sn(3)Se(7))(n)·1.25nH(2)O (5). These compounds show diverse structures with the selenidostannate anions varying from discrete, μ(2)- and μ(4)- (Sn(2)Se(6))(4-) anions, to one-dimensional (1-D) (1)(∞)(Sn(2)Se(5)(2-)) anionic chains, and two-dimensional (2-D) extended (2)(∞)(Sn(3)Se(7)(2-)) anionic layers, demonstrating different structure-directing abilities of the cotemplate and the three types of TM phen complex cations. This work clearly indicates that the approach of modifying the number of the free coordination sites of unsaturated TM phen complex cations is very exciting as a way to synthesize novel hybrid chalcogenidometalates. Of particular interest, the present compounds exhibit interesting optical properties that reflect the combined effects of both photoluminescence-active organic components and semiconducting inorganic chalcogenidometalate anionic networks.     

Synthesis, crystal structures and magnetic properties of dinuclear copper(II) compounds with NNO tridentate Schiff base ligands and bridging aliphatic diamine and aromatic diimine linkers

The synthesis and the characterization of new dinuclear copper(II) compounds of general formula [(L(a-d))(2)Cu(2)(μ-N-N)](ClO(4))(2) (1-6) with either neutral aliphatic diamine (N-N = piperazine, pip) or aromatic diimine (N-N = 4,4'-bipyridine, 4,4'-bipy) linker are reported. The copper ligands L(-) (L(a-) = (E)-2-((2-aminoethylimino)methyl)phenolate, L(b-) = (E)-2-((2-aminopropylimino)methyl)-phenolate, L(c-) = (E)-2-((2-aminoethylimino)methyl)4-nitrophenolate, L(d-) = (E)-2-((2-aminoethylimino)methyl)4-methoxyphenolate) are NNO tridentate Schiff bases derived from the monocondensation of a substituted salicylaldehyde 5-G-salH (G = NO(2), H, OMe) with ethylenediamine, en, or 1,3-propylenediamine, tn. The crystal structures of compounds [(L(a))(2)Cu(2)(MeOH)(2)(μ-4,4'-bipy)](ClO(4))(2) (1·2MeOH), [(L(b))(2)Cu(2)(MeOH)(2)(μ-4,4'-bipy)](ClO(4))(2) (2·2MeOH), [(L(d))(2)Cu(2)(μ-4,4'-bipy)](ClO(4))(2) (4), [(L(a))(2)Cu(2)(μ-pip)](ClO(4))(2) (5) and [(L(b))(2)Cu(2)(μ-pip)](ClO(4))(2) (6) have been determined, revealing the preferred (e-e)-chair conformation of the bridging piperazine in compounds 5 and 6. The presence of hydrogen-bond-mediated intermolecular interactions, that involve the methanol molecules, yields dimers of dinuclear units for 1·2MeOH, and infinite zig-zag chains for 2·2MeOH. The temperature dependences of the magnetic susceptibilities χ(M)(T) for all compounds were measured, indicating the presence of antiferromagnetic Cu-Cu exchange. For the compounds 2-4 with 4,4'-bipy, the coupling constants J are around -1 cm(-1), while in compound 1 no interaction could be detected. The compounds 5 and 6 with piperazine display higher Cu-Cu magnetic interactions through the σ-bonding backbone of the bridging molecule, with J around -8 cm(-1), and the coupling is favoured by the (e-e)-chair conformation of the diamine ring. The non-aromatic, but shorter, linker piperazine gives rise to stronger Cu-Cu antiferromagnetic couplings than the aromatic, but longer, 4,4'-bipyridine. In the latter case, the rotation along the C-C bond between the two pyridyl rings and the consequent non co-planarity of the two copper coordination planes play an important role in determining the magnetic communication. EPR studies reveal that the dinuclear species are not stable in solution, yielding the solvated [(L)Cu(MeOH)](+) and the mononuclear [(L)Cu(N-N)](+) species; it appears that the limited solubility of the dinuclear compounds is responsible for their isolation in the solid state.     

A cubic, 12-connected, microporous metal-organometallic phosphate framework sustained by truncated tetrahedral nodes

A rare example of a microporous metal-organic phosphate, [Co(12)(L)(6)(μ(3)-PO(4))(4)(μ(3)-F)(4)(μ-H(2)O)(6)][NO(3)](2) (1), is synthesized by the reaction of a [(η(5)-C(5)H(5))Fe(II)](+)-functionalized terephthalate ligand with Co(NO(3))(2)·6H(2)O and phosphate and fluoride ions generated from the in situ hydrolysis of hexafluorophosphate. 1 is a cubic, 12-connected, face-centered cubic framework sustained by the linear connection of unprecedented, dodecanuclear truncated tetrahedral coordination clusters.     

Syntheses, structures and properties of a series of non-heme alkoxide-Fe(III) complexes of a benzimidazolyl-rich ligand as models for lipoxygenase

The treatment of Fe(ClO(4))(2)·6H(2)O or Fe(ClO(4))(3)·9H(2)O with a benzimidazolyl-rich ligand, N,N,N',N'-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-1,2-ethanediamine (medtb) in alcohol/MeCN gives a mononuclear ferrous complex, [Fe(II)(medtb)](ClO(4))(2)·?CH(3)CN·?CH(3)OH (1), and four non-heme alkoxide-iron(III) complexes, [Fe(III)(OMe)(medtb)](ClO(4))(2)·H(2)O (2, alcohol = MeOH), [Fe(III)(OEt)(Hmedtb)](ClO(4))(3)·CH(3)CN (3, alcohol = EtOH), [Fe(III)(O(n)Pr)(Hmedtb)](ClO(4))(3)·(n)PrOH·2CH(3)CN (4, alcohol = n-PrOH), and [Fe(III)(O(n)Bu)(Hmedtb)](ClO(4))(3)·3CH(3)CN·H(2)O (5, alcohol = n-BuOH), respectively. The alkoxide-iron(III) complexes all show 1) a Fe(III)-OR center (R = Me, 2; Et, 3; (n)Pr, 4; (n)Bu, 5) with the Fe-O bond distances in the range of 1.781-1.816 ?, and 2) a yellow color and an intense electronic transition around 370 nm. The alkoxide-iron(III) complexes can be reduced by organic compounds with a cis,cis-1,4-diene moiety via the hydrogen atom abstraction reaction.     

Novel eclipsed 2D cadmium(II) coordination polymers with open-channel structure constructed from terephthalate and 3-(2-pyridyl)pyrazole: crystal structures, emission properties, and inclusion of guest molecules

Five new eclipsed two-dimensional (2D) coordination polymers, [[Cd(2)(TPT)(2)L(2)](GM(1))(3/2)(H(2)O)](infinity) (1) (TPT = terephthalate, L = 3-(2-pyridyl)pyrazole, GM(1) = terephthalic acid), [[Cd(TPT)L](GM(2))(H(2)O)(2)]( infinity) (2) (GM(2) = L = 3-(2-pyridyl)pyrazole), [[Cd(TPT)L](GM(3))(1/2)(H(2)O)](infinity) (3) (GM(3) = mesitylene), [[Cd(4)(TPT)(4)L(4)](GM(4))(7/2)](infinity) (4) (GM(4) = tetramethylbenzene), and [[Cd(TPT)L](GM(5))(1/2)](infinity) (5) (GM(5) = naphthalene), have been synthesized and characterized by X-ray diffraction. All the five complexes take the similar eclipsed 2D open-channel framework with different guest molecules included in the cavities of their channels. TGA analysis indicates that the eclipsed open-channel frameworks are thermally stable up to 300 degrees C. The porous property of the 2D framework of 5 was also investigated by the XRPD technique, which indicated that the guest molecules included in the open-channel frameworks are removable and the framework is maintained after the removal of the guest molecules. Moreover, complexes 1-5 also display strong blue emission in the solid state.     

Alkali metal and zinc complexes of a bridging 2,5-diamino-1,4-benzoquinonediimine ligand

Two alkali metal complexes of a bridging 2,5-diamino-1,4-benzoquinonediimine ligand (dipp-dabqdiH(2)), [(thf)(2)Li(μ-dipp-dabqdi)Li(thf)(2)] (1) and [(dme)(1.5)Na(μ-dipp-dabqdi)Na(dme)(1.5)](n) (2, dme = 1,2-dimethoxyethane), have been synthesized by the reaction of dipp-dabqdiH(2) with Li(n)Bu or sodium metal. In addition, treatment of 1,2,4,5-tetrakis(2,6-diisopropylamino)benzene (dipp-tabH(4)) with potassium metal in dme afforded the complex [(dme)(2)K(μ-dipp-tabH(2))K(dme)(2)] (3). X-ray crystal diffraction analyses revealed that complexes 1 and 3 have dinuclear structures, while the sodium complex 2 aggregates to a one-dimensional polymer through bridging dme ligands. With increasing ion radius, the coordination number of the alkali metal (Li, Na, and K) increases from four to five to six, while the coordination geometry changes from distorted tetrahedral to square pyramidal and further to octahedral in 1, 2, and 3, respectively. The salt metathesis reactions of 1 and 2 with anhydrous ZnCl(2) yielded the ion-contacted zinc complexes [(thf)(3)Li(μ-Cl)ClZn(μ-dipp-dabqdi)ZnCl(μ-Cl)Li(thf)(3)] (4), [(dme)(2)Li(μ-Cl)ClZn(μ-dippdabqdi)ZnCl(μ-Cl)Li(dme)(2)] (5), and [(dme)(2)Na(μ-Cl)(2)Zn(μ-dipp-dabqdi)Zn(μ-Cl)(2)Na(dme)(2)] (6), respectively. The ligand exists as the dianionic form in compounds 1-6 upon double deprotonation, and a complete electronic delocalization (except for 3) of the quinonoid π-system is observed between the metal centers over the two N═C-C═C-N halves of the ligand. The electronic structures of the complexes were studied by density functional theory (DFT) computations.     

Hydrido phosphanido bridged polynuclear complexes obtained by protonation of a phosphinito bridged Pt(I) complex with HBF4 and HF

The protonation of the phosphinito-bridged Pt(I) complex [(PHCy(2))Pt(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(PHCy(2))](Pt-Pt) (1) by aqueous HBF(4) or hydrofluoric acid leads selectively to the hydrido-bridged solvento species syn-[(PHCy(2))(H(2)O)Pt(μ-PCy(2))(μ-H)Pt(PHCy(2)){κP-P(OH)Cy(2)}](Y)(2)(Pt-Pt) ([2-H(2)O]Y(2)) {Y = BF(4), F(HF)(n)} when an excess of acid was used. On standing in halogenated solvents, complex [2-H(2)O](BF(4))(2) undergoes a slow but complete isomerization to [(PHCy(2))(2)Pt(μ-PCy(2))(μ-H)Pt{κP-P(OH)Cy(2)}(H(2)O)](BF(4))(2)(Pt-Pt) ([4-H(2)O][BF(4)](2)) having the P(OH)Cy(2) ligand trans to the hydride. The water molecule coordinated to platinum in [2-H(2)O][BF(4)](2) is readily replaced by halides, nitriles, and triphenylphosphane, and the acetonitrile complex [2-CH(3)CN][BF(4)](2) was characterized by XRD analysis. Solvento species other than aqua complexes, such as [2-acetone-d(6)](2+) or [2-CD(2)Cl(2)](2+) were obtained in solution by the reaction of excess etherate HBF(4) with 1 in the relevant solvent. The complex [2-H(2)O](Y)(2) [Y = F(HF)(n)] spontaneously isomerizes into the terminal hydrido complexes [(PHCy(2))Pt(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(H)(PHCy(2))](Y)(Pt-Pt) ([6](Y)). In the presence of HF, complex [6](Y) transforms into the bis-phosphanido-bridged Pt(II) dinuclear complex [(PHCy(2))(H)Pt(μ-PCy(2))(2)Pt{κP-P(OH)Cy(2)}](Y)(Pt-Pt) ([7](Y)). When the reaction of 1 with HF was carried out with diluted hydrofluoric acid by allowing the HF to slowly diffuse into the dichloromethane solution, the main product was the linear 60e tetranuclear complex [(PHCy(2)){κP-P(O)Cy(2)}Pt(1)(μ-PCy(2))(μ-H)Pt(2)(μ-PCy(2))](2)(Pt(1)-Pt(2)) (8). Insoluble compound 8 is readily protonated by HBF(4) in dichloromethane, forming the more soluble species [(PHCy(2)){κP-P(OH)Cy(2)}Pt(1)(μ-PCy(2))(μ-H)Pt(2)(μ-PCy(2))](2)(BF(4))(2)(Pt(1)-Pt(2)) {[9][BF(4)](2)}. XRD analysis of [9][BF(4)](2)·2CH(2)Cl(2) shows that [9](2+) is comprised of four coplanar Pt atoms held together by four phosphanido and two hydrido bridges. Both XRD and NMR analyses indicate alternate intermetal distances with peripheral Pt-Pt bonds and a longer central Pt···Pt separation. DFT calculations allow tracing of the mechanistic pathways for the protonation of 1 by HBF(4) and HF and evaluation of their energetic aspects. Our results indicate that in both cases the protonation occurs through an initial proton transfer from the acid to the phosphinito oxygen, which then shuttles the incoming proton to the Pt-Pt bond. The different evolution of the reaction with HF, leading also to [6](Y) or 8, has been explained in terms of the peculiar behavior of the F(HF)(n)(-) anions and their strong basicity for n = 0 or 1.     

Solution and mechanochemical syntheses, and spectroscopic and structural studies in the silver(I) (bi-)carbonate: triphenylphosphine system

Syntheses of a number of adducts of silver(I) (bi-)carbonate with triphenylphosphine, both mechanochemically, and from solution, are described, together with their infra-red spectra, (31)P CP MAS NMR and crystal structures. Ag(HCO(3)):PPh(3) (1:4) has been isolated in the ionic form [Ag(PPh(3))(4)](HCO(3))·2EtOH·3H(2)O. Ag(2)CO(3):PPh(3) (1:4) forms a binuclear neutral molecule [(Ph(3)P)(2)Ag(O,μ-O'·CO)Ag(PPh(3))(2)](·2H(2)O), while Ag(HCO(3)):PPh(3) (1:2) has been isolated in both mononuclear and binuclear forms: [(Ph(3)P)(2)Ag(O(2)COH)] and [(Ph(3)P)(2)Ag(μ-O·CO·OH)(2)Ag(PPh(3))(2)] (both unsolvated). A more convenient method for the preparation of the previously reported copper(I) complex [(Ph(3)P)(2)Cu(HCO(3))] is also reported.     

Formation of tungstate-containing cluster ions by polyoxotungstate anions under matrix-assisted laser desorption/ionization conditions in the gas phase

The gas-phase studies of transition-metal oxides continue to attract interest as such oxides are being used as catalysts in various oxidation processes. In this paper, singly negatively charged heteropolyoxotungstate and isopolyoxotungstate ion clusters were produced from Keggin-type polyoxotungstates by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS). It was found that the ion series [(PO(3))(WO(3))(n)](-), [(WO(3))(n)](-) and [(OH)(WO(3))(n)](-) were the main fragment ions in the mass spectra and the matrix greatly influenced the resulting cluster ion abundances. [(PO(3))(WO(3))(3)](-), [(WO(3))(3)](-) and [(OH)(WO(3))(4)](-) were the most intense ions in each series when 2-(4-hydroxyphenylazo)benzoic acid was the matrix, whereas [(PO(3))(WO(3))(4)](-), [(WO(3))(6)](-) and [(OH)(WO(3))(4)](-) were the most intense when dithranol (DIT) was the matrix. In addition, a new kind of hybrid ion [W(2)C(14)H(7)O(8)](-) was produced through the reaction of DIT and [(OH)(WO(3))](-) in the plume of the gas phase. These results highlight the utility of the MALDI-FT method for obtaining novel ion clusters and also show the stability of these clusters.     

Manganese(II) coordination polymers with mixed azide and pyridylbenzoate N-oxide ligands: structures and magnetism

Two novel Mn(II) coordination polymers with azide and 4-(4-pyridyl)benzoic acid N-oxide (4,4-Hopybz) were synthesized and structurally and magnetically characterized. They are formulated as {[Mn(2)(4,4-opybz)(2)(N(3))(2)(H(2)O)(2)]·H(2)O}(n) (1) and {[Mn(4)(4,4-opybz)(5)(N(3))(H(2)O)(8)](N(3))(2)·2H(2)O}(n) (2). Compound 1 contains 2D coordination layers in which the infinite Mn(II) chains with alternating (μ-EO-N(3))(2)(μ-COO) (EO = end-on) and (μ-COO)(μ-O) bridges are interlinked by the backbones of the organic ligands. Compound 2 is a 3D metal-organic framework in which the unique linear tetranuclear clusters with (μ-EO-N(3))(μ-COO) and (μ-COO)(μ-O) bridges are cross-linked by organic backbones, and it represents a new example of the rare 8-connected self-catenated 3D net with the point symbol 4(16)·6(12). Magnetic analyses on the compounds have been performed in the classical-spin approximation, revealing that all the above-mentioned mixed bridging motifs induce weak antiferromagnetic interactions between Mn(II) ions.     

Anion binding by metallo-receptors of 5,5'-dicarbamate-2,2'-bipyridine ligands

Three 5,5'-dicarbamate-2,2'-bipyridine ligands (L = L(1)-L(3)) bearing ethyl, isopropyl or tert-butyl terminals, respectively, on the carbamate substituents were synthesized. Reaction of the ligands L with the transition metal ions M = Fe(2+), Cu(2+), Zn(2+) or Ru(2+) gave the complexes ML(n)X(2)·xG (1-12, n = 1-3; X = Cl, NO(3), ClO(4), BF(4), PF(6), ?SO(4); G = Et(2)O, DMSO, CH(3)OH, H(2)O), of which [Fe(L(2))(3)???SO(4)]·8.5H(2)O (2), [Fe(L(1))(3)???(BF(4))(2)]·2CH(3)OH (7), [Fe(L(2))(3)???(Et(2)O)(2)](BF(4))(2)·2CH(3)OH (8), [ZnCl(2)(L(1))][ZnCl(2)(L(1))(DMSO)]·2DMSO (9), [Zn(L(1))(3)???(NO(3))(2)]·2H(2)O (10), [Zn(L(2))(3)???(ClO(4))(Et(2)O)]ClO(4)·Et(2)O·2CH(3)OH·1.5H(2)O (11), and [Cu(L(1))(2)(DMSO)](ClO(4))(2)·2DMSO (12) were elucidated by single-crystal X-ray crystallography. In the complexes ML(n)X(2)·xG the metal ion is coordinated by n = 1, 2 or 3 chelating bipyridine moieties (with other anionic or solvent ligands for n = 1 and 2) depending on the transition metal and reaction conditions. Interestingly, the carbamate functionalities are involved in hydrogen bonding with various guests (anions or solvents), especially in the tris(chelate) complexes which feature the well-organized C(3)-clefts for effective guest inclusion. Moreover, the anion binding behavior of the pre-organized tris(chelate) complexes was investigated in solution by fluorescence titration using the emissive [RuL(3)](2+) moiety as a probe. The results show that fluorescent recognition of anion in solution can be achieved by the Ru(II) complexes which exhibit good selectivities for SO(4)(2-).