Tetraphosphinitoresorcinarene complexes: dynamic clusters with silver(I) and copper(I) halides

Silver(I) and copper(I) halide derivatives of several tetrakis(diphenylphosphinito)resorcinarene ligands are reported. The complexes [resorcinarene(O(2)CR)(4)(OPPh(2))(4)(M(5)X(5))], with resorcinarene = (PhCH(2)CH(2)CHC(6)H(2))(4), R = C(6)H(11), 4-C(6)H(4)Me, C(4)H(3)S, OCH(2)CCH, or OCH(2)Ph, M = Ag, X = Cl, Br, or I, M = Cu, and X = Cl or I, contain a crownlike [P(4)M(5)X(5)] metal halide cluster. These crown clusters were found to be dynamic in solution, as studied by variable-temperature NMR, and easily fragment to give the corresponding complexes containing [P(4)M(4)X(5)](-) and [P(4)M(2)(micro-X)](+) units. Reaction of pentasilver crown clusters with triflic acid gave the corresponding disilver complexes [resorcinarene(O(2)CR)(4)(OPPh(2))(4)]Ag(2)(micro-Cl)]]CF(3)SO(3). Thus, these resorcinarene-based ligands act as a platform for the easy and reversible assembly of copper(I) and silver(I) clusters with novel structures.     

Tetraphosphinitoresorcinarene complexes: cationic silver(I) and copper(I) halide complexes as mercurate(II) anion receptors

The reactions of mercury(II) halides with the tetraphosphinitoresorcinarene complexes [P4M5X5], where M=Cu or Ag, X=Cl, Br, or I, and P4=(PhCH2CH2CHC6H2)4(O2CR)4(OPPh2)4 with R=C6H11, 4-C6H4Me, C4H3S, OCH2CCH, or OCH2Ph, have been studied. The reactions of the complexes with HgX2 when M=Ag and X=Cl or Br occur with elimination of silver(I) halide and formation of [P4Ag2X(HgX3)], but when M=Ag and X=I, the complexes [P4Ag4I5(HgI)] are formed. When M=Cu and X=I, the products were the remarkable capsule complexes [(P4Cu2I)2(Hg2X6)]. When M=Ag and X=I, the reaction with both CuI and HgI2 gave the complexes [P4Cu2I(Hg2I5)]. Many of these complexes are structurally characterized as containing mercurate anions weakly bonded to cationic tetraphosphinitoresorcinarene complexes of copper(I) or silver(I) in an unusual form of host-guest interaction. In contrast, the complex [P4Ag4I5(HgI)] is considered to be derived from an anionic silver cluster with an iodomercury(II) cation. Fluxionality of the complexes in solution is interpreted in terms of easy, reversible making and breaking of secondary bonds between the copper(I) or silver(I) cations and the mercurate anions.     

Silver(I) complexes of fixed, polytopic bis(pyrazolyl)methane ligands: influence of ligand geometry on the formation of discrete metallacycles and coordination polymers

Reactions of the arene-linked bis(pyrazolyl)methane ligands m-bis[bis(1-pyrazolyl)methyl]benzene, (m-[CH(pz)2]2C6H4, Lm), p-bis[bis(1-pyrazolyl)methyl]benzene, (p-[CH(pz)2]2C6H4, Lp), and 1,3,5-tris[bis(1-pyrazolyl)methyl]benzene (1,3,5-[CH(pz)2]3C6H3, L3) with AgX salts (pz = 1-pyrazolyl; X = BF4- or PF6-) yield two types of molecular motifs depending on the arrangement of the ligating sites about the central arene ring. Reactions of the m-phenylene-linked Lm with AgBF4 and AgPF6 afford complexes consisting of discrete, metallacyclic dications: [Ag2(mu-Lm)2](BF4)2 (1) and [Ag2(mu-Lm)2](PF6)2 (2). When the p-phenylene-linked Lp is treated with AgBF4 and AgPF6, acyclic, cationic coordination polymers are obtained: {[Ag(mu-Lp)]BF4}infinity (3) and {[Ag(mu-Lp)]PF6}infinity (4). Reaction of the ligand L3, containing three bis(pyrazolyl)methane units in a meta arrangement, with an equimolar amount of AgBF4 again yields discrete metallacyclic dications in which one bis(pyrazolyl)methane unit on each ligand remains unbound: [Ag2(mu-L3)2](BF4)2 (5). Treatment of L3 with an excess of AgBF4 affords a polymer of metallacycles, {[Ag3(mu-L3)2](BF4)3}infinity (6), with one of the bis(pyrazolyl)methane units on each ligand bound to a silver cation bridging two metallacycles. The supramolecular structures of the silver(I) complexes 1-6 are organized by noncovalent interactions, including weak hydrogen bonding, pi-pi, and anion-pi interactions.     

Polymeric silver(I) complexes with pyridyl dithioether ligands: experimental and theoretical investigations on the coordination properties of the ligands

The reactions of four flexible tetradentate ligands, 1,3-bis(2-pyridylthio)propane (L1), 1,4-bis(2-pyridylthio)butane (L2), 1,5-bis(2-pyridylthio)pentane (L3) and 1,6-bis(2-pyridylthio)hexane (L4) with AgX (X = BF4-, ClO4-, PF6-, or CF3SO3-) lead to the formation of seven new complexes: [AgL1(BF4)]2 (1), [[AgL2](ClO4)]infinity (2), [[AgL2(CH3CN)](PF6)]infinity (3), [[AgL3](BF4)(CHCl3)]2 (4), [[AgL3(CF3SO3)](CH3OH)(0.5)]infinity (5), [[Ag2L4(2)](BF4)2]infinity (6), and [[AgL4](PF6)]infinity (7), which have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that complexes 1 and 4 possess dinuclear macrometallacyclic structures, and complexes 2, 3 and 5-7 take chain structures. In all the complexes, the nitrogen atoms of ligands preferentially coordinate to silver atoms to form normal coordination bonds, while the sulfur atoms only show weak interactions with silver atoms and the intermolecular AgS weak contacts connect the low-dimensional complexes into high-dimensional supramolecular networks. Additional weak interactions, such as pi-pi stacking, F...F weak interactions, Ag...O contacts or C-H...O hydrogen bonds, also help to stabilize the crystal structures. It was found that the parity of the -(CH2)n- spacers (n = 3-6) affect the orientation of the two terminal pyridyl rings, thereby significantly influence the framework formations of these complexes. The coordination features of ligands and their conformation changes between free and coordination states have been investigated by DFT calculations.     

Novel chelate ring-opening induced by silver(I) of five-coordinate palladium(II) and platinum(II) complexes containing tripodal polyphosphines

The ionic complexes [Pd(NP 3)X]X [NP 3 = tris[2-(diphenylphosphino)ethyl]amine, X = Cl (1), Br(2)] and [M(PP 3)X]X [PP 3 = tris[2-(diphenylphosphino)ethyl]phosphine, M = Pd, X = Cl (3), Br(4); M = Pt, X = Cl (5), Br (6)] contain square pyramidal (1, 2) and trigonal bipyramidal (3- 6) cations with three fused chelate rings to M and one M-X bond. By addition of AgX salts (X = Cl, Br, NO 3) an unexpected ring-opening reaction occurs with formation of the heteronuclear species PdAg(NP 3)X 3 [X = Cl (7), Br (8)], MAg(PP 3)X 3 [M = Pd, X = Cl (9), Br (10), NO 3 (13);M = Pt, X = Cl (11), Br (12), NO 3 (14)]. The complexes have been characterized in the solid state and solution. The X-ray crystal structures of 9 and 13 reveal a distorted square-planar arrangement to Pd(II) that is coordinated to three P of PP 3 (the central and two terminal atoms) and to one chloride (9) or one oxygen atom of NO 3 (13). The resultant dangling phosphorus of the ring opening is bound to Ag(I) that completes the three- [PAgCl 2 ( 9)] and four-coordination [PAg(ONO 2)(O 2NO) (13)] through the donor atoms of the anions with the nitrates in 13 unusually acting as both mono- and bidentate ligands. Complexes 7, 8, 10, and 11 undergo oligomerization in solution. Complex 10 oligomerizes giving rise to the ionic compound [Pd 4Ag 2(PP 3) 2 Br 9]Br ( 10a) whose X-ray crystal structure indicates the presence of cations with a Pd(mu-Br) 3Pd unit that connects via bromide bridges two BrPdP 2PPAg Br 2 fragments containing distorted square-planar and trigonal-planar Pd(II) and Ag(I) centers, respectively. The palladium(II) metal centers in the central unit afford the five-coordination (PdBr 5) with a distorted trigonal bipyramidal geometry. The ionic system [Pt 2Ag 2(PP 3) 2 Cl 5]Cl (11a) consists of chloride anions and heteronuclear monocations. The X-ray crystal structure reveals that the cations contain two distorted square-planar ClPtP 3 units bridged by one PAgCl(mu-Cl) 2AgP fragment that is bearing tetrahedral (PAgCl 3) and trigonal planar PAgCl 2 silver(I) centers. Further additions of the corresponding AgX salts to complexes 7- 14 did not give rise to any new ring-opening reaction.     

Ring-opening polymerization of coordination complexes: silver(I) complexes with bis(amidopyridine) ligands derived from thiophene

The thiophene-based bis(N-methylamido-pyridine) ligand SC4H2-2,5-{C(=O)N(Me)-4-C5H4N}2 reacts with silver(I) salts AgX to give 1 : 1 complexes, which are characterized in the solid state as the macrocyclic complexes [Ag(2){SC4H2-2,5-(CONMe-4-C5H4N)2}2][X]2, which have the cis conformation of the C(=O)N(Me) group, when X = CF3CO2, NO3, or CF3SO3 but as the polymeric complex [Ag(n){SC4H2-2,5-(CONMe-4-C5H4N)2}n][X]n, with the unusual trans conformation of the C(=O)N(Me) group, when X = PF6. The bis(amido-pyridine) ligand SC4H2-2,5-{C(=O)NHCH2-3-C5H4N}2 reacts with silver(I) trifluoroacetate to give the polymeric complex [Ag(n){SC4H2-2,5-(CONHCH2-3-C5H4N)2}n][X]n, X = CF3CO2. The macrocyclic complexes contain transannular argentophilic secondary bonds. The polymers self assemble into sheet structures through interchain C=O...Ag and S...Ag bonds in [Ag(n){SC4H2-2,5-(CONMe-4-C5H4N)2}n][PF6]n and through Ag...Ag, C=O...Ag and Ag...O(trifluoroacetate)...HN secondary bonds in [Ag(n){SC4H2-2,5-(CONHCH2-3-C5H4N)2}n][CF3CO2]n.     

Metal complexes from 1,1'-di(pyrazinyl)ferrocene: coordination polymers and bridged diferrocenes

Ferrocene-based ligands 1,1'-di(pyrazinyl)ferrocene (L1) and 1,1'-di(2-pyrimidinyl)ferrocene (L2) were synthesized and copper and silver complexes were obtained from L1. Coordination polymers [{Cu(2)(PhCOO)(4)}(L1)](n) (1), [{Cu(2)(C(5)H(11)COO)(4)}(L1)](n) (2), and [{Cu(2)(OAc)(4)}(L1)](n).0.5n[Cu(2)(OAc)(4)(H(2)O)(2)].1.5nCH(3)CN (3) resulted from the reaction with the corresponding copper carboxylates. In all three complexes, L1 links the dinuclear copper carboxylate units to form one-dimensional step-like chains. In 2, these chains are further linked by [Cu(2)(OAc)(4)(H(2)O)(2)] dinuclear units via hydrogen bonding to form sheet structures. The reaction of L1 with copper(I) iodide resulted in a multinuclear complex [(CuI)(4)(L1)(2)].(L1) (4), which contains a [(CuI)(4)(L1)(2)] diferrocene unit with a step-like (CuI)(4) core. Reactions of L1 with silver(I) salts resulted in silver-bridged diferrocenes [Ag(2)(L1)(2)]X(2) (X = ClO(4) (5a, b), NO(3) (6a-c) and PF(6) (7)), some of which incorporate aromatic solvents into their crystal lattices. The intramolecular Ag...Ag separations in these metallamacrocycles (3.211-3.430 A) depended upon the counter-anions and on the coordination mode of the silver ions. In all of these coordination complexes, L1adopts a synperiplanar eclipsed conformation and acts as a bidentate ligand, with only the 5-nitrogen of each pyrazine ring involved in coordination.     

Ring-opening polymerisation of silver-diphosphine [M2L3] coordination cages to give [M2L3]infinity coordination polymers

[M2L3] coordination cages and linear [M2L3]infinity polymers of the rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts have been investigated in the solution and solid states. Unlike flexible diphosphines, 1:1 dppa/AgX mixtures do not selectively form discrete [Ag2(diphos)2(X)2] macrocycles; instead dynamic mixtures of one-, two- and three-coordinate complexes are formed. However, 3:2 dppa/AgX ratios (X = SbF6. BF4, O3SCF3 or NO3) do lead selectively to new [M2L3] triply bridged cage complexes [Ag2(dppa)3(X)2] 1a-d (X = SbF6 a, BF4 b, O3SCF3 c, NO3 d), which do not exhibit Ag-P bond dissociation at room temperature on the NMR time scale (121 MHz). Complexes la-d were characterised by X-ray crystallography and were found to have small internal cavities, helical conformations and multiple intramolecular aromatic interactions. The nucleophilicity of the anion subtly influences the cage shape: Increasing nucleophilicity from SbF6 (1a) through BF4 (1b) and O3SCF3 (1c) to NO3 (1d) increases the pyramidal distortion at the AgP3 centres, stretching the cage framework (with Ag...Ag distances increasing from 5.48 in 1a to 6.21 A in 1d) and giving thinner internal cavities. Crystal packing strongly affected the size of the helical twist angle, and no correlation between this parameter and the Ag-Ag distance was observed. When crystalline 1c was stored in its supernatant for 16 weeks, conversion occured to the isostoichiometric [M2L3]infinity coordination polymer [Ag(dppa)2Ag(dppa)(O3SCF3)2]infinity (1c'). X-ray crystallography revealed a structure with ten-membered Ag2(dppa)2 rings linked into infinite one-dimensional chains by a third dppa unit. The clear structural relationship between this polymer and the precursor cage 1c suggests a novel example of ring-opening polymerisation. With dppet, evidence for discrete [M2L3] cages was also found in solution, although 31P NMR spectroscopy suggested some Ag-P bond dissociation. On crystallisation, only the corresponding ring-opened polymeric structures [M2L3]infinity could be obtained. This may be because the greater steric bulk of dppet versus dppa destabilises the cage and favours the ring-opening polymerisation.     

Anion dependent structures of luminescent silver(i) complexes

The reaction of AgX, where X = trifluoroacetate (CF(3)CO(2)(-), tfa), nitrate (NO(3)(-)), trifluoromethanesulfonate (triflate, CF(3)SO(3)(-), OTf), hexafluorophosphate (PF(6)(-)), or perchlorate (ClO(4)(-)), with 2,2',3' '-tripyridylamine (tpa) yields five novel silver(I) complexes, which have been structurally characterized. The five complexes have the same 1:1 stoichiometry of Ag/tpa but exhibit different modes of coordination, depending upon the counterion present in the compound. Compound 1, [Ag(tpa)(tfa)](n)(), forms a 1D coordination polymer of [Ag(tpa)(tfa)](2) dimer units linked through bridging tfa counterions. Compound 2, [Ag(tpa)(CH(3)CN)(NO(3))](n), forms a zigzag chain 1D coordination polymer exclusively through Ag-N bonds. In compounds 1 and 2, each tpa ligand is bound to two Ag(I) ions via a 2-py and a 3-py group. Compound 3, [Ag(tpa)(OTf)](n), forms a ribbonlike 1D coordination polymer, in which each tpa ligand binds to three different silver centers via all three pyridyl groups, and the counterion remains coordinated to the Ag(I) center. Compounds 4, [Ag(tpa)(CH(3)CN)](n)(PF(6))(n), and 5, [Ag(tpa)(CH(3)CN)](n)() (ClO(4))(n), display ribbonlike structures resembling that of 3, except that the counterions are not coordinated. All complexes are luminescent in acetonitrile solution, with emission maxima in the near-UV region (lambda(max) = 366, 368, 367, 367, and 368 nm for 1-5, respectively). At 77 K, the emission maxima are red-shifted to lambda(max) = 452, 453, 450, 450, and 454 nm for 1-5, respectively.     

Luminescent complexes of silver(I) with pyridylbis(3-hexamethyleneiminyl thiosemicarbazone): effect of the counterion on the nuclearity

The reaction of pyridylbis(3-hexamethyleneiminyl thiosemicarbazone) (H(2)Plhexim) with various silver(I) salts and metal-ligand ratios led to the isolation of different complexes of the formulae [Ag(NO(3))(H(2)Plhexim)]·H(2)O (1), [Ag(2)(NO(3))(H(2)Plhexim)(CH(3)OH)](NO(3)) (2), [Ag(2)(ClO(4))(2)(H(2)Plhexim)] (3), [Ag(HPlhexim)]·xH(2)O (4), [Ag(HPlhexim)] (4a), [Ag(2)(Plhexim)(PPh(3))(4)]·2MeOH (5) and [Ag(4)(Plhexim)(2)]·DMF (6). The complexes were fully characterized by elemental analysis, ESI mass spectrometry, IR and NMR ((1)H, (31)P) spectroscopy. The structures of 4a, 5 and 6 were also identified by single crystal X-ray structure determination. The concentration dependence on the absorption spectra of the methanolic solutions indicates polymerization equilibria in the ground state in both the ligand and the complexes. While H(2)Plhexim is essentially non-fluorescent, complexes 1-5 fluoresce more strongly by comparison. This fluorescent behavior is consistent with the monomeric or dimeric nature of the complexes.     

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.     

Structure and dynamics of tetrakis(thiophosphinato)resorcinarene complexes of silver(I), gold(I), and palladium(II)

The coordination chemistry of the tetrakis(thiophosphinato)resorcinarene sulfur-donor ligands [(C6H2CH{CH2CH2Ph})4{OC(O)R}4{OP(=S)Ph2}4] (L), where R = OCH2Ph, 4-C6H4CH3, C6H11, C4H3S, or OCH2CCH, is reported. Both silver(I) and gold(I) form cationic complexes of the type [LM2]2+, in which the ligand acts as a bis(chelate) in forming complexes with linear S-M-S (M = Ag or Au) stereochemistry. Gold(I) also forms the unusual complex [L(AuCl)2][LAu2]2+, which forms a supramolecular polymer through intermolecular aurophilic attractions. Palladium(II) forms the complex [LPd2Cl2(mu-Cl)2], in which the dipalladium(II) unit extends the natural bowl structure of the resorcinarene. The solid-state and solution conformations of the complexes, as determined by X-ray structure determination and NMR spectroscopy, respectively, are similar, but several complexes were found to exhibit dynamic behavior in solution, involving either conformational mobility of the resorcinarene unit or intermolecular ligand exchange.     

Disilver(I) rectangular-shaped metallacycles: X-ray crystal structure and dynamic behavior in solution

Reaction of the ditopic semirigid ligand 1,2-bis(imidazolylmethyl)benzene (1,2-bImb) or the flexible ligand 1,4-bis(2-benzimidazolyl)butane (C4BIm) with AgX (X = ClO4-, BF4-, CF3CO2-) afforded five new complexes, namely, [Ag2(1,2-bImb)2](ClO4)2 (1), [Ag2(1,2-bImb)2](BF4)2 (2), [Ag2(1,2-bImb)2](CF3CO2)2.2CH3OH (3.2CH3OH), [Ag2(C4BIm)2](ClO4)2.2DMF (4.2DMF), and [Ag2(C4BIm)2](CF3CO2)2.2H2O (5.2H2O), all of which contain a centrosymmetric, rectangular-shaped cationic disilver(I) metallacycle [Ag2(L)2]2+. In 1-3, a pair of 1,2-bImb ligands takes on the syn conformation to connect two Ag(I) ions to give a compressed rectangle with a transannular Ag...Ag separation of 3.27-3.36 angstroms, whereas in 4 and 5, the pair of planar C4BIm ligands acts in the cis conformation to connect two Ag(I) ions to yield a normal rectangle with a transannular Ag...Ag separation of 7.67-7.91 angstroms. The anions form Ag...O or Ag...F weak interactions in 1-3 and O-H...O or N-H...O hydrogen bonds in 4 and 5 in crystal packing but exhibit no significant influence on the formation of the disilver(I) macrocycles. The solution structure and dynamic behavior of the complexes studied by electrospray ionization mass spectrometry, 1H NMR, and variable-temperature NMR indicated that the dynamic equilibrium between the [Ag2(L)2]2+ cation and the open-ring oligomers or other potential species occurs via solvent-assisted dissociative exchange. The metal-ligand exchange barrier was estimated to be 54.5 kJ mol(-1).     

Ag(I) and Cu(II) discrete and polymeric complexes based on single- and double-armed oxadiazole-bridging organic clips

Four new oxadiazole-bridging ligands (L1-L4) were designed and synthesized by the reaction of 2,5-bis(2-hydroxyphenyl)-1,3,4-oxadiazole with isonicotinoyl chloride and nicotinoyl chloride, respectively. L1 and L3 are unsymmetric single-armed ligands (4- or 3-pyridinecarboxylate arm), and L2 and L4 are symmetric double-armed ligands (4- or 3-pyridinecarboxylate arms). Nine new complexes, [Ag(L1)]PF6.CH3OH (1), [Ag(L1)]ClO4.CH3OH (2), Cu(L2)(NO3)2.2(CH2Cl2) (3), [Cu(L2)2](ClO4)2.2(CH2CCl2) (4), Cu(L2)Cl2 (5), [Cu4(L3)2(H2O)2](L3)4(ClO4)4 (6), [Ag(L4)(C2H5OH)]ClO4 (7), [Ag(L4)(C2H5OH)]BF4 (8), and [Ag(L4)(CH3OH)]SO3CF3 (9), were isolated from the solution reactions based on these four new ligands, respectively. L1, L2, and L3 act as convergent ligands and bind metal ions into discrete molecular complexes. In contrast, L4 exhibits a divergent spacer to link metal ions into one-dimensional coordination polymers. New coordination compounds were fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. In addition, the luminescent and electrical conductive properties of these new compounds were investigated.     

Silver(I) Ethynide Coordination Networks and Clusters Assembled with tert-Butylphosphonic Acid

Variation of the reaction conditions with AgC≡CR (R = Ph, C(6)H(4)OCH(3)-4, (t)Bu), (t)BuPO(3)H(2), and AgX (X = NO(3), BF(4)) as starting materials afforded four new silver(I) ethynide complexes incorporating the tert-butylphosphonate ligand, namely, 3AgC≡CPh·Ag(2)(t)BuPO(3)·Ag(t)BuPO(3)H·2AgNO(3) (1), 2AgC≡CC(6)H(4)OCH(3)-4·Ag(2)(t)BuPO(3)·2AgNO(3) (2), [{Ag(5)(NO(3)@Ag(18))Ag(5)}((t)BuC≡C)(16)((t)BuPO(3))(4)(H(2)O)(3)][{Ag(5)(NO(3)@Ag(18))Ag(5)} ((t)BuC≡C)(16)((t)BuPO(3))(4)(H(2)O)(4)]·3SiF(6)·4.5H(2)O·3.5MeOH (3), and [{Ag(8)(Cl@Ag(14))}((t)BuC≡C)(14)((t)BuPO(3))(2)F(2)(H(2)O)(2)]BF(4)·3.5H(2)O (4). Single-crystal X-ray analysis revealed that complexes 1 and 2 display different layer-type coordination networks, while 3 and 4 contain high-nuclearity silver(I) composite clusters enclosing nitrate and chloride template ions, respectively, that are supported by (t)BuPO(3)(2-) ligands.     

Tuning the coordination geometry of silver in bis(pyrazolyl)alkane complexes

Silver(I) complexes of the bis(pyrazolyl)methane ligands Ph(2)C(pz)(2), PhCH(pz)(2), and PhCH(2)CH(pz)(2) (pz = pyrazolyl ring) have been prepared in an attempt to explore how sterically hindered poly(pyrazolyl)methane ligands influence the variable coordination geometries exhibited by silver(I) complexes, especially its ability to participate in cation...pi interactions. The complex (Ag[(pz)(2)CPh(2)](2))(PF(6)).C(3)H(6)O adopts an unusual square planar coordination environment as indicated by the sum of the four N-Ag-N angles being 360 degrees. The proximity of phenyl groups above and below the AgN(4) core enforces the unusual coordination geometry about the metal center. This arrangement is not a result of silver(I)...pi arene interactions but rather of the constraints imposed by the steric crowding caused by (aryl)(2)C(pz)(2) ligands. In contrast, the complexes of the other two ligands, (Ag[(pz)(2)CHPh](2))(PF(6)).0.5CH(2)Cl(2) and (Ag[(pz)(2)CH(CH(2)Ph)](2))(PF(6)).CH(2)Cl(2), show normal tetrahedral geometry about the silver(I), also with no indication of silver(I)...pi arene interactions. All three new complexes have extended supramolecular structures supported by a combination of CH...pi and CH...F interactions.     

Formation of mono-, bi-, tri-, and tetranuclear Ag(I) complexes of C3-symmetric tripodal benzimidazole ligands

The C3-symmetric tripodal ligand tris(2-benzimidazolylmethyl)amine (ntb) and its alkyl-substituted derivatives tris(N-R-benzimidazol-2-ylmethyl)amine (R = methyl, Mentb; R = ethyl, Etntb; R = propyl, Prntb) react with various silver(I) salts to afford mononuclear [Ag(Prntb)(CF3SO3)].0.25H2O, 1, binuclear [Ag2(Mentb)2](CF3SO3)2.H2O, 2, trinuclear [Ag3(Etntb)2](ClO4)3.CH3OH, 3, and tetranuclear [Ag4(ntb)2(CH3CN)2(CF3CO2)2](CF3CO2)2.2H2O, 4. All four complexes have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. The Ag(I) ion in 1 is coordinated to the three imine nitrogen atoms of the Prntb ligand and one oxygen atom of the trifluoromethanesulfonate anion in a distorted tetrahedral environment. Dinuclear 2 has C2 symmetry with each Ag(I) atom trigonally coordinated by two arms of one Mentb and one arm of another. Trinuclear 3 has C3 symmetry with a Ag3 regular triangle sandwiched between a pair of Etntb ligands such that one arm of each ligand is involved in linear coordination about an Ag(I) atom. In the tetranuclear complex 4, two linearly coordinated Ag(I) atoms lying on the molecular C2 axis are bridged by a pair of ntb ligands and the remaining pendant arm of each ntb ligand is attached to another Ag(I) atom whose tetrahedral coordination sphere is completed by an acetonitrile molecule and a chelating trifluoroacetate anion. Complexes 2 and 3 may be regarded as an aggregation of two tridentate ligands by a silver dimer and a trinuclear cluster with weak Ag...Ag interactions, respectively, while in 4 the aggregation of two tripodal ligands by four Ag(I) ions affords a multicomponent internal cavity. The packing modes of complexes 1-3 are dominated by weak supramolecular pi...pi and CH...pi interactions. Hexagonal or square channels are generated in 1 and 2, and a honeycomb layer structure is formed in 3 with solvate molecules and counteranions occupying the voids. The crystal structure of 4 consists of a three-dimensional network consolidated by NH...O and OH...O hydrogen bonds.     

Structural study of silver(I) sulfonate complexes with pyrazine derivatives

In this Article, 11 silver complexes, namely, [Ag(L1)(2-Pyr)(H2O)] (1), Ag(L1)(2,3-Pyr) (2), [Ag2(L1)2(2Et,3Me-Pyr)2(H2O)] (3), [Ag(2,6-Pyr)](L1).1.5H2O (4), Ag(L1)(2,5-Pyr) (5), [Ag(H2O)2](L2).H2O (6), [Ag(L2)(2-Pyr)] (7), [Ag(L2)(2,3-Pyr)].1.5H2O (8), [Ag(L2)(2Et,3Me-Pyr)].2H2O (9), [Ag2(L2)(2,6-Pyr)(H2O)2](L2).H2O (10) and [Ag(L2)(2,5-Pyr)].H2O (11) (2-Pyr=2-methylpyrazine; 2,3-Pyr=2,3-dimethylpyrazine; 2Et,3Me-Pyr=2-ethyl-3-methylpyrazine; 2,6-Pyr=2,6-dimethylpyrazine; 2,5-Pyr=2,5-dimethylpyrazine; L1=p-aminobenzenesulfonate anion and L2=6-amino-1-naphthalenesulfonate anion), have been synthesized and characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. In 1, 3, and 4, Ag(I) centers are linked by bridging pyrazine ligands to form one-dimensional chains, whereas compound 2 shows a double-chain structure through weak Ag-C interactions. The structure analyses show that both 5 and 11 form two-dimensional networks composed of 26-membered metallocycles. Unexpectedly, compounds 6 and 10 show discrete structures. In compound 7, silver(I) centers are bridged by sulfonate anions to form a polymeric helical structure, and the 2-Pyr molecule acts as a monodentate ligand. Compounds 8 and 9 show hinged chain structures containing 14-membered rings, and these chains interlace with each other to generate unique three-dimensional structures. These results indicate that the substituting groups and the substituting sites of pyrazine derivatives play an important role in the framework formation of silver complexes. Additionally, the luminescent properties of these compounds are also discussed.     

Oxo- and imidovanadium complexes incorporating methylene- and dimethyleneoxa-bridged calix[3]- and -[4]arenes: synthesis, structures and ethylene polymerisation catalysis

Reaction of [V(X)(OR)3] (X=O, Np-tolyl; R=Et, nPr or tBu) with p-tert-butylhexahomotrioxacalix[3]areneH3, LH3, affords the air-stable complexes [{V(X)L}n] (X=O, n=1 (1); X=Np-tolyl, n=2 (2)). Alternatively, 1 is readily available either from interaction of [V(mes)3THF] with LH3, and subsequent oxidation with O2 or upon reaction of LLi3 with [VOCl3]. Reaction of [V(Np-tolyl)(OtBu)3] with 1,3-dimethylether-p-tert-butylcalix[4]areneH2, Cax(OMe)2(OH)2, afforded [{VO(OtBu)}2(mu-O)Cax(OMe)2(O)2].2 MeCN (42 MeCN), in which two vanadium atoms are bound to just one calix[4]arene ligand; the n-propoxide analogue of 4, namely [{VO(OnPr)}2(mu-O)Cax(OMe)2(O)2].1.5 MeCN (51.5 MeCN), has also been isolated from a similar reaction using [V(O)(OnPr)3]. Reaction of [VOCl3], LiOtBu, (Me3Si)2O and Cax(OMe)2(OH)2 gave [{VO(OtBu)Cax(OMe)2(O)2}2Li4O2].8 MeCN (68 MeCN), in which an Li4O4 cube (two of the oxygen atoms are derived from the calixarene ligands) is sandwiched between two Cax(OMe)2(O)2. The reaction between [V(Np-tolyl)(OtBu)3] and Cax(OMe)2(OH)2, afforded [V(Np-tolyl)(OtBu)2Cax(OMe)2(O)(OH)]5 MeCN (75 MeCN), in which two tert-butoxide groups remain bound to the tetrahedral vanadium atom, which itself is bound to the calix[4]arene through only one phenolic oxygen atom. Reaction of p-tert-butylcalix[4]areneH4, Cax(OH)4 and [V(Np-tolyl)(OnPr)3] led to loss of the imido group and formation of the dimeric complex [{VCax(O)4(NCMe)}2].6 MeCN (86 MeCN). Monomeric vanadyl oxo- and imidocalix[4]arene complexes [V(X)Cax(O)3(OMe)(NCMe)] (X=O (11), Np-tolyl (12)) were obtained by the reaction of the methylether-p-tert-butylcalix[4]areneH3, Cax(OMe)(OH)3, and [V(X)(OR)3] (R=Et or nPr). Vanadyl calix[4]arene fragments can be linked by the reaction of 2,6-bis(bromomethyl)pyridine with Cax(OH)4 and subsequent treatment with [VOCl3] to afford the complex [{VOCax(O)4}2(mu-2,6-(CH2)2C5H3N)].4 MeCN (134 MeCN). The compounds 1-13 have been structurally characterised by single-crystal X-ray diffraction. Upon activation with methylaluminoxane, these complexes displayed poor activities, however, the use of dimethylaluminium chloride and the reactivator ethyltrichloroacetate generates highly active, thermally stable catalysts for the conversion of ethylene to, at 25 degrees C, ultra-high-molecular-weight (>5, 500,000), linear polyethylene, whilst at higher temperature (80 degrees C), the molecular weight of the polyethylene drops to about 450,000. Using 1 and 2 at 25 degrees C for ethylene/propylene co-polymerisation (50:50 feed) leads to ultra-high-molecular-weight (>2,900,000) polymer with about 14.5 mol% propylene incorporation. The catalytic systems employing the methyleneoxa-bridged complexes 1 and 2 are an order of magnitude more active than the bimetallic complexes 5 and 13, which, in turn, are an order of magnitude more active than pro-catalysts 8, 11 and 12. These differences in activity are discussed in terms of the structures of each class of complex.     

Synthesis,Characterization, and Luminescent Properties of Silver(I) Complexes based on Diphosphine Ligands and 6,7‐Dicyanodipyridoquinoxaline

Five mono‐nuclear silver (I) complexes with 6,7‐dicyanodipyridoquinoxaline ligand, namely {[Ag(DPEphos)(dicnq)]NO₃}₂ · CH₃OH ( 1 ), [Ag(DPEphos)(dicnq)]BF₄ · CH₃OH ( 2 ), [Ag(XANTphos)(dicnq)]CF₃SO₃ ( 3 ), {[Ag(XANTphos)(dicnq)]NO₃}₂ ( 4 ), and [Ag(XANTphos)(dicnq)]ClO₄ · CH₂Cl₂ ( 5 ) {DPEphos = bis[2‐(diphenylphosphanyl)phenyl]ether, dicnq = 6,7‐dicyanodipyridoquinoxaline, XANTphos = 9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)xanthene} were characterized by X‐ray diffraction, IR, ¹H NMR, ³¹P NMR, fluorescence spectra, and terahertz time‐domain spectra (THz‐TDS). In the five complexes the Ag^I, which is coordinated by two kinds of chelating ligands, adopts four‐coordinate modes to generate mono‐nuclear structures. The C–H ··· π interactions lead to formation of a 1D infinite chain for complexes 2 and 3 . The crystal packing of complexes 1 and 5 reveal that they form 3D supermolecular network by several pairs of C–H ··· π interactions. The emissions of these complexes are attributed to ligands‐centered [π–π*] transition based on both of the P‐donor and N‐donor ligands.