Synthesis, structural, and magnetic studies on a redox family of tetrametallic vanadium clusters: {VIV4}, {VIII2VIV2}, and {VIII4} butterfly complexes

The synthesis, crystal structures, and magnetic properties are reported for a redox family of butterfly-type tetrametallic vanadium alkoxide clusters, namely [V2(VO)2(acac)4(RC{CH2O}3)2] (R=Me 1, Et 2, CH2OH 3), [V2(VO)2(acac)2(O2CPh)2(MeC{CH2O}3)2] (5), [(VO)4(MeOH)2(O2CPh)2({HOCH2}C{CH2O}3)2] (6), [V4Cl2(dbm)4(RC{CH2OH}3)2] (R=Me 7, Et 8, CH2OH 9), and [V4Cl2(dbm)4(MeO)6] (10). The cluster cores are {VIV4} (6), {VIII2VIV2} (1-5), and {VIII4} (7-10), with examples of both isomeric forms of the of the mixed-valence cores (either VIII or VIV ions forming the butterfly body). Magnetic studies reveal the clusters to be dominated by antiferromagnetic exchange interactions in each case. The magnetic exchange parameters are determined for representative examples of each core type. {VIV4} and {VIII4} have diamagnetic ground states. The two isomeric {VIII2VIV2} types are found to give rise to either an S=0 ground state with a number of low-lying excited states due to competing antiferromagnetic exchange interactions (VIII2 butterfly body) or to a well-isolated S=1 ground state (VIV2 butterfly body).     

A family of alkynylgold(III) complexes [AuI(mu-{CH2}2PPh2)2Au(III)(C triple bond CR)2] (R = Ph, tBu, Me3Si): facile and reversible comproportionation of gold(I)/gold(III) to digold(II)

The symmetric digold(II)dichloride bis(ylide) complex [Au2Cl2(mu-{CH2}2PPh2)2] reacts with acetylides to form the asymmetric heterovalent gold(I)/gold(III) complexes [AuI(mu-{CH2}2PPh2)2AuIII(CCR)2] [R = Ph, tBu, and SiMe3], the phenyl analogue of which was characterized by X-ray crystallography. These compounds represent the first examples of gold(III) complexes containing two acetylide ligands. [AuI(mu-{CH2}2PPh2)2AuIII(CCPh)2] undergoes a reversible comproportionation reaction upon treatment with [Ag(ClO4)tht] to give the symmetric digold(II) cationic complex [Au2(tht)2(mu-{CH2}2PPh2)2](ClO4)2. If this complex is treated with phenylacetylene in the presence of base, the heterovalent gold(I)/gold(III) complex is re-formed. This reversible interconversion between binuclear gold(I)/gold(III) and digold(II) bis(ylide) complexes is unprecedented.     

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.     

A ring cycle: studies of heterometallic wheels

The synthesis of a series of heterometallic rings and chains is reported. The family is based on the octanuclear cages of general formula [H(2)NR(2)][M(7)M'F(8)(O(2)CR')(16)], where M is a trivalent metal (Cr, Fe, V, Al, Ga or In), M' is a divalent metal (Mn, Fe, Co, Ni, Mg, Zn, Cd), R is a linear alkyl chain and O(2)CR' is one of around twenty carboxylates. Other members of the family with nonametallic and decametallic cores are described, and some new physics is outlined, including initial investigations of the proposed application of [Cr(7)Ni] rings as Qubits in quantum information processing.     

Luminescent heteronuclear Au(I)5Ag(I)8 complexes of [1,2,3-C6(C6H4R-4)3]3- (R = H, CH3, But) by cyclotrimerization of arylacetylides

Unusual AuI-AgI heterometallic complexes [Au5Ag8(mu-dppm)4{1,2,3-C6(C6H4R-4)3}(CCC6H4R-4)7]3+ (R = H 1, CH3 2, But 3) were isolated by reactions of polymeric silver arylacetylides (AgCCC6H4R-4)n with binuclear gold component [Au2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane), in which cyclotrimerization of arylacetylide -CCC6H4R-4 affords trianion {1,2,3-C6(C6H4R-4)3}3- with an unprecedented mu5-bonding mode. Compounds 1(SbF6)3-3(SbF6)3 exhibit intense photoluminescence derived from an MLCT (Au5Ag8 --> CCC6H4R-4) transition, mixed with a metal cluster-centered excited states.     

Synthesis of [(HIPTNCH2CH2)3N]Cr Compounds (HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3) and an evaluation of chromium for the reduction of dinitrogen to ammonia

Red-black [HIPTN3N]Cr (1) ([HIPTN3N]3- = [(HIPTNCH2CH2)3N]3- where HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3 = HexaIsoPropylTerphenyl) can be prepared from CrCl3, while green-black [HIPTN3N]Cr(THF) (2) can be prepared from CrCl3(THF)3. Reduction of {1|2} (which means either 1 or 2) with potassium graphite in ether at room temperature yields [HIPTN3N]CrK (3) as a yellow-orange powder. There is no evidence that dinitrogen is incorporated into 1, 2, or 3. Compounds that can be prepared readily from {1|2} include red [HIPTN3N]CrCO (4), blood-red [HIPTN3N]CrNO (6), and purple [HIPTN3N]CrCl (7, upon oxidation of {1|2} with AgCl). The dichroic (purple/green) Cr(VI) nitride, [HIPTN3N]CrN (8) was prepared from Bu4NN3 and 7. X-ray studies have been carried out on 4, 6, and 7, and on two co-crystallized compounds, 7 and [HIPTN3N]CrN3 (65:35) and [HIPTN3N]CrN3 and 8 (50:50). Exposure of a degassed solution of {1|2} to an atmosphere of ammonia does not yield "Cr(NH3)" as a stable and well-behaved species analogous to Mo(NH3). An attempt to reduce dinitrogen under conditions described for the catalytic reduction of dinitrogen by [HIPTN3N]Mo compounds with 8 yielded a substoichiometric amount (0.8 equiv) of ammonia, which suggests that some ammonia is formed from the nitride but none is formed from dinitrogen.     

Effect of Synthesis Conditions on the Molecular and Crystal Structures of Heterometallic 1D-Polymeric Acetate Complexes with the {Dy2Co}n Motif

Russian Journal of Coordination Chemistry - New heterometallic 1D-polymeric acetate complexes with the {Dy2Co}n motif of the metallic framework, [Dy2Co(CH3COOO)8(H2O)4]n ? 6nH2O (I) and...     

Metal-templated diyne cyclodimerization and cyclotrimerization

Reaction of [Pt(CH3)2(COD)] (COD = 1,5-cyclooctadiene) with Ph2PCCCCPPh2 led to a mixture of [{Pt(CH3)2}2(mu-Ph2PC4PPh2)2] (1) and [{Pt(CH3)2}3(mu-Ph2PC4PPh2)3] (2). Reaction of [PtCl2(COD)] with Ph2PCCCCPPh2 led to a mixture of the thermally unstable compounds [{PtCl2}2(mu-Ph2PC4PPh2)2] (3) and [{PtCl2}3(mu-Ph2PC4PPh2)3] (4) which transform into [{PtMe2}2{mu-C8(PPh2)4}] (5) and [{PtMe2}3{mu3-C12(PPh2)6}] (6) containing 8-membered diene-diyne and 12-membered triene-triyne rings, respectively. Compound 2 can be converted to [{PtMe2}3{C12(PPh2)6}] (7) by heating with CuCl at 80 degrees C, while 1 can be heated without significant cycloaddition.     

Rational synthesis and magnetic properties of a family of low-dimensional heterometallic Cr-Mn complexes based on the versatile building block [Cr(2,2'-bipyridine)(CN)4]-

Six heterometallic compounds based on the building block [Cr(bpy)(CN)4]- (bpy = 2,2'-bipyridine) with secondary and/or tertiary coligands as modulators, {Mn(H2O)2[Cr(bpy)(CN)4]2}n (1), {Mn(bpy)(H2O)[Cr(bpy)(CN)4]2 x H2O}n (2), [Mn(bpy)2][Cr(bpy)(CN)4]2 x 5H2O (3), {[Mn(dca)(bpy)(H2O)][Cr(bpy)(CN)4] x H2O}n (4) (dca = N(CN)2(-)), {Mn(N3)(CH3OH)[Cr(bpy)(CN)4] x 2H2O}n (5), and {Mn(bpy)(N3)(H2O)[Cr(bpy)(CN)4] x H2O}2 (6), have been prepared and characterized structurally and magnetically. X-ray crystallography reveals that the compounds 1, 2, 4, and 5 consist of one-dimensional (1D) chains with different structures: a 4,2-ribbon-like chain, a branched zigzag chain, a 2,2-CC zigzag chain, and a 3,3-ladder-like chain, respectively. It also reveals that compound 3 has a trinuclear [MnCr2] structure, and compound 6 has a tetranuclear [Mn2Cr2] square structure. Magnetic studies show antiferromagnetic interaction between Cr(III) and Mn(II) ions in all compounds. All of the chain compounds exhibit metamagnetic behaviors with different critical temperatures (Tc) and critical fields (Hc; at 1.8 K): 3.2 K and 3.0 kOe for 1; 2.3 K and 4.0 kOe for 2; 2.1 K and 1.0 kOe for 4; and 4.7 K and 5.0 kOe for 5, respectively. The noncentrosymmetric compound 2 is also a weak ferromagnet at low temperature because of spin canting. The magnetic analyses reveal Cr-Mn intermetallic magnetic exchange constants, J, of -4.7 to -9.4 cm(-1) (H = -JS(Cr) x S(Mn)). It is observed that the antiferromagnetic interaction through the Mn-N-C-Cr bridge increases as the Mn-N-C angle (theta) decreases to the range of 155-180 degrees, obeying an empirical relationship: J = -40 + 0.2theta. This result suggests that the best overlap between t(2g) (high-spin Mn(II)) and t(2g) (low-spin Cr(III)) occurs at an angle of approximately 155 degrees.     

Syntheses, Crystal Structures and Thermal and Optical Properties of Two Organic Templated Gallium Antimony Sulfides

Two new gallium antimony sulfides,[enH2][Ga2Sb2S7]·en(1) and [puH]2[Ga2Sb2S7](2)(en = ethylenediamine,pu = propyleneurea),have been solvothermally synthesized.In the pre-paration of compound 2,the protonated propyleneurea cation as counterion and template was in situ synthesized by the reaction of 1,3-diaminopropane with CO2 in pyridine.Both structures contain a two-dimensional network composed of novel heterometallic clusters of {Ga2Sb2S9} as the second-dary building unit.The thermal and optical properties of compounds 1 and 2 were characterized by TGA and UV-Vis,respectively.     

Synthesis and Crystal Structure of [(PPh3)(CH3COS)2NiB10H10]·0.4(C5H12)

The title compound [(PPh3)(CH3COS)2NiB10H10]·0.4(C5H12) has been synthesized by the reaction of [NiCl2(PPh3)2], closo-[B10H10]2- and CH3COSH in CH2Cl2 solution. It was recrystallized from n-pentane/CH2Cl2 solution and its structure was determined by X-ray diffraction analysis. The crystal is triclinic, space group P1, Mr=618.23, with a=10.049(1), b=12.638(2), c=14.077(2) , α=110.13(1), β=87.65(1), γ=96.01(1)°, V=1669.3(4)(A)3, Dc=1.230 g/cm3, Z=2, λ(MoKα)=0.71073(A), μ=7.76 cm-1, F(000)=642. The final refinement is converged with R=0.042 (5986 observed reflections with I≥2σ(I)), wR2 =0.151. The cluster is a nido eleven-vertex {NiB10} cage with the Ni atom in the open NiB4 face. Cyclizations resulting in two five-membered rings, Ni(7)-S(1)-C(1)-O(1)-B(2) and Ni(7)-S(2)-C(2)-O(2)-B(3), have occurred.     

Synthesis and properties of Rh(I) and Ir(I) distibine complexes with organometallic co-ligands

The first series of Rh(I) distibine complexes with organometallic co-ligands is described, including the five-coordinate [Rh(cod)(distibine)Cl], the 16-electron planar cations [Rh(cod)(distibine)]BF4 and [Rh{Ph2Sb(CH2)3SbPh2}2]BF4 and the five-coordinate [Rh(CO)(distibine)2][Rh(CO)2Cl2] (distibine=R2Sb(CH2)3SbR2, R=Ph or Me, and o-C6H4(CH2SbMe2)2). The corresponding Ir(I) species [Ir(cod)(distibine)]BF4 and [Ir{Ph2Sb(CH2)3SbPh2}2]BF4 have also been prepared. The complexes have been characterised by 1H and 13C{1H} NMR and IR spectroscopy, electrospray mass spectrometry and microanalysis. The crystal structure of the anion exchanged [Rh(CO){Ph2Sb(CH2)3SbPh2}2]PF(6).3/4CH2Cl2 is also described. The methyl-substituted distibine complexes are less stable than the complexes of Ph2Sb(CH2)3SbPh2, with C-Sb fission occurring in some of the complexes of the former. The salts [Rh(CO){Ph2Sb(CH2)3SbPh2}2]PF6 and [Rh{Ph2Sb(CH2)3SbPh2}2]BF4 undergo oxidative addition with Br2 to give the known [RhBr2{Ph2Sb(CH2)3SbPh2}2]+, while using HCl gives the same hydride complex from both precursors, which is tentatively assigned as [RhHCl2{Ph2Sb(CH2)3SbPh2}]. An unexpected further Rh(III) product from this reaction, trans-[RhCl2{Ph2Sb(CH2)3SbPh2}{PhClSb(CH2)3SbClPh}]Cl, was identified by a crystal structure analysis and represents the first structurally characterised example of a chlorostibine coordinated to a metal. [Rh{Ph2Sb(CH2)3SbPh2}2]BF4 reacts with CO to give [Rh(CO){Ph2Sb(CH2)3SbPh2}2]BF4 initially, and upon further exposure this species undergoes further reversible carbonylation to give a cis-dicarbonyl species thought to be [Rh(CO)2{Ph2Sb(CH2)3SbPh2}{kappa1Sb-Ph2Sb(CH2)3SbPh2}]BF4 which converts back to the monocarbonyl complex when the CO atmosphere is replaced with N2.     

Grafting and thermal stripping of organo-bimetallic clusters on AU surfaces: toward controlled CO/RU aggregates

The controlled stoichiometry of heterometallic carbonyl clusters make them attractive precursors for the stabilization of bare metal alloy clusters for magnetic applications. The mixed-metal molecular cluster [RuCo3(H)(CO)12] has been functionalized with the phosphane-thiol ligand Ph2PCH2CH2SH to allow subsequent anchoring on a gold surface. The resulting tetrahedral cluster [RuCo3(H)(CO)11(Ph2PCH2CH2SH)] (1) has been characterized by X-ray diffraction and the P-monodentate ligand is axially bound to a cobalt center and trans to the ruthenium cap. This synthesis also yielded the product of oxidative coupling, in which two SH groups were coupled intermolecularly to give a disulfide ligand that links two tetrahedral cluster units in [{RuCo3(H)(CO)11(Ph2PCH2CH2S)}2] (2). This cluster has also been characterized by X-ray diffractions studies. After deposition of 1 on a Au(111) surface by self-assembly, the carbonyl ligands were stripped off by thermal annealing in ultra-high vacuum (UHV) to form a metallic species. X-ray photoelectron spectroscopic measurements performed as a function of the annealing temperature show that the cobalt and ruthenium centers converge towards metallic character and that the stoichiometry of the alloy is retained during the annealing process. Preliminary X-ray absorption spectroscopy (XAS) synchrotron experiments indicate that clusters 1 and 2 behave similarly, which is consistent with the retention of their tetrahedral units on the gold surface after transformation of the thiol function or breaking of the disulfide bond to form Au--S bonds, respectively, has occurred.     

Relative conductances of alkaneselenolate and alkanethiolate monolayers on Au{111}

The electronic properties of alkanethiolate [CH3(CH2)nS-, n = 9 and 11] and alkaneselenolate [CH3(CH2)nSe-, n = 9 and 11] self-assembled monolayers on Au{111} have been quantitatively compared. Simultaneously acquired apparent tunneling barrier height (ATBH) and scanning tunneling microscopy (STM) images reveal that alkanethiolate molecules have a lower barrier to tunneling, and therefore a higher conductance than alkaneselenolates of the same alkyl chain length. Molecular and contact conductance differences were elucidated by using observed STM topographic tunneling height differences between the analogous species. This apparent topographic difference combined with comparative ATBH data indicate that the observed decrease in conductance for alkaneselenolates compared to alkanethiolates originates exclusively from the Au-chalcogenide physical, chemical, and electronic contact.     

Organometallic building blocks with amino-substituted cyclopentadienyl and boratabenzene ligands for the synthesis of heterometallic complexes and clusters

A comparative study of the reactivity of isolobal rhenium and molybdenum carbonylmetallates containing a borole, in [Re(eta5-C4H4BPh)(CO)3]- (2), a boratanaphthalene, in [Mo(eta5-2,4-MeC9H6BMe)(CO)3]- (4a) and [Mo(eta5-2,4-MeC9H6BNi-Pr2)(CO)3]- (4b), a boratabenzene, in [Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3]- (6) or a dimethylaminocyclopentadienyl ligand, in [Mo(eta5-C5H4NMe2)(CO)3]- (7), toward palladium(II), gold(I), mercury(II) and platinum(II) complexes has allowed an evaluation of the role of these pi-bonded ligands on the structures and unprecedented coordination modes observed in the resulting metal-metal bonded, heterometallic complexes. The new metallate 6 was reacted with [AuCl(PPh3)], and with 1 or 2 equiv. HgCl2, which afforded the new heterodinuclear complexes [Au{Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3}(PPh3)] (Mo-Au) (10) and [Hg{Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3}Cl] (Hg-Mo) (11) and the heterometallic chain complex [Hg{Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3}2] (Mo-Hg-Mo) (12), respectively. Reactions of the new metallate 7 with HgCl2, trans-[PtCl2(CNt-Bu)2] and trans-[PtCl2(NCPh)2] yielded the heterodinuclear complex [Hg{Mo(eta5-C5H4NMe2)(CO)3}Cl] (Mo-Hg) (15), the heterotrinuclear chain complexes trans-[Pt{Mo(eta5-C5H4NMe2)(CO)3}2(CNt-Bu)2] (Mo-Pt-Mo) (16) and trans-[Pt{Mo(eta5-C5H4NMe2)(CO)3}2(NCPh)2] (Mo-Pt-Mo) (17), the mononuclear complex [Mo(eta5-C5H4NMe2)(CO)3Cl] (18), the lozenge-type cluster [Mo2Pt2(eta5-C5H4NMe2)2(CO)8] (19) and the heterodinuclear complex [[upper bond 1 start]Pt{Mo(eta5-C5H4N[upper bond 1 end]Me2)(CO)3}(NCPh)Cl](Mo-Pt) (20), respectively. The complexes 11, 16, 17.2THF, 18 and 20 have been structurally characterized by X-ray diffraction and 20 differs from all other compounds in that the dimethylaminocyclopentadienyl ligand forms a bridge between the metals.     

New heterobimetallic and polymeric selenocarboxylates derived from [M(SeC{O}Ph)4]- (M = Ga and In) as molecular precursors for ternary selenides

(Et3NH)[In(SeC{O}Ph)4].H2O (1) along with heterobimetallic and polymeric metal selenocarboxylates, namely [NaGa(SeC{O}Ph)4] (2), [K(MeCN)2Ga(SeC{O}Ph)4] (3), [NaIn(SeC{O}Ph)4] (4), [K(MeCN)2In(SeC{O}Ph)4] (5), [(Ph3P)2CuIn(SeC{O}Ph)4].CH2Cl2 (6), and [(Ph3P)2AgIn(SeC{O}Ph)4].CH2Cl2 (7), have been synthesized by incorporating either alkali metal ions (Na+ and K+) or group 11 metal ions (Cu(I) and Ag(I)) into the [M(SeC{O}Ph)4]- anion. Crystal structures determined by X-ray crystallography indicate that 3 and 5 have one-dimensional coordination polymeric structures while 6 and 7 have an M(mu-Se)2In (M = Cu, Ag) core. The thermal decomposition of these compounds except 4 lead to the formation of the corresponding metal selenides as confirmed by thermogravimetric analysis and in some cases by powder X-ray diffraction studies.     

两种异金属链状配位聚合物的合成和晶体结构

在甲醇溶液中,将K2NiL·H2O和M(OAC)2(M = Co,Zn)按1:1的摩尔比进行组装反应,得到了镍、钴和镍、锌两种异金属一维链状配位聚合物,其化学组成分别为{[Ni2Co2L2(H2O)2]·CH3OH·3H2O}n（1）和{[Ni2Zn2L2 (H2O)2]·2CH3OH·H2O}n（2）,（H4L=2-羟基-3-[(E)-({2-(2-羟基苯甲酰胺基)乙基}亚氨基)甲基]苯甲酸,OAC- = CH3COO-）。通过IR谱,元素分析的方法对其进行了表征,利用X-射线单晶衍射方法对其晶体结构进行了测定,结构分析表明：它们都是由不对称四核单元组成链状配位聚合物。     

Cr(N)Cl4]2-: a simple nitrido complex synthesized by nitrogen-atom transfer

A new general route to nitrido complexes of Cr(V) based on nitrogen-atom transfer from Mn(N)(salen) to labile CrCl3(THF)3 is presented. By this approach, the simplest nitrido complex of a first row transition metal, [Cr(N)Cl4]2-, has been synthesized and isolated. [[N(CH3)4]2[Cr(N)Cl4].H2O crystallizes in the cubic space group Fm-3m with disordered anions. Cr-N is 1.555(19) A, Cr-Cl is 2.2912(16) A, and N-Cr-Cl is 101.24(4) degrees . The orbital splitting scheme of [Cr(N)Cl4]2- is extreme with the dx2-y2 orbital 10 000 cm-1 lower in energy than the degenerate {dzx, dyz} set of orbitals destabilized by pi-bonding with the nitrido ligand. Hydrolysis of [Cr(N)Cl4]2 preserves the {CrN}2+ moiety.     

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.