From a monomer to a protein-sized, doughnut-shaped coordination oligomer-the influence of side chains of C3-symmetric ligands in supramolecular chemistry

Herein we describe the importance of side chains in C3-symmetric ligands in supramolecular chemistry. The reaction of the new ligand tris(5-bromo-2-methoxybenzylidene)triaminoguanidinium chloride [H3Me3Br3L]Cl (1) with ZnCl2 results in the formation of the monomeric complex (Et3NH)2[(ZnCl2)3Me3Br3L] (2), in which the ligand remains in a conformation less favourable for the coordination of metal centres. The use of the related tris(5-bromo-2-hydroxybenzylidene)triaminoguanidinium chloride, [H6Br3L]Cl, under similar conditions, results in the formation of two different dimeric compounds (NH4)[{[Zn(NH3)]3Br3L}2{mu-(OH)}3]1/4MeOH (3) and [Zn{Zn2(OH2)3(NH3)Br3L}2] (4), depending on the solvent mixture used. The comparable reaction of the ligand tris(5-bromo-2-hydroxy-3-methoxybenzylidene)triaminoguanidinium chloride [H6(OMe)3Br3L]Cl (5), leads to the formation of a doughnut-shaped, protein-sized coordination oligomer (Et3NH)18[{Zn[Zn2Cl{(OMe)3Br3L}]2}6(mu-Cl)6(OH2)6]x CH3CN (6), which comprises six dimeric [Zn5{(OMe)3Br3L}2] units. Whereas 3 and 4 decompose in DMSO solution, 6 is surprisingly stable in the same solvent.     

Synthesis of new copper cyanide complexes via the transformation of organonitrile to inorganic cyanide

Hydrothermal reaction of diaminomaleonitrile and copper salts under different conditions resulted in copper cyanide coordination polymers {[Cu(H 2O)(NH 3) 4][Cu 3(CN) 5].H 2O} n ( 1), {(CH 3) 4N[Cu(H 2O)(NH 3) 4][Cu 4(CN) 7]} n ( 2), and {(CH 3OH 2) 2[Cu 2(CN) 3]} n ( 3). 1 and 2 are new mixed-valence Cu(I,II), two 3D organic-inorganic molecular framework complexes that exhibit ionic inclusion. 3 is an open copper cyanide framework hosting a guest molecule. Cyanides in 1, 2, and 3 are produced by in situ C-C bond cleavage of diaminomaleonitrile, and then the remaining product is oxidized to form an oxalate group. The potential porosity of the hydrated coordination polymer 3 was estimated using a computational method based on Connolly's algorithm.     

Syntheses of highly fluorinated 1,3,5-triazapentadienyl ligands and their use in the isolation of copper(I)-carbonyl and copper(I)-ethylene complexes

Fully fluorinated triazapentadienyl ligand [N{(C3F7)C(C6F5)N}2]- and the related [N{(C3F7)C(2-F,6-(CF3)C6H3)N}2]- have been synthesized in good yield via a convenient route and used in the isolation of three- and four-coordinate copper(I)-carbon monoxide complexes. They show fairly high nu(CO) values (>2100 cm(-1)), indicating the presence of electron-poor Cu sites. The copper(I)-ethylene adduct [N{(C3F7)C(C6F5)N}2]Cu(C2H4), featuring a three-coordinate Cu site, has also been synthesized using [N{(C3F7)C(C6F5)N}2]CuNCCH3 and C2H4.     

Gold(I) ethylene and copper(I) ethylene complexes supported by a polyhalogenated triazapentadienyl ligand

A rare gold(I) ethylene complex and the closely related copper(I) ethylene adduct have been isolated using [N{(C3F7)C(2,6-Cl2C6H3)N}2]- as the supporting ligand. [N{(C3F7)C(2,6-Cl2C6H3)N}2]Au(C2H4) (1) is an air-stable solid. It features a U-shaped triazapentadienyl ligand backbone and a three-coordinate, trigonal-planar gold center. The copper(I) adduct [N{(C3F7)C(2,6-Cl2C6H3)N}2]Cu(C2H4) (2) also has a similar structure. The 13C NMR signal corresponding to the ethylene carbons of 1 appears at about 64 ppm upfield from the free ethylene, while the ethylene carbons of 2 show a relatively smaller (39 ppm) upfield shift. [N{(C3F7)C(2,6-Cl2C6H3)N}2]M(C2H4) (M=Cu, Au) mediate carbene-transfer reactions from ethyl diazoacetate to saturated and unsaturated hydrocarbons.     

Synthesis and reactivity of uranium(IV) amide complexes supported by a triamidotriazacyclononane ligand

Reaction of [U{(SiMe2NPh)3-tacn}Cl] with LiNEt2 or LiNPh2 affords the corresponding amide compounds, [U{(SiMe2NPh)3-tacn}(NR2)] (R = Et (1), R = Ph (2)). The complexes have been fully characterized by spectroscopic methods and the solid-state structure of 1 was determined by single-crystal X-ray diffraction analysis. The six nitrogen atoms of the tris(dimethylsilylanilide)triazacyclononane ligand are in a trigonal prismatic configuration with the nitrogen atom of the diethylamide ligand capping one of the trigonal faces of the trigonal prism. Crystallization of 2 from CH3CN solution gave crystals of the six-membered heterocycle [U{(SiMe2NPh)3-tacn}{kappa2-(HNC(Me))2CC[triple bond]N}] (3). The reactivity of the amides was investigated. Both compounds undergo acid-base reactions with protic substrates such as HOC6H2-2,4,6-Me3, 3,5-Me2pzH (pz = pyrazolyl) and HSC5H4N to give the corresponding [U{(SiMe2NPh)3-tacn}X] (X = OC6H2-2,4,6-Me3 (4), 3,5-Me2pzH (5), kappa2-SC5H4N (6)) complexes. The solid-state structures of and were determined by single-crystal X-ray diffraction and revealed that the compounds are eight-coordinate with dodecahedral geometry.     

Structural diversity within analogous compounds: syntheses and studies of M(SCH2CH2NH2)Cl (M = Zn, Cd, Hg)

The novel complexes [Zn(L)Cl] (1), [Cd(L)Cl] (2), [Hg(L)Cl] (3), {[Hg(L)Cl].NaOH.2H2O} (3.NaOH.2H2O), and {[Hg3(HL)2Cl6].2H2O} (4) (L = -SCH2CH2NH2) were prepared and investigated by means of IR spectroscopy and single-crystal X-ray diffraction. The crystal structures of 1, 2, and 3.NaOH.2H2O show chelating N,S-coordination of the cysteaminate ligand, bridging S, and terminally coordinating Cl. Apart from these common features, the coordination geometries and modes of intermolecular association are different. 1 forms a cyclic tetramer with a Zn4S4 ring, and 3.NaOH.2H2O contains one-dimensional [Hg(L)Cl]n chains with S-bridged Hg atoms. Zn and Hg atoms in 1 and 3.NaOH.2H2O are tetracoordinate with a distorted tetrahedral M(ClNS2) geometry (M = Zn, Hg). Each Cd atom of 2 binds to three S atoms and vice versa, such that layers of distorted Cd3S3 hexagons are formed. 2 is the first example for a compound exhibiting a group 12-group 16 layer structure, which can be described as an analogue of a graphite layer. Additionally, each Cd atom binds to a chlorine atom and a nitrogen atom from a cysteaminate ligand resulting in pentacoordination with a distorted trigonal bipyramidal Cd(ClNS3) geometry. 4 contains two differently coordinate Hg atoms. One displays a distorted trans-octahedral Hg(Cl4S2) geometry, while the other is coordinated by four Cl atoms and one S atom and additionally forms a long Hg...Cl contact.     

Saccharinate as a versatile polyfunctional ligand. Four distinct coordination modes, misdirected valence, and a dominant aggregate structure from a single reaction system

The reaction system consisting of copper, saccharinate, and the auxiliary ligands H(2)O, PPh(3), and NH(3) produces a sequence of compounds in which saccharinate is coordinated to copper in four distinct manners. The complex trans-[Cu(sacch)(2)(H(2)O)(4)] (2) (produced by thermal dehydration of trans-[Cu(sacch)(2)(H(2)O)(4)].2H(2)O (1)) reacts with triphenylphosphine in CH(2)Cl(2) to produce any or all of three Cu(I) complexes, depending upon conditions. The three Cu(I) compounds are Cu(sacch)(PPh(3))(3) (3), in which saccharinate binds to copper through the carbonyl group of the ligand, Cu(sacch)(PPh(3))(2) (4), in which sacch binds to Cu through its charge-bearing nitrogen atom; and [Cu(sacch)(PPh(3))](2) (5), a dinuclear complex in which saccharinate bridges two Cu centers through its imidate nitrogen and carbonyl oxygen atoms. Complexes 3-5 can be isolated individually, although in solution they exist in a complex equilibrium which has been examined by NMR spectroscopy. Each of the three Cu(I) products reacts with NH(3) in CH(2)Cl(2) solution to produce trans-[Cu(sacch)(2)(NH(3))(4)] (6), an unstable Cu(II) complex that exhibits misdirected valence at the Cu-N(sacch) bond. Complex 6 evolves spontaneously to [Cu(sacch)(NH(3))(4)](sacch).H(2)O (7), which in the solid state is dominated by a supramolecular aggregate of two formula units, linked by hydrogen bonding in which the water molecule plays a central role. Alternative pathways exist to several of the products. The X-ray crystal structure analyses of 3-7 are reported and establish the coordination modes of saccharinate, the misdirected valence in 6, and the supramolecular aggregation in 7. The structure analysis of 7 by single-crystal neutron diffraction is reported and together with the previously reported neutron structure analysis of 1 establishes the substitution of the auxiliary ligand H(2)O by NH(3) in the Cu(II) products.     

Copper(I) and mercury(II) halide complexes of 1,2-bis(diphenylthioylphosphino)hydrazine

The reaction of 1,2-bis(diphenylthioylphosphino)hydrazine (L) with copper(I) and mercury(II) halides affords the complexes, [{CuLX}₂] (X = I, Br or Cl), [HgLX₂] (X = Cl or Br) and the tetrametallic complex, [{L(HgI₂)₂}₂]. Single crystal X-ray structures have been performed on the uncoordinated ligand, L, as well as the complexes [{CuLX}₂] (X = I, Br and Cl), [HgLBr₂] and [{L(HgI₂)₂}₂. The molecules of L exist as dimers as a result of pairs of N–HS hydrogen bonds. The copper(I) complexes are centrosymmetric dimetallic species, the two copper atoms being bridged by L and the X atoms. In all cases the coordination sphere around the Cu atoms is approximately trigonal pyramidal with an ‘S₂X₂’ donor set. The complex, [HgLBr₂], is a distorted tetrahedral monomer with an ‘S₂Br₂’ donor set and L acting as a bidentate thus forming a seven-membered chelate ring. The tetramercury iodo complex, [{L(HgI₂)₂}₂], contains two ‘L(HgI₂)₂’ units linked centrosymmetrically via an I atom from each moiety. The geometry around the Hg atoms is distorted tetrahedral. The influence of hydrogen bonding between the hydrazine backbone hydrogens of L and the coordinated halide ions in for the structures of the metal complexes is discussed.     

Synthesis of a chelating hexadentate ligand with a P3N3 donor set. Crystal and molecular structure of [OC-6-22]-[Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}](PF6)3

The first structurally authenticated example of a hexadentate chelating tertiary phosphine in which all six donors are bound to a single metal centre is described. The multidentate ligand (RP*,RP*,RP*)- and (RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3 has been prepared in 80% yield via the reaction of five equivalents of sodium (2-aminophenyl)phenylphosphide (generated in situ from (2-aminophenyl)phenylphosphine and sodium in thf) with 1,1,1-tri(bromomethyl)ethane in thf. The diastereomeric mixture has been complexed to cobalt(III) and the resulting pair of complexes, viz. [Co{(RP*,RP*,RP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl3 and [CoCl{(RP*,RP*,SP*)-CH3C(CH2PPhC6H4NH2-2)3}]Cl2, separated by ion exchange chromatography. The structure of the former (as the corresponding hexafluorophosphate salt) has been confirmed by X-ray crystallography and clearly shows all six donors of the P3N3 ligand coordinated to a single cobalt(III) centre. The related hexadentate ligand with internal N donors and terminal diphenylphosphino groups, viz. CH3C(CH2NHC6H4PPh2-2)3, has also been synthesised, albeit in low yield, via the reaction of [Li(tmeda)][2-NHC6H4PPh2] (generated in situ from (2-aminophenyl)diphenylphosphine, n-butyllithium and tmeda in diethyl ether) with 1,1,1-tri(iodomethyl)ethane in thf. No formation of a P3N3 ligand has been observed when either Na[2-PPhC6H4NH2] or [Li(tmeda)][2-NHC6H4PPh2] is reacted with the related tripodal substrate 1,1,1-tris(tolyl-4-sulfonyloxymethyl)ethane in thf. Rather the P-methyloxetane (+/-)-[3-{(2-aminophenyl)phenylphosphinomethyl}]-3-methyloxetane and the sulfonamide 2-(4-CH3C6H4SO2)NHC6H4PPh2 and the corresponding N-methyloxetane [3-{(2-diphenylphosphinophenyl)aminomethyl}]-3-methyloxetane have been isolated from the respective reactions. The structure of the sulfonamide has been confirmed by an X-ray analysis of the platinum(II) complex trans-[PtCl(CH3){2-PPh2C6H4NH(SO2C6H4CH(3-4)}2].     

Electronic and structural variation among copper(II) complexes with substituted phenanthrolines

A series of copper(II) complexes with substituted phenanthroline ligands has been synthesized and characterized electronically and structurally. The compounds that have been prepared include the monosubstituted ligand complexes of the general formula [Cu(5-R-phen)(2)(CH(3)CN)](BF(4))(2), where R = NO(2), Cl, H, or Me, and the disubstituted ligand complex [Cu(5,6-Me(2)-phen)(2)(CH(3)CN)](BF(4))(2). The complexes [Cu(5-NO(2)-phen)(2)(CH(3)CN](BF(4))(2) (1), [Cu(5-Cl-phen)(2)(CH(3)CN)](BF(4))(2) (2), [Cu(o-phen)(2)(CH(3)CN)](BF(4))(2) (3), and [Cu(5-Me-phen)(2)(CH(3)CN)](BF(4))(2) (4) each crystallize in the space group C2/c with compounds 1, 2, and 4 comprising an isomorphous set. The disubstituted complex [Cu(5,6-Me(2)-phen)(2)(CH(3)CN)](BF(4))(2) (5) crystallizes in the space group P2(1)/c. Each structure is characterized by a distorted trigonal bipyramidal arrangement of ligands around the central copper atom with approximate or exact C(2) symmetry. The progression from electron-withdrawing to electron-donating substituents on the phenanthroline ligands correlates with less accessible reduction potentials for the bis-chelate complexes.     

Synthesis and Crystal Structure of {(PPh3)2ClRu(μ-Cl)-Ru(PPh3)B10H7[OCH(CH3)2]3}·0.4(H2O)

The title compound has been synthesized by the reaction of [RuCl2(PPh3)3] and closo-[B10H10]2- in (CH3)2CHOH solution. Crystals suitable for a single crystal X-ray diffraction analysis were obtained from n-pentane diffused to CH2Cl2 solution. The crystal {(PPh3)2ClRu(μ-Cl)Ru(PPh3)B10H7[OCH(CH3)2]3}·0.4(H2O) is monoclinic , space group P21/n , Mr=1359.47, with a=19.434(4), b =14.340(4), c=25.865(9)(A), β= 95.48(3)°, V=7175(4)(A)3, Dc=1.258 g/cm3, Z=4, λ(MoKα)=0.71073(A),μ=6.03 cm-1, F(000)=2784, R=0.0631, wR2= 0.1425, S=1.001. The title compound is a bimetallic species in which the second ruthenium center is bound to the cluster {(PPh3)RuB10H7[OCH(CH3)2]3} via an Ru-Cl-Ru and two Ru-H-B-Ru bridges. The third isoproxy group replaces a hydrogen atom on B(10) of the cage, which indicates the activity of the cage.     

Proton and anion control of framework complexity in copper(II) complex structures derived from 2-(hydroxymethyl)pyridine

Three copper(II) complexes derived from 2-(hydroxymethyl)pyridine (LH) have been synthesised and a comparative X-ray investigation of their respective crystal structures undertaken. In the absence of added base, LH reacts with copper(II) chloride or nitrate to yield the five-coordinate [Cu(LH)₂Cl]Cl and six-coordinate [Cu(LH)₂(NO₃)₂] species. In the chloro complex the coordination geometry is distorted trigonal bipyramidal, with the pyridyl nitrogens occupying the axial position and two hydroxyl oxygens from the bidentate ligands together with a chloro group occupying the equatorial sites. The structure of the nitrate species, published previously, has been reinvestigated at low temperature in order to specify the weak interactions in the crystal; it contains two molecules of bidentate LH bound trans in the equatorial plane while monodentate nitrato ligands occupy the axial sites. In each of these complexes the hydroxyl protons act as hydrogen bond donors, interacting with the non-coordinated chloride anion in [Cu(LH)₂Cl]Cl and the coordinated nitrato groups in [Cu(LH)₂(NO₃)₂] to form bridged, hydrogen-bonded, copper(II)-organic arrays in each case; offset face-to-face π-stacking in the latter produces a two dimensional structure. Further weak CH?Cl, CH?O interactions stabilise both arrangements. The X-ray structure of the complex [Cu(L)₂] · 4H₂O containing the deprotonated ligand is also described. The presence of the latter results in the above hydrogen bonding arrangements being ‘switched off’ and instead a new two-dimensional network involving bridging tetrameric water clusters hydrogen bound to adjacent ligand hydroxo groups to give extended sheets is generated; offset face-to-face π-stacking occurs between sheets to yield a three dimensional array.     

Alkali metal complexes of sterically hindered mono- and di-carbanions containing Si-O bonds

The oxygen-bridged, silicon-substituted alkane {(Me3Si)2CH(SiMe2)}2O (1) may be prepared by the reaction of {(Me3Si)2CH}Li with ClSiMe2OSiMe2Cl in refluxing THF. Similarly, the alkane {(Me3Si)(Me2MeOSi)CH(SiMe2CH2)}2 (2) is readily accessible from the reaction between {(Me3Si)(Me2MeOSi)CH}Li and ClSiMe2CH2CH2SiMe2Cl under the same conditions. Compound 1 reacts with two equivalents of MeK to give the polymeric complex [[{(Me3Si)2C(SiMe2)}2O]K2(OEt2)]infinity [5(OEt2)] after recrystallisation. Treatment of 2 with two equivalents of either MeLi or MeK gives the corresponding complexes [{(Me3Si)(Me2MeOSi)C(SiMe2CH2)}2Li][Li(DME)3] [7(DME)3] and [{(Me3Si)(Me2MeOSi)C(SiMe2CH2)}2K2]n (8), respectively, after recrystallisation. Treatment of the alkane (Me3Si)2(Me2MeOSi)CH with one equivalent of MeK gives the polymeric complex [{(Me3Si)2(Me2MeOSi)C}K]infinity (3). These compounds have been identified by 1H and 13C{1H} NMR spectroscopy and elemental analyses and compounds 5(OEt2), 7(DME)3 and 3 have been further characterised by X-ray crystallography. Compound 7(DME)3 crystallises as a solvent-separated ion pair, whereas 5(OEt2) and 3 adopt polymeric structures in the solid state.     

A non-heme dinuclear iron(II) complex containing a single, unsupported hydroxo bridge

Complexation of the tetrapodal pentadentate NN4 ligand 2,6-C5H3N[CMe(CH2NH2)2]2 (I) with iron(II) perchlorate hydrate in methanol, in the presence of N-methylimidazole, produces a diferrous complex with a single, unsupported mu-OH ligand between two {(I)FeII} coordination modules.     

Versatility of heterocyclic thioamides in the construction of a trinuclear cluster [Cu3I3(dppe)3 (SC5H4NH)] and Cu(I) linear polymers {Cu6(SC5H4NH)6I6}n x 2nCH3CN and {Cu(I)6 (SC3H6N2)6X6}n (X = Br, I)

Reaction of copper(I) iodide with pyridine-2-thione (2-SC5H4NH) and 1,2-bis(diphenylphosphino)ethane (dppe) in a CH3CN-CHCl3 mixture yielded a triangular cluster, [Cu3I3(mu2-P,P-dppe)3 (eta1-SC5H4NH)], 1. Similar reaction with 2-SC5H4NH and a series of diphosphanes, Ph2P-X-Ph2P {X = -CH2- (dppm), -(CH2)3- (dppp), -(CH2)4- (dppb), -CH=CH- (dppen)}, gave a novel iodo-bridged hexanuclear Cu(I) linear polymer,{Cu6(mu3-SC5H4NH)4 (mu2-SC5H4NH)2 (I4)(mu-I)2-}n x 2nCH3CN, 2. Reactions of copper(I) iodide/copper(I) bromide with 1,3-imidazolidine-2-thione (SC3H6N2) in a CH3CN-CHCl3 mixture yielded hexanuclear Cu(I) linear chain polymers, [{Cu6(mu3-SC3H6N2)2 (mu2-SC3H6N2)4X2 (mu-X)4}n] (X = Br, 4; I, 5). In compound 1, two iodide atoms and one dppe form the dinuclear Cu(mu2-I)2 (mu2-dppe)Cu core, and two dppe ligands bridge this core with the third Cu(I) center coordinated to 2-SC5H4NH via the S atom. The chain polymer 2 has a centrosymmetric hexanuclear central core, Cu6S6I4 (mu-I)2--, formed by dimerization of six-membered trinuclear motifs, Cu3(mu2-SC3H6N2)3I3 via (mu3-S) bonding modes of the thione ligand, and has four terminal and two bridging iodine atoms in trans-orientations. Linear chains are separated by the nonbonded acetonitrile molecules. In 4 and 5, three copper(I) bromide or copper(I) iodide moieties and three SC3H6N2 ligands combined via bridging S donor atoms to form the six-membered trinuclear Cu3(mu2-SC3H6N2)3I3 cores which polymerized via S and X atoms in a side-on fashion to form linear chain polymers, [{Cu6(mu3-SC3H6N2)2 (mu2-SC3H6N2)4X2(mu-X)4}n]. The (mu3-S) modes of bonding of neutral heterocyclic thioamides are first examples, as are trinuclear cluster and linear polymers rare examples in copper chemistry.     

Yttrium and lanthanide complexes with various P,N ligands in the coordination sphere: synthesis, structure, and polymerization studies

Yttrium and lanthanide complexes with different P,N ligands in the coordination sphere have been synthesized. First the chloride complexes [{CH(PPh2NSiMe3)2}Ln{(Ph2P)2N}Cl] (Ln = Y (1 a), La (1 b), Nd (1 c), Yb (1 d)) having the bulky [CH(PPh2NSiMe3)2]- and the flexible [(Ph2P)2N]- ligands in the same molecule were prepared by three different synthetic pathways. Compounds 1 a-d can be obtained by reaction of [{[CH(PPh2NSiMe3)2]LnCl2}2] with [K(thf)nN(PPh2)2] (n = 1.25, 1.5) or by treatment of [{(Ph2P)2N}LnCl2(thf)3] with K[CH(PPh2NSiMe3)2]. Furthermore, a one-pot reaction of K[CH(PPh2NSiMe3)2] with LnCl3 and [K(thf)nN(PPh2)2] leads to the same products. Single-crystal X-ray structures of 1 a-d show that the conformation of the six-membered metallacycle (N1-P1-C1-P2-N2-Ln) which is formed by chelation of the [CH(PPh2NSiMe3)2]- ligand to the lanthanide atom is influenced by the ionic radius of the central metal atom. In solution dynamic behavior of the [(Ph2P)2N]- ligand is observed, which is caused by rapid exchange of the two different phosphorus atoms. Further reaction of 1 b with KNPh2 resulted in [{(Me3SiNPPh2)2CH}La{N(PPh2)2}(NPh2)] (2). Compounds 1 a-d and 2 are active in the ring-opening polymerization of epsilon-caprolactone and the polymerization of methyl methacrylate. In some cases high molecular weight polymers with good conversions and narrow polydispersities were obtained. In both polymerizations the catalytic activity depends on the ionic radius of the metal center.     

Structures and redox reactivities of copper complexes of (2-pyridyl)alkylamine ligands. Effects of the alkyl linker chain length

Ligand effects on the structures and redox reactivities of copper complexes have been examined using (2-pyridyl)alkylamine derivatives as the supporting ligands, where particular attention has been focused on the effects of the alkyl linker chain length connecting the tertiary amine nitrogen atom and the pyridine nucleus: N[bond]CH(2)[bond]Py (Pym) vs N[bond]CH(2)CH(2)[bond]Py (Pye). X-ray crystallographic analysis of the copper(I) complex of tridentate ligand (Phe)L(Pym2) [N,N-di(2-pyridylmethyl)-2-phenylethylamine] (complex 1) has demonstrated that it possesses a trigonal pyramidal geometry in which a d[bond]pi interaction with an eta(1)-binding mode exists between the metal ion and one of the ortho carbons of the phenyl ring of the ligand side arm (phenethyl). The result shows sharp contrast to the d[bond]pi interaction with an eta(2)-binding mode existing in the copper(I) complex of (Phe)L(Pye2) [N,N-di[2-(2-pyridyl)ethyl]-2-phenethylamine] (complex 2). Such a d-pi interaction has been shown to affect the stability of the copper(I) complex in CH(2)Cl(2). Oxygenation of copper(I) complex 1 supported by (Phe)L(Pym2) produces a bis(mu-oxo)dicopper(III) complex, also being in sharp contrast to the case of the copper(I) complex 2 with ligand (Phe)L(Pye2), which preferentially affords a (micro-eta(2):eta(2)-peroxo)dicopper(II) complex in the reaction with O(2). Such an effect of the alkyl linker chain length of the metal binding site has also been found to operate in the RSSR (disulfide)/2RS(-) (thiolate) redox system. Namely, ligand (S2,R)L(Pym1) (di[2-[(alkyl)(2-pyridinylmethyl)amino]ethyl] disulfide) with the methylene linker group (Pym) induced the reductive disulfide bond cleavage in the reaction with copper(I) ion to give a bis(micro-thiolato)dicopper(II) complex, while the ligand with the ethylene linker group (Pye), (S2,Bn)L(Pye1) (di[2-[(benzyl)(2-(2-pyridinyl)ethyl)amino]ethyl] disulfide), gave a disulfide-dicopper(I) complex. These ligand effects in the Cu(2)[bond]O(2) and Cu(2)[bond]S(2) systems have been discussed by taking into account the difference in electron-donor ability of the pyridine nucleus between the Pym and Pye ligand systems.     

Selenium-centered, undecanuclear silver cages surrounded by iodo and dialkyldiselenophosphato ligands. Syntheses, structures, and photophysical properties

Three clusters [Ag11(mu9-Se)(mu3-I)3{Se2P(OR)2}6] (R = Et, 1; iPr, 2; 2Bu, 3) were isolated from the reaction of [Ag(CH3CN)4](PF6), NH4[Se2P(OR)2], and Bu4NI in a molar ratio of 4:3:1 in CH2Cl2 in 47-55% yield. Compounds 1 and 2 can also be synthesized with high yield from the reaction of Ag10(Se)[Se2P(OR)2]8 with 8 equiv of Bu4NI. In the positive fast atom bombardment mass spectra of 1-3, two major peaks that correspond to the intact molecule with the loss of an iodide ion, [Ag11(mu9-Se)(mu3-I)(2){Se2P(OR)2}6]+, and a diselenophosphate ligand, [Ag11(mu9-Se)(mu3-I)3{Se2P(OR)2}5]+, were identified. Single-crystal X-ray analyses of 2 and 3 reveal an Ag11Se core stabilized by three iodide anions and six diselenophosphato ligands in a tetrametallic tetraconnective (mu2,mu2) coordination mode. The central core adopts the geometry of a 3,3,4,4,4-pentacapped trigonal prism with a selenium atom in the center. In addition, weak intermolecular Se...I interactions exist in 2 and form a one-dimensional polymeric chain structure. Furthermore, all compounds exhibit orange-red luminescence in both the solid state and solution.     

Metal aminocarboxylate coordination polymers with chain and layered structures

The synthesis and structures of metal aminocarboxylates prepared in acidic, neutral, or alkaline media have been explored with the purpose of isolating coordination polymers with linear chain and two-dimensional layered structures. Metal glycinates of the formulae [CoCl2(H2O)2(CO2CH2NH3)] (I), [MnCl2(CO2CH2NH3)2] (II), and [Cd3Cl6(CO2CH2NH3)4] (III) with one-dimensional chain structures have been obtained by the reaction of the metal salts with glycine in an acidic medium under hydro/solvothermal conditions. These chain compounds contain glycine in the zwitterionic form. 4-Aminobutyric acid transforms to a cyclic amide under such reaction conditions, and the amide forms a chain compound of the formula [CdBr2(C4H7NO)2] (IV). Glycine in the zwitterionic form also forms a two-dimensional layered compound of the formula [Mn(H2O)2(CO2CH2NH3)2]Br2 (V). 6-Aminocaproic acid under alkaline conditions forms layered compounds with metals at room temperature, the metal being coordinated both by the amino nitrogen and the carboxyl oxygen atoms. Of the two layered compounds [Cd{CO2(CH2)5NH2}2]2 H2O (VI) and [Cu{CO2(CH2)5NH2}2]2 H2O (VII), the latter has voids in which water molecules reside.     

Formation of intramolecular rings in ferramonocarbollide complexes

Addition of PPh 2Cl and Tl[PF 6] to CH 2Cl 2 solutions of [N(PPh 3) 2][6,6,6-(CO) 3- closo-6,1-FeCB 8H 9] ( 1) affords the isomeric B-substituted species [6,6,6-(CO) 3- n-(PHPh 2)- closo-6,1-FeCB 8H 8] [ n = 7 ( 2a) or 10 ( 2b)]. Deprotonation (NaH) of the phosphine ligand in 2a, with subsequent addition of [IrCl(CO)(PPh 3) 2] and Tl[PF 6], yields the neutral, zwitterionic complex [6,6,6-(CO) 3-4,7-mu-{Ir(H)(CO)(PPh 3) 2PPh 2}- closo-6,1-FeCB 8H 7] ( 3), which contains a B-P-Ir- B ring. Alternatively, deprotonation using NEt 3, followed by addition of HC[triple bond]CCH 2Br, affords [6,6,6-(CO) 3-7-(PPh 2CCMe)- closo-6,1-FeCB 8H 8] ( 4). Addition of [Co 2(CO) 8] to CH 2Cl 2 solutions of the latter gives [6,6,6-(CO) 3-7-(PPh 2-{(mu-eta (2):eta (2)-CCMe)Co 2(CO) 6})- closo-6,1-FeCB 8H 8] ( 5), which contains a {C 2Co 2} tetrahedron. In the absence of added substrates, deprotonation of the PHPh 2 group in compounds 2, followed by reaction of the resulting anions with CH 2Cl 2 solvent, affords [6,6,6-(CO) 3- n-(PPh 2CH 2Cl)- closo-6,1-FeCB 8H 8] [ n = 7 ( 6a) or 10 ( 6b)] plus [6,6-(CO) 2-6,7-mu-{PPh 2CH 2PPh 2}- closo-6,1-FeCB 8H 8] ( 7, formed from 2a), of which the latter species possesses an intramolecular B-P-C-P- Fe ring. Addition of Me 3NO to CH 2Cl 2 solutions of 2a causes loss of an Fe-bound CO ligand and formation of [6,6-(CO) 2-6,7-mu-{NMe 2CH 2PPh 2}- closo-6,1-FeCB 8H 8] ( 8), which incorporates a B-P-C-N- Fe ring. A similar reaction in the presence of ligands L yields [6,6-(CO) 2-6-L-7-(PPh 2CH 2Cl)- closo-6,1-FeCB 8H 8] [L = PEt 3 ( 9) or CNBu (t) ( 10)], in addition to 8.