Anti Arrangement Research Articles

Mechanistic Study of the Formation of a Phosphonate Ester Containing 2-Fluoroaniline: Theoretical Assignment of the Resulting Isomer

For the first time, theoretical calculations have been employed for assignment of the most stable isomers ([(2S*, 3S*) or (2R*, 3R*)] and [(2S*, 3R*) or (2R*, 3S*)] of a phosphonate ester containing 2-fluoroaniline at HF/6-31G(d,p) and B3LYP/6-311++G(d,p) levels of theory. The results were showed that the compound with gauche arrangement and [(2S*, 3S*) or (2R*, 3R*)] configuration was more stable than the anti arrangement with [(2S*, 3R*) or (2R*, 3S*)] geometry. In addition, experimental 1H, 13C and 31P NMR data along with X-ray crystallographic data of the compound were consistent with the results obtained from theoretical calculations. Kinetic studies were performed on the reaction between triphenyl phosphite, dialkylacetylene dicarboxylates in the presence of an NH-acid, namely as 2-fluoroaniline (as a protic/nucleophilic reagent) for the generation of the compound with a gauche arrangement and [(2S*, 3S*) or (2R*, 3R*)] configuration. Kinetic data were obtained spectrophotometrically and a temperature study yielded activation parameters. A mechanistic scheme is proposed which fits all the kinetic data.

Isolation and structure of the anti,anti isomer and a DFT study of it and the syn,anti isomer of bis(tricarbonylchromium)dibenzo-[a,e]cyclooctatetraene. Evidence for an attractive electrostatic interaction between carbonyl oxygen atoms and Cr(CO)3-coordinated arene carbon atoms

When dibenzo[a,e]cyclooctatetraene and hexacarbonylchromium are refluxed in di-n-butyl ether/THF for an extended period, both the syn,anti and anti,anti isomers of the bis-tricarbonylchromium complex are obtained. After separation by column chromatography, the syn,anti:anti,anti isomer ratio is approximately 12:1. The anti,anti arrangement of the Cr(CO)3 groups was verified by X-ray crystallographic structure determination. The orientations of the two tricarbonylchromium tripods relative to the 1,2-disubstituted arene rings differ. One is exo staggered while the other is eclipsed. Intermolecular C–H⋯O hydrogen bonding is prevalent in the crystal and is reminiscent of the syn,anti isomer. A dimeric motif in the solid resulting from C–H⋯π interactions is observed. DFT calculations on both isomers confirms that the syn,anti isomer is favored. The preferred orientation for the anti Cr(CO)3 groups in both cases is exo staggered. However, the barrier to rotation is low, allowing hydrogen bonding to readily overcome this barrier and control the orientation of the tripod. While thermodynamic consideration support the preference for the syn,anti isomer, kinetic factors may also be important as this isomer would be formed preferentially due to steric inhibition of the diene coordination site by the mononuclear anti isomer. The stabilization of the syn,anti isomer occurs by an electrostatic attraction of the syn carbonyl groups with the anti Cr(CO)3-coordinated arene carbon atoms. A reexamination of the structural parameters verifies nonbonded carbon–oxygen distances less than the sum of the van der Waals radii in the syn,anti isomer. A search of the Cambridge Structural Database results in a significant number of interactions of this nature for arenetricarbonylchromium complexes.

Sterically tuned Ag(i)- and Pd(ii)-N-heterocyclic carbene complexes of imidazol-2-ylidenes: synthesis, crystal structures, and in vitro antibacterial and anticancer studies

Unsymmetrically substituted sterically tuned Pd(II)–NHC complexes of the general formula [PdCl2(NHC)2] (NHC = 1-allyl-3-methylimidazolin-2-ylidene, 7; 1-allyl-3-butylimidazol-2-ylidene, 8; 1-benzyl-3-butyl imidazolin-2-ylidene, 9) were prepared through transmetallation from their corresponding Ag(I)–NHC complexes. The Pd complexes were structurally characterized by different spectroscopic and X-ray diffraction methods. Complexes 7 and 9 adopted a trans–anti arrangement of the NHC ligands, whereas complex 8 adopted a cis–syn arrangement. Preliminary antibiogram studies using Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria showed that Ag(I)–NHC complexes demonstrate higher activity compared with Pd(I)–NHC complexes. Furthermore, Pd(II)–NHC complexes were evaluated for their anticancer potential using the human colorectal cancer cell line. A higher anticancer activity was observed for complexes 8 and 9, with 26.5 and 6.6 mM IC50 values, respectively.

Host-guest complexes between cryptophane-C and chloromethanes revisited

Cryptophane-C is composed of two nonequivalent cyclotribenzylene caps, one of which contains methoxy group substituents on the phenyl rings. The two caps are connected by three OCH2CH2O linkers in an anti arrangement. Host–guest complexes of cryptophane-C with dichloromethane and chloroform in solution were investigated in detail by nuclear magnetic resonance techniques and density functional theory (DFT) calculations. Variable temperature proton and carbon-13 spectra show a variety of dynamic processes, such as guest exchange and host conformational transitions. The guest exchange was studied quantitatively by exchange spectroscopy measurements or by line-shape analysis. The conformational preferences of the guest-containing host were interpreted through cross-relaxation measurements, providing evidence of the gauche+2 and gauche−2 conformations of the linkers. In addition, the mobility of the chloroform guest inside the cavity was studied by carbon-13 relaxation experiments. Combining different types of evidence led to a detailed picture of molecular recognition, interpreted in terms of conformational selection. Copyright © 2012 John Wiley & Sons, Ltd.

Bond-stretch isomerism in 2-chalcogen-trimetallabicyclo[1.1.0]butane derivatives

Electronic and steric factors that control the bond-stretch isomerism phenomenon in 2-chalcogen-trimetallabicyclo[1.1.0]butane systems have been investigated using quantum chemical calculations. Beside the short-bond and long-bond extremes we found and characterized a third, stable conformer with significantly elongated central bond and anti arrangement of the bridgehead substituents. Electronic structures of the isomers have been described and interpreted in details within the framework of MO theory. Germanium analogues of trisilirene have been predicted to also react with sulphur to form the corresponding 2-thia-trimetallabicyclo[1.1.0]butane analogues. The systematic analysis of the relative stability dependence on the ring composition as well as the bridgehead substituents revealed that the hitherto unknown anti isomer is a promising synthetic target in germanium bridged bicyclo compounds with bridgehead substituents containing carbon contact atom.

Highly Enantioselective Nitroaldol Reactions Catalyzed by Copper(II) Complexes Derived from Substituted 2-(Pyridin-2-yl)imidazolidin-4-one Ligands

Ten optically pure substituted 2-(pyridin-2-yl)imidazolidin-4-ones, 1a-d, 2a-4a, and 2b-4b, were prepared and characterized. The absolute configurations of individual ligands were determined by X-ray analysis or NOESY experiments. The Cu(II) complexes of the respective ligands were studied as enantioselective catalysts of the nitroaldol (Henry) reaction of aldehydes with nitromethane, giving the corresponding substituted 2-nitroalkanols. In the case of an anti arrangement of the imidazolidin-4-one ring, the obtained result was 91-96% ee, whereas in the case of syn arrangement, a significant drop to 25-27% ee was observed.

Self-assembly of square-lattice copper sheets displaying intra-ferromagnetism

A homoleptic copper(II) complex supported by methyliminodiacetate [ CH 3 N ( CH 2 COO ) 2 2 - = MIDA] has been prepared and characterized by elemental, infra-red, X-ray diffraction and magnetic methods. The complex assembles as a two-dimensional lattice in which the copper centers are arranged in a square grid, bridged by the carboxylate moieties of the ligand. [Cu II 4MIDA 4] ∞ crystallizes in the tetragonal system P-4 2 1 c ( a = 9.8943(5), b = 9.8943(5), c = 14.4687(7) Å, Z = 8, R = 0.0495). Each Cu II atom displays severely distorted square pyramidal geometry ( τ = 0.44) and is bridged to four additional copper centers by a syn–anti arrangement of the carboxylate groups. Within the sheet, the copper centers are separated by approximately 4.96 Å. The sheets are layered by arranging the copper squares directly on top of one another, resulting in parallel channels that extend throughout the material. Variable temperature magnetic susceptibility measurements reveal the presence of ferromagnetic exchange between the spin carriers within each two-dimensional sheet and antiferromagnetic exchange across the layers.

Cyclopalladated Complexes of Perylene Imine: Formation of Acetato-Bridged Dinuclear Complexes with 6,6- and 5,6-Membered Metallacycles

Perylene-3-carbaldehyde (1) was condensed with 4-ethylaniline to give 3-perilenylmetilen-4′-ethylaniline (2). The metalation reaction of 2 with palladium acetate, in toluene at 60 °C, produced a mixture of palladium complexes where the two major components, 3 and 4, have been characterized as acetate-bridged dimers. Complex 3 is made of two identical six-membered endo cyclometalated Pd(C∧N) moieties, in which the palladium is bound to the peri site with anti arrangement. Compound 4 is the first example combining six- and five-membered metallacycles in a dinuclear compound and adopts an unusual syn arrangement of metal ligands. The X-ray structures of 3 and 4 show π−π stacking of perylenyl rings, intermolecular for 3 and intramolecular for 4. The intramolecular π−π stacking in 4 has a detrimental effect on luminescence. The imine 2 and all the palladium complexes exhibit fluorescence associated with the perylene fragment, with emission quantum yields, in solution at room temperature, in the range 0.04−0.13 (and emission lifetimes ∼5 ns). The similarity of the luminescence spectral pattern of the imine and their metalated complexes to that of perylene, although red-shifted, strongly suggests a perylene-dominated intraligand π−π* emissive state, metal-perturbed by interaction of the palladium fragment.

Oligo‐m‐phenyleneoxalamide Copper(II) Mesocates as Electro‐Switchable Ferromagnetic Metal–Organic Wires

Double-stranded copper(II) string complexes of varying nuclearity, from di- to tetranuclear species, have been prepared by the Cu(II)-mediated self-assembly of a novel family of linear homo- and heteropolytopic ligands that contain two outer oxamato and either zero (1 b), one (2 b), or two (3 b) inner oxamidato donor groups separated by rigid 2-methyl-1,3-phenylene spacers. The X-ray crystal structures of these Cu(II) (n) complexes (n=2 (1 d), 3 (2 d), and 4 (3 d)) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN(2)O(2) and inner CuN(4) chromophores. Two such nonplanar all-syn bridging ligands 1 b-3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso-helicate-type architecture for 1 d-3 d. Variable-temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 d-3 d show the occurrence of S=nS(Cu) (n=2-4) high-spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed Cu(II) ions (S(Cu)=1/2) through the two anti m-phenylenediamidate-type bridges (J values in the range of +15.0 to 16.8 cm(-1)). Density functional theory (DFT) calculations for 1 d-3 d evidence a sign alternation of the spin density in the meta-substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7-2.2 nm. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) electrochemical measurements for 1 d-3 d show several reversible or quasireversible one- or two-electron steps that involve the consecutive metal-centered oxidation of the inner and outer Cu(II) ions (S(Cu)=1/2) to diamagnetic Cu(III) ones (S(Cu)=0) at relatively low formal potentials (E values in the range of +0.14 to 0.25 V and of +0.43 to 0.67 V vs. SCE, respectively). Further developments may be envisaged for this family of oligo-m-phenyleneoxalamide copper(II) double mesocates as electroswitchable ferromagnetic 'metal-organic wires' (MOWs) on the basis of their unique ferromagnetic and multicenter redox behaviors.

ChemInform Abstract: Stereoelectronic Control of the Base-Catalysed Rearrangement of 2- Hydroxy-3-oxocarboxylates.

The stereochemistry of the alkali-catalysed rearrangement of α-acetohydroxybutyrate (2-ethyl-2-hydroxy-3-oxobutanoate) was studied. The rearrangement was found to proceed via a transition state in which a syn arrangement of the C–O bonds is preferred over the anti arrangement by a factor of ≥2:1.

Reactions of Acetyl Radical with Acetylene - A Computational Study

‡ ) of 39.6 kJ mol -1 is predicted for the preferred anti arrangement of reactants at the CCSD(T)/cc-pVDZ//BHandHLYP/cc-pVDZ level of theory. NBO analysis reveals additional interactions between the radical SOMO and the nearby C-H σ-bond in acetylene worth about 10% of the total transition state interaction energy. This type of orbital interaction has not pre- viously been observed in radical addition reactions involving C-C π-bonds.

Multifaceted Coordination of Naphthyridine−Functionalized N-Heterocyclic Carbene: A Novel “IrIII(C∧N)(C∧C)” Compound and Its Evaluation as Transfer Hydrogenation Catalyst

The 1,8-naphthyridine-functionalized N-heterocyclic carbene 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene (BIN) has been successfully coordinated to Pd(II), W(0), Rh(I), and Ir(III), exhibiting its diverse binding modes. Reaction of BIN x HBr with Ag(2)O, followed by transmetalation with PdCl(2)(COD)(2) provides a cis complex PdCl(2)(kappaC(2)-BIN)(2) (1). Treatment of BIN x HBr with W(CO)(4)(piperidine)(2) in acetonitrile affords a chelate complex W(CO)(4)(kappa(2)C(2),N(1)'-BIN) (2). Reaction of {RhCl(COD)}(2) with KO(t)Bu and subsequent treatment with BIN x HBr in 1:2 and 1:1 ratio results in the mono and dinuclear complexes [Rh(COD)Br(kappaC(2)-BIN)] (3) and [{Rh(COD)Br}(2)(kappaN(8)':kappaC(2)-BIN)] (4), respectively. In complex 3, the "Rh(COD)Br" unit is coordinated to the carbene center, whereas an additional "Rh(COD)Br" unit is attached to naphthyridine nitrogen in complex 4 in an anti arrangement. Under identical reaction condition, a novel Ir(III) complex [Ir(kappa(2)C(2),N(1)'-BIN)(kappa(2)C(3)',C(2)-BIN)(H(2)O)Br]Br (5) has been synthesized. Complex 5 is proved to be catalytically active in hydrogen transfer reaction from (i)PrOH. All complexes have been characterized by spectroscopic methods and X-ray crystallography.

Unmasking a third polymorph of a benchmark crystal-structure-prediction compound.

Unmasking a third polymorph of a benchmark crystal-structure-prediction compound.

Rac-(2R*,3R*)-S-Ethyl-4-Chloro-3-Hydroxy-2-Phenylbuthanethioate and Rac-(2R*,3R*)-S-Ethyl-2-Phenyl-3-(tosyloxy)buthanethioate: Dichotomy of the Stereoselectivity of the Mukaiyama Reaction

The title compounds, rac-(2R*,3R*)-S-ethyl-4-chloro-3-hydroxy-2-phenylbuthanethioate (I) and rac-(2R*,3R*)-S-ethyl-2-phenyl-3-(tosyloxy)buthanethioate (III), are both composed of a S-ethyl 2-phenylbutanethioate moiety but have different geometries. Compound I is substituted in the 3 and 4 positions by a hydroxyl group and a chlorine atom, respectively. In compound III the hydroxyl group in the 3 position of rac-(2R*,3R*)-S-ethyl-3-hydroxy-2-phenylbuthanethioate (II), has been tosylated in order to obtain suitable crystals for X-ray analysis. In compound I the phenyl substituent and the hydroxyl group have a syn arrangement, whereas in the tosylate derivative of II, i.e., compound III, they have an anti arrangement. In the crystal structure of I centrosymmetric hydrogen bonded dimers are formed via O–H···O hydrogen bonds, involving the hydroxyl group and the carbonyl O-atom. In the crystal structure of III symmetry related molecules are connect via a weak C–H···O intermolecular interaction, involving a tosylate O-atom and a phenyl H-atom, so forming zigzag chains propagating in the c direction. The compounds were prepared by the Mukaiyama crossed aldol reaction between the silyl enol ether of S-ethyl 2-phenylethanethioate and simple aldehydes, like 2-chloroacetaldehyde (for I) and acetaldehyde (for II). The syn/anti stereo descriptors clearly indicate that the stereoselectivity of the Mukaiyama aldol reaction has switched from a syn selective process for the reaction using 2-chloroacetaldehyde to an anti selective process for the reaction with acetaldehyde. In both compounds the relative stereochemistry at the newly created chiral centers, positions 2 and 3, is R/R. The compounds, rac-(2R*,3R*)-S-ethyl-4-chloro-3-hydroxy-2-phenylbuthanethioate (I) and rac-(2R*,3R*)-S-ethyl-3-hydroxy-2-phenylbuthanethioate (II), were prepared by the Mukaiyama crossed aldol reaction between the silyl enol ether of S-ethyl 2-phenylethanethioate and simple aldehydes, like 2-chloroacetaldehyde (for I) and acetaldehyde (for II). The stereoselectivity of the Mukaiyama aldol reaction was shown to have switched from a syn selective process for the reaction using 2-chloroacetaldehyde to an anti selective process for the reaction with acetaldehyde.

Hydroxy-1H-imidazole-3-oxides – Synthesis, Kinetic Acidity, and Application in Catalysis and Supramolecular Anion Recognition

Using ab initio calculations (B3LYP 6-31G*) the geometries of diethyl, dimethoxy and dimethylamino imidazolium salts were studied as representative models of imidazolium salts bearing heteroatoms directly attached to the ring nitrogen atoms of the imidazolium core units. In all cases the syn and anti arrangement of the substituents could be identified. In addition to the theoretical studies, eleven dialkoxy imidazolium salts were prepared by alkylation of six 1-hydroxy-imidazole-3-oxides using dimethyl or diethyl sulfate as strong alkylating reagents. The kinetic acidities of these compounds were studied by measuring the pseudo-first order reaction rates of the H/D exchange process of the C2-H proton of compounds 3 - 9. The observed kinetic acidities are much higher than reaction rates observed for simple imidazolium salts; half-lifes of the H/D exchange are usually in the range of minutes. Similar to dialkyl/aryl imidazolium salts, all prepared dialkoxy imidazolium salts could be used as precatalysts in standard aqueous Suzuki coupling reactions. In addition, two representative dialkoxy imidazolium salts could be used in supramolecular anion recognition, as demonstrated by binding studies towards iodide as guest.

Self-assembly of three new coordination complexes: Formation of 2-D square grid, 1-D chain and tape structures

Three distinct coordination complexes, viz., [Co(imi) 2(tmb) 2] ( 1) [where imi = imidazole], {[Ni(tmb) 2(H 2O) 3]·2H 2O} n ( 2) and [Cu 2(μ-tmb) 4(CH 3OH) 2] ( 3), have been synthesized hydrothermally by the reactions of metal acetates, 2,4,6-trimethylbenzoic acid (Htmb) and with or without appropriate amine. The Ni analogue of 1 and the Co analogue of 2 have also been synthesized. X-ray single-crystal diffraction suggests that complex 1 represents discrete mononuclear species and complex 2 represents a 1D chain coordination polymer in which the Ni(II) ions are connected by the bridging water molecules. Complex 3 represents a neutral dinuclear complex. In 1, the central metal ions are associated by the carboxylate moiety and imidazole ligands, whereas the central metal atom is coordinated to the carboxylate moiety and the respective solvent molecules in 2 and 3. In 3, the four 2,4,6-trimethylbenzoate moieties act as a bridge connecting two copper (II) ions and the O atoms of methanol coordinate in an anti arrangement to form a square pyramidal geometry, with the methanol molecule at the apical position. In all the three structures the central metal atom sits on a crystallographic inversion centre. In all the cases, the coordination entities are further organized via hydrogen bonding interactions to generate multifarious supramolecular networks. Complexes 1, 2 and 3 have also been characterized by spectroscopic (UV/Vis and IR) and thermal analysis (TGA). In addition, the complexes were found to exhibit antimicrobial activity.The magnetic susceptibility measurements, measured from 8 to 300 K, revealed antiferromagnetic interactions between the Co(II) ions in compound 1 and the Ni(II) ions in 1a, respectively.

Dimer of Diruthenium Compound Bridged by 1,1′-Diethynylferrocene: Ferrocene as a Weak Mediator for Electronic Coupling

The reaction between Ru2(ap)4Cl (ap = 2-anilinopyridinate) and lithiated 1,1′-diethynylferrocene resulted in the expected product 1,1′-[Ru2(ap)4(C≡C)]2Fc (1) and 1-(Me3SiC≡C),1′-[Ru2(ap)4(C≡C)]Fc (2) as a byproduct. X-ray diffraction study of compound 1 revealed an anti arrangement of two Ru2(ap)4(σ-C≡C) fragments around the Fc unit. Cyclic and differential pulse volatmmetric (CV and DPV) measurements indicated that two Ru2 termini in 1 are weakly coupled in the reduced form. Also reported is the MO analysis of coupling mechanism based on the extended Hückel calculation of 1.

1-(3-Bromopropyl)-4-(2-pyridyl)-1H-1,2,3-triazole

In the structure of the title compound, C10H11BrN4, the plane of the substituted 1,2,3-triazole ring is tilted by 14.84 (10)° with respect to the mean plane of the pyridine ring. The pyridine and closest triazole N atoms adopt an anti arrangement which removes any lone pair–lone pair repulsions between the N atoms. This conformation is further stabilized by weak intermolecular C—H⋯N inter­actions. There are two mol­ecules in the unit cell, which form a centrosymmetric head-to-tail dimer. The dimers are stabilized through π–π inter­actions [centroid–centroid distance = 3.733 (4) Å and mean inter­planar distance = 3.806 (12) Å] between the substituted 1,2,3-triazole ring and the pyridine rings in adjacent mol­ecules. Each dimer inter­acts with two neighbouring dimers above and below, forming a slipped stack of dimers through the crystal. The 3-bromo­propyl chain sits over the pyridine ring of a neighbouring mol­ecule and the triazole rings of nearby mol­ecules are adjacent.

4,6-Dinitro-N,N′-di-n-octylbenzene-1,3-diamine, 4,6-dinitro-N,N′-di-n-undecylbenzene-1,3-diamine andN,N′-bis(2,4-dinitrophenyl)octane-1,8-diamine

4,6-Dinitro-N,N'-di-n-octylbenzene-1,3-diamine, C(22)H(38)N(4)O(4), (I), 4,6-dinitro-N,N'-di-n-undecylbenzene-1,3-diamine, C(28)H(50)N(4)O(4), (II), and N,N'-bis(2,4-dinitrophenyl)octane-1,8-diamine, C(20)H(24)N(6)O(8), (III), are the first synthetic meta-dinitroarenes functionalized with long-chain aliphatic amine groups to be structurally characterized. The intra- and intermolecular interactions in these model compounds provide information that can be used to help understand the physical properties of corresponding polymers with similar functionalities. Compounds (I) and (II) possess near-mirror symmetry, with the octyl and undecyl chains adopting fully extended anti conformations in the same direction with respect to the ring. Compound (III) rests on a center of inversion that occupies the mid-point of the central C-C bond of the octyl chain. The middle six C atoms of the chain form an anti arrangement, while the remaining two C atoms take hard turns almost perpendicular to the rest of the chain. All three molecules display intramolecular N-H...O hydrogen bonds between the amine and nitro groups, with the same NH group forming a bifurcated intermolecular hydrogen bond to the nitro O atom of an adjacent molecule. In each case, these interactions link the molecules into one-dimensional molecular chains. In (I) and (II), these chains pack so that the pendant alkyl groups are interleaved parallel to one another, maximizing nonbonded C-H contacts. In (III), the alkyl groups are more isolated within the molecular chains and the primary nonbonded contacts between the chains appear to involve the nitro groups not involved in the hydrogen bonding.

Interconversion between ladder-type octanuclear and linear tetranuclear copper(i) complexes supported by tetraphosphine ligands

Linearly ordered tetraphosphine, meso-bis[(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm), readily reacted with 4 equiv. of CuX in dichloromethane to afford octanuclear copper(I) complexes, [Cu(8)(mu-X)(8)(mu-dpmppm)(2)] (X = Cl (1a), Br (1b), I (1c)), which involve a ladder-type {Cu(8)(mu-X)(2)(mu(3)-X)(6)} core supported by two dpmppm ligands in anti arrangement. Complex 1a was further transformed by treatment with Cu(OTf)(2) into [Cu(8)(mu-X)(6)(OTf)(2)(mu-dpmppm)(2)] (2) in which two TfO anions attached to both end of the Cu(8) ladder. When complexes 1 were dissolved in dimethyl sulfoxide (dmso) in the presence of 2 equiv. of dpmppm, the octacopper(I) ladder was unzipped to result in the linear tetranuclear copper(I) complex, [Cu(4)X(mu-X)(3)(mu-dpmppm)(2)(dmso)] (X = Cl (3a), Br (3b), I (3c)). Similar treatment of dpmppm with 2 equiv. of CuX in the presence of coordinative solvents, N,N'-dimethylformamide (dmf) and pyridine (py), yielded the symmetrical tetracopper(I) complexes, [Cu(4)(mu-Cl)(3)(mu-dpmppm)(2)(dmf)(2)][CuCl(2)] (4) and [Cu(4)(mu-I)(3)(mu-dpmppm)(2)(py)(2)]I (5). A series of tetracopper(I) complexes with terminal isocyanide ligands, [Cu(4)(mu-X)(3)(mu-dpmppm)(2)(RNC)(2)]PF(6) (X = Cl, R = Xyl (6a); X = Br, R = Mes (7b); X = I, R = Xyl (8a), Mes (8b), (t)Bu (8c)), were obtained from reactions of dpmppm with 2 equiv. of CuX in dmf or acetonitrile followed by addition of an excess of RNC and NH(4)PF(6). Complexes 3-8 possess a bending Cu(4)(mu-X)(3) chain supported by two dpmppm ligands in syn arrangement, where the terminal sites are reactive and accommodate a variety of terminal ligands. When complex 8c was treated with AgPF(6) in a CH(3)CN-CH(2)Cl(2) mixed solvent, the soft Lewis acidic Ag(I) ions took the copper(I)-binding dpmppm off and the resultant two {Cu(4)(mu-I)(3)(mu-dpmppm)((t)BuNC)(2)}(+) fragments were zipped up to form the ladder-type octacopper(I) complex, [Cu(8)(mu-I)(6)(mu-dpmppm)(2)((t)BuNC)(2)](PF(6))(2) (9). The apparent interconversion between the Cu(8) ladder and the Cu(4) chain might proceed through a labile intermediate with a {Cu(4)(mu-X)(3)(mu-dpmppm)}(+) unit, which could be useful synthon of further extended copper(I) halide clusters.