Cis Fashion Research Articles

Synthesis, structure and redox properties of a new ruthenium(II) complex containing the flexible tridentate ligand N,N-bis(2-pyridylmethyl)ethylamine, cis-fac-Ru(bpea)22+, and its homologue attached covalently to a polypyrrole film †

New ruthenium complexes bearing tridentate ligands of general formula cis-fac-[RuIIL2][PF6]2 (L = N,N-bis(2-pyridylmethyl)ethylamine (bpea) 1 or N-[3-bis(2-pyridylmethyl)aminopropyl]pyrrole (bpea-pyr) 2) have been prepared following two different synthetic routes. They have been characterised by elemental analyses, UV-Vis and 1H NMR spectroscopy. Furthermore, the crystal structure of complex 1 has been solved. The Ru is co-ordinated in a distorted octahedral fashion by six N atoms of two bpea ligands which occupy opposite faces of the octahedron. The aliphatic N atoms of the bpea ligands are co-ordinated in a cis fashion. 1-D together with 2-D NMR spectra show that in solution 1 has the same structure as in the solid state and that complex 2 has the same structural arrangement. The redox properties of 1 and 2 have been investigated by cyclic voltammetry and coulometry. In the anodic region, the pyrrole group of complex 2 polymerises forming a modified electrode containing Pt/poly-2. This new material has been characterised by electrochemical techniques and displays a remarkable chemical and electrochemical stability.

One-dimensional chains consisting of copper(II) ions and an orthogonal anthracene-pyrimidine derivative: hierarchical formation of high-dimensional networks and their magnetic properties

Recrystallization of 9-(5-pyrimidinyl)anthracene (1) with copper(II) nitrate trihydrate formed three kinds of complexes: 1·Cu(NO3)2·H2O (2), 1·Cu(NO3)2·MeOH·H2O (3) and 1·Cu(NO3)2·2EtOH (4) by changing the recrystallization solvent. The crystal structure of the three complexes showed cooperation of metal coordination, hydrogen bonding, and aromatic stacking interactions in the hierarchical formation of one-, two- and three-dimensional networks. Complexes 2 and 3 formed zigzag one-dimensional chains consisting of 1 and Cu2+ ions by coordination of pyrimidine to Cu2+ ion in equatorial trans fashion. Complex 4 formed a spiral one-dimensional chain by coordination in equatorial cis fashion. The magnetic behavior of 2, 3, and 4 were measured on a SQUID susceptometer to reveal that there existed strong antiferromagnetic interactions between Cu2+ ions. The magnetic data of one-dimensional antiferromagnetic chains were analyzed by the Bonner–Fisher model. The antiferromagnetic interaction between Cu2+ ions was around −55 K, which is the largest value observed in pyrimidine-bridged Cu2+ ions.

SYNTHESIS AND CHARACTERIZATION OF BIS(DIPHENYLPHOSPHINO)ACETYLENE BRIDGED BINUCLEAR PLATINUM(II) COMPLEXES WITH TERMINAL ORGANOCHALCOGENIDE GROUPS. X-RAY CRYSTAL STRUCTURE OF [Pt2(SC6F5)4 (μ-Ph2PC≡CPPh2)2

Binuclear platinum(II) complexes of the type [Pt2(ER)4(μ-Ph2PC≡CPPh2)2] (ER = SPr i , SBu t , SPh, SC6H4Cl-4, SC6F5, SePh) have been prepared and characterized by elemental analysis and NMR spectroscopy. A single-crystal X-ray structure determination of [Pt2(SC6 F5)4-(μ-Ph2PC≡CPPh2)2] has established the binuclear formulation with terminal thiolato groups. The platinum atoms lie in a distorted square planar environment with the sulfur and the phosphine ligands arranged in a cis fashion.

Manganese(II) complexes of 3,6,9-trioxaundecanedioic acid (3,6,9-tddaH 2): X-ray crystal structures of [Mn(3,6,9-tdda) (H 2O) 2]·2H 2O and {[Mn(3,6,9-tdda)(phen) 2·3H 2O]·EtOH} n

3,6,9-trioxaundecanedioic acid (3,6,9-tddaH 2) reacts with Mn(CH 3CO 2) 2·4H 2O in ethanol to give [Mn(3,6,9-tdda)]·H 2O ( 1). Recrystallization of 1 from methanol gives crystals of [Mn(3,6,9-tdda) (H 2O) 2]·2H 2O ( 2). Complex 1 reacts with an ethanolic solution of 1,10-phenanthroline (phen) to give {[Mn(3,6,9-tdda)(phen) 2]·3H 2O·EtOH} n ( 3). All of the complexes are extremely water soluble. Complexes 2 and 3 were structurally characterised. The manganese(II) ion in 2 is seven coordinate, with an approximately pentagonal bipyramidal O 7 coordination sphere. The axial donors are water molecules and the pentagonal plane is occupied by the diacid, acting as a pentadentate ligand through the three ethereal oxygens and one oxygen atom from each of the carboxylate functions. In complex 3 the manganese(II) ion is six-coordinate, being bound to two bidentate phenanthroline ligands and to the carboxylate oxygen atoms from two symmetry related diacids which are coordinated in a cis fashion. The structure consists of polymeric chains, with diacid ligands bridging the manganese ions. There is π-π stacking of pairs of phenanthroline ligands on adjacent chains, running along both the z and y directions.

Solution and Solid State Properties of [N-(2-Hydroxyethyl)iminodiacetato]vanadium(IV), -(V), and -(IV/V) Complexes(1).

A mononuclear vanadium(IV), a mononuclear vanadium(V), and a binuclear mixed valence vanadium(IV/V) complex with the ligand N-(2-hydroxyethyl)iminodiacetic acid (H(3)hida) have been structurally characterized. Crystal data for [VO(Hhida)(H(2)O)].CH(3)OH (1): orthorhombic; P2(1)2(1)2(1); a= 6.940(2), b = 9.745(3), c= 18.539(4) Å; Z = 4. Crystal data for Na[V(O)(2)(Hhida)(2)].4H(2)O (2): monoclinic; P2(1)/c; a = 6.333(2), b = 18.796(2), c = 11.5040(10) Å; beta = 102.53(2) degrees; Z = 4. Crystal data for (NH(4))[V(2)(O)(2)(&mgr;-O)(Hhida)(2)].H(2)O (3): monoclinic; C2/c; a = 18.880(2), b= 7.395(2), c = 16.010(2) Å; beta = 106.33(2) degrees; Z = 4. The mononuclear vanadium(IV) and vanadium(V) complexes are formed from the monoprotonated Hhida(2)(-) ligand, and their structural and magnetic characteristics are as expected for six-coordinate vanadium complexes. An interesting structural feature in these complexes is the fact that the two carboxylate moieties are coordinated trans to one another, whereas the carboxylate moieties are coordinated in a cis fashion in previously characterized complexes. The aqueous solution properties of the vanadium(IV) and -(V) complexes are consistent with their structures. The vanadium(V) complex was previously characterized; in the current study structural characterization in the solid state is provided. X-ray crystallography and magnetic methods show that the mixed valence complex contains two indistinguishable vanadium atoms; the thermal ellipsoid of the bridging oxygen atom suggests a type III complex in the solid state. Magnetic methods show that the mixed valence complex contains a free electron. Characterization of aqueous solutions of the mixed valence complex by UV/vis and EPR spectroscopies suggests that the complex may be described as a type II complex. The Hhida(2)(-) complexes have some similarities, but also some significant differences, with complexes of related ligands, such as nitrilotriacetate (nta), N-(2-pyridylmethyl)iminodiacetate (pmida), and N-(S)-[1-(2-pyridyl)ethyl]iminodiacetate (s-peida). Perhaps most importantly, the mixed valence Hhida(2)(-) complex is significantly less stable than the corresponding pmida and s-peida complexes of similar overall charge but very similar in stability to the nta and V(2)O(3)(3+) complexes with higher charges. Thus, there is the potential for designing stable mixed valence dimers.

Synthesis and magnetic properties of novel maleato-bridged cyclic tetranuclear manganese(II) complexes: Crystal structure of [Mn 4(μ-maleate) 2(bipy) 8](ClO 4) 4·(MeOH) 2(H 2O 2) 2

Novel cyclic tetranuclear manganese complexes with maleate dianions as bridging ligand, of formula [Mn 4(μ-C 4H 2O 4) 2(bipy) 8](ClO 4) 4·(MeOH) 2(H 2O) 2 ( 1) and [Mn 4(μ-C 4H 2O 4) 2(phen) 8](ClO 4) 4·H 2O ( 2), have been prepared and characterized by elemental analysis, IR spectra, X-ray analysis and magnetic measurements. The crystal structure determination of complex 1 reveals that the cation [Mn 4(μ-maleate) 2(bipy) 8] 4+ has a centre of symmetry and the four manganese atoms are bridged by two maleate dianions, forming an unusual 16-membered macrocyclic structure. Each manganese atom is coordinated in cis fashion by two oxygen atoms of bridging maleate ligands and then by four nitrogen atoms from terminal bipyridine ligands, leading to a distorted octahedral geometry. The variable-temperature magnetic properties have been investigated in the range 1.4–300 K. The results show that the magnetic susceptibilities obey the Curie law and no magnetic exchange interaction occurs between the carboxylato-bridged Mn II ions.

Facile planar-nonplanar N-amido interconversion at A Co III centre

The reaction of Co(OAC) 2 with excess H 2bpb [H 2bpb = 1,2-bis(2-pyridinecarboxamido)benzene] led to the isolation of Co(bpb) (OH 2) and a Co III nonplanar tetradentate amino complex Co(bpb)( n 2-Hbpb) ( 1), which has been characterized by X-ray crystallography. The geometry of 1 is octahedral with the Hbpb ligand coordinated in a cis fashion via a pyridyl and an amino oxygen, leaving the bpb in a nonplanar bonding mode. Other chelating bidentate ligands were also found to promote the nonplanar tetradentate binding mode of bpb, for example in [Co( n 4-bpb)( n 2-S 2CNEt 2] which was prepared by reaction of Co(bpb)·(OH 2) with Na(S 2CNEt 2) in air.

A calix[6]arene derived diphosphite, synthesis and complexation behaviour; X-ray structure of a palladium(II) chloride complex

Calix[6]arene reacts with 2 equiv. of PCl3 to form a bidentate diphosphite ligand L which coordinates to Pd, Pt and Re in a cis fashion and, according to X-ray analysis, with a bite angle of approximately 90° for a palladium complex [PdCl2L].

Stereochemistry of tRNA(m5U54)-methyltransferase catalysis: 19F NMR spectroscopy of an enzyme-FUraRNA covalent complex.

The catalytic mechanism of tRNA(m5U54)-methyltransferase (RUMT) involves the formation of a covalent adduct between Cys324 of RUMT and C6 of Ura54 in tRNA. The covalent adduct is subsequently methylated at C5 by S-adenosyl-L-methionine (AdoMet). We used an RNA substrate analog containing 5-fluorouracil (FUra) in place of Ura54 to trap the covalent complex and analyzed the adduct by 19F NMR spectroscopy. The 19F NMR spectrum of the adduct consisted of an overlapping doublet of quartets, with an H6-F coupling constant of 4 Hz and a CH3-F coupling constant of 22.4 Hz. On the basis of the magnitude of the H6-F coupling constant, we determined that Cys324 of RUMT and the methyl moiety from AdoMet added across the 5,6-double bond of FUra54 in cis fashion. We deduced that the nucleophilic addition was also cis in the normal enzymatic reaction and that the subsequent beta-elimination of the 5-H and catalytic cysteine was trans. Further, on the basis of chemical considerations, we proposed several conformational adaptations of enzyme-substrate complexes that must occur on the reaction pathway. Together with previous studies, this study enables the proposal of the complete stereochemical pathway for the RUMT-catalyzed methylation of Ura54 in tRNA.

Reactions of [Et3NH][(μ‐CO)(μ‐RS)Fe2(CO)6] with acetylenes. Synthesis of (μ‐σ,π‐p‐MeC6H4CCHPh)(μ‐RS)Fe2(CO)6 and (μ‐σ,π‐PhCCHC6H4Me‐p)(μ‐RS)Fe2(CO)6. The crystal structure of (μ‐σ,π‐p‐MeC6H4CCHPh)(μ‐tBuS)Fe2(CO)6

AbstractThe reactions of [Et3NH][μ‐CO)(μ‐RS)Fe2(CO)6] (1a‐d) (RnPr, nBu, tBu, Ph) with p‐MeC6H4C°CPh or m‐NO2C6H4C°CPh were studied and products of the vinyl type (μ‐σ,π‐p‐MeC5H4CCHPh)(μ‐RS)Fe2(CO)6 (2) and (μ‐σ, π‐phCCHC6H4Me‐p) (μ‐RS)Fe2(CO)6 (3) (RnPr, nBu, tBu, Ph) were obtained. While the structures of all the compounds 2a‐d and 3a‐d were characterized by elemental analysis, IR, 1H NMR and MS spectroscopies, the single‐crystal structure of 2c(RtBu) was determined by X‐ray diffraction method. The X‐ray diffraction result of 2c showed that the substituted vinyl ligand p‐MeG6H4CCHPh bridges the two iron centers, being σ‐bonded to one metal through the olefinic carbon attached to p‐MeC6H44 group, while π‐bonded to the other via olefinic linkage; the Fe2(CO)6 and proton units are in a cis fashion and the tBu group is bonded to sulfur atom through an e‐type of bond.

Nickel thioether chemistry: syntheses and crystal structures of [Ni2L2(µ-Cl)2][BF4]2(l = 1,4,7,10-tetrathiacyclododecane, 1,4,8,11-tetrathiacyclotetradecane or 1,5,9,13-tetrathiacyclohexadecane)

Reaction of NiCl2 with 1 molar equivalent of the macrocycles (L) 1,4,7,10-tetrathiacyclododecane ([12]aneS4), 1,4,8,11-tetrathiacyclotetradecane ([14]aneS4) or 1,5,9,13-tetrathiacyclohexadecane ([16]aneS4) and NaBF4 in MeNO2 for 30 min afforded green or blue solutions, from which the complexes [Ni2L2Cl2][BF4]2 can be isolated. The complex [Ni2([12]aneS4)2Cl2][BF4]2·2MeNO2 crystallises in the monoclinic space group C2/m with a= 11.0651(20), b= 13.4977(24), c= 12.7222(21)Å, β= 104.824(21)° and Z= 2. The complex [Ni2([14]aneS4)2Cl2][BF4]2·6MeNO2 crystallises in the triclinic space group P with a= 10.6341(18), b= 11.6481(22), C= 12.2457(25)Å, α= 88.547(7), β= 67.288(12), γ= 68.647(6)° and Z= 1. The complex [Ni2([16]aneS4)2Cl2][BF4]2·2MeNO2 crystallises in the monoclinic space group Ccwith a = 16.024(4), b= 1 3.6862(17), c= 1 9.7329(24)Å, β= 92.042(19)° and Z= 4. Single-crystal structure determinations on each of these products showed the presence of dichloro-bridged dimeric cations exhibiting edge-sharing bioctahedral structures, with the macrocyclic ligands co-ordinated in a cis fashion about the Ni. The Ni–S bond lengths and internal crystallographic symmetry vary significantly between the structures, the shortest distances being observed for [Ni2([14]aneS4)2Cl2]2+[Ni–S 2.3694(22), 2.3765(21), 2.3756(21), 2.3798(21)Å, Ni–Cl 2.4416(20), 2.4252(20)Å]; for [Ni2([12]aneS4)2Cl2]2+, Ni–S 2.412(3), 2.4144(25), 2.373(3), Ni–Cl 2.411(3), 2.382(3)Å and for [Ni2([16]aneS4)2Cl2]2+, Ni–S 2.4098(22)–2.4421 (22), Ni–Cl 2.3860(21 )–2.4205(20)Å. These variations are related to the differing hole sizes of the three tetrathia macrocyles. The Ni ⋯ Ni distances are similar in all three structures, 3.5534(12)–3.5692(12)Å. The complexes [Ni2L2Cl2][BF4]2 exhibit only irreversible electrochemical oxidation and reduction processes according to cyclic voltammetry in MeCN–0.1 mol dm–3 NBun4PF6 at 293 K. Reaction of NiCl2 with 1,4,7-trithiacyclononane ([9]aneS3) and NaBF4 affords the triply bridged dimeric complex [Ni2([9]aneS3)2Cl3]BF4.

Cycloadditions in synthesis. LXIII. Why molecular fluorine adds to ethylenes in a cis fashion.

The addition of dilute molecular fluorine to ethylenes proceeds stereoselectively to give the cis adducts, and the method has now gained potential synthetic utility for the preparation of a variety of fluorinated compounds. A possible mechanism accounting for this selectivity is proposed based on HOMO-LUMO theory, bond distances, and weakness of F-F bond.

Preparation and x-ray crystal structure of [Pd 2(μ-O 2CMe) 2(C 6H 5) 2(PPh 3) 2], a binuclear acetate-bridged palladium(II) phenyl complex formed by PC bond cleavage of triphenylphosphine

The new binuclear complex [Pd 2(μ-O 2CMe) 2(C 6H 5) 2(PPh 3) 2] is formed when [Pd 3(O 2CMe) 6] reacts with PPh 3 in methanol. An X-ray crystal structure analysis shows the complex to comprise two square planar palladium(II) atoms bridged by two acetate ligands in a cis fashion. The phosphine and phenyl ligands on each metal atom adopt positions which are mutually trans to the equivalent ligand on the other metal atom, so that the complex has an approximate two-fold axis perpendicular to the plane of the four acetate oxygens. The NMR ( 1H, 13C and 31P) spectra are reported.

Organic synthesis using haloboration reaction. I. A simple and selective synthesis of 2-bromo- and 2-iodo-1-alkenes

B-bromo- or B-iodo-9-borabicyclo[3.3.1]nonane reacts readily with 1-alkynes. Such haloboration reactions proceed through the Markovnikov addition of the X-B moiety to CC bonds and cis fashion. The bromoboration reaction occurs chemoselectively at terminal CC bonds but not at internal CC, terminal and internal CC bonds. The protonolysis of haloboration products with acetic acid gives corresponding 2-bromo- or 2-iodo-1-alkenes in excellent yields.

Structural genes of the mouse major urinary protein are on chromosome 4.

The major urinary proteins (MUPs) of mouse are a family of at least three major proteins which are synthesized in the liver of all strains of mice. The relative levels of synthesis of these proteins with respect to each other in the presence of testosterone is regulated by the Mup-a locus located on chromosome 4. In an effort to determine the mechanism of this regulation in molecular terms, a cDNA clone containing most of the coding region of a MUP protein has been isolated and identified by partial DNA sequence analysis. Using a combination of hybridization analysis and somatic cell genetics, the structural gene family has been unambiguously mapped to mouse chromosome 4. These data suggest that Mup-a regulation operates in a cis fashion and that models proposing trans regulation of MUP protein synthesis are unlikely.

The stereochemistry of organometallic compounds. XXII. The stereochemistry of metal-catalysed hydrogen cyanide addition to olefins

Reactions of (E)-3,3-dimethyl(1,2-D2)but-1-ene with hydrogen cyanide and of (E)-3,3-dimethyl-(1-D)but-1-ene with deuterium cyanide have been shown to proceed in a completely stereospecific cis fashion when a catalyst system based on Pd(diop)2 was used. Reaction between 4-t-butylcyclo-hexene and deuterium cyanide with the catalyst system gave only the equatorial nitriles trans- 4-t-butylcyclohexane-1-carbonitrile and cis-3-t-butylcyclohexane-1-carbonitrile with cis incorporation of deuterium. Use of a catalyst system based on Ni[P(OPh)3]4 and zinc chloride led to significant amounts of isotopic exchange and rearrangement. These results are compared with those from hydroformylation of the olefins, and the mechanism of hydrocyanation is discussed.

The crystal and molecular structure of μ-oxalatobis[di(η 5-cyclopentadienyl)titanium

μ-Oxalatobis[di-(η 5-cyclopentadienyl)titanium], [μ-(C 2O 4) {(η 5-C 5H 5) 2Ti} 2], 0.5 (C 2H 5) 2O crystallises in the orthorhombic space group Pbcn with a 17.228(13), b 12.224(13), c 30.309(23) Å and Z = 12. The final R was 0.061 ( R w 0.104). The oxalato group acts as a planar tetradentate bridging ligand, with the Ti atoms displaced in a cis fashion cut of the C 2O 4 2− plane. The reason for this displacement is analysed in terms of σ and π interaction between the metal and ligand, and steric contacts between the Cp rings. Comparison with the iso-electronic [μ-{C 2(N(C 6H 4CH 3- p)) 4} {(η 5-C 5H 5) 2Ti} 2] is made.

Investigation of the factors controlling the regioselectivity of the hydrosilylation of alkynes catalysed by trans-di-μ-hydridobis(tricylcohexylphosphine)bis(silyl)diplatinum complexes

The hydrosilylation of terminal and internal alkynes and also of some hydroxy-alkynes catalysed by trans-di-μ-hydridobis(tricyclohexylphosphine)bis(silyl)diplatinum complexes is described. These diplatinum complexes are very efficient catalysts for such hydrosilylations; high yields (80–98%) can be obtained under mild conditions with a catalysts/reactant ratio of 10 −4–10 −5/1. Addition of hydrosilanes X 3SiH to the alkynes RCCH, RCCR and RCCR′ proceeds in a cis fashion yielding trans-RCHCHSiX 3, cis-RC(SiX 3)CHR and mixtures of the regioisomers E-RC(SiX 3)CHR′ and E-RCHC(SiX 3)R′ respectively. In the case of terminal alkynes, minor amounts of internal adducts corresponding to Markownikow addition of the hydrosilanes are also formed. The effects of variation of the reaction conditions (concentration of reactants or catalyst and temperature) upon the rate and regioselectivity of the addition were assessed. The regioselectivity increases as the asymmetry of the electron density of the acetylenic π-bonds increases; the regioselectivity is explained in terms of a qualitative molecular orbital treatment of the transition state formed in the insertion step of the alkyne into the PtH bond.

ChemInform Abstract: A STRUCTURE ANALYSIS OF A BROMOACETATE OF HYDROXYPIPERENONE BY THE X‐RAY DIFFRACTION METHOD

Chemischer InformationsdienstVolume 7, Issue 17 Physical Organic Chemistry ChemInform Abstract: A STRUCTURE ANALYSIS OF A BROMOACETATE OF HYDROXYPIPERENONE BY THE X-RAY DIFFRACTION METHOD KUNIAKI MATSUI, KUNIAKI MATSUISearch for more papers by this authorKEIICHI FUKUYAMA, KEIICHI FUKUYAMASearch for more papers by this authorKUMIKO TSUKIHARA, KUMIKO TSUKIHARASearch for more papers by this authorTOMITAKE TSUKIHARA, TOMITAKE TSUKIHARASearch for more papers by this authorYUKITERU KATSUBE, YUKITERU KATSUBESearch for more papers by this authorKATSURA MUNAKATA, KATSURA MUNAKATASearch for more papers by this author KUNIAKI MATSUI, KUNIAKI MATSUISearch for more papers by this authorKEIICHI FUKUYAMA, KEIICHI FUKUYAMASearch for more papers by this authorKUMIKO TSUKIHARA, KUMIKO TSUKIHARASearch for more papers by this authorTOMITAKE TSUKIHARA, TOMITAKE TSUKIHARASearch for more papers by this authorYUKITERU KATSUBE, YUKITERU KATSUBESearch for more papers by this authorKATSURA MUNAKATA, KATSURA MUNAKATASearch for more papers by this author First published: April 27, 1976 https://doi.org/10.1002/chin.197617068AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue17April 27, 1976 RelatedInformation

A Structure Analysis of a Bromoacetate of Hydroxypiperenone by the X-Ray Diffraction Method

Abstract The structure of a bromoacetate of hydroxypiperenone, C24H31O7Br, has been determined by the X-ray diffraction method. The compound crystallized in the space group P21 with a=8.296, b=13.247, c=11.400 Å, and β=102.8°. The structure was solved by the heavy-atom method and refined to R=0.075 for 1614 reflections. The present analysis has established that the five- and six-membered rings are fused in the cis fashion. The absolute configuration of the molecule has been determined by using the anomalous dispersion effect of the bromine atom for Cu Kα radiation.