Syntheses,crystal structures and magnetic study of two binuclear manganese(II) complexes with aromatic N-oxide as bridging ligand

Two new binuclear complexes, [Mn₂(μ-dmpo)₂(SCN)₄(H₂O)₂] (1) (where dmpo?=?3,5-dimethylpyridine N-oxide), [Mn₂(μ-po)₂(H₂O)₆I₂]I₂ (2) (where po?=?pyridine N-oxide), have been synthesized and their crystal structures determined by X-ray crystallography. Complexes 1 and 2 crystallize in monoclinic, space group P2₁/c, with unit cell dimensions a?=?8.8836(18)?Å, b?=?15.450(3)?Å, c?=?15.484(3)?Å, β?=?91.020(3)° for 1, and a?=?8.8352(13)?Å, b?=?17.927(3)?Å, c?=?8.3338(12)?Å, β?=?103.765(2)° for 2. In each binuclear complex two Mn(II) were bridged by two 3,5-dimethylpyridine N-oxides or by two pyridine N-oxides and the distances between the bridged Mn(II) ions are 3.599?Å for 1 and 3.552?Å for 2. Variable temperature (4–300?K) magnetic measurements were performed for 1 and the susceptibility data were fitted by using a binuclear Mn(II) magnetic coupling formula producing the 2J?=??2.17?cm^?1.     

Three new thiocyanato-bridged complexes of cadmium(II): syntheses,X-ray crystal structures and thermal properties

Three new thiocyanato-bridged polymers of cadmium(II), [Cd(me₄dpt)(SCN)₂] _n (1) [me₄dpt = 3,3′-iminobis(N,N-dimethylpropylamine], [Cd(me₂tn)(SCN)₂] _n (2) (me₂tn = N,N′-dimethyl-1,3-propanediamine) and [{amphyH} {Cd(SCN)₃}] _n (3) (ampyH = 4-aminopyridinium cation), have been synthesized and their molecular structures determined through X-ray crystallography. In Complex 1 each square pyramidal mononuclear fragment is H-bonded (N ? H…S) to form a 1D supramolecular chain. Complex 2 is a 1D coordination polymer in which each distorted octahedral cadmium(II) ion is linked with the four bridging thiocyanates and one diamine. The structure of 3 reveals anionic [Cd(SCN)₃]^? zigzag chains arranged in an approximately hexagonal array with the 4-aminopyridinum cations occupying triangular channels. Each chain is H-bonded (N?H…N) to form a 2D supramolecular network. Upon heating, 1 and 2 melt and transform to transparent solid masses at ambient temperature over a few days. On scratching, these turn to a fine powder. This phenomenon is repeatable. Complex 3 upon heating loses a 4-aminopyridine molecule and transforms to [H][Cd(SCN)₃] at ??195°C.     

Solvothermal syntheses and crystal structures of new Cu(II) complexes with phenylsuccinic acid

Five new Cu(II) complexes [Cu(psa)(phen)] · 3H₂O (1), [Cu(psa)(2bpy)] · 0.5H₂O (2), [Cu(psa)(2bpy)(H₂O)] · 3H₂O (3), [Cu(psa)(4bpy)] · H₂O (4), and [Cu(psa)_0.5(N₃)(2bpy)] (5) (H₂psa = phenylsuccinic acid, phen = 1,10-phenanthroline, 2bpy = 2,2′-bipyridine, and 4bpy = 4,4′-bipyridine) were obtained under solvothermal conditions and characterized by single-crystal X-ray diffraction. Complexes 2 and 3 were formed by one-pot reaction. In complex 2, Cu(II) ion is four-coordinated and locates at a slightly distorted square center. In complex 3, the coordinated water molecule occupies the axial site of Cu(II) ion forming a tetragonal pyramid geometry. Complexes 1 and 3 are of 1D chain structures, and extended into 2D supramolecular network by hydrogen bonds. Complex 2 is of zipper structure, and further assembled into 2D supramolecular network by hydrogen bonds and π–π stacking interactions. Complex 4 is a 3D CdSO₄-like structure with twofold interpenetration, while complex 5 is a dinuclear compound. The different structures of complexes 1–5 can be attributed to using the auxiliary ligands, indicating an important role of the auxiliary ligands in assembly and structure of the title complexes.     

Synthesis, structural and magnetic properties of diphenoxo-bridged binuclear mixed-ligand Cu(II) complexes

The copper(II) complexes [Cu₂(phen)₂(HL¹)₂] (ClO₄)₂ (1) and [Cu₂(phen)₂(HL²)₂] (ClO₄)₂ (2) synthesized from two potentially tridentate ligands N-(2-hydroxybenzyl) propanolamine (H₂L¹) and N-(5-methyl-2-hydroxybenzyl) propanolamine (H₂L²) have centrosymmetric bis(μ₂-phenoxo)-bridged dicopper(II) structures. Variable temperature magnetic measurements have revealed the existence of relatively weak antiferromagnetic interactions (1: 2J=−212.5, 2: 2J=−337.0 cm⁻¹) with respect to the bridging angles (1: θ=101.47(18)°, 2: θ=102.79(12)°). The results suggest that the distortion index of the Cu(II) atoms (1: τ=0.73, 2: τ=0.53) may be the major factor governing the spin coupling between the copper(II) centers of these diphenoxo-bridged binuclear complexes. The coordination moieties of complex 1 are connected into a 1D linear structure via intermolecular hydrogen bonds between alkoxyl, amine, and perchlorate groups.     

Ternary copper(II) complexes of aroylhydrazones and mono/bidentate heterocycles with different structures: synthesis,crystal structure and properties

Two mixed-ligand Cu(II) complexes, [CuL¹(Himdz] · CH₃OH (1) and [CuL²(phen)] · 0.5DMF (2), with different structures have been synthesized by using substituted aroylhydrazones, 5-bromo-salicylaldehyde-benzoylhydrazone (H₂L¹) and 5-bromo-salicylaldehyde-3,5-dimethoxy-benzoylhydrazone (H₂L²), and mono/bidentate heterocycles, imidazole (Himdz) and 1,10-phenanthroline (phen). Their crystal structures and spectroscopic properties have been studied. X-ray analysis show a distorted square-planar geometry for 1 and a distorted square-pyramidal geometry for 2, in which the chelating phen ligand displays axial-equatorial bonding. In both structures the ONO tridentate ligand occupies the basal plane. Self-assembly via O–H ··· N, N–H ··· O and C–H ··· O interactions lead to one-dimensional chain arrangement in 1 and 2.     

Three new polynuclear tetracarboxylato-bridged copper(II) complexes: Syntheses, X-ray structure and magnetic properties

The synthesis, crystal structure and magnetic measurements of three new polynuclear tetracarboxylato-bridged copper(II) complexes, i.e. {[Cu₄(phen)₂(μ-O₂CC₂H₅)₈] · (H₂O)}_n (1), [Cu₂(μ-O₂CC₆H₄OH)₄(C₇H₇NO)₂] · 6H₂O (2) and [Cu₂(μ-O₂CCH₃)₄(C₇H₇NO)₂] (3) (phen = 1,10-phenanthroline, O₂CC₆H₄OH = 3-hydroxy benzoate, C₇H₇NO = 4-acetylpyridine) are reported. All compounds consist of dinuclear units, in which two Cu(II) ions are bridged by four syn,syn-η¹:η¹:μ carboxylates, showing a paddle-wheel cage type with a square-pyramidal geometry, arranged in different ways. The structure of compound 1 consists of an one-dimensional structure generated by an alternating classical dinuclear paddle-wheel unit and an unusual dinuclear Cu₂(μ-OCOC₂H₅)₂(μ-O₂CC₂H₅)₂(phen)₂unit, which are connected to each other via a syn,anti-triatomic propionato bridge in an axial-equatorial configuration. The adjacent chains are connected to generate a 2D structure through the face-to-face π–π interaction between phen rings. Structures of compounds 2 and 3 both consist of a symmetric dinuclear Cu(II) carboxylate paddle-wheel core and pyridyl nitrogen atoms of 4-acetylpyridine ligand at the apical position, and just differ in the substituents of the equatorial ligands.

The magnetic properties have been measured and correlated with the molecular structures. It is found that in the two classical paddle-wheel compounds the Cu(II) ions are strongly antiferromagnetically coupled with J = −278.5 and −287.0 cm⁻¹ for complexes 2 and 3, respectively. In compound 1 the magnetic susceptibility could be fitted with two different, independent Cu(II) units, one strongly coupled and one weakly coupled; the paddle-wheel dinuclear unit has the strongest antiferromagetic coupling with a value for J of −299.5 cm⁻¹, whereas the Cu(II) ions in the propionato-bridged dinuclear unit of 1 display a very weak antiferromagnetic coupling with a value for J = −0.75 cm⁻¹, due to the orthogonality of the magnetic orbitals. Also the exchange within the chain is therefore very weak. The magneto-structural correlations for complexes 1, 2, and 3 are discussed on the basis of the structural parameters and magnetic data for the complexes.     

Hydrothermal syntheses,crystal structures and antibacterial activities of two Cu(II) complexes with quinolones

Hydrothermal reactions of ciprofloxacin with Cu(ClO₄)₂?·?6H₂O, and ofloxacin with Cu(CH₃COO)₂?·?4H₂O, yield two metal complexes: [Cu(H-Cip)₂]?·?(ClO₄)₂?·?6H₂O (1) and [Cu(Ofl)₂?·?H₂O]?·?2H₂O (2), which were characterized by elemental analysis, IR and single crystal diffraction analyses. Compounds 1 and 2 were screened for antibacterial activities against Staphylococcus aureus, Escherichia coli, Candida albicans and pseudomonas aeruginosa.     

Bridging chlorides and hydroxides: syntheses and crystal structures of binuclear and tetranuclear NiII complexes derived from a reduced Schiff-base ligand 2-(2-pyridylmethylamino)ethanesulfonic acid

Two complexes, [Ni(pmt)(Cl)] (1) and [Ni₄(pmt)₄(OH)₄]·8H₂O (2) [Hpmt = 2-(2-pyridylmethylamino)ethanesulfonic acid], were synthesized by different experimental methods in methanol-water mixed solution. Compound 1 crystallizes in triclinic, space group P?1 with unit cell parameters: a = 8.315(2) Å, b = 8.383(2) Å, c = 9.128(2) Å, α = 103.654(2)°, β = 98.125(2)°, γ = 113.154(2)°, V = 548.6(2) ų, Z = 2. A pair of chlorides is μ ₂-bridges linking two Ni^II atoms in forming binuclear complex 1. The coordination environment at Ni^II is distorted square-pyramidal geometry. Compound (2) belongs to monoclinic, space group C2/c, with a = 16.5168(15) Å, b = 18.3718(17) Å, c = 17.5473(16) Å, α = γ = 90°, β = 93.3820(10)°, V = 5315.3(8) ų, Z = 4. Four hydroxides are μ ₃-bridges joining four Ni^II atoms to generate a cubic framework as a tetranuclear complex. The configuration at each Ni^II is distorted octahedral. Both π–π stacking of pyridine rings and intermolecular hydrogen bonds stabilize the solid state structures for 1 and 2.     

Synthesis,crystal structure and magnetic properties of a new binuclear copper(II)-copper(II) complex of a macrocyclic oxamide

The binuclear metal complex [Cu(μ-exoO₂)cyclamCu(bpy)](ClO₄)₂·H₂O (bpy?=?2,2′-bipyridine and (exoO₂)cyclam?=?1,4,8,11-tetraazacyclotradecanne-2,3-dione) has been synthesized and characterized by single-crystal X-ray analysis and spectroscopic and magnetic measurements. The structure consists of homobinuclear [Cu(μ-exoO₂)cyclamCu(bpy)]²⁺ cations, a weakly coordinated water molecule and perchlorate ions. In each binuclear unit, Cu1, coordinated by four nitrogen atoms of the macrocyclic organic ligand is connected to Cu2 via the exo-cis oxygen atoms of the macrocyclic ligand with Cu···Cu separations of 5.151?Å; Cu2 assumes square-pyramidal geometry. Magnetic properties measured at 2–300?K show antiferromagnetic exchange between adjacent copper(II) ions.     

Syntheses,crystal structures,and spectroscopic properties of copper(II) complexes with 3,14-diethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane

[Cu(L)(NO₃)₂] (1) and [Cu(L)(H₂O)₂](SCN)₂ (2) [L?=?3,14-diethyl-2,6,13,17-tetraazatricyclo(16.4.0.0^7,12)docosane] have been prepared and structurally characterized by single-crystal X-ray diffraction at 100?K. For these constrained macrocycle complexes, copper(II) exists in a tetragonally distorted octahedral environment with the four nitrogen atoms of the macrocyclic ligands and two oxygen atoms from either nitrate or water in axial positions. The macrocyclic ligands in both complexes adopt the most stable trans-III conformation. The Cu–N distances are 2.021(2)–2.047(2)?Å and typical but the axial ligands are weakly coordinating, with Cu–O bond lengths, 2.506(2)?Å for 1 and 2.569(2)?Å for 2, due to the pseudo Jahn–Teller effect. The crystals are stabilized by a 3-D network by intra and intermolecular hydrogen bonds that are formed among the secondary nitrogen hydrogen atoms and nitrate in 1, and intermolecular hydrogen bonds are formed by water and thiocyanates in 2. The electronic absorption and IR spectral properties are also discussed.     

Synthesis and structure of two lanthanide complexes with isonicotinic acid N-oxide (HL): [Ln(L)2(H2O)4]n·(NO3)n·n(H2O) (Ln = Sm or Tb)

Two new lanthanide complexes of isonicotinic acid N-oxide (HL), namely [Ln(L)₂(H₂O)₄]_n·(NO₃)_n·n(H₂O) for Ln = Sm or Tb, have been synthesized and characterized by spectroscopic and crystallographic methods. IR spectra suggest that isonicotinic acid N-oxide acts as a O,O′-bidentate ligand, the N-oxide group as well as the nitrate group are not involved in coordination. Single crystal analyses have shown that both complexes are isomorphous, where the Ln(III) centers are eight coordinated by four O atoms of four water ligands and other four O atoms of two isonicotinic acid N-oxide ligands. The carboxylate groups are only involved in the bidentate syn–syn bridging mode into infinite chains. Hydrogen bonds between aqua ligands, lattice molecules, nitrate and N-oxide groups are formed giving a three-dimensional network.     

Syntheses,crystal structures and magnetic properties of three new binuclear Ni(II) complexes derived from tripodal tetradentate (N4) ligands

Three new binuclear Ni(II) complexes [{Ni(L_22py)Cl}₂](ClO₄)₂ (1), [{Ni(L_23py)Cl}₂](ClO₄)₂ (2), and [{Ni(L_33py)Cl}₂](ClO₄)₂ (3), {L_22py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane, L_23py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,3-diaminopropane, L_33py = N-(2-pyridylmethyl)-N-(3-aminopropyl)-1,3-diaminopropane} have been synthesized. Single crystal X-ray structure analysis showed that in each complex two distorted octahedral Ni(II) ions are bridged asymmetrically by a pair of chloride anions. Variable temperature magnetic susceptibility measurements of 1 and 3 revealed dominant ferromagnetic exchange interactions.     

Two new lead(II) nitrite complexes,crystal structure of [Pb(phen)2(NO2)2] an eight-coordinate lead(II) complex

Two new lead(II) complexes containing nitrite, [Pb(L)₂(NO₂)₂], L?=?1,10-phenanthroline (phen) or 2,2′-bipyridine (bpy), have been synthesized and characterized. The crystal structure of [Pb(phen)₂(NO₂)₂] shows monomeric units. The coordination number is eight (four from “phen” ligands and four nitrite anions), weak interaction of lead(II) with oxygen atoms of adjacent molecules produce dimer units in the solid state. The arrangement of ligands exhibits a coordination hole around the lead(II), occupied possibly by a stereoactive lone pair of electrons on lead(II), and the coordination around lead is hemidirected. There is a π–π stacking interaction between the parallel aromatic rings that may help to increase the “gap” around lead(II).     

Electronic spectra of Cu(II) crystal complexes with S-methylthiosemicarbazones

Electronic spectra for a series of coordination compounds of copper(II) with tridentant ligands of salicyl aldehyde S-methylthiosemicarbazone and 8-quinoline aldehyde S-methylthiosemicarbazone were investigated. Coordinations of central ions were determined on the basis of X-ray data and IR spectra. Electronic transitions were detected by processing the diffusion-reflection spectra according to theKubelka-Munk theory. Identifications proved the presence of bands corresponding to intraligand transition, charge transfer spectra and the transition of d-d type which are the result of the elimination of d-orbital degeneration for Cu(II) ions in the crystal field. The effect of the symmetry of coordination polyhedrons is discussed.

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Elektronenspektren von Cu(II) Kristall-Komplexen mit S-Methylthiosemicarbazonen

Zusammenfassung Es wurden Elektronenspektren einer Serie von Koordinationsverbindungen des Kupfer(II) mit tridentaten Liganden (Salizylaldehyd-S-methylthiosemicarbazon und 8-Chinolinylaldehyd-S-methylthiosemicarbazon) untersucht. Die Zentralionkoordination wurde durch Röntgenstrahlenuntersuchungen und auf Grund der IR-Spektren festgestellt. Die Elektronenübergänge wurden nach derKubelka-Munk-Theorie aus den diffusen Reflexionsspektren ermittelt. Die Banden wurden den Intraligandübergängen, dem charge-transfer-Spektrum und den d-d-Typ-Übergängen, die als Resultat der Entartungsbeseitigung der Cu(II)-d-Orbitale im Kristallfeld verschiedener Symmetrie entstehen, zugeschrieben.

     

cis-bis(Saccharinato)cobalt(II) and -zinc(II) complexes with 2-dimethylaminoethanol: syntheses,crystal structures,spectroscopic and thermal studies

2-Dimethylaminoethanol (dmea) reacted with tetraaqua-bis(saccharinato)cobalt(II) and -zinc(II) in n-butanol to yield the new complexes cis-[Co(sac)₂(dmea)₂] (1), and cis-[Zn(sac)₂(dmea)₂] (2) (sac?=?saccharinate). The complexes were characterized by elemental analyses, IR spectroscopy, DTA-TG and X-ray crystallography. Both complexes are isomorphous and crystallize in the monoclinic space group P2₁/c. The cobalt(II) and zinc(II) ions are coordinated by two neutral dmea ligands and two sac anions in a distorted octahedral environment. The dmea ligand acts as a bidentate N, O donor through the amine N and hydroxyl O atoms, while the sac ligand exhibits non-equivalent coordination, behaving as an ambidentate ligand; one coordinates to the metal via the carbonyl oxygen atom, while the other is N-bonded. The packing of the molecules in the crystals of both complexes is achieved by aromatic π(sac)–π(sac) stacking interactions, C–H?·?π interactions and weak intermolecular C–H?·?O hydrogen bonds involving the methyl groups of dmea and the sulfonyl oxygen atoms of the sac ligands. IR and UV spectra and thermal analysis are in agreement with the crystal structures.     

Synthesis,structures, and magnetic properties of two pyrazolato-bridged trinuclear copper(II) complexes

One nonlinear and one linear trinuclear copper(II) complex [Cu₃(dien)₂(pdc)₂CH₃OH]₂?·?6CH₃OH (1) and [Cu₃(pdc)₂(CH₃OH)₆(H₂O)₄] (2) were prepared and characterized structurally, where dien is diethylenetriamine and pdc^3? the trianion of 3,5-pyrazoledicarboxylic acid. Both complexes consist of 3,5-pyrazoledicarboxylato-bridged trinuclear copper(II) centers. In 1, copper(II) ions are five-coordinate in distorted square pyramids with bond angles 164.78° for Cu(1)–Cu(2)–Cu(3) and 164.51° for Cu(4)–Cu(5)–Cu(6). In 2, the three copper(II) ions are six-coordinate with elongated octahedral geometry. The trinuclear units of 1 and 2 interact through hydrogen bonds to form 3-D and 2-D supramolecular networks, respectively. Variable temperature magnetic susceptibility measurements show that 1 and 2 are antiferromagnetically coupled with J values of ?11.2 and ?13.3?cm^?1.     

Synthesis,spectral properties,crystal structures and biological activity of copper(II) pyridinecarboxylates with N -heterocyclic ligands

Synthesis and characterization of four new 2,6-dimethoxynicotinate (2,6-(MeO)₂nic) copper(II) monomeric complexes [Cu(2,6-(MeO)₂nic)₂(py)₂] (py is pyridine), [Cu{2,6-(MeO)₂nic}₂(Etnic)₂(H₂O)] (Etnic is ethylnicotinate), [Cu{2,6-(MeO)₂nic}₂(Et₂nia)₂(H₂O)₂] (Et₂nia is N,N-diethylnicotinamide) as well as of the polymeric complex [Cu{2,6-(MeO)₂nic}₂(ron)₂] _n (ron is ronicol) are reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra. Crystal structures of two of the complexes have been determined. The copper(II) of [Cu{2,6-(MeO)₂nic}₂(py)₂] has a distorted tetragonal-bipyramidal (4 + 2) coordination environment. Both 2,6-(MeO)₂nic anions are asymmetrically chelating. The Cu(II) of [Cu{2,6-(MeO)₂nic}₂(Etnic)₂(H₂O)] is pentacoordinate in a slightly distorted tetragonal-pyramidal arrangement by two trans nitrogens, each of one Etnic, by two oxygens, each of the carboxyl group of one unidentate 2,6-(MeO)₂nic and the axial position occupied by water at a longer distance. Antimicrobial effects of the complexes have been tested on various strains of bacteria, yeasts and filamentous fungi. While the 2,6-(MeO)₂nicH alone did not influence the model bacteria growth, dimeric [Cu{2,6-(MeO)₂nic}₂(H₂O)]₂ and polymeric [Cu{2,6-(MeO)₂nic}₂(ron)₂] _n have pronounced influence on the growth of Staphylococcus aureus, Escherichia coli and Candida parapsilosis.     

Synthesis,crystal structures,and properties of copper(II) complexes with 2,6-bis(benzimidazol-2-yl)pyridine

Three new mononuclear copper(II) complexes, [CuL(2-fca)(CH₃OH)]ClO₄?·?CH₃OH (1), [CuL(m-nba)(CH₃OH)]ClO₄ (2), and [CuL(pic)(ClO₄)]?·?CH₃OH (3), were synthesized and structurally characterized, where L is 2,6-bis(benzimidazol-2-yl)pyridine, while 2-fca, m-nba, and pic are the anions of 2-furoic acid, m-nitrobenzoic acid, and picolinic acid, respectively. All of them were characterized by elemental analysis, infrared, UV-Vis, and X-ray crystallography. In 1 and 2, the Cu(II) resides within a distorted square-pyramidal N₃O₂ coordination sphere with three nitrogens of L, one carboxylate oxygen, and one methanol. In 3, Cu(II) is coordinated with three nitrogens of L, one nitrogen and one oxygen of picolinate, and one oxygen of perchlorate in a distorted octahedral geometry. Two molecules of 1, 2, and 3 are interacted by intermolecular hydrogen-bonding interactions and strong π–π stacking interactions to form a dinuclear structural unit. The dinuclear units are further connected by H-bonds via perchlorate or lattice methanol to form a 1-D chain for 1 and 2-D network structures for 2 and 3. Hydrogen-bonding and π–π stacking interactions are important for the stabilization of the final supramolecular structures of the three complexes.     

Self-assembly of copper(II) complexes with substituted aroylhydrazones and monodentate N-heterocycles: synthesis,structure and properties

Two ternary copper(II) complexes [Cu(L¹)(py)] (1) and [Cu(L²)(Himdz]?·?CH₃OH (2) with substituted aroylhydrazones, 5-bromo-salicylaldehyde-3,5-dimethoxy-benzoylhydrazone (H₂L¹) and 5-bromo-salicylaldehyde-p-methyl-benzoylhydrazone (H₂L²), pyridine (py) and imidazole (Himdz), have been synthesized. Their crystal structures and spectroscopic properties have been studied. In each complex, the metal is in a square-planar N₂O₂ coordination formed by the phenolate-O, the imine-N and the deprotonated amide-O atoms of L^2?, and the sp²?N atom of the neutral heterocycle. In the solid state, 1 exists as a centrosymmetric dimer due to very weak apical coordination of the metal bound phenolate-O. Complex 2 has no such apical coordination and exists as a monomer. Self-assembly via C–H?···?O, N–H?···?O and O–H?···?N interaction leads to a one-dimensional chain arrangement; other non-covalent interactions such as C–H?···?π and π?···?π are not involved.