Syntheses and characterization of luminescent dinuclear and polynuclear Cu(I) complexes containing 4,4′-bis(diphenylphosphino)biphenylene bridge

The dinuclear complex [Cu₂(dpbp)₂(NCMe)₄][BF₄]₂ (1) has been prepared by treating [Cu(NCMe)₄][BF₄] with 4,4′-bis(diphenylphosphino)biphenylene (abbreviated as dpbp). Reactions of 1 with 2,2′-bipyridine and 1,1′-bis(diphenylphosphino)ferrocene (abbreviated as dppf) afford [Cu₂(dpbp)₂(2,2′-bipy)₂][BF₄]₂ (2) and [Cu₂(dpbp)(dppf)₂][BF₄]₂ (3), respectively. In contrast, compound 1 reacts with tetra(2-pyridyl)ethyl-1,4-diaminobutane (abbreviated as tpyda) to produce the polymeric complex {[Cu₂(dpbp)(tpyda)][BF₄]₂}_n (4). Compounds 1-4 are photoluminescent with the emission band (λ_max) in the range 510-554 nm. The crystal structures of 1 and 4 have been determined by an X-ray diffraction study.     

Syntheses, characterization and crystal structures of copper(I) o-(diphenylphosphino)benzaldehyde complexes

The complexes [Cu(PCHO)₂(NCMe)][BF₄] (1) and [Cu(PCHO)₃][BF₄] (2) have been prepared by treating [Cu(NCMe)₄][BF₄] with two and three equivalents of Ph₂P(o-C₆H₄)C(O)H (abbreviated as PCHO) at room temperature, respectively. The reaction of 1 and (Ph₂PC₅H₄)₂Fe (abbreviated as DPPF) affords [Cu(PCHO)(DPPF)][BF₄] (3). The molecular structures of 1-3 have been determined by an X-ray diffraction study. The aldehyde groups in 1 are pendant, while one of the formyl groups in 2 is weakly coordinated to the copper ion through the oxygen atom. On the other hand, the copper atom in 3 is strongly chelated by both DPPF and PCHO ligands.     

Construction of one-, two- and three-dimensional Cu(I) polymeric architectures containing bis(diphenylphosphino)acetylene and 4,4′-bipyridine linking ligands

One-dimensional {[Cu₂(dppa)₂(4,4′-bipy)(CH₃CN)₂](BF₄)₂ · 2CH₃CN}_n (1), two-dimensional {[Cu₂(dppa)(4,4′-bipy)₂(CH₃CN)₂](BF₄)₂ · 4CH₂Cl₂ · 4H₂O}_n (2) and three-dimensional {[Cu₂(dppa)(4,4′-bipy)₃](BF₄)₂ · 2CH₂Cl₂ · 3CH₃CN · 3H₂O}_n (3) polymeric complexes have been prepared by self-assembly of [Cu(MeCN)₄]BF₄, Ph₂PCCPPh₂ (dppa) and 4,4′-bipyridine (4,4′-bipy) in a 2:2:1, 1:1:1 and 2:2:3 molar ratio, respectively. The structures of 1-3, determined by an X-ray diffraction study, reveal a linear spring-like architecture for 1, a planar honeycomb grid for 2 and an interlocked adamantoid network for 3.     

Rectangular tetranuclear silver(I) and μ8-selenide-centered octanuclear copper(I) complexes containing bis(diphenylphosphino)amide ligands

Interaction of Ag(CF₃CO₂) with bis(diphenylphosphino)amide (dppa) in THF gave a tetranuclear Ag₄-coplanar silver(I) complex [Ag₄(μ-dppa)₂(μ₄-O₂PPh₂)₂(μ-CF₃CO₂)₂] (1). The trinuclear trigonal-bipyramid copper(I) complex [Cu₃(μ₃-Cl)₂(μ-dppa)₃][CuCl₂] (2) was obtained from the reaction of [CuCl] powder with bis(diphenylphosphino)amide (dppa) in THF. Treatment of 2 with (Me₃Si)₂Se in THF afforded a μ₈-selenide-centered octanuclear copper(I) complex [Cu₈(μ₈-Se)(μ₄-Se)(μ₄-SeH)₃(μ-dppa)₄][(Ph₂PO)₂N] (3). The structures of 1-3 were determined by single-crystal X-ray diffraction analyses. Complex 1 comprises a rectangular Ag₄ array with each edge bridged with a pair of μ-dppa, μ₄-O₂PPh₂ and μ-CF₃CO₂ ligands that are approximately perpendicular to each other. Complex 2 contains a trigonal-bipyramid [Cu₃(μ₃-Cl)₂]⁺ core surrounded by three μ-dppa ligands. The cationic complex in 3 consists of four [Cu₂(μ-dppa)] fragments side-capped by one μ₄-Se and three μ₄-SeH ligands and center-connected by a μ₈-Se atom.     

Structural variations and spectroscopic properties of copper(I) complexes with bis(schiff base) ligands

Six copper(I) complexes {[Cu₂(L1)(PPh₃)₂I₂] · 2CH₂Cl₂}_n (1), {[Cu₂(L2)(PPh₃)₂]BF₄}_n (2), [Cu₂(L3)(PPh₃)₄I₂] · 2CH₂Cl₂ (3), [Cu₂(L4)(PPh₃)₄I₂] (4), [Cu₂(L5)(PPh₃)₂I₂] (5) and [Cu₂(L6)(PPh₃)₂I₂] (6) have been prepared by reactions of bis(schiff base) ligands: pyridine-4-carbaldehyde azine (L1), 1,2-bis(4′-pyridylmethyleneamino)ethane (L2), pyridine-3-carbaldehyde azine (L3), 1,2-bis(3′-pyridylmethyleneamino)ethane (L4), pyridine-2-carbaldehyde azine (L5), 1,2-bis(2′-pyridylmethyleneamino)ethane (L6) with PPh₃ and copper(I) salt, respectively. Ligand L1 or L2 links (PPh₃)₂Cu₂(μ-I)₂ units to form an infinite coordination polymer chain. Ligand 3 or 4 acts as a monodentate ligand to coordinate two copper(I) atoms yielding a dimer. Ligand 5 or 6 chelates two copper(I) atoms using pyridyl nitrogen and imine nitrogen to form a dimer. Complexes 1-4 exhibit photoluminescence in the solid state at room temperature. The emission has been attributed to be intraligand π-π* transition mixed with MLCT characters.     

Synthesis, characterization, crystal structures and photophysical properties of copper(I) complexes containing 1,1′-bis(diphenylphosphino)ferrocene (B-dppf) in doubly-bridged mode

Five copper(I) complexes having general formula [Cu₂(μ-X)₂(κ²-P,P-B-dppf)₂] (X = Cl(1), Br(2), I(3), CN(4), and SCN(5)) were prepared starting with CuX and B-dppf in 1:1 molar ratio in DCM-MeOH (50:50 V/V) at room temperature. The complexes have been characterized by elemental analyses, IR, ¹H NMR, ³¹P NMR and electronic spectral studies. Molecular structures for 1, 2 and 4 were determined crystallographically. Complexes 1, 2 and 4 exist as centrosymmetric dimers in which the two copper atoms are bonded to two bridging B-dppf ligands and two bridging (pseudo-)halide groups in a μ-η¹ bonding mode to generate nearly planar Cu₂(μ-η¹-X)₂ framework. Both bridging B-dppf ligands are arranged in antiperiplanar staggered conformation in 1 and 2 (mean value 56.40-56.76°), and twisted from the eclipsed conformation (mean value 78.19°) in 4. The Φ angle value in 4 is relatively larger as compared to 1 and 2. This seems to indicate that the molecular core [Cu₂(μ-η¹-X)₂] in 4 is a sterically demanding system that forces the B-dppf ligand to adopt a relatively strained conformation in comparison to less strained system in 1 and 2. All the complexes exhibit moderately strong luminescence properties in the solution state at ambient temperature.     

Dinuclear copper(I) complexes containing diimine and phosphine ligands: Synthesis, copper-copper separation and photophysical properties

Dinuclear copper(I) complexes with bridging bis(dicyclohexylphosphino)methane (dcpm) or bis(diphenylphosphino)methane (dppm) and 2,2′-bipyridine or 2-[N-(2-pyridyl)methyl]amino-5,7-dimethyl-1,8-naphthyridine (L), [Cu₂(bpy)₂(dppm)₂](BF₄)₂ (1), [Cu₂(bpy)₂(dcpm)](BF₄)₂ (2), [Cu₂(L)(dppm)](BF₄)₂ (3) and [Cu₂(L)(dcpm)](BF₄)₂ (4) were prepared, and their structures were determined by X-ray crystal analysis. Two-, three-, and four-coordinate copper(I) centers are found in these complexes. Compounds 3 and 4 show close Cu^I?Cu^I separations of 2.664(3) and 2.674(1) Å, respectively, whereas an intramolecular copper-copper distance of 3.038 Å is found in 2 having only dcpm as an additional bridge. Powdered samples of 1, 3, and 4 display intense and long-lived phosphorescence with λ_max at 533, 575, and 585 nm at room temperature, respectively. In the solid state, 2 exhibits only a weak emission at 555 nm. The time-resolved absorption and emission spectra of these complexes were investigated. The difference in the emission properties among complexes 1-4 suggests that both Cu^I?Cu^I distances and coordination environment of the copper(I) centers affect the excited-state properties.     

Synthesis and structural characterization of copper(I) complexes bearing N-methyl-1,3,5-triaza-7-phosphaadamantane (mPTA): Cytotoxic activity evaluation of a series of water soluble Cu(I) derivatives containing PTA, PTAH and mPTA ligands

New copper(I) complexes containing the water soluble N-methyl-1,3,5-triaza-7-phosphaadamantane (mPTA) phosphine have been synthesized by ligand-exchange reactions starting from [Cu(CH₃CN)₄][BF₄] or [Cu(CH₃CN)₄][PF₆] precursors and (mPTA)X (X = CF₃SO₃, I). Depending on the ligand counter ion, the hydrophilic [Cu(mPTA)₄][(CF₃SO₃)₄(BF₄)] 3a and [Cu(mPTA)₄][(CF₃SO₃)₄(PF₆)] 3c complexes or the iodine-coordinated [Cu(mPTA)₃I]I₃4 species were obtained respectively and fully characterized by spectroscopic methods. Single crystal structural characterization was undertaken for [Cu(mPTA)₃I]I₃·H₂O, 4·H₂O, and [Cu(mPTA)₄][(CF₃SO₃)₂(BF₄)₃] ·0.25H₂O, 3b·0.25H₂O, the latter obtained by crystallization of [Cu(mPTA)₄][(CF₃SO₃)₄(BF₄)] 3a. The cytotoxicity of analogous tetrahedral homoleptic Cu(I) derivatives [Cu(PTA)₄](BF₄) 1, [Cu(PTAH)₄][Cl₄(BF₄)] 2, [Cu(mPTA)₄][(CF₃SO₃)₄(BF₄)] 3a and [Cu(mPTA)₄][(CF₃SO₃)₄(PF₆)] 3c was evaluated against a panel of several human tumor cell lines. All the complexes showed in vitro antitumor activity comparable to that of the reference metallodrug cisplatin. Tests performed on cisplatin sensitive and resistant cell lines showed that against human ovarian 2008/C13^* cell line pair, the resistance factor of copper derivatives was roughly 7-fold lower than that of cisplatin, whereas against human cervix cancer A431/A431-Pt cell line pair it was about 2.5-fold lower. These results, confirming the circumvention of cisplatin resistance, support the hypothesis that phosphine copper(I) complexes follow different cytotoxic mechanisms than do platinum drugs.     

Mixed-ligand compounds incorporating quadruply bonded dimolybdenum(II) core: Syntheses, structures and reactivity studies

Reaction of cis-[Mo₂(OAc)₂(CH₃CN)₆][BF₄]₂ with NP-Et,Me (2-ethyl-3-methyl-1,8-naphthyridine) in acetonitrile provides trans-[Mo₂(NP-Et,Me)₂(OAc)₂(CH₃CN)][BF₄]₂ (1). Partial protonation of 1 by HBF₄·Et₂O in acetonitrile leads to trans-[Mo₂(NP-Et,Me)₂(OAc)(CH₃CN)₃][BF₄]₃ (2). In both compounds, NP-R ligands are arranged in a head-to-head (HH) fashion leaving one of the axial sites vacant. Substitution of acetonitriles by NP-Me (3-methyl-1,8-naphthyridine) in trans-[Mo₂(NP-tz)₂(OAc)(CH₃CN)₂][BF₄]₃ provides trans-[Mo₂(NP-tz)₂(OAc)(NP-Me)][BF₄]₃ (3) with retention of configuration. Fully solvated dimolybdenum(II) compound reacts with NP-NH₂ to provide [Mo₂(NP-NH₂)₂(NP-NH)(CH₃CN)₂][BF₄]₃ (4) in which the NP-NH₂ ligands are trans and arranged in a HH fashion. The deprotonated ligand (NP-NH⁻) binds the dimetal unit utilizing naphthyridine nitrogen and amido nitrogen. Treatment of [Mo₂(NP-tz)₂(CH₃CN)₄][CF₃SO₃]₄ with bpym (2,2′-bipyrimidine) followed by crystallization in air provided an oxo complex [Mo₂(NP-tz)₂(μ₂-O)₂(bpym)₂][CF₃SO₃]₄ (5). Compounds 1-5 have been characterized by a variety of spectroscopic techniques and by X-ray crystallography. The reactivity pattern is rationalized based on ligand labilities and thermodynamic stabilities.     

Coordination polymers of 1,8-bis(2-methylthioethoxy)anthraquinone and 1,5-bis(2-methylthioethoxy)anthraquinone with Ag(I): Synthesis and X-ray crystallography

The reaction of 2-(methylthioethanol) with 1,8-dichloroanthraquinone and 1,5-dichloroanthraquinone in THF with base produces 1,8-bis(2-methylthioethoxy)anthraquinone (1) and 1,5-bis(2-methylthioethoxy)anthraquinone (2), respectively. Silver(I) complexes of 1 and 2 have been synthesized after combination with [Ag(CH₃CN)₄]BF₄ in 1:1 M ratio to yield, [(1,8-bis(2-methylthioethoxy)anthraquinone)Ag]BF₄, (3) and [(1,5-bis(2-methylthioethoxy)anthraquinone)Ag·CH₃CN]BF₄, (4). X-ray crystal structures of the free ligand (1) and the Ag(I) complexes (3 and 4) are reported. The intraannular carbonyl group forms a coordinate-covalent bond with Ag(I) and, in the solid state, both silver(I) complexes are found as coordination polymers.     

Preparation, characterization and redox chemistry of oxo-centered triruthenium dimers linked by bis(diphenylphosphino)anthracene and -ferrocene

Diphosphine-bridged dimers of oxo-centered triruthenium-acetate cluster units, i.e., [{Ru₃O(OAc)₆(py)₂}₂(dppan)](PF₆)₂ (2) and [{Ru₃O(OAc)₆(py)₂}₂(dppf)](PF₆)₂ (3) were prepared by reaction of 2.3 equivalent [Ru₃O(OAc)₆(py)₂(CH₃OH)](PF₆) with 9,10-bis(diphenylphosphino)anthracene (dppan) or 1,1′-bis(diphenylphosphino)ferrocene (dppf), respectively. Apparent redox wave splitting is observed in complex 2, revealing the presence of electronic communication between two triruthenium units mediated through bridging dppan. The complexes were characterized by elemental analysis, IR, UV-Vis, ³¹P NMR, and ES-MS spectroscopies, and cyclic and differential-pulse voltammetry. The crystal structure of complex 3 was determined by X-ray crystallography.     

Copper(I) and silver(I) tertiary phosphines complexes: Synthesis, X-ray structures and spectroscopic characterization

Six new complexes, [Cu₄I₄(PPh₂Cy)₄]·2H₂O (1), [CuI(PPhCy₂)₂] (2), [CuCl(PPhCy₂)₂] (3), and [CuBr(PPh₃)₃]·CH₃CN (4), [Ag(PPhCy₂)₂(NO₃)] (5), [Ag(PCy₃)(NO₃)]₂ (6) [where Ph = phenyl, Cy = cyclohexyl], have been synthesized and structurally characterized by X-ray diffraction, IR absorption spectra and NMR spectroscopic studies (except complex 4). The X-ray diffraction analysis of complex (1), pseudo polymorph of complex [Cu₄I₄(PPh₂Cy)₄], reveals a stella quadrangula structure. The four corners of the cube are occupied by copper(I) atoms and four I atoms are present at the alternative corners of the cube, further more the copper(I) atoms are coordinated to a monodentate tertiary phosphine. Complexes (2) and (3) are isostructural with trigonal planar geometry around the copper(I) atom. The crystal structure of complex (4) is a pseudo polymorph of complex [CuBr(PPh₃)₃] and the geometrical environment around the copper(I) centre is distorted tetrahedral. In the Ag^I complexes (5) and (6), the central metal atoms have pseudo tetrahedral and trigonal planar geometry, respectively. Spectroscopic and microanalysis results are consistent with the single crystal X-ray diffraction studies.     

Synthesis, structure and spectroscopic properties of 2,3-bis(diphenylphosphino)quinoxaline (dppQx) and its copper(I) complexes

Phosphinoquinoxalines were prepared by treatment of 2,3-dichloroquinoxaline (3) with phosphorus nucleophiles. The Arbuzov reaction of 3 with PPh(O-i-Pr)₂ gave a mixture of diastereomers of 2,3-(PPh(O)(O-i-Pr))₂quinoxaline (6); the crystal structure of rac-6 was determined, but attempts at reduction to yield bis(phenylphosphino)quinoxaline 7 resulted in P-C cleavage and formation of phenylphosphine. The bis(secondary phosphine) 7 could be generated from 3 and LiPHPh(BH₃), but was not isolated in pure form. Copper-catalyzed coupling of PHPh₂ with 3 gave 2,3-bis(diphenylphosphino)quinoxaline (4, dppQx), whose coordination chemistry was investigated, with comparison to data for the analogous 1,2-bis(diphenylphosphino)benzene (dppBz) complexes. Reaction of dppQx with [Cu(NCMe)₄][PF₆] gave [Cu(dppQx)₂][PF₆] (8); CuCl yielded [Cu(dppQx)Cl]₂ (9). Reaction of [Cu(NCMe)₄][PF₆] with one equiv of DPEphos, followed by one equiv of dppQx, gave [Cu(dppQx)(DPEphos)][PF₆] (10). Ligand 4 and copper complexes 8 and 9 were crystallographically characterized. The UV-Vis spectra of dppQx and its copper complexes were red-shifted from those of the dppBz analogs; in contrast to results for the dppBz complexes, those of dppQx were not luminescent in solution.     

Binuclear copper and zinc complexes based on polypyridyl ligand 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz): Synthesis, spectral and structural characterization

The reaction of MCl₂ · 2H₂O (M = Cu, Zn) with 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz) (referred hereafter as L) in 2:1 molar ratio in acetonitrile at room temperature afforded binuclear complexes [M₂(κ³-L)Cl₄] [Cu (1), Zn (2)] where the ligand is bis-tridentate manner. The complexes have been characterized by elemental analyses, FAB-MS, IR, EPR, NMR and electronic spectral studies. Solid state structures of both the [Cu₂(κ³-L)Cl₄] · 5H₂O (1), [Zn₂(κ³-L)Cl₄] · H₂O (2) have been determined by single crystal X-ray analyses. A well-resolved uudd cyclic water tetramer and water monomer were reported in the crystal host of [Cu₂(κ³-L)Cl₄] · 5H₂O (1) and [Zn₂(κ³-L)Cl₄] · H₂O (2) showing the contribution of the water cluster to the stability of the crystal host 1 and 2.     

Synthesis, structural and spectroscopic characterization of mono- and binuclear copper(I) complexes with substituted diimine and phosphine ligands

The reaction of [Cu(CH₃CN)₄]BF₄, 6-(4-methoxyl)phenyl-2,2′-bipyridine (designated as MeO-CNN), and/or tricyclohexylphosphine (PCy₃) and diimine ligands derived from 4,4′-bipyridine gave four mono- and binuclear copper(I) complexes, [Cu(MeO-CNN)₂]BF₄ (1), [Cu₂(MeO-CNN)₂(PCy₃)₂(4,4′-bipy)](BF₄)₂ · 1.5CH₂Cl₂ (2) (bipy = bipyridine), [Cu₂(MeO-CNN)₂(PCy₃)₂(bpete)](BF₄)₂ · 4CH₂Cl₂ (3) (bpete = trans-1,2-bis(4-pyridyl)ethene) and [Cu₂(MeO-CNN)₂(PCy₃)₂(4,4′-azpy)] (BF₄)₂ · 1.5CH₂Cl₂ (4) (azpy = azobispyridine). Crystallographic studies of complexes 1-4 show that each copper(I) center adopts a pseudo-tetrahedral coordination geometry. Complexes 2-4 consists of -Cu(MeO-CNN)(PCy₃) units which are linked through 4,4′-bipy, bpete and 4,4′-azpy, respectively. The UV-Vis spectra of these four complexes all exhibit intense high-energy absorptions at λ_max < 340 nm and broad visible bands in a range of 430-550 nm, ascribed to intraligand (IL π → π^∗) transitions and metal-to-ligand charge-transfer (MLCT) transitions, respectively. The density functional theory calculation was used to interpret the absorption spectrum of 1, which further supports the assignment of MLCT character. The binuclear complexes 2 and 3 both display red solid-state emissions centred at 620 and 660 nm from metal-to-ligand charge-transfer excited state, respectively. Interestingly, the electron paramagnetic resonance (EPR) spectral measurements confirm copper(I) complexes oxidized to corresponding copper(II)-halide product upon excitation at 355 nm in dichloromethane solution.     

Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H₂O)] · 2H₂O (H₃Sas = N-(2-hydroxybenzyl)-l-aspartic acid) (1), [Cu(HMeSglu)(H₂O)] · 2H₂O (H₃MeSglu = (N-(2-hydroxy-5-methylbenzyl)-l-glutamic acid) (2), [Cu₂(Smet)₂] (H₂Smet = (N-(2-hydroxybenzyl)-l-methionine) (3), [Ni(HSas)(H₂O)] (4), [Ni₂(Smet)₂(H₂O)₂] (5), and [Ni(HSapg)₂] (H₂Sapg = (N-(2-hydroxybenzyl)-l-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6.     

Copper(II) chloride/1-methylbenzotriazole chemistry: influence of various synthetic parameters on the product identity, structural and magnetic characterization, and quantum-chemical studies

A systematic investigation of the CuCl₂/Mebta (Mebta = 1-methylbenzotriazole) reaction system is described, involving the determination of the influence of the Cu^II:Mebta ratio, the nature of solvent and the presence of counterions on the identity of the reaction products. As a consequence, complexes [Cu₂Cl₄(Mebta)₄] (1), [CuCl₂(Mebta)₂] (2), {[Cu₂Cl₄(Mebta)₂]}_n (3), [Cu₄OCl₆(Mebta)₄] · 0.25H₂O (4 · 0.25H₂O) and [Cu₂Cl₂(Mebta)₆](ClO₄)₂ (5) have been isolated and structurally characterized by single-crystal X-ray studies. Mebta behaves as a monodentate ligand binding through N(3). 1 is a dinuclear complex, the structure of 2 consists of discrete monomeric units, and that of 3 is composed of linear, well-separated polymeric chains of Cu^II atoms. The molecules of 4 · 0.25H₂O have a central μ₄-oxide ion surrounded tetrahedrally by four Cu^II atoms. In the cations of 5 the two Cu^II centres are asymmetrically bridged by two chloro ligands, with three Mebta molecules completing five coordination at each metal. Complexes were characterized by spectroscopic (IR, far-IR, solution UV/Vis) and thermal decomposition (TG, DTG, and DTA) techniques. Variable-temperature magnetic susceptibility data for 1, 3 and 5 showed intramolecular (1, 5) and intrachain (3) ferromagnetic exchange interactions. Estimates of the Jparameters, experimentally derived, were in close agreement with a new magneto-structural criterion developed by us, holding for bis(μ-chloro) copper(II) dimers. A comparison between the CuCl₂/Mebta and CuBr₂/Mebta systems is also presented.     

Aliphatic and aromatic C-H activation of benzo[h]quinolines by Rh(I). Unique precursor dependent formation of mono-, di- and trinuclear complexes

Treatment of 7,8-benzo[h]quinoline (bhq-H, 1) and 10-methyl benzo[h]quinoline (bhq-Me, 3) with [Rh(C₂H₄)₂(THF)₂][BF₄] resulted in double C-H activation of aliphatic and aromatic C-H bonds, yielding the Rh(III) complexes 4 and 5, respectively. The structures of 4 and 5 were revealed by X-ray diffraction. The reaction of 1 with two other slightly different rhodium precursors, [Rh(olefin)_n(THF)₂][BF₄] (COE (n = 2), COD (n = 1)), led to completely different products, a dinuclear complex 7 and a trinuclear complex 6, respectively, which were characterized by X-ray diffraction. Complex 6 exhibits a rare linear Rh-Rh-Rh structure. Utilizing excess of 1 with [Rh(COD)(THF)₂][BF₄] led to the formation of a new product 8 with no C-H bond activation taking place. Additional C-H activation products of 1, cationic and neutral, in the presence of PⁱPr₃ (9a, 9b and 10) are also presented.     

Dinuclear alkoxo-bridged copper(II) coordination polymers: Syntheses, structural and magnetic properties

The alkoxo-bridged dinuclear copper(II) complexes [Cu₂(ap)₂(NO₂)₂] (1), [Cu₂(ap)₂(C₆H₅COO)₂] (2) and [Cu₂(ap)₂μ-1,3-C₆H₄(COO)₂(dmso)₂]·dmso (3) (ap = 3-aminopropanolato and dmso = dimethyl sulfoxide) have been synthesized via self-assembly from copper(II) perchlorate, 3-aminopropanol as main chelating ligand and nitrite and isophthalate anions as spacers and benzoate anion as auxiliary ligand. Complexes 1 and 3 crystallize as 2D and 1D coordination polymers, respectively, and their structures consist of dinuclear [Cu₂(ap)₂]²⁺ units connected with nitrite and isophthalate ligands. The adjacent dinuclear units of 2 and 1D polymers of 3 are further connected by hydrogen bonds resulting in the formation of 2D layers. The variable temperature crystallographic measurements of 1 at 100, 173 and 293 K indicate the static Jahn-Teller distortion with librational disorder in the nitrite group. Experimental magnetic studies showed that complexes 1-3 exhibit strong antiferromagnetic couplings. The values of the magnetic exchange coupling constant for 1-3 are well reproduced by the theoretical calculations.     

The influence of substituents (R) at N atom of thiophene-2-carbaldehyde thiosemicarbazones {(C4H3S)HCN-N(H)-C(S)NHR} on bonding, nuclearity and H-bonded networks of copper(I) complexes

The nuclearity, bonding and H-bonded networks of copper(I) halide complexes with thiophene-2-carbaldehyde thiosemicarbazones {(C₄H₃S)HC²N³-N(H)-C¹(S)N¹HR} are influenced by R substituents at N¹ atom. Thiophene-2-carbaldehyde-N¹-methyl thiosemicarbazone (HttscMe) or thiophene-2-carbaldehyde-N¹-ethyl thiosemicarbazone (HttscEt) have yielded halogen-bridged dinuclear complexes, [Cu₂(μ-X)₂(η¹-S-Htsc)₂(Ph₃P)₂] (Htsc, X: HttscMe, I, 1; Br, 2; Cl, 3; HttscEt, I, 4; Br, 5; Cl, 6), while thiophene-2-carbaldehyde-N¹-phenyl thiosemicarbazone (HttscPh) has yielded mononuclear complexes, [CuX(η¹-S-HttscPh)₂] (X, I, 7a; Br 8; Cl, 9) and a sulfur bridged dinuclear complex, [Cu₂(μ-S-HttscPh)₂(η¹-S-HttscPh)₂I₂] 7b co-existing with 7a in the same unit cell. These results are in contrast to S-bridged dimers [Cu₂(μ-S-Httsc)₂(η¹-Br)₂(Ph₃P)₂] · 2H₂O and [Cu₂(μ-S-Httsc)₂(η¹-Cl)₂(Ph₃P)₂] · 2CH₃CN obtained for R = H and X = Cl, Br (Httsc = thiophene-2-carbaldehyde thiosemicarbazone) as reported earlier. The intermolecular CH_Ph?π interaction in 1-3 (2.797 Å, 1; 3.264 Å, 2; 3.257 Å, 3) have formed linear polymers, whereas the CH_Ph?X and N³?HCH interactions in 4-6 (2.791, 2.69 Å, 5; 2.776, 2.745 Å, 6, respectively) have led to the formation of H-bonded 2D polymer. The PhN¹H?π, interactions (2.547 Å, 8, 2.599 Å, 9) have formed H-bonded dimers only. The Cu?Cu separations are 3.221-3.404 Å (1-6).