The gas‐phase ligand exchange of copper and nickel acetylacetonate,hexafluoroacetylacetonate and trifluorotrimethylacetylacetonate complexes

The gas‐phase ligand‐exchange reactions between Cu(II) and Ni(II) complexes containing the acetylacetonate (acac), hexafluoroacetylacetonate (hfac), and trifluorotrimethylacetylacetonate (tftm) ligands were investigated using a triple quadrupole mass spectrometer. The gas‐phase mixed‐ligand products of [Cu(acac)(tftm)]⁺, [Ni(acac)(tftm)]⁺, [Cu(hfac)(tftm)]⁺, and [Ni(hfac)(tftm)]⁺ were formed following the co‐sublimation of either homo‐metal or hetero‐metal precursors. The gas‐phase formation of [Cu(acac)(tftm)]⁺, [Cu(hfac)(tftm)]⁺, [Ni(acac)(tftm)]⁺, and [Ni(hfac)(tftm)]⁺ complexes is reported herein for the first time. The corresponding fragmentation patterns of these species along with those of Cu(tftm)₂ and Ni(tftm)₂ are also presented. Mass‐selected ion‐neutral reactions were investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

The gas-phase ligand exchange reactions of cobalt and zinc acetylacetonate, hexafluoroacetylacetonate, and trifluorotrimethylacetylacetonate complexes

The gas-phase ligand exchange reactions between Co(II) and Zn(II) complexes containing the acetylacetonate (acac), hexafluoroacetylacetonate (hfac), and trifluorotrimethylacetylacetonate (tftm) ligands were investigated using a triple quadrupole mass spectrometer. The gas-phase mixed ligand products of [Cu(acac)(tftm)](+), [Ni(acac)(tftm)](+), [Cu(hfac)(tftm)](+), and [Ni(hfac)(tftm)](+) were formed following the co-sublimation of either homo-metal or hetero-metal precursors and are reported herein for the first time. The fragmentation patterns of these mixed ligand species along with those of Cu(tftm)(2) and Ni(tftm)(2) are also presented. The collision cell of the instrument was utilized to examine the gas-phase reactions between mass-selected ions and specific neutral target compounds.     

Solid,Solution, and Theoretical Approach of [Cu(CN‐acac)(dmeen)]+

The reaction of bis(3‐cyano‐2,4‐pentanedionato)copper(II), [Cu(NC‐acac)₂] with the nitrogenous base N,N‐dimethyl, N′‐ethyl‐1,2‐ethylenediamine (dmeen) in the presence of Cu(ClO₄)₂ · 6H₂O, afforded a new cationic mixed‐ligand chelate [Cu(CN‐acac)(dmeen)]⁺. Its structure was characterized spectroscopically (IR, UV/Vis, EPR) and verified by X‐ray diffraction studies as [Cu(CN‐acac)(dmeen)(H₂O)]ClO₄. The coordination of CN‐acac^– as bridging ligand leads to a polymeric helical chain, which extends in the crystallographic c axis. Density functional theory (DFT) calculations suggest that in the solid state the anion CN‐acac^– binding is envisaged through the nitrogen atom of the cyanido group, establishing an octahedral arrangement around copper, whereas in solution, the square‐planar arrangement is prevailed, in accordance with the EPR findings.     

Insertion of Molecular Oxygen in Transition‐Metal Hydride Bonds,Oxygen‐Bond Activation,and Unimolecular Dissociation of Metal Hydroperoxide Intermediates. Short Communication

Thermal activation of molecular oxygen is observed for the late‐transition‐metal cationic complexes [M(H)(OH)]⁺ with M=Fe, Co, and Ni. Most of the reactions proceed via insertion in a metal? hydride bond followed by the dissociation of the resulting metal hydroperoxide intermediate(s) upon losses of O, OH, and H₂O. As indicated by labeling studies, the processes for the Ni complex are very specific such that the O‐atoms of the neutrals expelled originate almost exclusively from the substrate O₂. In comparison to the [M(H)(OH)]⁺ cations, the ion? molecule reactions of the metal hydride systems [MH]⁺ (M=Fe, Co, Ni, Pd, and Pt) with dioxygen are rather inefficient, if they occur at all. However, for the solvated complexes [M(H)(H₂O)]⁺ (M=Fe, Co, Ni), the reaction with O₂ involving O? O bond activation show higher reactivity depending on the transition metal: 60% for the Ni, 16% for the Co, and only 4% for the Fe complex relative to the [Ni(H)(OH)]⁺/O₂ couple.     

Production and isolation of ligated metal(IV)‐oxo ions by tandem mass spectrometry

High valent metal(IV)‐oxo species, [M(?O)(MeIm)_n(OAc)]⁺ (M = Mn–Ni, MeIm = 1‐methylimidazole, n = 1–2), which are relevant to biology and oxidative catalysis, were produced and isolated in gas‐phase reactions of the metal(II) precursor ions [M(MeIm)_n(OAc)]⁺ (M = Mn–Zn, n = 1–3) with ozone. The precursor ions [M(MeIm)(OAc)]⁺ and [M(MeIm)₂(OAc)]⁺ were generated via collision‐induced dissociation of the corresponding [M(MeIm)₃(OAc)]⁺ ion. The dependence of ozone reactivity on metal and coordination number is discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Coordination Complexes of a Neutral 1,2,4‐Benzotriazinyl Radical Ligand: Synthesis,Molecular and Electronic Structures,and Magnetic Properties

A series of d‐block metal complexes of the recently reported coordinating neutral radical ligand 1‐phenyl‐3‐(pyrid‐2‐yl)‐1,4‐dihydro‐1,2,4‐benzotriazin‐4‐yl ( 1 ) was synthesized. The investigated systems contain the benzotriazinyl radical 1 coordinated to a divalent metal cation, Mn^II, Fe^II, Co^II, or Ni^II, with 1,1,1,5,5,5‐hexafluoroacetylacetonato (hfac) as the auxiliary ligand of choice. The synthesized complexes were fully characterized by single‐crystal X‐ray diffraction, magnetic susceptibility measurements, and electronic structure calculations. The complexes [Mn( 1 )(hfac)₂] and [Fe( 1 )(hfac)₂] displayed antiferromagnetic coupling between the unpaired electrons of the ligand and the metal cation, whereas the interaction was found to be ferromagnetic in the analogous Ni^II complex [Ni( 1 )(hfac)₂]. The magnetic properties of the complex [Co( 1 )(hfac)₂] were difficult to interpret owing to significant spin–orbit coupling inherent to octahedral high‐spin Co^II metal ion. As a whole, the reported data clearly demonstrated the favorable coordinating properties of the radical 1 , which, together with its stability and structural tunability, make it an excellent new building block for establishing more complex metal–radical architectures with interesting magnetic properties.     

Heterotrimetallic Mixed‐Valent Molecular Precursors Containing Periodic Table Neighbors: Assignment of Metal Positions and Oxidation States

A known trinuclear structure was used to design the heterobimetallic mixed‐valent, mixed‐ligand molecule [Co^II(hfac)₃?Na?Co^III(acac)₃] ( 1 ). This was used as a template structure to develop heterotrimetallic molecules [Co^II(hfac)₃?Na?Fe^III(acac)₃] ( 2 ) and [Ni^II(hfac)₃?Na?Co^III(acac)₃] ( 3 ) via isovalent site‐specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple‐wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies. Molecules of 2 and 3 are true heterotrimetallic rather than a statistical mixture of two heterobimetallic counterparts. Trinuclear platform 1 exhibits flexibility in accommodating a variety of di‐ and trivalent metals, which can be further utilized in the design of molecular precursors for the NaMM′O₄ functional oxide materials.     

Ligand‐Centred Reactivity of Bis(picolyl)amine Iridium: Sequential Deprotonation,Oxidation and Oxygenation of a “Non‐Innocent” Ligand

Treatment of [Ir(bpa)(cod)]⁺ complex [ 1 ]⁺ with a strong base (e.g., tBuO^?) led to unexpected double deprotonation to form the anionic [Ir(bpa?2H)(cod)]^? species [ 3 ]^?, via the mono‐deprotonated neutral amido complex [Ir(bpa?H)(cod)] as an isolable intermediate. A certain degree of aromaticity of the obtained metal–chelate ring may explain the favourable double deprotonation. The rhodium analogue [ 4 ]^? was prepared in situ. The new species [M(bpa?2H)(cod)]^? (M=Rh, Ir) are best described as two‐electron reduced analogues of the cationic imine complexes [M^I(cod)(Py‐CH₂‐N?CH‐Py)]⁺. One‐electron oxidation of [ 3 ]^? and [ 4 ]^? produced the ligand radical complexes [ 3 ]^. and [ 4 ]^.. Oxygenation of [ 3 ]^? with O₂ gave the neutral carboxamido complex [Ir(cod)(py‐CH₂‐N‐CO‐py)] via the ligand radical complex [ 3 ]^. as a detectable intermediate.     

"Jumping crystals": oxygen-evolving metal-nitroxide complexes

The crystals of heterospin complexes [M(hfac)(2)L(2)] (where M = Cu, Ni, Co, or Mn; hfac = hexafluoroacetylacetonate; and L = nitronyl nitroxide, 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl) were found to make unusual jumping motions. Under ambient conditions, the jumping and various displacements of crystals lasted for several weeks. The mechanical motion was accompanied by the cracking and disintegration of crystals, and a solid [M(hfac)(2)(L(1))(2)] complex with the corresponding imino nitroxide 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-1-oxyl (L(1)) was detected. The jumping was accompanied by the spontaneous elimination of oxygen, the source of which was the nitronyl nitroxyl fragment of coordinated L. An X-ray study of [M(hfac)(2)L(2)] (where M = Cu, Ni, Co, or Mn) showed that the molecular structure of all [M(hfac)(2)L(2)] and their packing in the solid state were identical. The packing of [M(hfac)(2)L(2)] was concluded to be critical to the mechanical effect. In complexes with different stoichiometries or different sets of diamagnetic ligands ([Cu(hfac)(2)L](2), [Cu(hfac)(acac)L]·EtOH, [CuPiv(2)L(2)]·2CH(2)Cl(2), and [Cu(hfac)(2)L(2)Cu(2)Piv(4)]·3C(7)H(8) (where acac is acetylacetonate and Piv is trimethylacetate), or free L), the effect vanished when the packing changed.     

Structural and Magnetic Properties of 2p‐3d‐4f Hetero‐Tri‐Spin Chains Comprising [{Cu(hfac)2‐Radical}2] Dimers and Ln(hfac)3 (hfac=hexafluoroacetylacetonate)

A new family of 2p‐3d‐4f hetero‐tri‐spin complexes [Ln(hfac)₃{Cu(hfac)₂(NIT‐3 PyPh)}₂] (Ln=Gd ( 1 ), Tb ( 2 ), Dy ( 3 ), Ho ( 4 ); NIT‐3 PyPh=2‐[4‐(3‐pyridinylmethoxy)phenyl]‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide; hfac=hexafluoroacetylacetonate) have been synthesized. Four complexes possess a 1D chain structure in which two radical ligands join two Cu(hfac)₂ molecules to form a [{Cu(hfac)₂‐rad)}₂] dimer cycle and the dimer rings are linked by Ln(hfac)₃ units. Magnetic studies show that ferromagnetic exchange couplings exist between the coordinated NO groups of radical ligands and metal ions. Field‐induced slow relaxation of the magnetization was observed in the Tb and Dy compounds.     

Microsolvation of the [Ni(acac)(tmen)]+ complex

Microsolvation of the [Ni(acac)(tmen)]⁺ complex by a series of aliphatic n-alcohols (Solv) has been studied in ClCH₂CH₂Cl solutions by spectrophotometry. Based on the changes in the electronic spectrum of the afore-mentioned complex, observed under the influence of any alcohol, the equilibrium constants for the formation of the [Ni(acac)(tmen)Solv]⁺ and [Ni(acac)(tmen)Solv₂]⁺ species have been computed according to the algorithm presented in this work. It was found that, in all the systems studied, the stability of five-coordinated [Ni(acac)(tmen)Solv]⁺ is higher than that of octahedral [Ni(acac)(tmen)Solv₂]⁺. The resulting values are discussed in terms of the Lewis basicity of alcohols.     

Primary Fragmentation Pathways of Gas Phase [M(Uracil−H)(Uracil)]+ Complexes (M=Zn,Cu, Ni,Co, Fe,Mn, Cd,Pd , Mg,Ca, Sr,Ba, and Pb): Loss of Uracil versus HNCO

Complexes formed between metal dications, the conjugate base of uracil, and uracil are investigated by sustained off‐resonance irradiation collision‐induced dissociation (SORI‐CID) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Positive‐ion electrospray spectra show that [M(Ura?H)(Ura)]⁺ (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd, Mg, Ca, Sr, Ba, or Pb) is the most abundant ion even at low concentrations of uracil. SORI‐CID experiments show that the main primary decomposition pathway for all [M(Ura?H)(Ura)]⁺, except where M=Ca, Sr, Ba, or Pb, is the loss of HNCO. Under the same SORI‐CID conditions, when M is Ca, Sr, Ba, or Pb, [M(Ura?H)(Ura)]⁺ are shown to lose a molecule of uracil. Similar results were observed under infrared multiple‐photon dissociation excitation conditions, except that [Ca(Ura?H)(Ura)]⁺ was found to lose HNCO as the primary fragmentation product. The binding energies between neutral uracil and [M(Ura?H)]⁺ (M=Zn, Cu, Ni, Fe, Cd, Pd ,Mg, Ca, Sr Ba, or Pb) are calculated by means of electronic‐structure calculations. The differences in the uracil binding energies between complexes which lose uracil and those which lose HNCO are consistent with the experimentally observed differences in fragmentation pathways. A size dependence in the binding energies suggests that the interaction between uracil and [M(Ura?H)]⁺ is ion–dipole complexation and the experimental evidence presented supports this.     

Remarkable solvent effects in the hydro‐ and solvothermal synthesis of copper‐1,10‐phenanthroline complexes

Compound {[Cu(II)/Cu(I)]₂(ophen)₄(Htpt)}^?2H₂O ( 1 ) was obtained by hydrothermal reaction. Compound 1 is a mixed‐valence copper coordination complex with a different coordination environment. The X‐ray structural analysis of 1 revealed two crystallographically independent dimeric [Cu₂(ophen)₂]⁺ units bridged by two µ₁‐carboxylate groups of the tpt ligand into a butterfly‐shaped molecule in the crystal structure. Compound [Cu(I)₃(CN)₃(phen)₃] ( 2 ) was synthesized using ethanol instead of water, and consisted of an infinite helix chain formed from [Cu(I)(phen)]⁺ units bridged by cyano groups. Copyright © 2007 John Wiley & Sons, Ltd.     

Redox Non‐Innocence and Isomer‐Specific Oxidative Functionalization of Ruthenium‐Coordinated β‐Ketoiminate

This article deals with isomeric ruthenium complexes [Ru^III(L^R)₂(acac)] (S=1/2) involving unsymmetric β‐ketoiminates (AcNac) (L^R=R‐AcNac, R=H ( 1 ), Cl ( 2 ), OMe ( 3 ); acac=acetylacetonate) [R=para‐substituents (H, Cl, OMe) of N‐bearing aryl group]. The isomeric identities of the complexes, cct (cis‐cis‐trans, blue, a ), ctc (cis‐trans‐cis, green, b ) and ccc (cis‐cis‐cis_, pink, c ) with respect to oxygen (acac), oxygen (L) and nitrogen (L) donors, respectively, were authenticated by their single‐crystal X‐ray structures and spectroscopic/electrochemical features. One‐electron reversible oxidation and reduction processes of 1 – 3 led to the electronic formulations of [Ru^III(L)(L ^? )(acac)]⁺ and [Ru^II(L)₂(acac)]^? for 1 ⁺‐ 3 ⁺ (S=1) and 1^? – 3^? (S=0), respectively. The triplet state of 1 ⁺‐ 3 ⁺ was corroborated by its forbidden weak half‐field signal near g≈4.0 at 4 K, revealing the non‐innocent feature of L. Interestingly, among the three isomeric forms ( a – c in 1 – 3 ), the ctc ( b in 2 b or 3 b ) isomer selectively underwent oxidative functionalization at the central β‐carbon (C?H→C=O) of one of the L ligands in air, leading to the formation of diamagnetic [Ru^II(L)(L ′ )(acac)] (L ′ =diketoimine) in 4 / 4′ . Mechanistic aspects of the oxygenation process of AcNac in 2 b were also explored via kinetic and theoretical studies.     

Tetrakis(diethyl‐phosphonat)‐, Tetrakis(ethyl‐phenylphosphinat)‐ und Tetrakis(diphenylphosphin‐oxid)‐substituierte Phthalocyanine

Tetrakis(diethyl phosphonate), Tetrakis(ethyl phenylphosphinate)‐, and Tetrakis(diphenylphosphine oxide)‐Substituted Phthalocyanines The title compounds 7, 9 , and 11 are obtained by tetramerization of diethyl (3,4‐dicyanophenyl)phosphonate ( 5 ), ethyl (3,4‐dicyanophenyl)phenylphosphinate ( 8 ), and 4‐(diphenylphosphinyl)benzene‐1,2‐dicarbonitrile ( 10 ). The ³¹P‐NMR spectra of the phthalocyanines 7, 9 , and 11 and of their metal complexes present five to eight signals confirming the formation of four constitutional isomers with the expected C_4h, D_2h, C_2v, and C_s symmetry. In the FAB‐MS of the Zn, Cu, and Ni complexes of 7 and 9 , the peaks of dimeric phthalocyanines are observed. By gel‐permeation chromatography, the monomeric complex [Ni( 7 )] and a dimer [Ni( 7 )]₂ can be separated. These dimers differ from the known phthalocyanine dimers, i.e., possibly the P(O)(OEt)₂ and P(O)(Ph)(OEt) substituents in 7 and 9 are involved in complexation. The free phosphonic acid complex [Zn( 12 )] and [Cu( 12 )] are H₂O‐soluble. In the FAB‐MS of [Zn( 12 )], only the peaks of the dimer are present; the ESI‐MS confirms the existence of the dimer and the metal‐free dimer. In the UV/VIS spectrum of [Zn( 12 )], the hypsochromic shift characteristic for the known type of dimers from 660–700 nm to 620–640 nm is observed. As in the FAB‐MS of [Zn( 12 )], the free phosphinic acid complex [Zn( 13 )] shows only the monomer, an ESI‐MS cannot be obtained for solubility problems. The UV/VIS spectrum of [Zn( 13 )] demonstrates the existence of the monomer as well as of the dimer.     

Two New Nitronyl Nitroxide Radicals and Their Complexes with M（hfac）2 [M=Co（II）, Ni（ll）, Mn（ll）]： Syntheses,Crystal Structures,and Magnetic Characterizations

Two new nitronyl nitroxides with amido units L1 and L2 were synthesized and characterized. Reactions of L1 and L2 with M（hfac）2 [hfac=hexafluoroacetylacetonate, M=Co（II）, Ni（II）, Mn（II）] afforded five hetero-spin complexes LiCo（hfac）2, LlNi（hfac）2, L2Co（hfac）2, L2Ni（hfac）2 and L2Mn（hfac）2. The crystal structures and magnetic characterizations of L1, L2 and their metal complexes LM（hfac）2 were described and discussed. Crystal structural analysis shows that both the carbonyl oxygen and the nitroxide oxygen are coordinated to the metal ions. Strong antiferromagetic coupling between the nitronyl nitroxides and metal ions were observed for all the five LM（hfac）2 complexes.     

Responses of Metalloporphyrin‐Based Ion‐Selective Electrodes to pH

The ISEs based on [M(tpp)Cl] (M: Al, Ga, In, Mn, Fe; H₂tpp: tetraphenylporphin) had pH responses across their respective pH ranges, which had some correlation with the pH ranges of the two‐phase hydrolysis. Such pH responses are ascribed to the phase boundary potentials relating to the acid‐base pairs of [M(tpp)(H₂O)]⁺ and [M(tpp)(OH)] and/or [M₂(tpp)₂O]. The potential responses of the In and Fe complexes had the upper limitation to pH of 90 % hydrolysis, whereas those of the Al and Ga complexes had the extension to at least pH 12, indicating stable existence of [M(tpp)(H₂O)]⁺ even in contact with strongly alkaline solutions.     

New Cu(I) Coordination Complexes Based on Tetrathiafulvalene Substituted Triazol‐pyridine Ligand: Synthesis,Properties and Theoretical Studies

Two Cu(I) complexes based on the thioethyl‐bridged triazol‐pyridine ligand with tetrathiafulvalene unit (TTF‐TzPy, L ), [Cu(I)(Binap)(L)]BF₄ ( 5 , Binap=2,2’‐bis(diphenylphosphino)‐1,1’‐binaphthyl) and [Cu(I)(Xantphos)(L)]BF₄ ( 6 , Xantphos=9,9‐dimethyl‐4,5‐bis(diphenylphosphino)‐xanthene), have been synthesized. All new compounds are characterized by elemental analyses, ¹H NMR and mass spectroscopies. The complex 5 has been determined by X‐ray structure analyses which shows that the central copper (I) ion assumes distorted tetrahedral geometry. The photophysical, computational and electrochemical properties of L and 5 ‐ 6 have been investigated. The most representative molecular orbital energy‐level diagrams and the spin‐allowed singlet? singlet electronic transitions of the three compounds have been calculated with density functional theory (DFT) and time‐dependent DFT (TD‐DFT). The luminescence bands of Cu(I) complexes 5 ‐ 6 have been assigned as mixed intraligand and metal‐to‐ligand charge transfer ³(MLCT+π→π^*) transitions through analysis of the photophysical properties and DFT calculations. The electrochemical studies reveal that 5 ‐ 6 undergo reversible TTF/TTF^+?/TTF²⁺ redox processes and one irreversible Cu⁺→Cu²⁺ oxidation process.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of tridentate di‐tert‐butylphenylhydrazone: Synthesis,characterization, X‐ray crystal structures,Hirshfeld surface analysis,molecular docking and in vivo anti‐inflammatory activity

A new hydrazone (LH₂) derived from the condensation of 2‐(4‐fluorobenzamido)benzohydrazide with 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde was used to synthesize Co(III), Ni(II) and Cu(II) complexes. These were characterized using various physicochemical, thermal, spectroscopic and single‐crystal X‐ray diffraction techniques. All the complexes crystallize in a monoclinic crystal system with P2₁/n space group and Z = 4. Structural studies of [Co(L)(LH)]?H₂O indicate the presence of both amido and imidol tautomeric forms of the ligand, resulting in a distorted octahedral geometry around the Co(III) ion. On the other hand, in the [Ni(L)(DMF)] and [Cu(L)(H₂O)] complexes, the ligand coordinates to the metal through imidol form resulting in distorted square planar geometry, in which the fourth position is occupied by the oxygen of coordinated DMF in [Ni(L)(DMF)] and by a water molecule in [Cu(L)(H₂O)]. Hirshfeld surface calculations were performed to explore hydrogen bonding and C―H???π interactions. Molecular docking studies were carried out to study the interaction between the synthesized compounds and proteins (cyclooxygenase‐2 and 5‐lipoxygenase). The complexes along with the parent ligand were screened for their in vivo anti‐inflammatory activity, using the carrageenan‐induced rat paw oedema method. The complexes show significant anti‐inflammatory potencies.     

Mixed‐ligand Copper(II) Complexes with N‐isopropyl‐iminodiacetato(2‐) and C‐phenyl‐imidazole Ligands. Crystal Structures of H2iPIDA, [Cu(iPIDA)(H2ϕim)(H2O)]·3H2O and [Cu(iPIDA)(H5ϕim)]n

The crystal of the N‐isopropyl‐iminodiacetic acid ( 1 ) consists of a 3D H‐bonded framework where the zwitterion (H₂iPIDA^±) is intra‐stabilized by one N⁺‐H···O interaction and both carboxyl are half‐protonated and involved in linear O‐H···O inter‐molecular bridges of 2.46 Å. The mixed‐ligand complexes [Cu(iPIDA)(H2?im)(H₂O)]·3H₂O ( 2 ) and [Cu(iPIDA)(H5?im)]_n ( 3 ) have also been synthesized and studied by thermal, spectral, magnetic and X‐ray diffraction methods. Both complexes exhibit a square base pyramidal coordination, type 4+1. Compound 3 is the less steric hindered 'remote' isomer, with H5?im instead of H4?im.