Monomeric Homoleptic (2‐Pyridylmethyl)(tert‐butyldimethylsilyl)amido Complexes of the Divalent Metals Mg,Mn, Fe,Co, and Zn

The transamination reaction of M[N(SiMe₃)₂]₂ with (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amine yields the corresponding homoleptic metal bis[(2‐pyridylmethyl)(tert‐butyldimethylsilyl)amides] of Mg ( 1 ), Mn ( 2 ), Fe ( 3 ), Co ( 4 ) and Zn ( 5 ). All these compounds crystallize from hexane isotypic in the space group C2/c. From toluene the zinc derivative precipitates as toluene solvate 5 ·toluene. The molecular structures of these compounds are very similar with large NMN angles to the amide nitrogen atoms with NMN values of 148° ( 1 ) and 150° ( 5 ) for the diamagnetic compounds and 156° for the paramagnetic derivatives 2 and 3 . The Co derivative 4 displays a rather small NCoN angle of 142°. Different synthetic routes have been explored for compound 3 which is also available via the metallation reaction of bis(2,4,6‐trimethylphenyl)iron with (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amine and via the metathesis reaction of lithium (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amide with [(thf)₂FeCl₂]. In course of the metathesis reaction, an equimolar amount of lithium (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amide and [(thf)₂FeCl₂] yields heteroleptic (2‐pyridylmethyl)(tert‐butyldimethylsilyl)amido iron(II) chloride ( 6 ) which crystallizes as a centrosymmetric dimeric molecule. The oxidative C‐C coupling reaction of 5 with Sn[N(SiMe₃)₂]₂ leads to the formation of tin(II) 1,2‐bis(2‐pyridyl)‐1,2‐bis(tert‐butyldimethylsilylamido)ethane, tin metal and Zn[N(SiMe₃)₂]₂.     

Potassium,rubidium and ammonium salts of μ‐(formato‐κ2O:O′)‐μ‐oxido‐bis[oxidobis(peroxido‐κ2O,O′)molybdate(VI)]

The unit‐cell parameters of the three title salts, namely, tripotassium, K₃[Mo₂(CHO₂)O₃(O₂)₄], trirubidium, Rb₃[Mo₂(CHO₂)O₃(O₂)₄], and triammonium μ‐(formato‐κ²O:O′)‐μ‐oxido‐bis[oxidobis(peroxido‐κ²O,O′)molybdate(VI)], (NH₄)₃[Mo₂(CHO₂)O₃(O₂)₄], which were all crystallized at pH 3, are quite similar, but the potassium and rubidium salt structures are noncentrosymmetric, whereas that of the ammonium salt is centrosymmetric. Formate acts as an O:O′‐bridging ligand in the complex anion and is bound to a μ‐oxido‐bis(oxidodiperoxidomolybdate) unit.     

Crystal Structures,Magnetic Properties and Catecholase‐Like Activities of μ‐Alkoxo‐μ‐Carboxylato Double Bridged Dinuclear and Tetranuclear Copper(II) Complexes

One μ‐alkoxo‐μ‐carboxylato bridged dinuclear copper(II) complex, [Cu₂(L¹)(μ‐C₆H₅CO₂)] ( 1 )(H₃L¹ = 1,3‐bis(salicylideneamino)‐2‐propanol)), and two μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear copper(II) complexes, [Cu₄(L¹)₂(μ‐C₈H₁₀O₄)(DMF)₂]·H₂O ( 2 ) and [Cu₄(L²)₂(μ‐C₅H₆O₄]·2H₂O·2CH₃CN ( 3 ) (H₃L² = 1,3‐bis(5‐bromo‐salicylideneamino)‐2‐propanol)) have been prepared and characterized. The single crystal X‐ray analysis shows that the structure of complex 1 is dimeric with two adjacent copper(II) atoms bridged by μ‐alkoxo‐μ‐carboxylato ligands where the Cu···Cu distances and Cu‐O(alkoxo)‐Cu angles are 3.5 11 Å and 132.8°, respectively. Complexes 2 and 3 consist of a μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear Cu(II) complex with mean Cu‐Cu distances and Cu‐O‐Cu angles of 3.092 Å and 104.2° for 2 and 3.486 Å and 129.9° for 3 , respectively. Magnetic measurements reveal that 1 is strong antiferromagnetically coupled with 2J =‐210 cm^?1 while 2 and 3 exhibit ferromagnetic coupling with 2J = 126 cm^?1 and 82 cm^?1 (averaged), respectively. The 2J values of 1–3 are correlated to dihedral angles and the Cu‐O‐Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ) catalyzed by 1–3 was studied. Complexes 1–3 exhibit catecholase‐like active at above pH 8 and 25 °C for oxidation of 3,5‐di‐tert‐butylcatechol.     

Monodentate Coordination of 4,4′‐Bipyridine Leading to a Supramolecular Network – Synthesis and Crystal Structure of [H2bpp][{Cu(Hbpy)2}{α‐HP2W18O62}]·4H2O

The new supramolecular compound [H₂bpp][{Cu(Hbpy)₂}{α‐HP₂W₁₈O₆₂}]·4H₂O ( 1 ) (bpy = 4,4′‐bipyridine, bpp = 1,3‐bis(4‐pyridyl)propane) was synthesized hydrothermally and characterized byelemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray diffraction. In compound 1 , the cationic fragment [Cu(Hbpy)₂]⁺ connects to the Dawson anion through a coordinating Cu←O bond, and the copper atom is coordinated by another polyoxoanion through a weak covalent bond with a Cu1–O26 distance of 2.879(2) Å, forming a polymeric chain. The bpy ligand in [Cu(Hbpy)₂]⁺ adopts a monodentate coordination mode, the other nitrogen atom of the bpy ligand is protonated. The protonated Hbpy⁺ acts as hydrogen‐bond donor and constructs a two‐dimensional double‐sheet supramolecular network involving the one‐dimensional chains through the hydrogen bonds. The H₂bpp²⁺ ion connects twoα‐HP₂W₁₈O₆₂^6– clusters from two supramolecular networks through hydrogen bonds and creates a three‐dimensional supramolecular architecture. The thermal decomposition of 1 happens over a wide temperature range (450–800 °C), which indicates that it might include complicated oxidation–reduction processes.     

Di‐μ‐hydroxido‐bis{[bis(6‐methyl‐2‐pyridylmethyl)(2‐phenylethyl)amine‐κ3N′,N′′,N′′′]copper(II)} bis(perchlorate)

The title compund, [Cu₂(OH)₂(C₂₂H₂₅N₃)₂](ClO₄)₂, is a copper(II) dimer, with two [CuL]²⁺ units [L is bis(6‐methyl‐2‐pyridylmethyl)(2‐phenylethyl)amine] bridged by hydroxide groups to define the {[CuL](μ‐OH)₂[CuL]}²⁺ cation. Charge balance is provided by perchlorate counter‐anions. The cation has a crystallographic inversion centre halfway between the Cu^II ions, which are separated by 3.0161 (8) Å. The central core of the cation is an almost regular Cu₂O₂ parallelogram of sides 1.931 (2) and 1.935 (2) Å, with a Cu—O—Cu angle of 102.55 (11)°. The coordination geometry around each Cu^II centre can be best described as a square‐based pyramid, with three N atoms from L ligands and two hydroxide O atoms completing the coordination environment. Each cationic unit is hydrogen bonded to two perchlorate anions by means of hydroxide–perchlorate O—H...O interactions.     

Lanthanide(II) Complexes Supported by N,O‐Donor Tripodal Ligands: Synthesis,Structure, and Ligand‐Dependent Redox Behavior

The preparation and characterization of a series of complexes of the Yb and Eu cations in the oxidation state II and III with the tetradentate N,O‐donor tripodal ligands (tris(2‐pyridylmethyl)amine (TPA), BPA^? (HBPA=bis(2‐pyridylmethyl)(2‐hydroxybenzyl)amine), BPPA^? (HBPPA=bis(2‐pyridylmethyl)(3.5‐di‐tert‐butyl‐2‐hydroxybenzyl)amine), and MPA^2? (H₂MPA=(2‐pyridylmethyl)bis(3.5‐di‐tert‐butyl‐2‐hydroxybenzyl)amine) is reported. The X‐ray crystal structures of the heteroleptic Ln²⁺ complexes [Ln(TPA)I₂] (Ln=Eu, Yb) and [Yb(BPA)I(CH₃CN)]₂, of the Ln²⁺ homoleptic [Ln(TPA)₂]I₂ (Ln=Sm, Eu, Yb) and [Eu(BPA)₂] complexes, and of the Ln³⁺ [Eu(BPPA)₂]OTf and [Yb(MPA)₂K(dme)₂] (dme=dimethoxyethane) complexes have been determined. Cyclic voltammetry studies carried out on the bis‐ligand complexes of Eu³⁺ and Yb³⁺ show that the metal center reduction occurs at significantly lower potentials for the BPA^? ligand as compared with the TPA ligand. This suggests that the more electron‐rich character of the BPA^? ligand results in a higher reducing character of the lanthanide complexes of BPA^? compared with those of TPA. The important differences in the stability and reactivity of the investigated complexes are probably due to the observed difference in redox potential. Preliminary reactivity studies show that whereas the bis‐TPA complexes of Eu²⁺ and Yb²⁺ do not show any reactivity with heteroallenes, the [Eu(BPA)₂] complex reduces CS₂ to afford the first example of a lanthanide trithiocarbonate complex.     

Mononuclear nickel(II) and zinc(II) complexes with deprotonated forms of the tripodal hexadentate ligand 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine

In the crystal structures of both title compounds, [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]nickel(II) [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]nickel(II) chloride methanol disolvate, [Ni(C₂₆H_25.5N₃O₃)]₂Cl·2CH₄O, and [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]zinc(II) perchlorate [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]zinc(II) methanol trisolvate, [Zn(C₂₆H₂₅N₃O₃)]ClO₄·[Zn(C₂₆H₂₆N₃O₃)]·3CH₄O, the 3d metal ion is in an approximately octahedral environment composed of three facially coordinated imine N atoms and three phenol O atoms. The two mononuclear units are linked by three phenol–phenolate O—H...O hydrogen bonds to form a dimeric structure. In the Ni compound, the asymmetric unit consists of one mononuclear unit, one‐half of a chloride anion and a methanol solvent molecule. In the O—H...O hydrogen bonds, two H atoms are located near the centre of O...O and one H atom is disordered over two positions. The Ni^II compound is thus formulated as [Ni(H_1.5L)]₂Cl·2CH₃OH [H₃L is 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine]. In the analogous Zn^II compound, the asymmetric unit consists of two crystallographically independent mononuclear units, one perchlorate anion and three methanol solvent molecules. The mode of hydrogen bonding connecting the two mononuclear units is slightly different, and the formula can be written as [Zn(H₂L)]ClO₄·[Zn(HL)]·3CH₃OH. In both compounds, each mononuclear unit is chiral with either a Δ or a Λ configuration because of the screw coordination arrangement of the achiral tripodal ligand around the 3d metal ion. In the dimeric structure, molecules with Δ–Δ and Λ–Λ pairs co‐exist in the crystal structure to form a racemic crystal. A notable difference is observed between the M—O(phenol) and M—O(phenolate) bond lengths, the former being longer than the latter. In addition, as the ionic radius of the metal ion decreases, the M—O and M—N bond distances decrease.     

Coordination Chemistry of Acrylamide: 1. Cobalt(II) Chloride Complexes with Acrylamide – Synthesis and Crystal Structures

The molecular structures of blue dichloro‐tetrakis(acrylamide) cobalt(II), [Co{O‐OC(NH₂)CH=CH₂}₄Cl₂] ( 1 ) and pink hexakis(acrylamide)cobalt(II) tetrachlorocobaltate(II), [Co{O‐OC‐(NH₂)CH=CH₂}₆][CoCl₄] ( 2 ), characterized by single X‐ray diffraction, IR spectroscopy and elemental analyses, are described. The coordination of Co^II in 1 involves a tetragonally distorted octahedral structure with four O‐donor atoms of acrylamide in the equatorial positions and two chloride ions in the apical positions. The second complex 2 in ionic form contains Co^II cations surrounded by an octahedral array of O‐coordinated acrylamide ligands, accompanied by a [CoCl₄]^2? anion.     

Syntheses,Crystal Structure and Reactivity of Tin(II) Bis[N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide]

Metallation of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with n‐butyllithium in toluene yields lithium N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 1 ), which crystallizes as a tetramer. Transamination of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with an equimolar amount of Sn[N(SiMe₃)₂]₂ leads to the formation of monomeric bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 2 ). The addition of another equivalent of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine gives homoleptic tin(II) bis[N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide] ( 3 ). In these complexes the N‐(diphenylphosphanyl)(2‐pyridylmethyl)amido groups act as bidentate bases through the nitrogen bases. At elevated temperatures HN(SiMe₃)₂ is liberated from bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 2 ) yielding mononuclear tin(II) 1,2‐dipyridyl‐1,2‐bis(diphenylphosphanylamido)ethane ( 4 ) through a C–C coupling reaction. The three‐coordinate tin(II) atoms of 2 and 4 adopt trigonal pyramidal coordination spheres.     

[Cl5Ta(μ‐O)TaCl3{iPrS(CH2)2SiPr}] and [(TaCl4)2(μ‐O)(μ‐Me2Se2)]: two chalcogenoether complexes of Ta2OCl8 with very different geometries

The title compounds, [1,2‐bis(isopropylsulfanyl)ethane‐2κ²S,S′]octachlorido‐1κ⁵Cl,2κ³Cl‐μ‐oxido‐ditantalum(V), [Ta₂Cl₈O(C₈H₁₈S₂)], (I), and μ‐dimethyldiselane‐κ²Se:Se′‐μ‐oxido‐bis[tetrachloridotantalum(V)], [Ta₂Cl₈O(C₂H₆Se₂)], (II), contain six‐coordinate Ta^V centres linked by a nonlinear oxide bridge. Compound (I) contains one Ta^V centre bonded to a chelating dithioether and three terminal chloride ligands, with the second Ta^V centre bonded to five terminal chloride ligands. In (II), two tetrachloridotantalum(V) residues are bridged by the diselenide, giving a puckered five‐membered Ta/O/Ta/Se/Se ring. The Ta—O distances in the bridges are short in both compounds, indicating that significant multiple‐bond character is retained despite the deviation from linearity, and the bond lengths reveal a clear trans influence order of O > Cl > S > Se on the hard Ta^V centre. The structures are compared with the [Ta₂Cl₁₀O]²⁻ anion, which contains a linear oxide bridge.     

Two transition metal coordination polymers of the 7,7,8,8‐tetracyanoquinodimethane dianion (TCNQ2−)

Each of the two novel title transition metal coordination polymers, namely catena‐poly[[bis{[tris(2‐pyridylmethyl)amine]cobalt(II)}‐μ₄‐7,7,8,8‐tetracyanoquinodimethanide(2−)] bis[7,7,8,8‐tetracyanoquinodimethanide(1−)] methanol disolvate], {[Co₂(C₁₂H₄N₄)(C₁₈H₁₈N₄)₂](C₁₂H₄N₄)₂·2CH₃OH}_n, (I), and catena‐poly[[[[tris(2‐pyridylmethyl)amine]iron(II)]‐μ₂‐7,7,8,8‐tetracyanoquinodimethanide(2−)] methanol solvate], {[Fe(C₁₂H₄N₄)(C₁₈H₁₈N₄)]·CH₃OH}_n, (II), contains η⁴‐TPA and cis‐bridging TCNQ²⁻ ligands [TPA is tris(2‐pyridylmethyl)amine and TCNQ is 7,7,8,8‐tetracyanoquinodimethane], but the two compounds adopt entirely different structural motifs. Compound (I) consists of a ribbon coordination polymer featuring μ₄‐TCNQ²⁻ radical anion ligands bridging four different octahedral Co^II centers. Each formula unit of the polymer is flanked by two uncoordinated TCNQ⁻ anions and two methanol solvent molecules. All three TCNQ anions have crystallographic inversion symmetry. In (II), the 2₁ symmetry operator generates a one‐dimensional zigzag chain of octahedral Fe^II centers with μ₂‐TCNQ²⁻ bridges. A methanol solvent molecule forms hydrogen bonds to one of the terminal N atoms of the bridging TCNQ²⁻ dianion. To the best of our knowledge, these are the first examples of one‐dimensional coordination polymers forming from cis coordination of two TCNQ ligands to octahedral metal centers.     

Magnetism and crystal structure of an N3O3‐coordinated iron(II) complex

The reaction of [FeL(MeOH)₂] {where L is the tetradentate N₂O₂‐coordinating Schiff base‐like ligand (E,E)‐diethyl 2,2′‐[1,2‐phenylenebis(nitrilomethylidyne)]bis(3‐oxobutanoate)(2−) and MeOH is methanol} with 3‐aminopyridine (3‐apy) in methanol results in the formation of the octahedral complex (3‐aminopyridine‐κN¹){(E,E)‐diethyl 2,2′‐[1,2‐phenylenebis(nitrilomethylidyne)]bis(3‐oxobutanoato)(2−)‐κ⁴O³,N,N′,O^3′}(methanol‐κO)iron(II), [Fe(C₂₀H₂₂N₂O₆)(C₅H₆N₂)(CH₄O)] or [FeL(3‐apy)(MeOH)], in which the Fe^II ion is centered in an N₃O₃ coordination environment with two different axial ligands. This is the first example of an octahedral complex of this multidentate ligand type with two different axial ligands, and the title compound can be considered as a precursor for a new class of complexes with potential spin‐crossover behavior. An infinite two‐dimensional hydrogen‐bond network is formed, involving the amine NH group, the methanol OH group and the carbonyl O atoms of the equatorial ligand. T‐dependent susceptibility measurements revealed that the complex remains in the high‐spin state over the entire temperature range investigated.     

The Coordination Chemistry of Iron with the 1,4‐Bis(2‐pyridyl‐methyl)piperazine Ligand

The behaviour of Fe^II and Fe^III ions in combination with the potential ligand 1,4‐bis(2‐pyridyl‐methyl)piperazine (BPMP) under anhydrous conditions has been investigated. BPMP has been reacted with FeCl₂, FeCl₃ and [Fe(OTf)₂(MeCN)₂]. This led to the isolation of four new complexes, which were fully characterized and structurally investigated by single crystal X‐ray diffraction. It turned out that in the presence of chloride co‐ligands Fe^III favours the tetradentate coordination mode of BPMP with the piperazine unit in a boat configuration, like for instance in [BPMP(Cl)Fe(μ‐O)FeCl₃] or [BPMP‐FeCl₂][FeCl₄], ( 1 ). However, the employment of FeCl₂ leads to the formation of a coordination polymer [BPMP‐FeCl₂]_n, ( 2 ), containing the piperazine ring in a chair configuration binding to two iron centres each. 2 can only be dissolved in very polar solvents like dmf which is capable of breaking up the polymeric structure under formation of [Cl₂(dmf)Fe(μ‐BPMP‐1κ²N,N:2κ²N,N))Fe(dmf)Cl₂]·2 dmf, ( 3 ). In contrast, using [Fe(OTf)₂(MeCN)₂] instead of FeCl₂ as the starting material leads to a mononuclear Fe^II complex with BPMP bound in the desirable tetradentate fashion: [BPMP‐Fe(OTf)₂], ( 4 ). Unlike other complexes with tetradentate N/py ligands the two residual ligands in 4 are bound almost trans to each other with the potential to adopt a cis orientation under oxidising conditions, and it will be interesting to exploit its catalytic properties in future.     

Pyridylmethylamines as Ligands in Iron Halide Complexes – Coordination Behaviour Depending on the Halide,the Denticity of the Amino Ligand and the Oxidation State of Iron

2‐Pyridylmethylamine (amp) and 8‐aminochinoline (ach) readily form the following complexes with iron halides in methanol: [(amp)₂FeCl₂] ( 1a ), [(amp)₂FeBr₂] ( 1b ), [(ach)₂Fe(MeOH)₂]Br₂ ( 1c ), and [(amp)FeCl₂(μ‐OMe)]₂ ( 2 ). Methanol was chosen as a solvent because these reactions are rather complex in ether. For example, FeCl₃ forms the ionic complex pair [(dme)₂FeCl₂] [FeCl₄] ( 3 ) with 1,2‐dimethoxyethane (dme). The reaction of FeBr₂ with tridentate di(2‐pyridylmethyl)amine (dpa) and tetradentate 1,2‐dipyridyl‐1,2‐diaminoethane (dpdae) yields the complexes [(dpa)₂Fe]Br₂·2 MeOH ( 4 ) and [(dpdae)₂Fe] [FeBr₄] ( 5 ), respectively. Crystallographic and magnetochemical investigations show the high‐spin configuration for the complexes 1 and 2 , whereas the short Fe‐N distances of 4 clearly indicate a low‐spin state. Compound 2 exhibits an antiferromagnetic exchange interaction with a coupling constant J = ?29.4 cm^?1 (H;af = ?J S;af_A·S;af_B).     

Di‐μ‐acetato‐O:O′‐di‐μ‐acetato‐O,O′:O′‐bis­{[(cyclo­penta­dienyl)tris­(di­methyl­phosphito‐P)­cobalt‐O,O′,O′′]neodymium(III)}

In the title compound, [{η⁵‐CpCo[P(O)(OMe)₂]₃}Nd(O₂CCH₃)₂]₂, with a centrosymmetric mol­ecule, each Nd atom has an eight‐coordination environment, surrounded by a tripodal {L_OMe = CpCo[P(O)(OMe)₂]₃} and four bridging acetato ligands. The coordination geometry around each Nd centre is described as a distorted square‐antiprism and the two different types of acetato ligands have μ‐O:O′‐ and μ‐O,O′:O′‐acetato coordination modes. The Nd—O distances are in the range 2.378 (4)–2.594 (5) Å and the Nd?Nd distance is 3.9913 (6) Å.     

Dinuclear Complexes of Copper(I) with Crown Ether‐containing N‐Thiophosphorylated Bis‐thioureas and 2,2′‐Bipyridine or 1,10‐Phenanthroline: Synthesis,Characterization, and Picrate Extraction Properties

Reaction of O,O′‐diisopropylthiophosphoric acid isothiocyanate (iPrO)₂P(S)NCS with 1,10‐diaza‐18‐crown‐6, 1,7‐diaza‐18‐crown‐6, or 1,7‐diaza‐15‐crown‐5 leads to the N‐thiophosphorylated bis‐thioureas N,N′‐bis[C(S)NHP(S)(OiPr)₂]‐1,10‐diaza‐18‐crown‐6 ( H₂L^I ), N,N′‐bis[C(S)NHP(S)(OiPr)₂]‐1,7‐diaza‐18‐crown‐6 ( H₂L^II ) and N,N′‐bis[C(S)NHP(S)(OiPr)₂]‐1,7‐diaza‐15‐crown‐5 ( H₂L^III ). Reaction of the potassium salts of H₂L^I–III with a mixture of CuI and 2,2′‐bipyridine ( bpy ) or 1,10‐phenanthroline ( phen ) in aqueous EtOH/CH₂Cl₂ leads to the dinuclear complexes [Cu₂(bpy)₂L^I–III] and [Cu₂(phen)₂L^I–III] . The structures of these compounds were investigated by ¹H, ³¹P{¹H} NMR spectroscopy, and elemental analysis. The crystal structures of H₂L^I and [Cu₂(phen)₂L^I] were determined by single‐crystal X‐ray diffraction. Extraction capacities of the obtained compounds in comparison to the related compounds 1,10‐diaza‐18‐crown‐6, N,N′‐bis[C(=CMe₂)CH₂P(O)(OiPr)₂]‐1,10‐diaza‐18‐crown‐6, N,N′‐bis[C(S)NHP(O)(OiPr)₂]‐1,10‐diaza‐18‐crown‐6 towards the picrate salts LiPic, NaPic, KPic. and NH₄Pic were also studied.     

Structural studies of (prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine hetero‐scorpionate copper complexes

The structures of five compounds consisting of (prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine complexed with copper in both the Cu^I and Cu^II oxidation states are presented, namely chlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(I) 0.18‐hydrate, [CuCl(C₁₅H₁₇N₃)]·0.18H₂O, (1), catena‐poly[[copper(I)‐μ₂‐(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ⁵N,N′,N′′:C²,C³] perchlorate acetonitrile monosolvate], {[Cu(C₁₅H₁₇N₃)]ClO₄·CH₃CN}_n, (2), dichlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II) dichloromethane monosolvate, [CuCl₂(C₁₅H₁₇N₃)]·CH₂Cl₂, (3), chlorido{(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II) perchlorate, [CuCl(C₁₅H₁₇N₃)]ClO₄, (4), and di‐μ‐chlorido‐bis({(prop‐2‐en‐1‐yl)bis[(pyridin‐2‐yl)methylidene]amine‐κ³N,N′,N′′}copper(II)) bis(tetraphenylborate), [Cu₂Cl₂(C₁₅H₁₇N₃)₂][(C₆H₅)₄B]₂, (5). Systematic variation of the anion from a coordinating chloride to a noncoordinating perchlorate for two Cu^I complexes results in either a discrete molecular species, as in (1), or a one‐dimensional chain structure, as in (2). In complex (1), there are two crystallographically independent molecules in the asymmetric unit. Complex (2) consists of the Cu^I atom coordinated by the amine and pyridyl N atoms of one ligand and by the vinyl moiety of another unit related by the crystallographic screw axis, yielding a one‐dimensional chain parallel to the crystallographic b axis. Three complexes with Cu^II show that varying the anion composition from two chlorides, to a chloride and a perchlorate to a chloride and a tetraphenylborate results in discrete molecular species, as in (3) and (4), or a bridged bis‐μ‐chlorido complex, as in (5). Complex (3) shows two strongly bound Cl atoms, while complex (4) has one strongly bound Cl atom and a weaker coordination by one perchlorate O atom. The large noncoordinating tetraphenylborate anion in complex (5) results in the core‐bridged Cu₂Cl₂ moiety.     

Copper(II) and Cadmium(II) Complexes Based on N,N‐Bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine Ligand: Syntheses,Structures, Magnetic,and Luminescent Properties

The reaction of the aryl‐oxide ligand H₂L [H₂L = N,N‐bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine] with CuSO₄ · 5H₂O, CuCl₂ · 2H₂O, CuBr₂, CdCl₂ · 2.5H₂O, and Cd(OAc)₂ · 2H₂O, respectively, under hydrothermal conditions gave the complexes [Cu(H₂L¹)₂] · SO₄ · 3CH₃OH ( 1 ), [Cu₂(H₂L²)₂Cl₄] ( 2 ), [Cu₂(H₂L²)₂Br₄] ( 3 ), [Cd₂(HL)₂Cl₂] ( 4 ), and [Cd₂(L)₂(CH₃COOH)₂] · H₂L ( 5 ), where H₂L¹ [H₂L¹ = 2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenol] and H₂L² [H₂L² = 2‐(2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenoxy)‐4, 6‐dimethylphenol] were derived from the solvothermal in situ metal/ligand reactions. These complexes were characterized by IR spectroscopy, elementary analysis, and X‐ray diffraction. A low‐temperature magnetic susceptibility measurement for the solid sample of 2 revealed antiferromagnetic interactions between two central copper(II) atoms. The emission property studies for complexes 4 and 5 indicated strong luminescence emission.     

Novel Trinuclear MnII/MnII/MnII Complexes – Crystal Structures and Catalytic Properties

The trinuclear manganese(II) complexes [Mn₃(L¹)₂(μ‐OAc)₄]·2Et₂O {HL¹ = (1‐hydroxy‐4‐nitrobenzyl)((2‐pyridyl)methyl)((1‐methylimidazol‐2‐yl)methyl)amine} ( 1·2EtOH ), [Mn₃(L²)₂(μ‐OAc)₄] {HL² = ((1‐methylimidazol‐2‐yl)methyl)(1‐hydroxybenzyl)amine} ( 2 ) and [Mn₃(L³)₂(μ‐OAc)₆] {L³ = bis(1‐methylimidazol‐2‐yl)methanone} ( 3 ) were synthesized. The compounds were characterized by X‐ray crystallography, mass spectrometry, IR, UV‐vis spectroscopy, and elemental analysis. The manganese atoms in 1 and 2 are bridged by phenol moieties of the ligands and acetates. In 3 they are only bridged by acetates in a mono‐ and bi‐dentate way. The resulting Mn···Mn distances are 3.233(1) Å ( 1 ), 3.364(1) Å ( 2 ) and 3.643(7) Å ( 3 ). In the present compounds different limiting cases for the phenomenon of the carboxylate shift are realized. Besides symmetric mono‐ and bi‐dentate bridging an unusual intermediate is also observed. 1·2EtOH is the first example of a trinuclear model for the OEC that shows catalase activity. Furthermore it was characterized by temperature dependent magnetic susceptibility measurements and a total spin ground state of S_t = 5/2 was found. The results for 1 reveals antiferromagnetic coupling between the central and the terminal manganese ions, with J = ?1.2 cm^?1, g = 2.00 (fixed), χ_TIP = 150×10^?6 cm³mol^?1.     

Phenylimidorhenium(V) Complexes with 1,3‐Diethyl‐4,5‐dimethylimidazole‐2‐ ylidene Ligands

The phenylimidorhenium(V) complexes [Re(NPh)X₃(PPh₃)₂] (X = Cl, Br) react with the N‐heterocyclic carbene (NHC) 1,3‐diethyl‐4,5‐dimethylimidazole‐2‐ylidene (L^Et) under formation of the stable rhenium(V) complex cations [Re(NPh)X(L^Et)₄]²⁺ (X = Cl, Br), which can be isolated as their chloride or [PF₆]^? salts. The compounds are remarkably stable against air, moisture and ligand exchange. The hydroxo species [Re(NPh)(OH)(L^Et)₄]²⁺ is formed when moist solvents are used during the synthesis. The rhenium atoms in all three complexes are coordinated in a distorted octahedral fashion with the four NHC ligands in equatorial planes of the molecules. The Re–C(carbene) bond lengths between 2.171(8) and 2.221(3) Å indicate mainly σ‐bonding between the NHC ligand and the electron deficient d² metal atoms. Attempts to prepare analogous phenylimido complexes from [Re(NPh)Cl₃(PPh₃)₂] and 1,3‐diisopropyl‐4,5‐dimethylimidazole‐2‐ylidene (L^i?Pr) led to a cleavage of the rhenium‐nitrogen multiple bond and the formation of the dioxo complex [ReO₂(L^i?Pr)₄]⁺.