Diphenyldichalcogenide complexes of iron, chromium and rhenium carbonyls

The substitution of a labile THF ligand in Cr(CO)₅(THF) by the Ph₂Se₂ molecule provided the monomeric complex Cr(CO)₅(Ph₂Se₂) (I). The similar diiodo-tricarbonyl-iron complex (CO)₃FeI₂(Ph₂Se₂) (II) (along with [(CO)₃Fe(??-SePh)₃Fe(CO)₃]⁺(I₅)^? (III) as a by-product) was separated upon the treatment of ??phenylselenyl iodide?? [PhSeI] with iron pentacarbonyl, Fe(CO)₅. Complex II is isostructural with the known tellurium-containing analogue, (CO)₃FeI₂(Te₂Ph₂). The latter have provided the dimeric tellurophenyl bridged iodo-tricarbonyl-iron complex [(CO)₃IFe(??-TePh)]₂ (IV) under action of the excess of Fe(CO)₅. Its bromide analogue [(CO)₃BrFe(??-TePh)]₂ (V) was prepared upon the treatment of PhTeBr with the excess of Fe(CO)₅. The reaction of [PhSeI] with Re(CO)₅Cl afforded only [(CO)₆Re₂(??-I)₂(??-Se₂Ph₂)] (VI) in contrast to the (CO)₃Re(PhTeI)₃(??₃-I) formation in similar known reaction of [PhTeI]. The molecular and crystal structures of I?CVI is discussed.     

Polymerization of ethylene by SiO2-supported two-component catalytic systems containing bis(imino)pyridine and bis(imine) ligands

The polymerization of ethylene initiated by SiO₂-supported two-component catalytic systems based on 2,6-bis[1-(2,4-dimethyl-6-cyclohexylphenylimino)ethyl]pyridine iron (II) chloride (I) and 1,2-bis(2-cyclohexyl-4,6-dimethylphenylimino)acenaphthene] nickel bromide (II) was studied. Methylaluminoxane was used as a cocatalyst during support. It was shown that the activity of two-component catalytic systems and the molecular mass and short-chain branching of polyethylene samples depend on the supporting procedure: simultaneous immobilization of components I and II, separate immobilization of components on the support (first I, then II, and vice versa), and the use of a mixture of components I and II immobilized separately on SiO₂.     

Neutral and monocationic dinuclear (carbonyl)(cyclopentadienyl)(phenylchalcogenate) iron complexes of the general formulas [(RC5H4)Fe(CO)EPh]2 and [(RC5H4)Fe(CO)EPh]2PF6 (E = S or Te; R = H or Me): Synthesis, molecular structures, and EPR spectra

Heating of the compounds (RC₅H₄)Fe(CO)₂TePh (R = H (I) and Me (II)) in heptane afforded the dinuclear complexes [(RC₅H₄)Fe(CO)TePh]₂ (III and IV, respectively). By oxidation with Fc⁺PF ₆ ^? , these complexes were transformed into the paramagnetic cationic complexes [(RC₅H₄)Fe(CO)TePh]₂PF₆ (V and VI, respectively). Structures III–V and [(C₅H₅)Fe(CO)SPh]₂PF₆ (VII) were characterized by X-ray diffraction.     

1,3,2-Diazasilols based on 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene

Reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (1, dpp-bian) in the presence of SiCl₄ with two equivalents of potassium graphite (KC₈) in tetrahydrofuran leads to the formation of compound (dpp-bian)SiCl₂ (2), which was also synthesized by the exchange reaction of SiCl₄ with the magnesium complex (dpp-bian)Mg(THF)₃. An analog of compound 2, the bromo derivative (dpp-bian)SiBr₂ (3), was obtained by the reaction of SiBr4 with one equivalent of Na2(dpp-bian) (in situ from Na and dpp-bian) in toluene. The silylene (dpp-bian)Si (4) was synthesized by the reduction of a mixture of dpp-bian and SiCl₄ (1: 1) with four equivalents of potassium graphite in tetrahydrofuran. Treatment of compound 4 with diimine 1 gives the derivative (dpp-bian)₂Si (5). Compounds 2–5 were characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy, as well as by elemental analysis, their molecular structure was established by X-ray diffraction studies.     

Selective coupling of carbon dioxide and epoxystyrene via salicylaldimine-, thiophenaldimine-, and quinolinaldimine-iron(II), iron(III), chromium(III), and cobalt(III)/Lewis base catalysts

A series of chromium(III)-, cobalt(III)-, and iron(III)-based complexes of the general formula [(N∩O)₂MCl] (1–7) (N∩O: N-salicylidene(R)amine, R = 1-naphthyl or cyclohexyl) have been applied as catalysts for the coupling reaction of carbon dioxide and epoxystyrene (styrene oxide) in the presence of tetrabutylammonium bromide (Bu₄NBr) as a cocatalyst. The reactions were carried out under relatively low pressure and solvent-free conditions. In addition, iron complexes (8–10) containing the ligands, N′-(thiophene-2-methylene)benzene-1,2-diamine, (8), N′-(quinoline-2-methylene)benzene-1,2-diamine (9), and sodium N-(4-sulfonato-salicylidene)-1,2-phenylenediamine (10) were also utilized for the catalytic reaction. The influence of metal center, ligand, temperature, and reaction time on the coupling reaction was investigated. The catalyst systems proved to be selective in the coupling reaction of CO₂ and styrene oxide, resulting in cyclic styrene carbonate. In general, the iron(III)- and cobalt(III)-based catalysts bearing the aromatic 1-naphthyl terminal groups showed the highest catalytic activity under similar reaction conditions.     

A new member of tetranuclear dinitrosyl iron complexes (DNICs) with 2-mercaptothiazoline ligand: synthesis,structure and properties

A new tetranuclear dinitrosyliron complex [(μ-SC₃H₄SN)Fe(NO)₂]₄ (2), each of a Fe center coordinated with two S or two N, was prepared by CO replacement from the reduced precursor (CO)₂Fe(NO)₂ with 1 equiv of HSC₃H₄SN (2-mercaptothiazoline) in the presence of O_2(g). The structure of 2 is similar to [(Imid-iPr)Fe(NO)₂]₄ (Imid-iPr = 2-isopropylimidazole) (Hess et al. J Am Chem Soc 133:20426–20434, 2011), and both complexes comprise a quadrilateral plane of irons with corresponding ligands, SC₃H₄SN^? or Imid-iPr^?, bridging the edges and two nitrosyl ligands capping the irons at the corners. An additional equiv of SC₃H₄SN^? was added to 2, which results in the mononuclear {Fe(NO)₂}⁹ (SC₃H₄SN)₂Fe(NO) ₂ ^? (3), in the manner of N bound-[SC₃H₄SN]. Reaction of (TMEDA)IFe(NO)₂ (TMEDA = tetramethylethylenediamine) and complex 3 leads to the formation of complex 2. Dinuclear complex [(μ-C₅H₇N₂)Fe(NO)₂]₂ (4) can be synthesized by the ligand displacement of SC₃H₄SN^? to C₅H₇N₂ ^? (3,5-dimethylpyrazolate) of 2 (Chong et al. Can J Chem 57:3119–3125, 1979). Complexes 2–4 were characterized by IR and UV–Vis. The molecular structures of 2 and 3 were determined by X-ray single crystal diffraction.     

Addition of phenylacetylene and camphor to the complex [(dpp-bian)Eu(dme)<Subscript>2</Subscript>] (dpp-bian is the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene dianion)

The reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with an excess of europium metal in 1,2-dimethoxyethane (dme) produces a divalent europium complex with the dpp-bian dianion, [(dpp-bian)Eu(dme)₂] (1). The reactions of 1 with phenyl-acetylene and camphor proceed via protonation of the diimine ligand to form the monomeric amido-amino complexes of divalent europium — [H(dpp-bian)Eu(C≡CPh)(dme)₂] (2) and [H(dpp-bian)Eu(camphor)(dme)₂] (3), respectively. Compounds 2 and 3 were characterized by IR spectroscopy and elemental analysis. Their molecular structures were determined by X-ray diffraction. Compounds 2 and 3 were shown to be monomeric seven-coordinate europium(ii) complexes with terminal phenylethynyl and enol ligands, respectively. According to the IR spectroscopic data, the terminal ligands in complexes 2 and 3 undergo tautomerization involving backward proton transfer from the amido-amino ligand to the substrate. The magnetic moment of compound 2 (8.03 μB) remains constant in the temperature range of 4—300 К and confirms the presence of divalent europium.     

Synthetic aspects, crystal structures and antibacterial activities of manganese(III) and cobalt(III) complexes containing a tetradentate Schiff base

Three new Schiff base complexes, namely [Mn(L)Cl] · H₂O (1), [Co(L)Cl]₂ · 2CH₃COCH₃ (2) and [Co(L)NCS]₂ (3), where H₂L = 2,2′-[propane-1,2-diylbis(nitriloeth-1-yl-1-ylidene)]diphenol, have been prepared and characterized. The syntheses of 1 and 2 have been achieved by reacting equimolar amounts of the respective metal chloride and the tetradentate Schiff base ligand (H₂L). While the mononuclear Mn(III) complex 1 was obtained with MnCl₂ in acetone medium, the same synthetic system yielded the binuclear Co(III) complex 2 in the presence of CoCl₂. Dissolution of 1 and 2 followed by crystallization with ammonium thiocyanate in methanol yielded two isostructural phenoxo-bridged binuclear complexes, namely [Mn(L)NCS]₂ (previously reported by us) and a new complex [Co(L)NCS]₂ (3), respectively. All the complexes 1–3 have been characterized by microanalytical, spectroscopic, single crystal X-ray diffraction and other physicochemical studies. Structural studies reveal that 1 adopts a distorted tetragonal pyramidal geometry while 2 and 3 comprise dimeric Co(III) units with bridging phenolate oxygen atoms. All the complex units in 1–3 and the respective solvent molecules are held together by weak intermolecular H-bonding to constitute a supramolecular network in the solid state. The antibacterial activity of the complexes has been tested against some Gram(+) and Gram(?) bacteria.     

Iron(II) closo-borate complexes with 1,2,4-triazole derivatives: Spin crossover in the iron(II) closo-borate complexes with tris(pyrazol-1-yl)methane

Methods of synthesis of iron(II) complexes containing cluster closo-borate anions—[Fe(Htrz)₃]B₁₀Cl₁₀ (I) (HTrz is 1,2,4-triazole), [Fe(NH₂Trz)₃]B₁₀Cl₁₀ · 2H₂O (II) (NH₂Trz is 4-amino-1,2,4-triazole), [Fe{HC(pz)₃}₂]B₁₀Cl₁₀ (III), [Fe{HC(pz)₃}₂]B₁₀H₁₀ (IV), and [Fe{HC(pz)₃}₂]B₁₂H₁₂ · 2H₂O (V) (HC(pz)₃ is tris(pyrazol-1-yl)methane)—have been developed. The compounds have been studied by the static magnetic susceptibility method (78–500 K) and electronic, IR, and EXAFS spectroscopy. Complexes I and II in the temperature range under consideration remain in the high-spin state. Low-spin complex III shows incomplete spin crossover and decomposes on heating above 440 K. Complexes IV and V are characterized by reversible spin crossover ¹ A ₁ ? ⁵ T ₂ accompanied by thermochromism (the pink ? white color change). The crossover temperature (T _c) for IV and V is 375 and 405 K, respectively.     

(<Emphasis Type="Italic">Z</Emphasis>)-diiodo(2-iodo-2-phenylvinyl)(phenyl)tellurium PhIC=CHTeI<Subscript>2</Subscript>Ph: Synthesis and complexing properties in a reaction with iron pentacarbonyl

Electrophilic addition of PhTeI₃ to phenylacetylene (PhC₂H) in boiling THF stereoselectively gave (Z)-diiodo(2-iodo-2-phenylvinyl)(phenyl)tellurium PhIC=CHTeI₂Ph (I). In a reaction with Fe(CO)₅, this complex easily eliminated two iodine atoms from tellurium to give PhTe-CH=CPhI. This ligand was coordinated to iron in a monodentate fashion through the Te atom in the resulting complex (CO)₃FeI₂(PhTeHC=CPhI) (II). The reaction also yielded the known complex Fe(CO)₄I₂ (III). The structures of complexes I–III were determined by X-ray diffraction analysis. The Fe-Te bond in structure II is substantially shortened.     

Five-, six- and eight-membered ring organosilicon chalcogenides of the types Z2(SiMe2)2E (Z = Me2Si, H2C; E = S, Se, Te), Z(SiMe2E)2MR2 (Z = Me2Si, H2C, O; E = S, Se, Te; M = Si, Ge, Sn, R = Me, Ph) and (SiMe2ZSiMe2E)2 (Z = Me2Si, H2C; E = S, Se)

Reactions of ClMe₂Si–Z–SiMe₂Cl (Z = SiMe₂ (1a), CH₂ (1c), O (1e)) with Li₂E (E = S, Se) yielded eight-membered ring compounds (SiMe₂ZSiMe₂E)₂ (3a–d) as well as acyclic oligomers (SiMe₂ZSiMe₂E)_x of different chain lengths. If 1:1 molar mixtures of 1a, 1c or 1e and a diorganodichlorosilane, -germane or -stannane (R₂MCl₂) are reacted with Li₂E (E = S, Se, Te), six-membered ring compounds Z(SiMe₂E)₂MR₂ (4a–7g) are formed exclusively. Five-membered rings Z₂(SiMe₂)₂E (Z = SiMe₂ (8a–c), CH₂ (9a–c); E = S, Se, Te) are obtained starting from the tetrasilane ClMe₂Si–(SiMe₂)₂–SiMe₂Cl (1b) or the disilylethane ClMe₂Si–(CH₂)₂–SiMe₂Cl (1d) by treatment with Li₂E. All products were characterized by multinuclear NMR spectroscopy (¹H, ¹³C, ²⁹Si, ¹¹⁹Sn, ⁷⁷Se, ¹²⁵Te, including coupling constants) and the effects of the different ring sizes towards NMR chemical shifts are discussed.     

Derivatives of Bis(diphenylphosphino)maleic Anhydride as Ligands in Polynuclear Gold(I) Complexes

Based on the new binuclear gold(I) complex [(AuCl)₂(L1)] (1) (L1?=?2,3-bis(diphenylphosphino)maleic anhydride) four new polynuclear compounds were synthesized by reactions of 1 with E(SiMe₃)₂ (E?=?S, Se). During the formation of these new compounds the initial ligand L1 undergoes various transformations (e.g. substitution, hydration or hydrogenation) leading to the new ligands: trans-2,3-bis(diphenylphosphino)succinic anhydride (L2), 2-diphenylphosphino-3-mercapto-maleic anhydride anion (L3), 2-diphenylphosphino-3-selenolato-maleic anhydride anion (L4) and 2,3-bis(diphenylphosphino)succinic acid (L5). In case of using the sulfur species S(SiMe₃)₂ a pentanuclear cluster, [Au₅(PPh₂)₃(L3)₂] (2), and a 24-nuclear cluster, [Au₂₄S₆(PPh₂)₄(L3)₈] (3), could be obtained. With Se(SiMe₃)₂ the binuclear complex, [(AuCl)₂(L2)] (4), and the dodecanuclear cluster, [Au₁₂Se₄(L4)₄(L5)₂] (5), were yielded.     

Anionic and neutral bis(diimine)lanthanide complexes

Oxidation of ytterbium(II) complex (dpp-BIAN)Yb(DME)₂ (1) with dpp-BIAN affords an ionic compound [(dpp-BIAN)₂Yb]^?[(dpp-BIAN)Yb(DME)₂]⁺ (2) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene), in which the oxidation states of the metals in anionic and cationic counterparts are different. Structurally related lanthanum(III) complex [(dpp-BIAN)₂La]^?[(dpp-BIAN)La(DME)₂]⁺ (3) has been prepared reacting excess of metallic lanthanum with dpp-BIAN. Compound [(dpp-BIAN)₂La]^?[K(Et₂O)₄]⁺ (4) has been isolated from the reaction of LaI₃ with three molar equivalents of potassium and one molar equivalent of dpp-BIAN in diethyl ether. The reaction of SmI₂ with dpp-BIAN and potassium affords complex [(dpp-BIAN)₂Sm]^?[K(C₆H₆)]⁺ (5). Treatment of compound 5 with 0.5 molar equivalent of iodine produces neutral complex (dpp-BIAN)₂Sm (6). Molecular structures of complexes 2–6 have been determined by X-ray crystallography.     

Synthesis and structure of bis(monohaloacetates) of tris(5-bromo-2-methoxyphenyl)antimony

Tris(5-bromo-2-methoxyphenyl)antimony bis(monohaloacetates) [(5-Br)(2-MeO)C₆H₃]₃Sb[OC(O)CH₂X]₂, X = Cl (I), Br (II), I (III) have been synthesized by the reaction of tris(5-bromo-2-methoxyphenyl)antimony with chloro-, bromo-, and iodoacetic acids in the presence of hydrogen peroxide. According to X-ray analysis the antimony atom in I–III has a distorted trigonal-bipyramidal coordination.     

Copper(II), iron(III) and cobalt(III) complexes of the pendent-arm cyclam derivative 6,6,13-trimethyl-13-amino-1,4,8,11-tetraazacyclotetradecane

The interaction of Cu(II), Fe(III) and Co(III) with 6,6,13-trimethyl-13-amino-1,4,8,11-tetraazacyclotetradecane (L ³ ) incorporating a pendent amine group has led to isolation of the new octahedral complexes [Cu(HL ³ )(ClO₄)₂]Cl·H₂O (1), [Fe(L ³ )Cl](S₂O₆)·H₂O (2), [Co(L ³ )Cl](ClO₄)_1.5Cl_0.5·0.25H₂O (3), [Co(HL ³ )Cl₂](ClO₄)₂·H₂O (4) and [Co(L ³ )Cl]₂(S₂O₄)(ClO₄)₂ (5). In (1) the copper ion occupies the macrocyclic cavity of protonated (–NH₃ ⁺) L ³ which is present in its trans-III configuration; weakly bound ClO₄ ^? ligands occupy the axial positions. The X-ray structure of (2) showed that Fe(III) occupies the N₄-macrocyclic cavity of L ³ in a trans-III configuration, with the pendent amine group binding in an axial position. The remaining axial position is occupied by a Cl^? ligand. Chromatography of the product obtained from the reaction of Na₃[Co(CO₃)₃] with L ³ yielded three fractions. Fraction 1 yielded crystals (3) composed of three crystallographically independent species incorporating cations of type [Co(L ³ )Cl]²⁺ with very similar structures; in each case the macrocyclic ring nitrogens of L ³ are bound to the Co(III) in an asymmetric cis-fashion. Fraction 2 yielded the trans-III octahedral cationic complex (4) incorporating L ³ in its protonated form. The Co(III) complex (5) from fraction 3 shows a different coordination arrangement to the products from fractions 1 or 2. The macrocyclic ring coordinates in its trans-III form, but the axial sites in this case are occupied by the pendent-NH₂ group and a Cl^? ligand.     

Synthesis, characterization and bromination of bis(phosphinoferrocenyl) gold(I) compounds

Reaction of [(dppf)Au₂Br₂] (3) {dppf = 1,1′-bis(diphenylphosphino)ferrocene} and [(dippf)Au₂Br₂] (4) {dippf = 1,1′-bis(diisopropylphosphino)ferrocene} with excess bromine yields two new complexes [(C₅H₄Br₃)(PR₂)AuBr] (R = Ph, 5; R = i-Pr, 6). Bromination of the free diphosphinoferrocene ligands produces the expected brominated cyclopentenes (C₅H₄Br₃)(PR₂) (R = Ph, 7; R = i-Pr, 8) in good yields; however, these compounds could not be complexed to gold due to reduced basicity of 7 and 8. When the bromination is performed under wet aerobic conditions the oxidized pseudo-centrosymmetric product, [doppf][FeBr₄] (9) {doppf = 1,1′-bis(oxodiphenylphosphino)ferrocene, is formed as the major product. Solid-state structures of 1, 2, 4, 6, and 9 have been established by means of single-crystal X-ray crystallography.     

Formation of carbon-carbon bonds between activated alkynes and diimine ligands in the aluminum complexes

The gallium and aluminum complexes containing the redox-active ligand (dpp-bian)Ga-Ga(dpp-bian) (1), (dpp-bian)Al-Al(dpp-bian) (2), or (dpp-bian)AlI(Et₂O) (3) (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) react with alkyl butynoates Me-C≡C-CO₂R (R = Me, Et) to form C-C bonds between the dpp-bian ligand and alkyne. The reaction of complex 1 with methyl 2-butynoate and 4-chloroaniline in a molar ratio of 1: 2: 2 affords 7-(2,6-diisopropylphenyl)-10-methylacenaphtho[1,2-b]pyridin-8(7H)-one (4) containing no gallium. In the reaction of complex 2 with methyl 2-butynoate, alkyne is inserted into the skeleton of the dpp-bian ligand to form 4-(dpp-AIE)-9-(2,6-diisopropylphenyl)-8-(1,3-dpp-2MBIDP)-3,7-dimethoxy-1,5-dialuma-9-aza-2,6-dioxabicyclo[3.3.1]nonadiene-3,7 (5) (dpp-AIE is 1-[2-(2,6-diisopropylphenylimino)acenaphthen-1(2H)-ylidene]ethyl; 1,3-dpp-2MBIDP is 1,3-bis(2,6-diisopropylphenylimino)-2-methyl-2,3-dihydro-1H-phenalen-2-yl). The reactions of complex 3 with methyl and ethyl 2-butynoates afford dimeric derivatives [-OC(OR)=C(2,3-dpp-1MBIDP)Al(I)-]₂ (2,3-dpp-1MBIDP is 2,3-bis(2,6-diisopropylphenylimino)-1-methyl-2,3-dihydro-1H-phenalen-2-yl; R = Me (6), Et (7)). The reaction of complex 3 with methyl 2-butynoate gives the product isomeric to compound 6: [-OC(OCH₃)=C(1,3-dpp-2MBIDP)Al(I)-]₂ (8), which cleaves THF resulting in complex [-OC(OCH₃)=C(1,3-dpp-2MBIDP)Al(OC₄H₈I)-]₂ (9). Complex (dpp-bian)Al(acac) (10), obtained by the reduction of dpp-bian with aluminum in the presence of Al(acac)₃ in diethyl ether at ambient temperature, is inert towards acetylene, phenylacetylene, and alkyl butynoates. Compounds 4–7 and 10 were characterized using IR spectroscopy, and compounds 4, 7, and 10 were additionally characterized by ¹H NMR spectroscopy. The structures of compounds 4–7, 9, and 10 were determined by X-ray diffraction analysis.     

Syntheses, structures and magnetic properties of five iron(II) coordination polymers with flexible bis(imidazole) and bis(triazole) ligands

Five iron(II) coordination polymers, {[Fe(bte)₂(NCS)₂][Fe(bte)(H₂O)₂(NCS)₂]}_n (1), [Fe(bime)(NCS)₂]_n (2), [Fe(bime)(dca)₂]_n (3), [Fe(bime)₂(N₃)₂]_n (4) and [Fe(btb)₂(NCS)₂]_n (5), were synthesized using the flexible ligands 1,2-bis(1,2,4-triazol-1-yl)ethane (bte), 1,2-bis(imidazol-1-yl)ethane (bime) and 1,4-bis(1,2,4-triazol-1-yl)butane (btb), together with NCS⁻, dicyanamide (dca) and N₃⁻. The compound 1 contains two kinds of motifs (double chain and single chain) and forms a three-dimensional hydrogen bonded network; 2 and 3 contain one-dimensional triple chains; and 4 and 5 form two-dimensional (4, 4) networks. The coordination anions (NCS⁻, dca and N₃⁻) and the structural characteristics of the ligands (bte, bime and btb) play an important role in the assembly of the topologies. Magnetic studies reveal that 1-5 remain in the high-spin state over the whole temperature range 2-300 K and no detectable spin-crossover is observed.     

Synthesis and structure of iron(III) complexes with a new ligands based on Girard’s reagent

Condensation of 5-bromosalicylaldehyde with Girard’s reagent T yields a new ligand in the form of a salt, 5-bromosalicylaldehyde (carboxymethyl)trimethylammonium chloride hydrazone (5-BrH₂SalGT)Cl (I). Ligand I is readily soluble in water and reacts with iron chloride to give the complex [Fe(5-BrSalGT)Cl₂] (II). Treatment of II with KCNS leads to the compound [Fe(5-BrSalGT)(NCS)₂(H₂O)] (III). At any ratio of the initial reagents, only complexes with the ratio metal: ligand = 1: 1 are isolated. Comparison of the structural data for compounds I–III shows that ligand I is deprotonated in the course of complex formation and is coordinated in the anionic form. Its conformational rearrangement is minimal and involves only a change in the orientation of the terminal group N(CH₃)₃. In complexes II and III, ligand I is coordinated to the metal ion through the ONO donor atoms. The structures of the complexes with different acido ligands are significantly different. Although the complexes contain each two inorganic anions, their coordination polyhedra differ from each other. In II, the iron atom is at the center of a trigonal bipyramid, whereas in III the iron atom has a tetragonal-bipyramidal environment due to the extra coordination of a water molecule. In both complexes, the iron atom is in the high-spin state: at room temperature, μ_eff is 5.86 and 5.81 μ_B for II and III, respectively. Complexes II and III are ordinary paramagnets down to 2 K.     

Synthesis and some properties of anionic chloranilate complexes of iron(iii). Crystal and molecular structure of rubidium and cesium chloranilatoferrates

New anionic chloranilate complexes of iron(iii) Cs[Fe(C₆O₄Cl₂)₂(H₂O)₂]·4H₂O (1), Rb[Fe(C₆O₄Cl₂)₂(H₂O)₂]·4H₂O (2), Rb₂[Fe(C₆O₄Cl₂)₂(H₂O)₂]₂·5H₂O (3), Cs₃Fe(C₆O₄Cl₂)₃ (4), (Bu₄N)Fe(C₆O₄Cl₂)₂ (5), (Bu₄N)₄Fe₂(C₆O₄Cl₂)₅ (6), and (R₄N)₃Fe(C₆O₄Cl₂)₃ (R = Pr (7), Bu (8), C₅H₁₁ (9)) were synthesized in an aqueous medium. The Mössbauer spectra of the synthesized chloranilatoferrates are characteristic of the high-spin state of Fe^III in an octahedral oxygen coordination. The crystal and molecular structures of compounds 1–3 were determined by X-ray diffraction. The complex anions [Fe(C₆O₄Cl₂)₂(H₂O)₂]^2? involved in these compounds are composed of two chelate chloranilate ions and two water molecules trans-(1,2) or cis-coordinated (3) to the iron atom. Since tetraalkylammonium tris(chloranilato)ferrates 7–9 and binuclear complex 6 are soluble in many organic solvents, they are promising precursors for the synthesis of metal-organic coordination polymers. Tetrabutylammonium bis(chloranilato)ferrate (Bu₄N)Fe(C₆O₄Cl₂)₂ (5) is the first example of the preparation of an anionic chloranilate complex of iron(iii) with a plausible chain structure in an aqueous medium.