Synthesis of [SnPh2(SR)2] SR = SC6F4-4-H, SC6F5: Reactivity towards group 10 transition metal complexes

The organometallic tin(IV) complexes [SnPh₂(SR^F)₂] SR^F = ⁻SC₆F₄-4-H (1), ⁻SC₆F₅ (2), were synthesized and their reactivity with [MCl₂(PPh₃)₂] M = Ni, Pd and Pt explored. Thus, transmetallation products were obtained affording polymeric [Ni(SR^F)(μ-SR^F)]_n, monomeric cis-[Pt(PPh₃)₂(SC₆F₄-4-H)₂] (3) and cis-[Pt(PPh₃)₂(SC₆F₅)₂] (4) and dimeric species [Pd(PPh₃)(SC₆F₄-4-H)(μ-SC₆F₄-4-H)]₂ (5) and [Pd(PPh₃)(SC₆F₅)(μ-SC₆F₅)]₂ (6) for Ni, Pt and Pd, respectively. The crystal structures of complexes 1, 2, 3, 4 and 6 were determined.     

Solvent and electrolyte effects in enhancing the identification of intramolecular electronic communication in a multi redox-active diruthenium tetraferrocenoate complex, a triple-sandwiched dicadmium phthalocyanine and a ruthenocene-containing β-diketone

Enhanced electrochemical resolution of anodic processes is possible in the presence of [N(ⁿBu)₄][B(C₆F₅)₄], 1, as supporting electrolyte over that obtained in the presence of [N(ⁿBu)₄][PF₆]. By changing the anion of the supporting electrolyte to a salt having [B(C₆F₅)₄]⁻, anions, electrochemical processes of especially cationic analytes can benefit. Thus, the redox chemistry of 0.5 mmol dm⁻³ solutions of [Ru₂(μ-FcCOO)₄·(CH₃CH₂OH)₂][PF₆], 2, Fc = ferrocenyl, in CH₂Cl₂/[N(ⁿBu)₄][B(C₆F₅)₄] were found to involve four well-resolved ferrocenyl-based electrochemical reversible redox processes as well as reduction of Ru^III-Ru^II. At 1.0 mmol dm⁻³ concentrations of 2, or in the presence of [N(ⁿBu)₄][PF₆], the four ferrocenyl processes coalesced into only two waves as a result of (Fc⁺)?() ion paring. Seventeen of the possible 18 one-electron transfer processes of the biscadmium trisphthalocyaninato complex [Cd₂{Pc(C₆H₁₃)₈}₃], 3, could be observed in THF/[N(ⁿBu)₄][B(C₆F₅)₄], but the electrochemical window of CH₂Cl₂/[N(ⁿBu)₄][B(C₆F₅)₄] only allowed detection of 15 of these processes. Although reduction processes were unaffected, THF solvation leading to species such as (3ⁿ⁺)(THF)_x with 1 ? n ? 4 and x ? 1 as well as ion pair formation of the type (3ⁿ⁺)?() prevented good resolution of oxidation processes. The CH₂Cl₂/[N(ⁿBu)₄][B(C₆F₅)₄] system also allowed detection of reversible one-electron transfer ferrocenyl (Fc/Fc⁺) and ruthenocenyl-based (Rc/Rc⁺) processes for both enol and keto isomers of the β-diketone FcCOCH₂CORc, 4, Rc = ruthenocenyl. In CH₃CN/[N(ⁿBu)₄][PF₆], the ruthenocenyl moiety was oxidised to a Ru^IV species.     

Analysis of the main structural trends for biscyclometalated dinuclear rhodium compounds of general formula Rh2(O2CR)2(PC)2 · 2H2O

A new series of biscyclometalated dinuclear rhodium (II) compounds with the general formula Rh₂(O₂CR)₂(PC)₂ · 2H₂O, being PC = (C₆H₄)P(C₆H₅)₂, R = CH₃ (1 · 2H₂O), PC = [(p-CH₃ OC₆H₃)P(p-CH₃ OC₆H₄)₂], R = CF₃ (2 · 2H₂O), PC = (C₆H₄)P[CH(CH₃)₂]₂, R = CH₃ (3 · 2H₂O) and PC = (C₆H₄)P(C₆H₅)₂, R = C₆F₅ (4 · 2H₂O) has been obtained. The crystal structures for these compounds have been determined by X-ray diffraction and the main structural trends, bond lengths, bond angles and torsion angles have been analyzed, and have also been compared with the structural parameters for different analogous complexes described previously in the literature.     

Diferrocenes containing thiadiazole connectivities

2,5-Diferrocenyl-1,3,4-thiadiazole, 2,5-Fc₂-^cC₂N₂S, (3) has been synthesized by a two-fold Negishi ferrocenylation of dibromothiadiazole (1) with FcZnCl (2) (Fc = Fe(η⁵-C₅H₄)(η⁵-C₅H₅)) in presence of [Pd(Ph₃P)₄] as catalyst. Additional spacer units between the ferrocenyls and the ^cC₂N₂S core could be introduced by using the Sonogashira C,C cross-coupling protocol. Reaction of 2,5-Br₂-^cC₂N₂S (1) or 2,5-(C₆H₄-4′-I)₂-^cC₂N₂S (6) with FcCCH (4) using [PdCl₂(Ph₃P)₂] and [CuI] as catalyst produced the appropriate organometallics 2,5-(FcCC)₂-^cC₂N₂S (5) or 2,5-(C₆H₄-4′-CCFc)₂-^cC₂N₂S (7). The electronic and structural properties of 3, 5, and 7 were investigated with UV-Vis spectroscopy and single crystal X-ray diffraction (3). Complex 3 adopts a solid state structure with none of the ferrocenyl substituents being coplanar with the thiadiazole ring. Cyclic, square wave, linear sweep voltammetry and in-situ NIR spectro-electrochemistry highlight the electrochemical properties of 3. In dichloromethane (0.1 mol L⁻¹ [N(ⁿBu)₄][B(C₆F₅)₄]), compound 3 displays two well resolved electrochemical reversible one-electron events with formal reduction potentials of 0.192 and 0.338 V versus FcH/FcH⁺. In contrast, in presence of [N(ⁿBu)₄][PF₆], the thiadiazoles 3 (E⁰ = 0.22 V), 5 (E⁰ = 0.18 V) and 7 (E⁰ = 0.09 V) show simultaneously oxidation of the two ferrocenyl termini versus FcH/FcH⁺. Spectro-electrochemical studies, performed in a dichloromethane solution of 0.2 mol L⁻¹ [N(ⁿBu)₄][B(C₆F₅)₄], also show that 3 can successively be oxidized via 3⁺ to 3²⁺. A weak IVCT absorption (ε ca. 300 L mol⁻¹ cm⁻¹) at 1560 nm was found and is consistent with appreciable interactions between neutral ferrocenyl and positively charged ferrocenium mixed valent intermediates. Mixed-valent compound 3⁺ corresponds to a class II molecule according to Robin and Day.     

New aryl phosphinite ligands avoiding ortho-metallation: Synthesis and molecular structures of trans-[PdCl2(PPh2OR)2] and trans-[Rh(CO)Cl(PPh2OR)2] (R = 2,4,6-Me3C6H2; 2,6-Ph2C6H3)

The new aryl phosphinites PPh₂OR (R = 2,4,6-Me₃C₆H₂, 1; R = 2,6-Ph₂C₆H₃, 2) have been prepared from chlorodiphenylphosphine and the corresponding phenols. In these ligands, the ortho-positions of the aromatic phosphite function are blocked by methyl and phenyl substituents, which allows coordination to metal centres without ortho-metallation. Thus, reaction with [PdCl₂(cod)] leads to the complexes trans-[PdCl₂(PPh₂OR)₂] (R = 2,4,6-Me₃C₆H₂, 3; R = 2,6-Ph₂C₆H₃, 4), while the reaction with [Rh₂(CO)₄Cl₂] gives trans-[Rh(CO)Cl(PPh₂OR)₂] (R = 2,4,6-Me₃C₆H₂, 5; R = 2,6-Ph₂C₆H₃, 6). The single-crystal X-ray structure analyses of 3 and 5 confirm the trans-coordination of the new ligands in these square-planar complexes.     

New palladacyclic complexes with pyridylphosphine ligands: crystal structures of [Pd(Azb)(Ph2POCH2Py-P,N)][PF6] and [Pd(Phpy)(Ph2PNHPy-P,N)][PF6]

The synthesis of palladacyclic derivatives with the hybrid pyridylphosphine ligands Py(CH₂)OPPh₂ (a) and PyNHPPh₂ (b) in a neutral P,N-chelating coordination mode has been achieved. Treatment of selected chloride-bridged cyclometallated precursors [Pd(C^∧N)(μ-Cl)]₂ [C^∧N = 2-pyridinin-phenyl Phpy, I-compounds; 7,8-benzoquinolyl Bzq, II-compounds; phenylazophenyl Azb, III-compounds or 2-(2-oxazolinyl)phenyl Phox, IV-compounds] with a or b in the presence of stoichiometric KPF₆ gave the mononuclear derivatives Ia-IVa and Ib-IVb. The crystal structures of compounds [Pd(Azb)(Ph₂POCH₂Py-P,N)][PF₆] (IIIa) and [Pd(Phpy)(Ph₂PNHPy-P,N)][PF₆] (Ib) have been determined. The new palladacyclopentadiene precursor [Pd{C₄COOMe₄}(CH₃CN)₂] (V) has been prepared starting from the polymeric complex [Pd{C₄COOMe₄}]_n. Its usefulness in the preparation of new derivatives has been tested by means of the straightforward reaction with ligands (a) or (b) to give mononuclear compounds [Pd{C₄(COOMe)₄}(Ph₂POCH₂Py-P,N)] (Va) and [Pd{C₄(COOMe)₄}(Ph₂PNHPy-P,N)] (Vb). The reactions of hydroxo-bridged precursors [Pd(C^∧N)(μ-OH)]₂ or [Pd₂{C₄(COOMe)₄}₂ (μ-OH)₂][NBu₄]₂ with PyNHPPh₂ afforded mononuclear complexes Ic-Vc in which a less common anionic P,N-binding mode is forced as a result of ligand deprotonation. The new complexes were characterised by partial elemental analyses and spectroscopic methods (IR, FAB, ¹H and ³¹P{¹H} NMR).     

Synthesis, isolation and spectroscopic characterization of Dawson polyoxotungstate-supported, organometallic complex, [{(C6H6)Ru}P2W15V3O62]: The two positional isomers

The Dawson polyoxotungstate (POM)-based, organometallic ruthenium(II) complex, [{(C₆H₆)Ru}P₂W₁₅V₃O₆₂]⁷⁻, was synthesized as two materials, i.e. 1 · 2Bu₄NCl and 1 · 1Bu₄NCl (1 = (Bu₄N)₇[{(C₆H₆)Ru}P₂W₁₅V₃O₆₂]), which contained two positional isomers a and b as major or minor species. In isomer a with the overall C_s symmetry, the (C₆H₆)Ru²⁺ group was supported on one vanadium(V) octahedral site (two V-O-V bridging oxygens and one OV terminal oxygen) of the three edge-shared vanadium(V) octahedra (V₃ site, B-site) in the Dawson POM-support [1,2,3-P₂W₁₅V₃O₆₂]⁹⁻, whereas in the other isomer b with the overall C_3v symmetry, the (C₆H₆)Ru²⁺ group was supported on the center of the V₃ site in the Dawson POM-support. Material 1 · 2Bu₄NCl was prepared by a stoichiometric reaction in CH₂Cl₂ at ambient temperature of the Dawson POM-support (Bu₄N)₉[1,2,3-P₂W₁₅V₃O₆₂] with the precursor [(C₆H₆)RuCl₂]₂, whereas material 1 · 1Bu₄NCl was prepared by a stoichiometric reaction in CH₃CN under refluxing conditions. The temperature-varied ³¹P NMR spectra revealed that b was thermodynamically more stable thana.     

Electrochemical behavior of S,S-bridged adducts of square planar metalladithiolene complexes [M(S2C2Ph2)2](M=Ni, Pd, and Pt)

The electrochemical behavior of the S,S^′-bridged adducts of square planar metalladithiolene complexes was investigated by using cyclic voltammetry and electrochemical spectroscopies (visible, near-IR, and ESR). The norbornene-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(C₇H₈)] (2a; C₇H₈=norbornene) formed by [Ni(S₂C₂Ph₂)₂] (1a) and quadricyclane (Q) was dissociated by an electrochemical reduction, and anion 1a⁻ and norbornadiene (NBD) were formed. Q was isomerized to NBD in the overall reaction. The o-xylyl-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(CH₂)₂(C₆H₄)] (3a; (CH₂)₂(C₆H₄)=o-xylyl) was also dissociated by an electrochemical reduction, and this reaction gave the o-xylyl radical (o-quinodimethane). The reduction of complex 3a in the presence of excess o-xylylene dibromide underwent the catalytic formation of o-quinodimethane. The butylene-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(CH₂)₄] (4a; (CH₂)₄=butylene) was stable on an electrochemical reduction. The lifetimes of reduced species of these adducts 2a-4a were influenced by the stability of the eliminated group (stability: NBD > o-xylyl radical (o-quinodimethane) > butylene radical). Therefore, the reduced species are stable in the sequence 4a⁻ > 3a⁻ > 2a⁻. Although the palladium complex [Pd(S₂C₂Ph₂)₂] (1b) was easier to reduce than the nickel complex 1a or the platinum complex [Pt(S₂C₂Ph₂)₂] (1c), their S,S^′-adducts were easier to reduce in the order of Ni adduct > Pd adduct > Pt adduct.     

Synthesis of trialkyl[60]fullerene C60(CH2SiMe3)3H and its potassium and rhodium(I) complexes

The reaction of [60]fullerene with Me₃SiCH₂MgCl in 1,2-Cl₂C₆H₄/THF (1/1) under dry air afforded a bis-alkyl adduct, C₆₀(CH₂SiMe₃)₂ (1), in 54% yield. Treatment of 1 with Me₃SiCH₂MgCl in THF under argon then afforded a trialkyl[60]fullerene, C₆₀(CH₂SiMe₃)₃H (2), in 37% yield. Further treatment of 2 with KO^tBu gave a potassium salt, [K(thf)_n][C₆₀(CH₂SiMe₃)₃] (3), which was then converted to a C_s-symmetric Rh(I) complex, Rh[η⁵-C₆₀(CH₂SiMe₃)₃](1,5-cyclooctadiene) (4), in 91% yield.     

Heterobimetallic Fe-Pd and Fe-Pt NCN pincer complexes (NCN = [C6H2(CH2NMe2)2-2,6])

The meta-diaminoaryl ferrocenes Fc-NCN-H (3) and Fc-CC-NCN-H (5) (Fc = (η⁵-C₅H₅)(η⁵-C₅H₄)Fe, NCN-H = C₆H₃(CH₂NMe₂)₂-3,5) can be used as precursors in the preparation of heterobimetallic transition metal complexes of structural type Fc-NCN-MX (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]⁻; MX = PdCl (7), PtCl (8), PtI (9)) and Fc-CC-NCN-MX (MX = PdCl (11), PdI (12), PtCl (13)), respectively. They are accessible by applying different synthesis procedures, including oxidative addition and metallation-transmetallation processes.Cyclovoltammetric studies show that the ferrocene moieties in 3, 5, 7-9 and 11-13 can reversibly be oxidised. The potential of the Fe(II)/Fe(III) redox couple decreases with increasing electron density at the NCN pincer unit. The use of 8 as a possible (electro)chemical sensor in the detection of SO₂ is discussed as well.The solid-state structures of 8 and 13 are reported. The crystals of 8 contain two molecules of 8 in the asymmetric unit. The plane of the C₆H₂ moiety is with 27.2(3)° and 38.2(3)° tilted towards the C₅H₄ entity, while in 13 an angle of 45.9(3)° can be found. The d⁸-electron configured platinum atoms possess a somewhat distorted square-planar surrounding, setup by two Me₂NCH₂ortho-substituents, the NCN C_ipso carbon atom and the chloride ligand.     

Substitution reactions of tetrahydrofuran in [Cr(thf)3Cl3] with mono and bidentate N-donor ligands: X-ray crystal structures of [Cr(bipy)(OH2)Cl3] and [HpyNH2][Cr(bipy)Cl4]

Substitution of thf ligands in [Cr(thf)₃Cl₃] and [Cr(thf)₂(OH₂)Cl₃] was investigated. 2,2′-Bipyridine (bipy) was reacted with [Cr(thf)₃Cl₃] to form [Cr(bipy)(thf)Cl₃] (1), which was subsequently reacted with water to give [Cr(bipy)(OH₂)Cl₃] (2). Reaction of 1 with acetonitrile (CH₃CN), pyridine (py) and pyridine derivatives to form [Cr(bipy)(L)Cl₃] (L = CH₃CN 3, py 4 and 4-pyR with R = NH₂5, Bu^t6 and Ph 7). In addition, the substitution of bipy in [Cr(thf)₃Cl₃] was followed by ¹H NMR spectroscopy at room temperature, which showed completion of the reaction in ca. 100 min. Complex 2 was characterised by single crystal X-ray diffraction. The theoretical powder diffraction pattern of 2 was compared to the experimentally obtained powder X-ray diffraction pattern, and shows excellent agreement. The dimer [Cr₂(bipy)₂Cl₄(μ-Cl)₂] was cleaved asymmetrically to give the anionic complex [Cr(bipy)Cl₄]⁻ (8) and [Cr(bipy)₂Cl₂]⁺ (9). Complexes 8 and 9 were characterised by single crystal X-ray diffraction.     

Organometallic nickel(II) complexes with dithiophosphate, dithiophosphonate and monothiophosphonate ligands

The hydroxo complex [NBu₄]₂[Ni₂(C₆F₅)₄(μ-OH)₂] reacts with ammonium O,O^′-dialkyldithiophosphates, O-alkyl-p-methoxyphenyldithiophosphonate acids and ammonium O-alkylferrocenyldithiophosphonates in dichloromethane under mild conditions to give, respectively, [NBu₄][Ni(C₆F₅)₂{S(S)P(OR)₂}] (R=Me (1), Et (2), ⁱPr (3)) and [NBu₄][Ni(C₆F₅)₂{S(S)P(OR)Ar}] (Ar=p-MeOC₆H₄, R=Me (4), Et (5), ⁱPr (6); Ar=ferrocenyl; R=Me (7), Et (8), ⁱPr (9)). The monothiophosphonate nickel complexes [NBu₄][Ni(C₆F₅)₂{S(S)P(OR)(ferrocenyl)}] (R=Et (10), ⁱPr (11)) are obtained by reaction of the hydroxo complex with O-alkylferrocenyldithiophosphonate acids. Analytical (C, H, N, S), conductivity, and spectroscopic (IR, ¹H, ¹⁹F and ³¹P NMR, and FAB-MS) data were used for structural assignments. A single-crystal X-ray diffraction study of [NBu₄][Ni(C₆F₅)₂{S(S)P(OMe)(p-MeOC₆H₄)}] (4) and [NBu₄][Ni(C₆F₅)₂{S(O)P(OEt)(ferrocenyl)}] (10) shows that in both cases the coordination around the nickel atom es essentially square planar with NiC₂S₂ and NiC₂SO central cores, respectively.     

Arylboron complexes of the acids Ph2C(XH)CO2H (X = O, NH)

The acids Ph₂C(XH)CO₂H (X = O, NH) readily react with the triarylboron reagents BAr₃ (Ar = Ph, C₆F₅) to form the complexes [Ph₂C(O)CO₂BPh] (1) and [Ph₂C(NH₂)CO₂BPh₂] (2), Ph₂C(p-CH₃C₆H₄)CO₂H (3a) [in the presence of Et₃N the complex HNEt₃[Ph₂C(OH)CO₂B(C₆F₅)₃] (3b) was formed], and [Ph₂C(NH₃)CO₂B(C₆F₅)₃] (4), respectively. The synthesis and crystal structures of 1-4 (synchrotron radiation was necessary for 2) are reported.     

Solution-mediated syntheses and characterizations of two new zincophosphites [C6H14N2]0.5[Zn(H2PO3)2] and [C4H12N2]0.5[(CH3)2NH2][Zn2(HPO3)3]

Two new zincophosphites [C₆H₁₄N₂]_0.5[Zn(H₂PO₃)₂] 1 and [C₄H₁₂N₂]_0.5[(CH₃)₂NH₂][Zn₂(HPO₃)₃] 2 have been solvothermally synthesized in mixed solvents of N,N-dimethylformamide (DMF) and 1,4-dioxane (DOA), respectively. Single-crystal X-ray diffraction analysis reveals that compound 1 exhibits a neutral inorganic chain formed by ZnO₄ and HPO₂(OH) units. Interestingly, the left- and right-handed hydrogen-bonded helical chains are alternately formed via the hydrogen-bonds between two adjacent chains. Compound 2 exhibits a layer structure with 4- and 12-MRs formed by ZnO₄ and HPO₃ units, in which two kinds of organic amine molecules both act as countercations to compensate the overall negative electrostatic charge of the anionic network.     

Novel long bipyridine-type linking ligands containing an intervening naphthalene fragment: [Zn(L)(NO3)2], [Zn(L)(NO3)2], and [Cd(L)1.5(NO3)2] (L = (4-py)-CHN-C10H6-NCH-(4-py); L = (3-py)-CHN-C10H6-NCH-(3-py))

Novel bipyridine-type linking ligands L¹ ((4-py)-CHN-C₁₀H₆-NCH-(4-py)) and L² ((3-py)-CHN-C₁₀H₆-NCH-(3-py)), a pair of isomers due to possessing different pairs of terminal pyridyl groups, were prepared by the Schiff-base condensation. In ligand L¹, the N?N separation between the terminal pyridyl groups is 16.0 Å, with their nitrogen donor atoms at the para positions (4,4′). The corresponding N?N separation in ligand L² is 14.2 Å, with the nitrogen donor atoms at the meta positions (3,3′). 1-D zigzag-chain coordination polymers [Zn(L¹)(NO₃)₂] (1) and [Zn(L²)(NO₃)₂] (2) were prepared by reactions of Zn(NO₃)₂ · 6H₂O with ligands L¹ and L², respectively, by solution diffusion. Polymer 3, [Cd(L¹)_1.5(NO₃)₂], prepared from Cd(NO₃)₂ · 4H₂O and L¹, exhibits a 1-D ladder structure, whose repeating ladder unit consists of four Cd metals and four L¹ ligands to create a large 76-membered ring with dimensions of 20.8 × 20.8 Å. All products were structurally characterized by X-ray diffraction.     

Investigation on the coordination modes: Syntheses, characterization and crystal structures of diorganotin (IV) dichloride with 4(5)-imidazoledithiocarboxylic acid

A series of diorganotin (IV) complexes of the types of R₂SnCl(SSCC₃H₃N₂) (R = CH₃1, ⁿBu 2, C₆H₅3 and C₆H₅CH₂4), R₂Sn(SSCC₃H₃N₂)₂ (R = CH₃5, ⁿBu 6, C₆H₅7 and C₆H₅CH₂8) and R₂Sn(SSCC₃H₂N₂) (R = CH₃9, ⁿBu 10, C₆H₅11 and C₆H₅CH₂12) have been obtained by reactions of 4(5)-imidazoledithiocarboxylic acid with diorganotin (IV) dichlorides in the presence of sodium ethoxide. All complexes are characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectra analyses. Also, the complexes 1, 7 and 9 are characterized by X-ray crystallography diffraction analyses, which reveal that the complex 1 is monomeric structure with five-coordinate tin (IV) atom, the complex 7 is monomeric structure with six-coordinate tin (IV) atom and the complex 9 is one-dimensional chain with five-coordinate tin (IV) atom.     

Synthesis and characterization of new AMTTO-imine-ligands and their silver(I) complexes: crystal structures of TAMTTO, [Ag2(TAMMTO)4](NO3)2 · 4MeOH, [Ag(TAMTTO)(PPh3)2]NO3 · 1.5THF, [Ag(FAMTTO)(PPh3)2]NO3

Reaction of 4-amino-6-methyl-1,2,4-triazin-thione-5-one (AMTTO, 1) with 2-thiophenecarboxaldehyde and 2-furaldehyde led to the corresponding iminic compounds 6-methyl-4-[thiophene-2-yl-methylene-amino]-3-thioxo-[1,2,4]-triazin-3,4-dihydro(2H)-5-one (TAMTTO, 2) and 4-[furan-2-yl-methylene-amino]-6-methyl-3-thioxo-[1,2,4]-triazin-3,4-dihydro(2H)-5-one (FAMTTO, 3). Treatment of 2 with AgNO₃ gave the complex [Ag₂(TAMMTO)₄](NO₃)₂ · 4MeOH (4) and of 2 and 3 with [Ag(PPh₃)₂]NO₃ gave the complexes [Ag(TAMTTO)(PPh₃)₂]NO₃ · 1.5THF (5) and [Ag(FAMTTO)(PPh₃)₂]NO₃ (6), respectively. All the compounds have been characterized by elemental analyses, IR spectroscopy and mass spectrometry. Compound 2 and all the complexes have been characterized by X-ray diffraction studies, respectively. In addition, 5 and 6 have been characterized by ³¹P NMR spectroscopy. Crystal data for 2 at −80 °C: monoclinic, space group C2/c, a=2319.6(2), b=609.8(1), c=1673.6(2) pm, β=106.14(1)°, Z=8, R₁=0.0523; for 4 at −80 °C: triclinic, space group , a=877.6(1), b=1085.2(1), c=1557.7(2) pm, α=77.14(1)°, β=80.87(1)°, γ=78.18(1)°, Z=1, R₁=0.0407; for 5 at 20 °C: triclinic, space group , a=1151.1(2), b=1225.1(2), c=1887.4(3) pm, α=78.04(1)°, β=86.20(1)°, γ=76.03(1)°, Z=2, R₁=0.0662; for 6 at −80 °C: triclinic, space group , a=1189.7(2), b=1387.8(2), c=1410.9(2) pm, α=94.74(2)°, β=95.12(2)°, γ=112.41(2)°, Z=2, R₁=0.0511.     

Dinitrosyl iron complexes [E5Fe(NO)2] (E = S, Se): A precursor of Roussin’s black salt [Fe4E3(NO)7]

[PPN][Se₅Fe(NO)₂] (1) and [K-18-crown-6-ether][S₅Fe(NO)₂] (2′) were synthesized and characterized by IR, UV-Vis, EPR spectroscopy, magnetic susceptibility, and X-ray structure. [PPN][Se₅Fe(NO)₂] easily undergoes ligand exchange with S₈ and (RS)₂ (R = C₇H₄SN (5), o-C₆H₄NHCOCH₃ (6), C₄H₃S (7)) to form [PPN][S₅Fe(NO)₂] and [PPN][(SR)₂Fe(NO)₂]. The reaction displays that [E₅Fe(NO)₂]⁻ (E = Se (3), S (4)) facilely converts to [Fe₄E₃(NO)₇]⁻ by adding acid HBF₄ or oxidant [Cp₂Fe][BF₄] in THF, respectively. Obviously, complexes 1 and 2′ serve as the precursors of the Roussin’s black salts 3 and 4. The electronic structure of {Fe(NO)₂}⁹ core of [Se₅Fe(NO)₂]⁻ is best described as a dynamic resonance hybrid of {Fe⁺¹(NO)₂}⁹ and {Fe⁻¹(NO⁺)₂}⁹ modulated by the coordinated ligands. The findings, EPR signal of g = 2.064 for 1 at 298 K, implicate that the low-molecular-weight DNICs and protein-bound DNICs may not exist with selenocysteine residues of proteins as ligands, since the existence of protein-bound DNICs and low-molecular-weight DNICs in vitro has been characterized with a characteristic EPR signal at g = 2.03. In addition, complex 2′ treated human erythroleukemia K562 cancer cells exposed to UV-A light greatly decreased the percentage survival of the cell cultures.     

Ruthenium(VI) and osmium(VI) nitrido complexes with halogenated phenoxide and thiophenoxide ligands

Treatment of [Buⁿ₄N][Ru(N)Cl₄] with Na(OR) afforded [Buⁿ₄N][Ru(N)(OR)₄] (R = C₆F₅ (1), C₆F₄H (2), C₆Br₅ (3)), whereas that with [Buⁿ₄N][Os(N)Cl₄] gave [Buⁿ₄N][Os(N)(OR)₃Cl] (R = C₆F₅ (4), C₆F₄H (5), C₆Br₅ (6)). Treatment of [Buⁿ₄N][M(N)Cl₄] with Na(SC₆F₄H) and Na(Sxyl) (xyl = 2,6-dimethylphenyl) afforded [Buⁿ₄N][M(N)(SC₆F₄H)₄] (M = Ru (7), Os (8)) and [Buⁿ₄N][M(N)(Sxyl)₄] (M = Ru (9), Os (10)), respectively. The crystal structures of compounds 1, 6 and 9 have been determined.     

Supramolecular salts containing the anionic [Ge(C2O4)3] complex and heteroaromatic amines

The crystalline compounds (Hbipy)₂[Ge(C₂O₄)₃] (1) and (Hphen)₂[Ge(C₂O₄)₃] · 2(H₂O) (2) [Hbipy⁺ is the 2,2′-bipyridinium cation (C₁₀H₉N₂), and Hphen⁺ is the 1,10′-phenathrolinium cation (C₁₂H₉N₂)] were isolated from mild hydrothermal syntheses and their structures were elucidated from single-crystal X-ray diffraction. The two compounds were further characterised by vibrational spectroscopy (FT-IR and FT-Raman), thermogravimetric analysis (TGA) and CHN elemental composition. Compounds 1 and 2 comprise the tris(oxalato-O,O′)germanate dianion complex, [Ge(C₂O₄)₃]²⁻, which co-crystallises with Hbipy⁺ (in 1), or Hphen⁺ and water molecules (in 2). In 1, the germanium oxalate anionic complex, [Ge(C₂O₄)₃]²⁻, and the Hbipy⁺ organic residues interact mutually via N-H?O hydrogen bonding interactions, leading to supramolecular discrete hydrogen-bonded units which are further interconnected via π-π stacking. Compound 2, on the other hand, exhibits a more complex hydrogen bonding network due to the presence of the water molecules of crystallisation which, along with π-π stacking between neighbouring Hphen⁺ residues, mediate the crystal packing.