Transformationen von clustern mit dem (μ3-RP)Fe3(CO)9-Gerüst. Synthese und reaktionen von [(μ3-RP)Fe3(CO)9]2−

The clusters (μ₃-RP)Fe₃(CO)₁₀ (1) or (μ₃-RP)Fe₃(CO)₉(μ₂-H)₂ (2) can reversibly be transformed into the cluster anions [(μ₃-RP)Fe₃(CO)₉ (μ₂-H)]⁻ (3) and [(μ₃-RP)Fe₃(CO)₉]²⁻ (4). The pyrophoric clusters 4 react with the divalent electrophile CH₂I₂ to give the complexes (μ₃-η²-RP=CH₂)Fe₃(CO)₁₀ (5), which contain a cluster-stabilized phosphaalkene, RP=CH₂, as a ligand. With monovalent electrophiles R′X, such as Me₂SO₄, compound 4 (R = anisyl), yields, upon protolytic work-up, the complexes (μ₃-η³-R′P-anisyl)Fe₃(CO)₉(μ₂-H) (6) in which the phosphorus-bound aryl residue of the μ₂-bridging phosphide ligand (R′P-anisyl) forms an η²-coordination to the third iron atom of the cluster. The η²-coordination of the aryl substituent may be reversibly released by two-electron ligands L under formation of (μ₂-R′P-anisyl)(μ₂-H)Fe₃(CO)₉L (7). In addition, the transformation sequence of 5 into 6 is accomplished by an H⁻, H⁺ addition sequence. The experiments are documented by analytic and spectroscopic data as well as by X-ray analyses.     

ESR study on the reactions of iron carbonyls with nitro and nitrosoparaffines. A mechanism of the reductive carbonylation of nitro compounds

The interaction of Fe_n(CO)_m, (n and m equal 1 and 5, 2 and 9, 3 and 12, respectively) with 2-methyl-2-nitrosopropane and sodium salts of nitromethane and nitrocyclohexane was studied. The initial stages of the process, following the activating complex-formation, involves redox disproportionation to give rise to the radical Fe(I) carbonyl complexes and radical anions Fe₂(CO)₈⁻_. (I) Fe₃(CO)₁₁⁻_. (II), Fe₄(CO)₁₃⁻_. (III) and Fe₃(CO)₁₂⁻_. (IV). Also, radical anions I–IV are formed in the interaction of salts of carbonyl ferrate anions Na₂Fe(CO)₄·1.5 diox and PPN₂[Fe_n(CO)_m−1] (where PPN = (PPh₃)₂N⁺), with nitro- and nitroso-tert-butane.Radical anions I–III act as catalytically active species in the coordination sphere of which the nitro compounds undergo a successive deoxygenation to nitrene radical complexes with their subsequent carbonylation to isocyanates. A scheme of the reductive carbonylation is proposed.     

The formation of iron carbonyl radical anions in the reactions of iron carbonyls with trimethylamine N-oxide

The interaction of iron carbonyls, Fe(CO)₅, Fe₂(CO)₉ and Fe₃(CO)₁₂ with Me₃NO occurs according to a one-electron redox-disproportionation scheme giving rise to iron carbonyl radical anions: Fe₂(CO)₈^·− (1), Fe₃(CO)₁₂^·− (2), Fe₃(CO)₁₁^·− (3) and Fe₄(CO)₁₃^·− (4). The role of Me₃NO, inducing CO-substitution, consists of the generation of reactive 17-electron species with a labile coordination sphere in which the substitution for other ligands occurs, resulting from fast ligand and electron exchange in the confines of the ETC-reaction.     

Indium monohalide insertion reactions into metal—metal bonds. Crystal structure of [InCl(THF){Mo(CO)3(η-C5H5)}2]

The reaction between InCl and [Mo₂(CO)₆(η-C₅H₅)₂] affords [InCl&{;Mo(CO)₃(η-C₅H₅)&};], 6a which has been characterised as a THF adduct [InCl(THF)&{;Mo(CO)₃(η-C₅H₅)&};₂], 10, by X-ray crystallography. An additional complex, [InCl₂&{;Mo(CO)₃(η-C₅H₅)&};₂]⁻, 11, is also formed in this reaction. Similar products are reported for reactions involving [M₂(CO)₆(η-C₅H₅)₂] (M = Cr, W). The reaction between InCl and [Fe₂(CO)₄(η-C₅H₅)₂] affords [InCl{Fe(CO)₂(η-C₅H₅)}₂], 17, and [InCl₂{Fe(CO)₂(η-C₅H₅)}], whilst that between InI and [Fe₂(CO)₄(η-C₅H₅)₂] affords [InI{Fe(CO)₂(η-C₅H₅)}₂], 19.     

Übergangsmetall-heteroallen-komplexe XVII .Reaktionen des aza-allyl-komplexes (ketenimin)Fe2(CO)6 mit phosphanen

The aza-allyl complex (ketene imine)Fe₂(CO)₆ (3a) reacts with phosphanes PR₃ to give substitution products of the type (ketene imine)Fe₂(CO)₅PR₃ (4a,b). In addition, the phosphane PMe₃ yields a ferrole complex (5). Phosphites react with complex 3a to form mono- and di-substitution products (ketene imine)- Fe₂(CO)₅P(OR)₃ (4c,d) and (ketene imine)Fe₂(CO)₄(P(OR)₃)₂ (6). Diphosphanes yield substituted complexes of type (ketene imine)Fe₂(CO)₄(μ-Ph₂P ^⌢ PPh₂) (7). The structures of (ketene imine)Fe₂(CO)₅PMe₃ (4a), the ferrole complex 5, and (ketene imine)Fe₂(CO)₄(ν-Ph₂PCH₂CH₂PPh₂) (7b) were determined by X-ray analysis.     

Übergangsmetall-heteroallen-komplexe: XIII. Reaktionen der cobalt-thioketen-komplexe [Co(R2CCS)(C5H5)] mit elektrophilen

Reaction of the η²(C,S)-coordinated thioketene cobalt complex [Co(C₁₁H₁₈S)-(PMe₃(C₅H₅)] (2a) with the electrophils [Mn(CO)₂(THF)(C₅H₅] and [Cr(CO)₅(THF)] gives the dinuclear thioketene complexes (4) with two different metal atoms in the molecule. The structure of the cobalt manganese compound was determined by X-ray diffraction. Protonation of the mononuclear thioketene complexes 2 give novel cationic η²-bonded thioacyl compounds [Co(η²-RCS)-(PMe₃(C₅H₅)]⁺ (9), as confirmed by X-ray analysis.     

6-Azabicyclo[3.1.0]hex-30-en-2-ol Derivative,photochemically generated building blocks for bicyclic β-lactams

The title compounds 4 are obtained by photolysis of simple N-alkylpyridinium salts in H₂O or alcohol. On reaction with [Fe₂(CO)₉] in THF, 4 gives bicyclic tricarbonyliron complexes 13a – d , which on oxidative decomplexation with ceric ammonium nitrate afford cis-fused cyclopenteno-β-lactams 15a – d .     

Reactions of iron carbonyl complexes with dimethylthiocarbamoyl chloride

The reactions of dimethylthiocarbamoyl chloride with a number of neutral and ionic iron carbonyl complexes in tetrahydrofuran are described. A variety of unusual products were obtained, viz. Fe(CO)₂(S₂CNMe₂)₂ from Fe(CO)₅; Fe(CO)₂(S₂CNMe₂)(CSNMe₂) from Fe₂)CO)₉, Fe₃(CO)₁₂, and Fe(CO)₄^2?; [Fe-(CO)₂(S₂CNMe₂)(CNMe₂)(CNMe₂)₂S]⁺ from Fe(CO)₄^2?, and Fe₄(CO)₁₂S(CSNMe₂)-(CNMe₂) from Fe₂(CO)₈^2?, as well as Fe₂(CO)₆(CSSEt)₂ from Fe₂(CO)₉ and ClCSSEt. The structures and behavior and some reactions of these complexes are described.     

Synthese von N-phenolat-funktionalisierten Makrocyclen des 1,4,7-Trazacyclononans sowie des 1-Oxa-4,7-diazacyclononans und ihre Komplexchemie mit Eisen(III)

Synthesis of N-Phenolate-functionalized Macrocycles of 1,4,7-Triazacyclononane and of 1-Oxa-4,7-diazacyclononane and their Coordination Chemistry with Iron(III) Six new tetra- or pentadentate, N-phenolate functionalized, pendant, arm macrocyclic containing a 1,4,7-traizacyclononane or a 1-oxa-4,7-diazacyclononane backbone have been synthesized and their coordination chemistry with iron(III) has been investigated. Electronic spectra of these octahedral high-spin Fe^III complexes have been measured. The Phenolate-to-iron(III) charge transfer band has been studied as a function of the number of coordinated phenolate residues (1,2, or 3) and of the substituents at the phenolate arms. The dinuclear complex [LFe₂(μ-O₂CPh)](C1O)₄)₃ has been synthesized where the two Fe^III centres are connected via a symmetric μ-benzoato bridge and two phenolate oxygen atoms (L⁷ = N-(2-hydroxybenzyl)-1,4,7-triazacyclononane).     

Unexpected fragmentation of phenyldithiobenzoate, formation and X-ray structure of [μ,η(S,S)-1,2-(dithio)-1,2-(diphenylethylene)] diiron hexacarbonyl complex

The reaction of Fe₂(CO)₉ with phenyldithiobenzoate PhCS₂Ph 1 afforded four colored compounds: [(μ-η³(C,S,S)PhCS₂Ph)]Fe₂(CO)₆2, (μ-S)₂Fe₃(CO)₉3, (μ-SPh)₂Fe₂(CO)₆4 and [μ-η²(S,S)][PhC(S)C(S)Ph]Fe₂(CO)₆5. Complex 5 was characterized by X-ray crystallography. The formation of complexes 4 and 5 was unexpected since it involved a fragmentation of the organic ligand 1 during its reaction with Fe₂(CO)₉. The electrochemical studies of 1, complexes 2 and 3 were undertaken in order to get information about the chemical behaviors of the intermediates generated by electron transfer. The results of cyclic voltammetry studies of 2 and 1 suggested that the reaction of 1 with Fe₂(CO)₉ involved two competitive reactions: (i) a thermal reaction which led to the expected compounds 2 and 3 and (ii) an electron transfer reaction involving a fragmentation of starting ligand 1 led to the unexpected complex 5. The required electrons may be provided by iron during the thermal decay of complexes 2 or 3 or Fe₂(CO)₉.     

Reversible alkin-addition an rp-verbrückte carbonyleisen-cluster

The clusters (μ₃-RP)₂Fe₃(CO0₉ (1) photochemically add alkines R′CCR′ across their bridging phosphorus centers to yield (μ₃-η⁴-RPCR′CR′PR)Fe₃(CO)₉ (2). Thermal activation of 2 opens two different reaction channels: Complezes 2 may split into R′CCR′ and 1 in a thermally induced reversion of their photoinitiated formation reaction: in another pathway they may lose Fe(CO)₃ to yield (μ₂-η²-(PFe)RPCR′CR′PR)Fe₂(CO)₆ (3). Complex 3 is an Fe₂(CO)₆ derivative of the butterfly type with the μ₂-bridging phosphorus centers linked by an R′CCR′ moeity. The reverse transformation 3 → 2 is induced by Fe₂(CO)₉ as an “Fe(CO)₃” source.Compounds 2 undergo a CO substitution reaction with R′CCR′ to give (μ₃-η²- RPCR′CR′PR)(μ₃-η²-R′CCR′)Fe₃(CO)₇ (4) which, upon heating, also transforms into 3. The above reactions 1 ⇋ 2 ⇋ 3 and 2 → 4 → 3 ⇋ 2 present a rare example of a complete closed set of cluster transformations. An analogous subset of reactions is also verified for the arsenic homologues 1, 2 and 4.     

Syntheses, structures and reactivities of diindenyl-coordinated diiron bridging carbene complexes

Compound [Fe₂(μ-CO)₂(CO)₂(η⁵-C₉H₇)₂] (1) reacts with aryllithium reagents, ArLi (Ar = C₆H₅, p-CH₃C₆H₄, p-CF₃C₆H₄) followed by alkylation with Et₃OBF₄ to give the diindenyl-coordinated diiron bridging alkoxycarbene complexes [Fe₂{μ-C(OC₂H₅)Ar}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (2, Ar = C₆H₅; 3, Ar = p-CH₃C₆H₄, 4, Ar = p-CF₃C₆H₄). Complex 4 reacts with HBF₄ · Et₂O at low temperature to yield cationic bridging carbyne complex [Fe₂(μ-CC₆H₄CF₃-p)(μ-CO)(CO)₂(η⁵-C₉H₇)₂]BF₄ (5). Cationic 5 reacts with NaBH₄ in THF at low temperature to afford diiron bridging arylcarbene complex [Fe₂{μ-C(H)C₆H₄CF₃-p}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (6). The reaction of 5 with NaSC₆H₄CH₃-p under the similar conditions gave the bridging arylthiocarbene complex [Fe₂{μ-C(C₆H₄CF₃-p)SC₆H₄CH₃-p}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (7). Complex 5 can also react with carbonylmetal anionic compounds Na[M(CO)₅(CN)] (M = Cr, Mo, W) to produce the diiron bridging aryl(penta-carbonylcyanometal)carbene complexes [Fe₂{μ-C(C₆H₄CF₃-p)NCM(CO)₅}(μ-CO)(CO)₂(η⁵-C₉H₇)₂] (8, M = Cr; 9, M = Mo; 10, M = W). The structures of complexes 4, 6, 7, and 10 have been established by X-ray diffraction studies.     

Seleniumselenium bond reactions of μ-(diselenium)bis(tricarbonyliron), an inorganic mimic of organic diselenides

μ-(Diselenium)bis(tricarbonyliron), (μ-Se₂)Fe₂(CO)₆, has been found to have reactivity typical of organic diselenides, RSeSeR. Reaction with two molar equivalents of LiBEt₃H converts (μ-Se₂)Fe₂(CO)₆ to the dianion, (μ-LiSe)₂Fe₂(CO)₆. Organolithium reagents, RLi, cleave its SeSe bond, giving (μ-LiSe)(μ-RSe)Fe₂(CO)₆. Low valent transition metal species, e.g., (Ph₃P)₂Pt, insert into the SeSe bond. (μ-Se₂)Fe₂(CO)₆ is fragmented by the action of dicobalt octacarbonyl, giving (μ₃-Se)FeCo₂(CO)₉.     

Radical Exchanges and Structural Transformations on the Iron Carbonyl-Bulky Tin Cluster Complex, Fe2(μ-SnBu 2 t )2(CO)8 by Solvents Toluene, Xylenes and Ethylbenzene

The reaction of Fe₂(CO)₉ and Bu ₃ ^t SnH yielded the bimetallic cluster complexes Fe₂(??-SnBu ₂ ^t )₂(CO)₈, 1, and Fe₄(??₄-Sn)(??-SnBu ₂ ^t )₂(CO)₁₆, 3. Compound 3 contains two Fe₂(CO)₈(??-SnBu ₂ ^t ) groups held together by a central quadruply bridging tin atom, giving an overall bow-tie structure for the one tin and four iron atoms. Refluxing compound 1 in toluene solvent affords the complex Fe₂[??-SnBu^t(CH₂Ph)]₂(CO)₈, 4, where two of the Bu^t groups in 1 have been replaced with benzyl groups, as a result of selective benzylic C?CH bond activation of solvent toluene. Similarly refluxing compound 1 in ortho-, meta- and para-xylene solvents gives the complexes where two, three and four of the Bu^t groups in 1 have been replaced by the respective xylyl groups. Compound 1 also reacts with ethylbenzene to furnish the complex Fe₂[??-SnBu^t(MeCHPh)]₂(CO)₈, 14, where two of the Bu^t groups in 1 have been replaced as a result of the benzylic C?CH activation of ethylbenzene. A mechanism based on a radical pathway is proposed for the selective C?CH bond activation by 1.     

Syntheses and structures of iron carbonyl complexes derived from N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine and N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine

The reaction of N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine (1) with Fe₂(CO)₉ in refluxing acetonitrile yielded di-(μ₃-thia)nonacarbonyltriiron (2), μ-[N-(5-methyl-2-thienylmethyl)-η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido]hexacarbonyldiiron (3), and N-(5-methyl-2-thienylmethylidene)amine (4). If the reaction was carried out at 45 °C, di-μ-[N-(5-methyl-2-thienylmethylidene)-η¹(N);η¹(S)-2-thiolethylamino]-μ-carbonyl-tetracarbonyldiiron (5) and trace amount of 4 were obtained. Stirring 5 in refluxing acetonitrile led to the thermal decomposition of 5, and ligand 1 was recovered quantitatively. However, in the presence of excess amount of Fe₂(CO)₉ in refluxing acetonitrile, complex 5 was converted into 2-4. On the other hand, the reaction of N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine (6) with Fe₂(CO)₉ in refluxing acetonitrile produced 2, μ-[N-(6-methyl-2-pyridylmethyl)-η¹ (N_py);η¹:η¹(N); η¹:η¹(S)-2-thiolatoethylamido]pentacarbonyldiiron (7), and μ-[N-(6-methyl-2-pyridylmethylidene)-η²(C,N);η¹:η¹(S)-2- thiolethylamino]hexacarbonyldiiron (8). Reactions of both complex 7 and 8 with NOBF₄ gave μ-[(6-methyl-2-pyridylmethyl)-η¹(N_py);η¹:η¹(N);η¹:η¹(S)-2-thiolatoethylamido](acetonitrile)tricarbonylnitrosyldiiron (9). These reaction products were well characterized spectrally. The molecular structures of complexes 3, 7-9 have been determined by means of X-ray diffraction. Intramolecular 1,5-hydrogen shift from the thiol to the methine carbon was observed in complexes 3, 7, and 9.     

Models of the iron-only hydrogenase: Reactions of [Fe2(CO)6(μ-pdt)] with small bite-angle diphosphines yielding bridge and chelate diphosphine complexes [Fe2(CO)4(diphosphine)(μ-pdt)]

Reactions of [Fe₂(CO)₆(μ-pdt)] (1) (pdt = SCH₂CH₂CH₂S) and small bite-angle diphosphines have been studied. A range of products can be formed being dependent upon the nature of the diphosphine and reaction conditions. With bis(diphenylphosphino)methane (dppm), thermolysis in toluene leads to the formation of a mixture of bridge and chelate isomers [Fe₂(CO)₄(μ-dppm)(μ-pdt)] (2) and [Fe₂(CO)₄(κ²-dppm)(μ-pdt)] (3), respectively. Both have been crystallographically characterised, 3 being a rare example of a chelating dppm ligand in a first row binuclear system. At room temperature in MeCN with added Me₃NO · 2H₂O, the monodentate complex [Fe₂(CO)₅(κ¹-dppm)(μ-pdt)] (4) is initially formed. Warming 4 to 100 °C leads the slow conversion to 2, while oxidation (on alumina) gives [Fe₂(CO)₅(κ¹-dppmO)(μ-pdt)] (5). With bis(dicyclohexylphosphino)methane (dcpm), heating in toluene cleanly affords [Fe₂(CO)₄(μ-dcpm)(μ-pdt)] (6). With Me₃NO · 2H₂O in MeCN the reaction is not clean as the phosphine is oxidised but monodentate [Fe₂(CO)₅(κ¹-dcpm)(μ-pdt)] (7) can be seen spectroscopically. With 1,2-bis(diphenylphosphino)benzene (dppb) and cis-1,2-bis(diphenylphosphino)ethene (dppv) the chelate complexes [Fe₂(CO)₄(κ²-dppb)(μ-pdt)] (8) and [Fe₂(CO)₄(κ²-dppv)(μ-pdt)] (9), respectively are the final products under all conditions, although a small amount of [Fe₂(CO)₅(κ²-dppvO)(μ-pdt)] (10) was also isolated. Protonation of 2 with HBF₄ affords a cation with poor stability while with the more basic diiron centre in 6 readily forms the stable bridging-hydride complex [(μ-H)Fe₂(CO)₄(μ-dcpm)(μ-pdt)][BF₄] (11) which has been crystallographically characterised.     

Synthesis of single and double butterfly iron carbonyl complexes by reactions of [(μ-RSe)(μ-CO)Fe2(CO)6]− anions. Crystal structures of (μ-p-MeC6H4Se)[μ-PhCH2N(H)CS]Fe2(CO)6 and [(μ-PhSe)(μ-MeAs)Fe2(CO)6]2

The in situ reactions of the [Et₃NH]⁺ and [MgBr]⁺ salts of [(μ-RSe)(μ-CO)Fe₂(CO)₆]⁻ (1) anions with PhC(Cl)NPh gave single butterfly complexes (μ-RSe)(μ-PhCNPh)Fe₂(CO)₆ (2, R=Ph; 3, R=p-MeC₆H₄; 4, R=Et), whereas those of the [Et₃NH]⁺ salts of 1 with R′NCS afforded single butterfly complexes (μ-RSe)[μ-R′N(H)CS]Fe₂(CO)₆ (5, R=Ph, R′=Ph; 6, R=p-MeC₆H₄ R′=Ph; 7, R=p-MeC₆H₄, R′=PhCO; 8, R=p-MeC₆H₄, R′=PhCH₂). Compound 8 could also be prepared by reaction of the [MgBr]⁺ salt of 1 (R=p-MeC₆H₄) with PhCH₂NCS followed by treatment with CF₃CO₂H. More interestingly, while the [Et₃NH]⁺ salt of 1 (R=Ph) reacted with Et₃OBF₄ to give a carbyne ligand-bridged single butterfly complex (μ-PhSe)(μ-EtOC)Fe₂(CO)₆ (9), reaction of the [Et₃NH]⁺ salt of 1 (R=Ph) with MeAsI₂ produced a MeAsAsMe ligand-bridged double butterfly complex [(μ-PhSe)(μ-MeAs)Fe₂(CO)₆]₂ (10). All the new complexes, 2–10, were characterized by elemental analysis and various spectroscopic methods, for complexes 8 and 10, the structures were also confirmed by X-ray diffraction techniques.     

Reactions of [Y(BDI)(I)2(THF)] [BDI = {HC(CMeNAr)2}−, Ar = 2,6-diisopropylphenyl] with Na[M(Cp)(CO)3] (M = Cr,W): X-ray crystal structures of [{Y(BDI)[Cr(Cp)(CO)3]2(THF)}2] and [W(Cp)(CO)3][Na(THF)2]

Reaction of [Y(BDI)(I)₂(THF)] (1) with two equivalents of Na[Cr(Cp)(CO)₃] affords the dimeric complex [{Y(BDI)[Cr(Cp)(CO)₃]₂(THF)}₂] (2). Complex 2 contains two yttrium-BDI units which are each linked by two isocarbonyl bridging [Cr(Cp)(CO)₃]^? anions; a terminal, isocarbonyl bound [Cr(Cp)(CO)₃]^? anion and THF molecule completes the coordination sphere at each yttrium. This results in formation of a centrosymmetric, 12-membered C₄O₄Cr₂Y₂ ring. Forcing conditions were required to produce carbonyl metallate derivatives such as 2, as exemplified by the isolation of crystals of [W(Cp)(CO)₃][Na(THF)₂] (3) from the analogous reaction between 1 and two equivalents of Na[W(Cp)(CO)₃]. Complex 3 loses coordinated THF very easily and all isolated samples exhibit spectra consistent with the known, un-solvated form of Na[W(Cp)(CO)₃]. The crystal structure of 3 shows dimeric sodium units bridged by two THF molecules and one isocarbonyl group. Each sodium centre is further coordinated by one THF molecule and two isocarbonyl ligands. There are two crystallographically distinct [W(Cp)(CO)₃]^? units; one exhibits two bridging isocarbonyl groups and the other exhibits three bridging isocarbonyl groups to different sodium dimer units. This results in a 2-dimensional polymeric sheet network in the solid state. Complex 2 was characterised by single crystal X-ray diffraction, NMR spectroscopy, FTIR spectroscopy and CHN microanalysis; complex 3 was characterised by single crystal X-ray diffraction only.     

The synthesis, structural characterization, magnetochemistry and Mössbauer spectroscopy of [Fe3LnO2(CCl3COO)8H2O(THF)3] (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Lu and Y)

The new tetranuclear complexes [Fe₃Ln(μ₃-O)₂(CCl₃COO)₈(H₂O)(THF)₃]·THF (Ln = Ce^III (1), Pr^III (2), Nd^III (3)) and [Fe₃Ln(μ₃-O)₂(CCl₃COO)₈(H₂O)(THF)₃]·THF·C₇H₁₆ (Ln = Sm^III (4), Eu^III (5), Gd^III (6), Tb^III (7), Dy^III (8), Ho^III (9), Lu^III (10) and Y^III (11)) have been prepared. All compounds were prepared by the reaction between [Fe₂BaO(CCl₃COO)₆(THF)₆] and the corresponding Ln^III nitrate salt. The crystal structures of 1–4, 8 and 9 have been determined; these isostructural molecules have a non-planar {Fe₃Ln(μ₃-O)₂} “butterfly” core. Magnetic susceptibility measurements show dominant intramolecular antiferromagnetic exchange interactions for all the complexes. ⁵⁷Fe Mössbauer spectroscopy shows three different environments for the Fe^III metal ions, all in their high-spin state S = 5/2 (confirming that no electron transfer from Ce^III to Fe^III occurs in 1). At the time scale of the Mössbauer spectroscopy (about 10⁻⁷ s), evidence of magnetization blocking, i.e. slow relaxation of the magnetization, is observed below 3 K for 7, which was confirmed by ac susceptibility measurements.     

Reactions of a phosphido-bridged unsymmetrical diiron complex (η-C5Me5)Fe2(CO)4(μ-CO)(μ-PPh2) with various alkynes

A phosphido-bridged unsymmetrical diiron complex (η⁵-C₅Me₅)Fe₂(CO)₄(μ-CO)(μ-PPh₂) (1) was synthesized by a new convenient method; photo-dissociation of a CO ligand from (η⁵-C₅Me₅)Fe₂(CO)₆(μ-PPh₂) (2) that was prepared by the reaction of Li[Fe(CO)₄PPh₂] with (η⁵-C₅Me₅)Fe(CO)₂I. The reactivity of 1 toward various alkynes was studied. The reaction of 1 with ^tBuCCH gave a 1:1 mixture of two isomeric complexes (η⁵-C₅Me₅)Fe₂(CO)₃(μ-PPh₂)[μ-CHC(^tBu)C(O)] (3) containing a ketoalkenyl ligand. The reactions of 1 with other terminal alkynes RCCH (R=H, CO₂Me, Ph) afforded complexes incorporating one or two molecules of alkynes and a carbonyl group. The principal products were dinuclear complexes bridged by a new phosphinoketoalkenyl ligand, (η⁵-C₅Me₅)Fe₂(CO)₃(μ-CO)[μ-CR¹CR²C(O)PPh₂] (4a: R¹=H, R²=H; 4b: R¹=CO₂Me, R²=H; 4c: R¹=H, R²=Ph). In the cases of alkynes RCCH (R=H, CO₂Me), dinuclear complexes having a new ligand composed of two molecules of alkynes, a carbonyl group, and a phosphido group; i.e. (η⁵-C₅Me₅)Fe₂(CO)₃[μ-CRCHCHCRC(O)PPh₂] (5a: R=H; 5b: R=CO₂Me), were also obtained. In all cases, mononuclear complexes, (η⁵-C₅Me₅)Fe(CO)[CR¹CR²C(O)PPh₂] (6a: R¹=H, R²=H; 6b: R¹=H, R²=CO₂Me; 6c: R¹=H, R²=Ph) were isolated in low yields. The structures of 1, 4c, 5b, and 6a were confirmed by X-ray crystallography. The detailed structures of the products and plausible reaction mechanisms are discussed.