Zur kenntnis der cyclopentadienyl-nitrosyl-carbonyl-isonitril-komplexe der VI. Und der cyclopentadienyl-dicarbonyl-isonitril-komplexe der VII. Nebengruppe

The nitrosylcarbonylisonitrile complexes η⁵-C₅H₅M(NO)(CO)CNR (R = Me for Cr, Mo, W; R = Et, SiMe₃, GeMe₃, SnMe₃ for Mo) are formed by treatment of the nitrosylcarbonylcyanometalates Na[η⁵-C₅H₅M(NO)(CO)CN] with [R₃O]BF₄ (R = Me, Et), Me₃SiCl, Me₃GeCl or Me₃SnCl. The isoelectronic dicarbonylisonitrile compounds η⁵-C₅H₅Mn(CO)₂CNR (R = SiMe₃, GeMe₃, SnMe₃, PPh₂, AsMe₂) and η⁵-C₅H₅Re(CO)₂CNAsMe₂ are obtained by analogous reactions of Na[η⁵-C₅H₅M(CO)₂CN] (M = Mn, Re) with Me₃ECl (E = Si, Ge, Sn), Ph₂PCl and Me₂AsBr.With phosgene the anionic complexes Na[η⁵-C₅H₅M(CO)₂CN] (M = Mn, Re) can be transformed into the new carbonyldiisocyanide-bridged dinuclear complexes η⁵-C₅H₅M(CO)₂CN-C(O)-NC(OC)₂M-η⁵-C₅H₅. Finally, the reactions of η⁵-C₅H₅M(NO)(CO)CNMe (M = Cr, Mo, W) with NOPF₆, leading to the cationic dinitrosylisonitrile complexes [η⁵-C₅H₅M(NO)₂CNMe]⁺, are described.     

Synthesis and structures of the η5-C5H5Cl(CO)2W-η1,η5-(PPh2)C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3 and MeSi[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)2PPh3]3 complexes

The metallation of the η⁵-C₅H₅(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ complex with BuⁿLi (THF, ?78 °C) followed by the treatment of the lithium derivative with Ph₂PCl afforded the η⁵-Ph₂PC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ complex. The reaction of the latter with η⁵-C₅H₅(CO)₃WCl in the presence of Me₃NO produced the trinuclear complex η⁵-C₅H₅Cl(CO)₂W-η¹,η⁵-(Ph₂P)C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃. The structure of the latter complex was established by IR, UV, and 1H and ³¹P NMR spectroscopy and X-ray diffraction. The reaction of MeSiCl₃ with three equivalents of LiC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₂PPh₃ gave the hexanuclear complex MeSi[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₂PPh₃]₃.     

Synthesis and characterization of complexes η5,η5-(CO)3Mn(C5H4-C5H4)(CO)2Fe-η1,η5-C5H4Mn(CO)3 and μ-(C≡C)[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3]2

The complex η⁵,η⁵-(CO)₃Mn(C₅H₄-C₅H₄)(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ was synthesized by the reaction of η⁵-Cp(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with BuⁿLi (THF, ?78 °C) and then with anhydrous CuCl₂. The complex μ-(C≡C)[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃]₂ was prepared by the reaction of η⁵-IC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with Me₃SnC≡CSnMe₃ (2:1) in the presence of Pd(MeCN)₂Cl₂.     

Reductions of metal carbonyls by quaternary ammonium borohydrides

Quaternary ammonium borohydrides, used directly or generated in phase transfer reactions, are highly effective reagents for preparing metal carbonyl anions from metal carbonyls [Mo(CO)₆, Mn₂(CO)₁₀, Re₂(CO)₁₀, CO₂(CO)₈, Fe₃(CO)₁₂, Ru₃(CO)₁₂ and (η⁵-C₅H₅)₂Mo₂(CO)₆] and from some metal carbonyl halides [BrMn(CO)₅ and η⁵-C₅H₅Mo(CO)₃Cl]. Where strongly basic anions would be formed from a halide [BrMn(CO)₄PPh₃ and η⁵-C₅H₅Ru(CO)₂Br], the reactions provide efficient syntheses of the corresponding hydrides instead. The anion η⁵-C₅H₅Fe(CO)₂^? is not accessible by these techniques; reaction of η⁵-C₅H₅Fe(CO)₂Br yields the iron dimer (via the highly nucleophilic anion) and the dimer is unreactive toward Q⁺BH₄^?. Reductions of Re₂(CO)₁₀ conducted in CH₂Cl₂ provide Re₂(CO)₉Cl^? in high yield.     

The preparation and crystal structures of dicarbonylcyclopentadienylnitrosylchromium and dicarbonylfluorenylnitrosylchromium

The X-ray-crystal structures of both (η⁵-C₅H₅)Cr(CO)₂(NO) (I) and (η⁵-C₁₃H₉)Cr(CO)₂(NO) (II, η⁵-C₁₃H₉ = η⁵-9H-fluorenyl) are described. I crystallizes in the monoclinic space group P2₁/n with lattice constants a 10.998(4), b 7.066(3), c 11.940(4) Å, β 116.37(4)°, and ?_calc 1.63 g cm^?3 for Z = 4. II belongs to the orthorhombic space group Pnma with a 6.463(4), b 15.512(6), c 12.916(6) Å, and ?_calc 1.55 g cm^?3 for Z = 4. Least-squares refinement gave final conventional R values of 0.037 based on 1081 independent observed reflections for I, and 0.042 with 630 reflections for II. The carbonyl and nitrosyl groups are disordered in I, but the nitrosyl ligand in II occupies a position “trans” to the electron-rich C(9) of the fluorenyl system. Photolysis of II in liquid olefins (L) or acetyleness leads to substituted derivatives of the type (η⁵-C₁₃H₉)Cr(CO)(NO)L (L = cyclooctene, cycloocta-1,5-diene, norbornene, norbornadiene, phenylacetylene).     

Preparation of new (η5-C5H4CH3)Mn(NO)(PPh3) and (η7-C7H7)Mo(CO)-(PPh3) complexes

The complex (η⁵-C₅H₄CH₃)Mn(NO)(PPh₃)I has been prepared by the reaction of NaI with [(η⁵-C₅H₄CH₃)Mn(NO)(CO)(PPh₃)]⁺ and also by the reaction of [(η⁵-C₅H₄CH₃)Mn(NO)(CO)₂]⁺ with NaI followed by PPh₃. This iodide compound reacts with NaCN to yield (η⁵-C₅H₄CH₃)Mn(NO)(PPh₃)CN which is ethylated by [(C₂H₅)₃O]BF₄ to yield [(η⁵-C₅H₄CH₃)Mn(NO)(PPh₃)(CNC₂H₅)]⁺. Both [(η⁵-C₅H₄CH₃)Mn(NO)(CO)₂]⁺ and [(η⁵-C₅H₄CH₃)Mn(NO)(PPh₃)(CO)]⁺ react with NaCN to yield [(η⁵-C₅H₄CH₃)Mn(NO)(CN)₂]^?. This anion reacts with Ph₃SnCl to yield cis-(η⁵-C₅H₄CH₃)Mn(NO)(CN)₂SnPh₃ and with [(C₂-H₅)₃O]BF₄ to yield [(η⁵-C₅H₄CH₃)Mn(NO)(CNC₂H₅)₂]⁺. The reaction of (η⁵-C₅-H₄CH₃)Mn(NO)(PPh₃)I with AgBF₄ in acetonitrile yields [(η⁵-C₅H₄CH₃)Mn-(NO)(PPh₃)(NCCH₃)]⁺. The complex (η⁵-C₅H₄CH₃)Mn(NO)(CO)I, produced in the reaction of [(η⁵-C₅H₄CH₃)Mn(NO)(CO)₂]⁺ with NaI, is not stable and decomposes to the dimeric complex (η⁵-C₅H₄CH₃)₂Mn₂(NO)₃I for which a reasonable structure is proposed. Similar dimers can be prepared from the other halide salts. The reaction of (η⁷-C₇H₇)Mo(CO)(PPh₃)I with NaCN yields (η⁷-C₇-H₇)Mo(CO)(PPh₃)CN which is ethylated by [(C₂H₅)₃O]BF₄ to yield [(η⁷-C₇H₇)-Mo(CO)(PPh₃)(CNC₂H₅)]⁺. The interaction of this molybdenum halide complex with AgBF₄ in acetonitrile and pyridine yields [(η⁷-C₇H₇)Mo(CO)(PPh₃)-(NCCH₃)]⁺ and [(η⁷-C₇H₇)Mo(CO)(PPh₃)(NC₅H₅)]⁺, respectively. Both (η⁵-C₅-H₄CH₃)Mn(NO)(PPh₃)I and (η⁷-C₇H₇)Mo(CO)(PPh₃)I are oxidized by NOPF₆ to the respective 17-electron cations in acetonitrile at ?78°C but revert to the neutral halide complex at room temperature. This result is supported by electrochemical data.     

Novel complexes of manganese with phenylvinylidene as a ligand

Three novel stable complexes of manganese were prepared by interaction of [(η⁵-C₅H₅)Mn(CO)₂ (THF)] with phenylacetylene. X-ray structure analysis of two of the complexes established the presence of a phenylvinylidene ligand. In [(η⁵-C₅H₅Mn(CO)₂(CCHPh)] this ligand forms an unusual double MnC bond and in [(η⁵-C₅H₅)Mn₂(CO)₄(CCHPh)] it acts as a bridge strengthening the MnMn bond.     

Säureinduzierte carbin-acylumwandlung

The reaction of dicarbonyl- and carbonyl(trimethylphosphine)(cyclopentadienyl)-carbyne complexes of molybdenum and tungsten η⁵-C₅H₅(CO)_2−n(PMe₃)_nMCR (n = 0, 1; M = Mo, W; R = CH₃, C₆H₅, C₆H₄CH₃, C₃H₅) with protic nucleophiles HX (X = Cl, CF₃COO, CCl₃COO) leads, through a combined protonation/carbon-carbon coupling reaction, to η²-acyl complexes η⁵-C₅H₅(CO)_1−nX₂(PMe₃)_n-M(η²-COCH₂R). The reaction conditions, the results of the spectroscopic measurements and the X-ray structure of η⁵-C₅H₅(CO)(Cl₂)W(η²-COCH₂CH₃) are reported.     

The hapticity of cyclooctatetraene in its first row mononuclear transition metal carbonyl complexes: Several examples of octahapto coordination

The two cyclooctatetraene metal carbonyls that have been synthesized are the tetrahapto derivative (η⁴-C₈H₈)Fe(CO)₃ and the hexahapto derivative (η⁶-C₈H₈)Cr(CO)₃ using the reactions of cyclooctatetraene with Fe(CO)₅ and with fac-(CH₃CN)₃Cr(CO)₃, respectively. Related C₈H₈M(CO)_n (M = Ti, V, Cr, Mn, Fe, Co, Ni; n = 4, 3, 2, 1) species have now been investigated by density functional theory in order to explore the scope of cyclooctatetraene metal carbonyl chemistry. In this connection, the existence of octahapto (η⁸-C₈H₈)M(CO)_n species is predicted as long as the central metal M does not exceed the 18-electron configuration by receiving eight electrons from the η⁸-C₈H₈ ring. Thus the lowest energy structures (η⁸-C₈H₈)Ti(CO)_n (n = 3, 2, 1), (η⁸-C₈H₈)M(CO)_n (M = V, Cr; n = 2, 1), and (η⁸-C₈H₈)Mn(CO) all have octahapto η⁸-C₈H₈ rings. An exception is (η⁶-C₈H₈)Fe(CO), with a hexahapto η⁶-C₈H₈ ring and thus only a 16-electron configuration for the iron atom. Hexahapto (η⁶-C₈H₈)M(CO)_n structures are predicted for the known (η⁶-C₈H₈)Cr(CO)₃ as well as the unknown (η⁶-C₈H₈)Ti(CO)₄, (η⁶-C₈H₈)V(CO)₃, (η⁶-C₈H₈)Mn(CO)₂, and (η⁶-C₈H₈)Fe(CO)₂ with 18, 18, 17, 17, and 18 electron configurations, respectively, for the central metal atoms. There are two types of tetrahapto C₈H₈M(CO)_n complexes. In the 1,2,3,4-tetrahapto (η⁴-C₈H₈)M(CO)_n complexes two adjacent CC double bonds, forming a 1,3-diene unit similar to butadiene, are bonded to the metal atom. In the 1,2,5,6-tetrahapto (η^2,2-C₈H₈)M(CO)₃ derivatives two non-adjacent CC double bonds of the C₈H₈ ring are bonded to the metal atom. The known (η⁴-C₈H₈)Fe(CO)₃ is a 1,2,3,4-tetrahapto complex. The unknown isomeric 1,2,5,6-tetrahapto complex (η^2,2-C₈H₈)Fe(CO)₃ is predicted to lie ∼15 kcal/mol above (η⁴-C₈H₈)Fe(CO)₃. The related 1,2,5,6-tetrahapto complexes (η^2,2-C₈H₈)Cr(CO)₄, (η^2,2-C₈H₈)Mn(CO)₄, [(η^2,2-C₈H₈)Mn(CO)₃]⁻, (η^2,2-C₈H₈)Co(CO)₂, and (η^2,2-C₈H₈)Ni(CO)₂ are all predicted to be low-energy structures.     

Reactions of bis(η4-1,5-cyclooctadiene)nickel(0) with transition metal halides,and the crystal structure of μ-dichloro-bis(tetrahydrofuran)hexacarbonyldimanganese

Bis-(η⁴-1,5-cyclooctadiene)nickel(0) reacted with η⁵-C₅H₅Fe(CO)₂Cl, η³-C₅H₅Fe(CO)₃Cl, Mn(CO)₅Cl and {Mn[P(OMe)₃](CO)₄}₂ to form metal metal bonded coupling products. Partial reduction of Mn(CO)₅Cl gave [MnCl(CO)₃(THF)]₂ shown to have a chlorine-bridged C_2h structure by X-ray diffraction analysis. Ligand transfer also accompanied the reduction of Fe[P(OMe)₃]₂(CO)₂Br₂ and Fe(CO)₄Cl₂ to Fe[P(OMe)₃]₂(CO)₃ and Fe(CO)₅, respectively. Only partial reduction was observed for Ti(acac)₂Cl₂ and (η⁵-C₅H₅)₂TiCl₂ which gave [Ti(acac)₂Cl]₂ and (η⁵-C₅H₅)₂Ti(py)Cl, respectively.     

Reaktionen von Nitrosylkomplexen. XIII. Synthese neuer zwei- und dreikerniger heterobimetallischer Komplexe mit NO-Brückenliganden

Reactions of Nitrosyl Complexes. XIII. Synthesis of Novel Di- and Trinuclear Heterobimetallic Complexes with Bridging NO Ligands By reaction of [{Cp′Fe(μ-NO)}₂] with [Cp′Mn(CO)₂ · (THF)] (Cp′ = μ⁵-C₅H₄Me) in THF [Cp₃′Fe₂Mn(μ-CO)₂(μ-NO) · (μ₃-NO)] 1 is formed in high yield. The reaction of [{Cp′Fe(μ-NO)}₂]Na with [Cp′Mn(CO)₂NO]BF₄ in DME/acetone yields besides known [{Cp′Mn(CO)(NO)}₂] 2 the novel complex [Cp₂′FeMn(μ-NO)₂NO] 3 . By interaction between [Cp′Mn(CO)₂(THF)] and 3 , [Cp₃′FeMn₂(μ-CO)(μ-NO)₂ · (μ₃-NO)] 4 is formed. The complex 4 represents the hitherto unknown missing link in the series of the isoelectronic clusters [Cp₃′Mn₃(μ-NO)₃(μ₃-NO)], 1 , and [Cp₃′Fe₃(μ-CO)₃(μ₃-NO)]. Attempts to synthesize the unknown complex [(Cp′FeNO)₂ · Cr(CO)₅] by addition of carbene analogous Cr(CO)₅ fragments to the Fe=Fe bond in [{Cp′Fe(μ-NO)}₂] only led to very low yields of [Cp₂′FeCr(CO)₅] 5 . The new complexes were characterized by mass, NMR and IR spectra.     

Darstellung und Charakterisierung von kationischen η2-1-Buten- und Acetonitrilkomplexen

Preparation and Characterization of Cationic η²-1-Butene and Acetonitrile Complexes The reaction of the species η⁵-C₅H₅M(CO)_n-σ-C₄H₇ (M = Fe, Mo, W; n = 2, 3) with (C₆H₅)₃CBF₄ yielded – instead of the expected cationic butadiene complexes of the type [η⁵-CpM(CO)_n?1-η⁴-C₄H₆][BF₄], which would have been formed in case of hydride cleavage – compounds of the type [η⁵-CpM(CO)_n η²-C₄H₈][BF₄], which were formed by protonation of the σ-C₄H₇ ligands. The reaction proceeded quantitatively. The BF₄^? anion can be substituted by other anions, such as ClO₄^?, B(C₆H₅)₄^?, PF₄^?, and [Cr(SCN)₄(NH₃)₂]^? in the complexes obtained. The mechanism of the reaction leading to the η²-bonded 1-butene complexes was determined by isotope experiments. In trying to recrystallize the butene complexes from acetonitrile the cationic complexes [η⁵-C₅H₅ Fe(CO)₂CH₃CN]BF₄ and [η⁵-C₅H₅ M(CO)₃CH₃CN]BF₄ were observed; the X-ray structure analysis of the former is reported.     

Derivative des borols: VI. Dehydrierende komplexierung von borolenen mit carbonylmetallen: (borol)metall-komplexe von mangan,eisen und cobalt

The reaction of 2-borolenes and 3-borolenes C₄H₆BR (R = Ph, Me, C₆H₁₁, OMe) with Mn, Fe, and Co carbonyls leads to dehydrogenating complexation with formation of simple, i.e. C-unsubstituted (η⁵-borole)metal complexes. Thus, Mn₂(CO)₁₀ gives the triple-decked complexes (μ-η⁵-C₄H₄BR)[Mn(CO)₃]₂ (R = Ph, OMe). By irradiation of Fe(CO)₅ the half-sandwich complexes Fe(CO)₃ (η⁵-C₄H₄BR) (R = Ph, Me, C₆H₁₁, OMe) are formed, whereas Co₂(CO)₈ yields the dinuclear complexes (μ-CO)₂[Co(CO)(η⁵-C₄H₄BR)]₂ (Co-Co) (R = Ph, Me). A low-temperature X-ray structure determination of Fe(CO)₃(η⁵-C₄H₄BPh) is described in detail.     

Transition metal nitrosyls as nitrosylation agents : II.Photo-nitrosylation of η5-C5H5V(CO)3L(L = CO,Pz3) by [Co(NO)2Br]2

η⁵-C₅H₅V(NO)₂CO is prepared in 40% yield by the photo-reaction between η⁵-C₅H₅V(CO)₄ and [Co(NO)₂Br]₂.η⁵-C₅H₅V(NO)₂CO reacts by an S_N1 mechanism with various phosphines PZ₃ to yield η⁵-C₅-H₅V(NO)₂PZ₃. The phosphine complexes are also obtained by photo-induced ligand interchange between η⁵-C₅H₅V(CO)₃PZ₃ and [Co(NO)₂Br]₂, or η⁵-C₅H₅V(CO)₄ and Co(NO)₂Br(PZ₃). In all cases, the main cobalt species formed is Co(NO)(CO)₃. While the one-bond vanadiumphosphorus coupling constants of most of the phosphine complexes are virtually the same (ca 410 Hz),the chemical shift values δ(⁵¹V) (?1328 to ?973 ppm rel. VOCl₃) decrease in the order PF₃ > CO > P(OR)₃ > P(alkyl)₃ > PPh₃ > PPh(NEt₂)₂, reflecting the decreasing π-acceptor ability of the ligands. δ(⁵¹V) also decreases in the series of alkylphosphines PR₃ (R = Me, Et, Prⁿ, Buⁱ, Prⁱ, BU^t) as the cone angle of PR₃increases.     

Hydrothermal Raman microscopy studies of manganese carbonyls

We present here the application of Raman microscopy in providing simultaneous visual and spectroscopic characterisation of the physical and chemical changes occurring in organometallic materials while undergoing hydrothermal treatment. The effect of water at elevated pressures and temperatures on three prototype manganese carbonyls, Mn₂(CO)₁₀, (η⁵-C₅H₅)Mn(CO)₃ and Mn(CO)₅Br, was investigated. A Bassett-type hydrothermal diamond-anvil cell (HDAC) was used to subject each compound to conditions of at least 22.1 MPa and 374 °C (i.e., beyond the critical point of water), while Raman microscopy was used to monitor the structural changes occurring during the heating and cooling cycles of the cell. The hydrothermal studies showed that Mn₂(CO)₁₀, (η⁵-C₅H₅)Mn(CO)₃ and Mn(CO)₅Br dissolved in subcritical water at 150, 125 and 225 °C, respectively. Moreover, Mn(CO)₅Br is also believed to have dimerized to Mn₂(CO)₈Br₂ when the cell temperature was increased to 425 °C.     

Complexes in polymers: FT-IR spectra and photochemistry of some monomeric organometallic carbonyl complexes in polystyrene,poly(methyl methacrylate), polystyrene—poly(methyl methacrylate) and polystyrene—polyacrylonitrile copolymers

A convenient method for embedding organometallic complexes in polymer films has been developed and the FT-IR spectra of these films have been investigated at room temperature. Infrared data in the n?(CO) stretching region are reported for M(CO)₆ (M = Cr, Mo, W), CpMn(CO)₃ (Cp = η⁵-C₅H₅), η-C₆H₆Cr(CO)₂L [L = CO, P(n-Bu)₃], (η₆-C₆H₅NH₂)Cr(CO)₃, [η⁶-o-C₆H₄(NH₂)MeCr(CO)₃], CpFe(CO)LR [L = CO, PPh₃; R = Me, C(O)Me] embedded in poly(methyl methacrylate) (PMMA), polystyrene (PS), polystyrene-poly(methyl methacrylate) (PS-PMMA), and polystyrene–polyacrylonitrile (PS-AN) plastic films. These matrices appear to approximate the common solvents ethyl acetate, toluene, toluene–ethyl acetate, and toluene–acetonitrile, respectively, with respect to n?(CO) vibrational band behavior. Several of the films have been subjected to UV irradiation and the photoproducts formed have been identified by FT-IR spectroscopy. PS-AN effectively traps photogenerated coordinatively unsaturated species via coordination of its pendant nitrile groups.     

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.     

Studies of lambert's reaction: The formation of [Mn2(CO)8(μ-AsR2)2] complexes from tertiary arsines and [Mn2(CO)10] at high temperatures

Although very bulky ligands e.g.(o-MeC₆H₄)₃E or (μ-C₁₀H₇)₃E (E = P or As) are inert, the normal photochemical or thermal reaction of tertiary phosphines or arsines, L, with [Mn₂(CO)₁₀] is CO substitution with the formation of [Mn₂(CO)₈(L)₂] derivatives (I). At elevated temperatures some triarylarsines, R₃As, undergo Lambert's reaction with ligand fragmentation to give [Mn₂(CO)₈(μ-AsR₂)₂] complexes (II) (R = Ph, p-MeOC₆H₄, p-FC₆H₄, or p-CIC₆H₄) even though, in the absence of [Mn₂(CO)₁₀] R₃As are stable under the same conditions. Exceptional behaviour is exhibited by (p-Me₂NC₆H₄)_3- As which forms a product of type I; by some HN(C₆H₄)₂AsR which give a product of type II as a result of loss of the non-aryl groups R = PhCH₂, cyclo-C₆H₁₁, or MeO; and by Ph(α-C₁₀H₇₂P which is the only phosphine to form a product of type II, albeit in trace amounts only. The thermal decomposition of a n-butanol solution of [Mn₂(CO)₈(AsPh₃)₂] in a sealed tube gives C₆H₆ and [Mn₂(CO)₈(α-AsPh₂)₂], whilst in an open system in the presence of various tertiary phosphines, L, [Mn(H)(CO)₃(L)₂] are obtained. It is suggested that Lambert's reaction is a thermal fragmentation of [Mn(CO)₄(AsR₃]^* radicals, the first to be recognised. They lose the radical R^* which abstracts hydrogen from the solvent. The resulting [Mn(CO)₄(AsR₂)] moiety dimerises to [Mn₂(CO)_8-(α-AsR₂)₂]. the reaction is facilitated by the stability of the departing radical (e.g. PhCH₂ or MeO) and, as the crowding about As is relieved, by its size (e.g. Ph, cyclo-C₆H₁₁, o-MeC₆H₄, or α-C₁₀H₇). In general, phosphine-substituted radicals [Mn(CO)₄(PR)₃]^* do not undergo this decomposition, probably because the PC bonds are much stronger than AsC.     

Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen: XVII. Selen- und tellur-brücken in organometallkomplexen: AUFBAU,protonierung und methylierung

Selenium acts as a bridging ligand between two iron atoms in the novel complex (μ-Se)(η⁵-C₅H₅)Fe(CO)₂]₂ (1), obtained in 60% yield from Na⁺[(η⁵-C₅H₅)Fe(CO)₂] and Se₂Cl₂. 1 displays nucleophilic reactivity towards protic acids (e.g., HBF₄·OEt₂) and methyl triflate, CF₃SO₃CH₃, thus giving the protonated and methylated ionic species [(μ-SeR)(η⁵-C₅H₅)Fe(CO)₂₂]⁺ (R = H: 2a, BF₄ salt; R = CH₃: 2b, PF₆ salt) in quantitative yields. Rapid deprotonation of 2a occurs in the presence of bases such as diethylamine. Analogous protonation and methylation reactions have been observed with the tellurium complex (μ-Te)[(η⁵-C₅H₅)Cr(CO)₃]₂ (3); the ionic compounds [(μ-TeH)(η⁵-C₅H₅)Cr(CO)₃₂]BF₄ (4a) and [(μ-TeCH₃) (η⁵-C₅H₅)Cr(CO)₃₂]PF₆(4a), respectively, are obtained. In contrast, the electron-deficient tellurium ligand of the manganese complex (μ₃-Te)[(η⁵-C₅H₅)Mn(CO)₂]₃ (5) is neither attacked by Brønsted acids nor by electrophilic methylating agents (e.g., CF₃SO₃CH₃) but is rather methylated by methyllithium to give the anionic species [(μ₃-TeCH₃)η⁵-C₅H₅)Mn(CO)₂₃]^? that can be isolated pure as the PPN⁺ salt 6.     

Übergangsmetallketen-verbindungen: XXXVIII. Synthese wolframhaltiger fünfringheterocyclen durch addition von trimethylphosphin an phosphino- und arsinoketenkomplexe

The reaction of phosphino- and arsino-ketene complexes of tungsten η⁵-C₅H₅(CO[P(CH₃)₃] XW[η¹-R₂Y(C₆H₄CH₃)CCO] (X = Cl, I; Y = P, As) with trialkylphosphines does not lead to a substitution of the phosphino- and arsinoketene ligands but to a nucleophilic attack of the phosphine at the central ketene carbon and a concomitant substitution of the halogene ligand via the former ketene oxygen, affording the cationic compelex η⁵-C₅H₅(CO)[P(CH₃)₃]W[η²-R₂YC-(C₆H₄CH₃C(PR′₃)O]X and P,O and As,O chelate ligands. The substitution products R₂Y(C₆H₄CH₃)CCO and η⁵-C₅H₅(CO)[P(CH₃)₃]XW(PR′₃) initially expected could only be obtained as a result of a selective rearrangement/elimination reaction as shown in the case of the arsenic substituted complex η⁵-C₅H₅(CO)(PMe₃)IWAs(CH₃)₂C(C₆H₄CH₃)C=O.