Reactive Free Radicals : by J.M. Hay, Academic press, London, 1974, 158 pages, £4.40.

The linkage isomers CpM(CO)_nSCN and CpM(CO)_nNCS (Cp = η-C₅H₅; M = Fe, n = 2; M = Mo, n = 3) are interconverted by 366 nm irradiation in tetrahydrofuran solution at 30°C. Molybdenum and tungsten halide complexes CpM(CO)₂-(PPh₃)X undergo cistrans isomerization and disproportionation to CpM(CO)(PPh₃)₂X and CpM(CO)(PPh₃)₂X under similar conditions (benzene solution).     

Substituierte halogencarbonylmetallate des chroms,Molybdäns und Wolframs : II. Photochemische phosphin-abspaltung,ein neuer weg zu metall (VI A) carbonylderivaten

Irradiation of bis(phosphine) tetracarbonyl complexes L₂M(CO)₄ (M = Cr, Mo, W) in the presence of donor ligands (amine, nitrile, halide ion) leads, via loss of one phosphine ligand, to neutral (LL′M(CO)₄) or ionic ([LM(CO)₄X]^?) metal carbonyl compounds. The use of this reaction as the first step in a general synthesis of unsymmetrically disubstituted derivatives of Group VIA hexacarbonyls is discussed.     

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.     

The reaction between [η5-C5H5M(CO)3]2, η5-C5H5M(CO)3I (M  Mo,W) and isonitriles

The reaction between η⁵-C₅H₅M(CO)₃I (M  Mo, W) and isonitriles, RNC, (RNC  PhCH₂NC, t-BuNC and 2,6-dimethylphenylisocyanide (XyNC)) is catalysed by the dimer [η⁵-C₅H₅M(CO)₃]₂ (M = Mo, W) to yield η⁵-C₅H₅M(CO)_3?n(RNC)_nI (n = 1–3) and [η⁵-C₅H₅Mo(RNC)₄]I. The complexes (η⁵-C₅H₅)₂Mo₂(CO)₆?n(RNC)_n (n = 1, RNC = MeNC, PhCH₂NC, XyNC, t-BuNC; n = 2, RNC = t-BuNC) have been prepared in moderate yield from the direct reaction between [η⁵-C₅H₅Mo(CO)₃]₂ and RNC, and also catalyse the above reaction. A reaction pathway involving a fast non-chain radical mechanism and a slower chain radical mechanism is proposed to account for the catalysed reaction.     

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.     

Preparation and characterization of mono-cyclopentadienylvanadium dihalide bis-phosphine complexes; crystal structure of (η5-C5H5)VCL2(PMe3)2

Mono-cyclopentadienyl complexes CpVX₂(PR₃)₂ and Cp′VX₂ (PR₃)₂ (Cp = η⁵- C₅H₅; Cp′ = η⁵-C₅H₄Me; R = Me, Et; X = Cl, Br) have been prepared by reaction of VX₃(PR₃)₂ with CpM (M = Na, T1, SnBuⁿ3, 1/2 Mg) or Cp′Na. Attempts to prepare analogous complexes with other phosphine ligands, PPh₃, PPh₂ Me, PPhMe₂, Pcy₃, DMPE and DPPE failed. Reduction of CpVCl₂(PEt₃)₂ with zinc or aluminium under CO (1 bar) offers a simple method for the preparation of CpV(CO)₃(PEt₃). The crystal structure of the trimethylphosphine complex CpVCl₂(PMe₃)₂ is reported.     

Reaktionen von carbonylcyclopentadienylhydriden des molybdäns und des wolframs mit inaminen

The hydrides (η⁵-C₅H₅)(CO)₃MH (M = Mo, W) react with ynamines R′CCNR₂ under mild conditions to form 1 : 1 adducts. According to the ¹H and ¹³C NMR spectra depending on the metal and the ynamine substituents carbene acyl chelate or complexes with η³-aminoacryloyl ligands are formed:

A Dicarbene chelate compound is obtained by alkylation of I, R = Et, R′ = Me. CC-η² keteneimmonium complexes are formed in the reaction of the phosphite substituted hydrides (η⁵-C₅H₅)(CO)₂P(OMe)₃MH (M = Mo, W) with MeCCN Et; an intermediate 1-aminovinyl compound has been isolated.     

Basicity of transiton metal carbonyl complexes : XIII. Reactions of the π-cyclopentadienyl complexes of molybdenum and tungsten with aprotic acids

The aprotic acids HgCl₂ and SnX₄ (X  Cl, Br) react with the π-complexes C₅H₅M(CO)(NO)(L) (II, M  Mo W; L  PPh₃) by attack at the metal center. With HgCl₂ complexes II yield stable neutral 1:1 adducts CpM(CO)(NO)(L)HgCl₂(III). In the case of SnCl₄, complexes II initially produce the ionic 1:2 adducts [CpM(CO)(NO)(L)(SnCl₃)]⁺SnCl₅^-(IV) which, as a result of oxidative elimination of CO, turn into the neutral complexes CpM(NO)(L)(SnCl₃)(Cl)(V). In reactions of II with SnBr₄ the corresponding CpM(NO)(L)(SnB₃)(Br) complexes are formed directly. The formation of III–V is accompanied by a considerable increase of the frequencies ν(CO) and ν(NO). The structures of the complexes IV (M  Mo) and V (M  Mo) have been established by an X-ray structure analysis.     

SYNTHESIS OF ORGANOTRANSITION METAL COMPLEXES CONTAINING p-METHOXYCARBONYLBENZOYLCYCLO-PENTADIENYL AND p-METHOXYCARBONYLPHENYL (HYDROXYMETHYL)CYCLOPENTADIENYL LIGANDS FROM SODIUM p-METHOXYCARBONYLBENZOYLCYCLO-PENTADIENIDE. X-RAY STRUCTURE OF η5-p-MeO2CC6H4COC5H4Mo(CO)3I

Abstract

A new functionally substituted cyclopentadienyl salt p-MeO₂CC₆H₄COC₅H₄Na (1) was prepared from cyclopentadienylsodium and dimethyl terephthalate in THF, and which might be utilized to synthesize a series of novel transition metal complexes containing difunctional group-substituted cyclopentadienyl ligands; 1 reacted with M(CO)₆(M = Mo, W) followed by treatment with PBr₃ or I₂ to give mononuclear organomolybdenum (or tungsten) halides η⁵-p-MeO₂CC₆H₄COC₅H₄M(CO)3X(2, M = Mo, X = Br; 3, M = W, X = Br; 4, M = Mo, X = I; 5, M = W, X = I), whereas reaction of 1 with W(CO)₆ and successive treatment with selenium powder and MeI or PhCH₂Cl afforded mononuclear organotungsten selenolate complexes η⁵-p-MeO₂CC₆H₄COC₅H₄W (CO)₃SeMe (6) and η⁵-p-MeO₂CC₆H₄COC₅H₄W(CO)₃SeCH₂Ph (7). In addition, 1 reacted with M(CO)₆(M = Mo, W) followed by treatment with FeCo₂(CO)₉(μ₃-S) to produce the corresponding polynuclear complexes η⁵-p-MeO₂CC₆H₄COC₅H₄MFeCo(CO)₈(μ₃?S) (8, M = Mo; 9, M = W), which could be converted with NaBH₄ into hydroxyl derivatives η⁵-p-MeO₂CC₆H₄CH(OH)C₅H₄MFeCo(CO)₈(μ₃?S) (10, M = Mo; 11, M = W). All the new transition metal complexes 2–11 have been fully characterized by elemental analysis, IR and ¹H NMR spectroscopy, as well as for 4 by an X-ray diffraction analysis.     

Isomerism and fluxional behaviour in η2 -vinyl complexes resulting in inversion of configuration at an asymmetric carbon atom. The crystal and molecular structures of two isomeric forms of [MoCl{η2 -C(CF3)C(CF3)(PEt3)} (CF3CCCF3)(η5 -C5H5)]

η² -Vinyl complexes [MCl{η² -C(CF₃)C(CF₃)L} (CF₃CCCF₃)(η⁵ -C₅H₅)] (M = Mo, W: L = tertiary phosphine or phosphite or pyridine) have been shown by NMR and X-ray diffraction studies to exist in two distinct isomeric forms which exhibit (a) different orientations of the η² -vinyl ligand (b) different configurations at the asymmetric carbon atom of the η² -vinyl ligand: variable temperature NMR studies reveal fluxional behaviour thought to involve reversible inversion of configuration at this carbon atom.     

Reaktionen der Cycloheptatrienylkomplexe [η7-C7H7W(CO)3]BF4 und η7-C7H7Mo(CO)2 Br mit Neutralliganden und die elektrochemische Reduktion des Wolframkomplexes

Reactions of the Cycloheptatrienyl Complexes [η⁷-C₇H₇W(CO)₃]BF₄ and η⁷-C₇H₇Mo(CO)₂Br with Neutral Ligands and the Electrochemical Reduction of the Wolfram Complex Compounds of the type [η⁷-C₇H₇M(CO)₂L][BF₄] (L = P(C₆H₅)₃, As(C₆H₅)₃, Sb(C₆H₅)₃ for M = W and L = N₂H₄ for M = Mo) were synthesized and characterisized. The iodide η⁷-C₇H₇W(CO)₂I reacts with the diphosphine ((C₆H₅)₂PCH₂)₂ to give the trihapto complex η³-C₇H₇ W(CO)₂I((C₆H₅)₂PCH₂)₂. In the case of η⁷-C₇H₇Mo(CO)₂ Br reaction with hydrazine leads to the substitution product [η⁷-C₇H₇ Mo(CO)₂N₂H₄]^⊕, which can be stabilized by large anions. The binuclear complex [C₇H₇W(CO)₃]₂ has been synthesized electrochemically.     

Metalated 1, 3‐Azaphospholes: η1‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)5 and μ2‐[(1, 3‐Benzazaphospholide‐P)(cyclopentadienide)nickel] Complexes

1H‐1, 3‐Benzazaphospholes react with M(CO)₅(THF) (M = Cr, Mo, W) to give thermally and relatively air stable η¹‐(1H‐1, 3‐Benzazaphosphole‐P)M(CO)₅ complexes. The ¹H‐ and ¹³C‐NMR‐data are in accordance with the preservation of the phosphaaromatic π‐system of the ligand. The strong upfield ³¹P coordination shift, particularly of the Mo and W complexes, forms a contrast to the downfield‐shifts of phosphine‐M(CO)₅ complexes and classifies benzazaphospholes as weak donor but efficient acceptor ligands. Nickelocene reacts as organometallic species with metalation of the NH‐function. The resulting ambident 1, 3‐benzazaphospholide anions prefer a μ₂‐coordination of the η⁵‐CpNi‐fragment at phosphorus to coordination at nitrogen or a η³‐heteroallyl‐η⁵‐CpNi‐semisandwich structure. This is shown by characteristic NMR data and the crystal structure analysis of a η⁵‐CpNi‐benzazaphospholide. The latter is a P‐bridging dimer with a planar Ni₂P₂ ring and trans‐configuration of the two planar heterocyclic phosphido ligands arranged perpendicular to the four‐membered ring.     

Übergangsmetall-substituierte vb elementsysteme : VIII. Darstellung und komplexchemisches verhalten von cyclopentadienyl(tricarbonyl)viametall-dimethylstibinen

Starting with the cyclopentadienyl(carbonyl)metal anions [π-C₅H₅(CO)₃M]^? (M = Cr, Mo, W) and (CH₃)₂SbBr, transition metal-substituted stibines of the form π-C₅H₅(CO)₃MSb(CH₃)₂ are obtained. The nucleophilic character of the VB element primarily determines the reactivity of these species, and shows itself in alkyl halide quarternization (a) or ligand exchange on activated metal carbonyl complexes (b). (a) yields the trialkylstibine-substituted metal cations [π-C₅H₅-(CO)₃MSb(CH₃)₂R]X (R = CH₃, CH₂CH=CH₂, CH₂C₆H₅; X = Br, J), (b) leads to the formation of the metal carbonyl derivatives LM(CO)₅, L₂M(CO)₄ (M = Cr, Mo, W), LNi(CO)₃ and LFe(CO)₄ [L = (CH₃)₂SbM(CO)₃-π-C₅H₅] which are the first (CH₃)₂Sb-bridged polynuclear complexes. Phosphorus ylides cause heterolytic cleavage of the antimonytransition metal bond. Transfer of the (CH₃)₂Sb-group to the ylidic carbanion occurs via substitution/transylidation. All new compounds have been fully characterized by means of ¹H NMR, IR and mass spectroscopy     

η-Allyl-molybdenum and -tungsten carbonyl,complexes containing aliphatic α-diimines as ligands and their solvent dependent infrared and electronic spectra

Pronounced solvent dependence is observed in the infrared and electronic spectra of the new η-allyl complexes (η-R′ C₃ H₄)M(CO)₂ L₂X (M = Mo or W; R′ = H or Me; X = Ct, By, I or NCS; L₂ = 1,2-ethanediylidenediimines or 2-pyridinaldimines).     

Preparation and Ir, 31P,and 93Nb NMR spectroscopic investigation of phosphine derivatives of η5-C5H5Nb(CO)4

UV irradiation of η⁵-C₅H₅Nb(CO)₄ in the presence of the phosphine ligands L (L = 2 PEt₃, Ph₂P(CH₂)₂PPh₂ (p₂(n), n = 1–5), cis-Ph₂PCH=CHPPh₂ (c-dpe)), and the mixed arsine-phosphine ligands Ph₂AsCH₂CH₂PPh₂ (arphos) and o-C₆H₄(AsPh₂)(PPh₂) (pab) yields the well defined complexes cis-[η⁵-C₅H₅Nb(CO)₂L]. The monosubstituted species η⁵-C₅H₅Nb(CO)₃L have been characterized spectroscopically. P₂Ph₄ forms mono- and dinuclear, mono- and biligate carbonylniobium complexes.Shielding of the ⁹³Nb nucleus increases in the sequences (i) Ph₂As- < Ph₂P-, (ii) chelate 4-ring < chelate 5-ring and (iii) η⁵-C₅H₅Nb(CO)₂L < η⁵-C₅H₅Nb(CO)₃L < η⁵-C₅H₅Nb(CO)₄, and ³¹P coordination shifts decrease in the order c-dpe > pab > arphos > p₂(2) > p₂(5) > p₂(4) ～ PEt₃ > p₂(3) > p₂(1). The trends generally parallel those for the corresponding NMR parameters of the vanadium complexes. Paramagnetic contributions to the overall shielding are smaller for the ⁹³Nb than for the ⁵¹V nucleus, and this is explained in terms of increased covalency and decreased π-interaction in the niobium complexes.     

Use of an optically active germanium species for the resolution of diastereoisomeric transition metal complexes with five different and independent ligands

Reaction of optically active MePh(1-C₁₀H₇)GeLi with (η⁵-C₅H₅)M(CO)₂NO (M = Mo, W) results in replacement of CO and formation of anionic species which can be alkylated with CH₃I to afford mixtures of diastereoisomeric complexes, (η⁵-C₅H₅)M(CO)(NO)(GeR₃)CH₃ (R₃ = MePh(1-C₁₀H₇); M = Mo, W). These complexes are the first in which a transition metal, surrounded by five different ligands shows optical activity. These compounds are not fluxional and show a high optical stability; under forcing conditions decomposition occurs before epimerisation.     

Chloromethylsilane functionalised dendrimers: synthesis and reactivity

Tetraallylsilane was functionalised using (chloromethyl)dimethylsilane to give the first generation chloromethyl terminated dendrimer 1. The resulting dendrimer was successfully reacted with K[CpM(CO)₂] (Cp=η⁵-C₅H₅; M=Fe, Ru) to give Si[(CH₂)₃SiMe₂CH₂MCp(CO)₂]₄ functionalised dendrimers in satisfactory yield. Reaction of dendrimer 1 with NaI in acetone gave the -SiMe₂CH₂I functionalised dendrimer, while reactions of 1 with K[CpM(CO)₃] (M=Mo, W, Re), Li[C₅Me₄H], Na[C₅Me₄H], the cobaloxime nucleophile or tert-BuLi were not successful.     

Halogen‐bridged Cationic Complexes of the Type [{CpM(CO)3}2X]SbF6 (M = Mo,W; X = Cl,I), [{CpW(CO)2Cl2}2Cl]SbCl6, and the Trichloride CpW(CO)2Cl3

The reaction of CpMo(CO)₃X (X = Cl, I) with SbF₅ in toluene leads to the cationic, halogen bridged compounds [{CpMo(CO)₃}₂X]SbF₆ ( 1 , 2 ). CpW(CO)₃Cl reacts with SbF₅ to yield [{CpW(CO)₃}₂Cl]SbF₆ ( 3 ), whereas with SbCl₅, the oxidative substitution product [{CpW(CO)₂Cl₂}₂Cl]SbCl₆ ( 4 ) is formed, which decomposes in solution to yield the trichloride CpW(CO)₂Cl₃ ( 5 ). The strong Lewis acid SbF₅ separates the halide from CpM(CO)₃X (M = Mo, W), and the resulting cationic fragment “CpM(CO)₃⁺” reacts with a further CpM(CO)₃X forming a halonium bridge ( 1 – 3 ). The exclusive formation of SbF₆^– can be explained by the oxidizing power of SbF₅. The IR, MS and NMR spectra of the compounds 1 – 5 as well as the X‐ray structure analysis of 5 are reported and discussed.     

Photoinduzierte und thermische reaktionen der übergangsmetallethylverbindungen CpM(CO)3Et (Cp = η5-cyclopentadienyl; Et = ethyl; M = Mo,W)

In the compounds CpM(CO)₃Et (M = Mo, W) the metal-ethyl σ-bond is photolabile. Upon irradiation of a solution of CpM(CO)₃Et with UV light mainly [CpM(CO)₃]₂, CpM(CO)₃H, ethane, and ethylene are produced. Formation of CpM(CO)₃H is indicative of a β-elimination pathway for the photo-induced degradation. In the presence of trimethylphosphane (L) UV-irradiation of a solution of CpM(CO)₃Et leads to the products Cp(CO)(L)₂MM-(CO)₃Cp, CpM(CO)₂(L)Et and CpM(CO)₂(L)H, while the thermal reaction produces the propionyl complexes CpM(CO)₂(L)(COEt).     

Synthesis and Structures of Bis(alkene) Complexes of Tungsten and Molybdenum, [M(CO)2(dpphen)(dbf)2] (M = W or Mo; dpphen = 4,7‐diphenyl‐1,10‐phenanthroline; dbf = dibutylfumarate)

Tungsten and molybdenum complexes [M(CO)₂(dpphen)(dbf)₂] (M = W 1 or Mo 2 ; dpphen = 4,7‐diphenyl‐1,10‐phenanthroline; dbf = dibutylfumarate) have been synthesized and structurally characterized by X‐ray diffraction analysis. In both complexes which have similar structure, the metal atom co‐ordination is distorted octahedral with dpphen and two CO groups in the equatorial plane and the metal atom binds in an η²‐fashion to the C–C bonds of two dbf ligands. The two C–C bonds are almost mutually orthogonal. The two complexes are different in conformation which result from face selection of the two dbf ligands for coordination to the metal atom.