Mass spectra of organometallic compounds—VIII. Some transition metal organometallic halide derivatives

The positive ion mass spectra of the transition metal organometallic halide derivatives C₅H₅M(CO)₃Cl(M ? Mo or W), C₇H₇W(CO)₂I, C₃H₅Fe(CO)₃I, [C₃H₅PdCl]₂, and [C₅H₅Mo(NO)I₂]₂ have been investigated. Further examples of the elimination of CO and C₂H₂ fragments were noted. In addition the following effects of particular interest were observed: (i) Evidence in the mass spectra of the chlorides for reactions with adventitious iodine and even bromine present in the mass spectrometer; (ii) Evidence for conversion of the compounds C₅H₅Mo(CO)₃X to the new halides [C₅H₅Mo(CO)X]₂ upon pyrolysis; (iii) Evidence for facile losses of the π-allyl group, the iodine atom, and methyl iodide in the mass spectrum of the π-allyl derivative C₃H₅Fe(CO)₃I; (iv) Evidence for loss of iodine upon introducing [C₅H₅Mo(NO)I₂]₂ into the mass spectrometer to give ions derived from [C₅H₅Mo(NO)I]₂.     

Mass spectra of organometallic compounds—VII; Organonitrogen derivatives of metal carbonyls

The positive-ion mass spectra of the following organonitrogen derivatives of metal carbonyls are discussed: (i) The compounds NC₅H₄CH₂Fe(CO)₂C₅H₅, NC₅H₄CH₂COMo(CO)₂C₅H₅, NC₅H₄CH₂W(CO)₃C₅H₅, NC₅H₄CH₂COMn(CO)₄, C₅H₁₀NCH₂CH₂Fe(CO)₂C₅H₅, (CH₃)₂NCH₂CH₂COFeCOC₅H₅ and (CH₃)₂NCH₂CH₂COMn(CO)₄ obtained from metal carbonyl anions and haloalkylamines, (ii) The isocyanate derivative C₅H₅Mo(CO)₃CH₂NCO; (iii) The arylazomolybdenum derivatives RN₂Mo(CO)₂C₅H₅ (R ? phenyl, p-tolyl, or p-anisyl); (iv) The compound (C₆H₅N)₂COFe₂(CO)₆ obtained from Fe₃(CO)₁₂ and phenyl isocyanate; (v) The N,N,N′,N′-tetramethylethylenediamine complex (CH₃)₂NCH₂CH₂N(CH₃)₂W(CO)₄. Further examples of eliminations of hydrogen, CO, and C₂H₂ fragments were noted. In addition evidence for the following more unusual processes was obtained: (i) Elimination of HCN fragments from the ions [NC₅H₄CH₂MC₅H₅]⁺ to give the ions [(C₅H₅)₂M]⁺ (M ? Fe, Mo and W); (ii) Conversion of C₅H₅Mo(CO)₃CH₂NCO to C₅H₅Mo(CO)₂CH₂NCO within the mass spectrometer; (iii) Elimination of N₂ from [RN₂MoC₅H₅]⁺ to give [RMoC₅H₅]⁺; (iv) Novel eliminations of HNCO, FeNCO, and C₆H₅NC fragments in the mass spectrum of (C₆H₅N)₂COFe₂(CO)₆; (v) Facile dehydrogenation of the N,N,N′,-N′-tetramethylethylenediamine ligand in the complex (CH₃)₂NCH₂CH₂N(CH₃)₂W(CO)₄.     

Mass spectra of organometallic compounds–XII: Tetraphenylcyclobutadiene derivatives

The mass spectra of the tetraphenylcyclobutadiene complexes (C₆H₅)₄C₄Fe(CO)₃, C₅H₅CoC₄(C₆H₅)₄ and C₉H₇CoC₄(C₄H₅)₄ are reported. Evidence is presented for the loss of the tetraphenylcyclobutadiene ring by a two-step sequence involving successive losses of two (C₆H₅)₂C₂ fragments. Significant differences are observed in the fragmentations of the monopositive and dipositive molecular ions of C₉H₇CoC₄(C₆H₅)₄.     

Mass spectra of organometallic compounds–XI: Pyrrolyl,indenyl and fluorenyl derivatives of manganese carbonyl

The positive ion mass spectra of the π-pyrrolyl derivatives C₄H₄NMn(CO)₂L (L = (C₆H₅)₃E or CO; E = P, As, or Sb), the π-indenyl derivatives C₉H₇Mn(CO)₂L (L = (C₆H₅)₃E or CO; E = P, As, or Sb) and the π-fluorenyl derivatives C₁₃H₉Mn(CO)₂L (L = (C₆H₅)₃P or CO) have been investigated. The relative tendencies of ions of the type [QMnE(C₆H₅)₃]⁺ (Q = π-pyrrolyl, π-indenyl, or π-fluorenyl; E = P, As, or Sb) to fragment by losses of the Q ring system and the (C₆H₅)₃E ligand are compared. Phenyl transfers from phosphorus, arsenic, or antimony to manganese to form relatively high abundances of [C₆H₅Mn]⁺ are also observed. Other processes typical of metal carbonyl derivatives (CO losses), aromatic derivatives (C₂H₂ eliminations) and (C₆H₅)₃E derivatives (phenyl losses, conversion of [(C₆H₅)₃E]⁺ directly to [C₆H₅E]⁺, and formation of [C₁₂H₈E]⁺ 9-heterofluorenyl ions) are observed in these mass spectra and are supported in many cases by the presence of appropriate metastable ions.     

Mass spectra of organometallic compounds—IX: Compounds with metal-metal bonds

The mass spectra of the following compounds have been investigated: (i) The organotin derivatives (CH₃)₃SnMo(CO)₃C₅H₅ and (CH₃)₃SnNCW(CO)₅; (ii) The mercury derivatives Hg[Mn(CO)₅]₂, Hg[Co(CO)₄]₂, Hg[Mo(CO)₃C₅H₅]₂ and ClHgMo(CO)₃C₅H₅; (iii) The polynuclear cyclopentadienyl metal derivatives [C₅H₅Ru(CO)₂]₂, [C₅H₅Cr(CO)₃]₂, [C₅H₅Cr(NO)₂]₂ and [C₅H₅Fe-CO]₄; (iv) The trinuclear cobalt carbonyl derivatives YCCo₃(CO)₉ (Y = Cl and CH₃); (v) The binuclear triene-iron carbonyl derivatives C₄H₄Fe₂(CO)₆ and C₈H₁₀Fe₂(CO)₆. The mass spectra of the trimethyltin derivatives exhibited stepwise loss of methyl groups as well as of carbonyl groups. The mass spectra of the mercury derivatives exhibited the facile loss of mercury. The mass spectrum of [C₅H₅Cr(CO)₃]₂ indicated a very weak chromium-chromium bond since it exhibited no ion containing two chromium atoms. The mass spectrum of the nitrosyl derivative [C₅H₅Cr(NO)₂]₂ exhibited the stepwise loss of its four nitrosyl groups. The mass spectrum of [C₅H₅FeCO]₄ was rather complex and exhibited a variety of unusual processes including eliminations of neutral Fe and C₅H₅Fe fragments. Unusual ions observed in the mass spectrum of CH₃CCo₃(CO)₉ include the bare polymetallic ions [Co_n]⁺ (n = 3 and 2). Many examples of the elimination of neutral CO, C₂H₂ and H₂ fragments were noted in this work.     

Mass spectra of heterocyclic compounds: V—dihydro-1,3,5-dioxazines

N-Substituted dihydro-1,3,5-dioxazines show a general fragmentation pattern supported by metastable ions, exact mass measurements and deuterium labelling. There are two well-defined pathways: one is initiated by elimination of the N-substituent and the other by loss of a hydrogen atom from the heterocyclic ring.     

Electron-impact studies of organometallic molecules—VIII: Some transition metal derivatives of polyfluorobenzenes

The mass spectra of (π-C₅H₅)₂Ti(C₆F₅)X (X ? Cl and C₆F₅), C₆F₅Re(CO)₅, R_fFe(CO)₂(π-C₅H₅) (R_f ? C₆F₅, 4-HC₆F₄, and three isomeric H₂C₆F₃), and C₆F₅Ru(CO)₂(π-C₅H₅) are compared to those of C₆F₅X (X ? F, Cl, Br, I) and the three isomers of C₆F₄H₂. Significant differences occur, apparently depending on the relative thermodynamic stabilities of the various fragments which may be formed. Comparison of the mass spectra of pentafluorophenyl- and pentafluorobicyclo[2.2.0]hexa-2,5-dien-2-yl-Re(CO)₅ show that similar ions are produced by both complexes, perhaps because of thermal isomerisation before ionisation.     

Electron-impact studies of organometallic molecules—XI:. Some polyfluoroaromatic derivatives of ferrocene

The mass spectra of eight ferrocene derivatives containing C₆F₅, C₆F₅CO, C₆F₅CH₂ or p-CH₃OC₆F₄ groups attached to one or both cyclopentadienyl rings are described and discussed. In addition to features normally found in the mass spectra of ferrocene compounds, the migration of fluorine to the iron atom leads to the formation of ions such as [C₅H₄COFeF]⁺. The elimination of neutral FeF₂ or C₅H₅FeF molecules is also found.     

Mass spectra of liquid crystals. III—phenylpyrimidine derivatives

The 70 eV electron impact mass spectra of 34 1-phenyl-2,5-pyrimidine derivatives are presented. Based on the observed mass shifts by the various substituents, the nature of the main fragment ions is rationalized.     

Mass spectrometry of hop compounds—II: Mass spectra of related oxygen heterocyclic compounds

Mass spectra have been determined of a number of phloroglucinol derivatives and closely-related compounds encountered in chemical studies of hop components. Initial fission involving acyl, alkyl or alkenyl side-chains gives predominantly even-electron ions which then fragment their oxygen heterocyclic rings by elimination of neutral molecules, whilst gem-dialkenyl centres show preference for loss of an alkenyl group. The fragment ions induced by electron-impact may be correlated to a useful extent with molecular structure.     

Chemistry of lichen constituents—VII: Mass spectra of some pulvic acid derivatives

The mass spectra of three methoxypulvic dilactones, four methyl esters of methoxypulvic acids and five methyl ethers of pulvic acid derivatives have been measured and rationalised employing accurate mass measurements and metastable peak assignments to substantiate the proposed fragmentations and rearrangements. In particular, the mass spectral differences and similarities between the isomeric methoxypulvic dilactones, between their methanolysis products and between the isomeric methyl ethers, are rationalised.     

Electron-impact studies of organometallic molecules—VI. Some transition metal derivatives of alicyclic fluorocarbons

The mass spectra of a series of alicyclic fluorocarbon complexes of manganese, rhenium, iron and ruthenium are described and discussed. It is shown that the breakdown of these complexes after ionization depends on the nature of the metal, and of the other groups attached to the metal. Effects due to elimination of metal halides, formation of metal fluoride ions, and ligand transfer reactions are found, and result in significant differences in the fragmentation patterns of the complexes from those of the parent fluorocarbons.     

Mass spectra of organometallic compounds—XIII: Metal carbonyl complexes of tris(dimethylamino)arsine

The mass spectra of the tris(dimethylamino)arsine metal carbonyl complexes [(CH₃)₂N]₃-AsM(CO)₅ (M = Cr, Mo and W), trans-[(CH₃)₂N]₃AsCr(CO)₄As[N(CH₃)₂]₃ and [(CH₃)₂N]₃-AsFe(CO)₄ were examined and compared with those of the corresponding tris(dimethylamino)-phosphine complexes. The molecular ions in the mass spectra of the tris(dimethylamino)arsine complexes have a greater tendency to eliminate a (CH₃)₂N fragment than the molecular ions in the mass spectra of the corresponding tris(dimethylamino)phosphine complexes. The mass spectrum of the tungsten derivative [(CH₃)₂N]₃AsW(CO)₅ exhibits not only the usual series of ions [(CH₃)₂N]₃-AsW(CO)n+ and [(CH₃)₂N]₂AsW(CO)n[+ but also the series of ions (CH₃)₂NAsW(CO)n]+ (n = 5, 4, 3, 2, 1 and 0) and even the nitrogen-free ions [AsW(CO)_n]+ (n = 2, 1 and 0). Metastable ion evidence was obtained for arsine (AsH₃) elimination from the [(CH₃)₂N]₂AsFeH⁺ ion in the mass spectrum of [(CH₃)₂N]₃AsFe(CO)₄.     

Mass spectra of liquid crystals. IV—diphenylethyne derivatives (nematic tolans)

The 70 eV electron impact mass spectra of 19 dipheaylethyne derivatives are presented and discussed in terms of observed substituent effects.     

Mass spectra of organoarsenic compounds. III—Electron-impact-induced fragmentation of trialkylarsenates and penta-alkoxyarsoranes

The mass spectra of a series of trialkylarsenates are reported, together with those of dimethyl methylarsonate, pentamethoxyarsorane and pentaethoxyarsorane. Their behaviour under electron-impact is discussed and compared with that reported for trialkylphosphates.     

Chemistry of lichen constituents—VI: Mass spectra of usnic acid,lichexanthone and their derivatives

The mass spectra of usnic acid, decarbousnic acid, usnetic acid and usnetol are reported and mechanistically interpreted. The mass spectra of lichexanthone and lichexanthone methyl ether were also examined, and the unusal features of the latter spectrum have been rationalized.     

Mass spectral studies of some π-benzoylcyclopentadienylmanganese tricarbonyl derivatives

The loss of three CO groups from derivatives of π-C₆H₅COC₅H₄Mn(CO)₃ is a two-step mechanism in which the loss of two CO groups is followed by a third. Subsequent fragmentations generally involve rearrangement processes which often result in ring closure within the organic substrate. The central metal atoms plays an important part in such rearrangement processes and the positive charge can reside either on the metal or the ligand depending on the nature of the ligand. Fragmentation patterns are proposed for these systems.