Reductive Elimination Process Research Articles

Theoretical study of reaction pathways for the rhodium phosphine-catalysed borylation of C-H bonds with pinacolborane.

The reaction mechanism of the rhodium-phosphine catalysed borylation of methyl-substituted arenes using pinacolborane (HBpin) has been investigated theoretically using DFT calculations at the B3PW91 level. Factors affecting selectivity for benzylic vs. aromatic C-H bond activation have been examined. It was found that [Rh(PR3)2(H)] is the active species which oxidatively adds the C-H bond leading to an eta3-benzyl complex which is the key to determining the unusual benzylic regioselectivity observed experimentally for this catalyst system. Subsequent reaction with HBpin leads to a [Rh(PR3)2(eta3-benzyl)(H)(Bpin)] complex from which B-C reductive elimination provides product and regenerates the catalyst. The electrophilic nature of the boryl ligand assists in the reductive elimination process. In contrast to Ir(L)2(boryl)3-based catalysts, for which Ir(III)-Ir(V) cycles have been proposed, the Rh(I)-Rh(III) cycle is operating with the system addressed herein.

Reductive elimination/oxidative addition of carbon-hydrogen bonds at Pt(IV)/Pt(II) centers: mechanistic studies of the solution thermolyses of Tp(Me2)Pt(CH3)2H.

Reductive elimination of methane occurs upon solution thermolysis of kappa(3)-Tp(Me)2Pt(IV)(CH(3))(2)H (1, Tp(Me)2 = hydridotris(3,5-dimethylpyrazolyl)borate). The platinum product of this reaction is determined by the solvent. C-D bond activation occurs after methane elimination in benzene-d(6), to yield kappa(3)-Tp(Me)2Pt(IV)(CH(3))(C(6)D(5))D (2-d(6)), which undergoes a second reductive elimination/oxidative addition reaction to yield isotopically labeled methane and kappa(3)-Tp(Me)2Pt(IV)(C(6)D(5))(2)D (3-d(11)). In contrast, kappa(2)-Tp(Me)2Pt(II)(CH(3))(NCCD(3)) (4) was obtained in the presence of acetonitrile-d(3), after elimination of methane from 1. Reductive elimination of methane from these Pt(IV) complexes follows first-order kinetics, and the observed reaction rates are nearly independent of solvent. Virtually identical activation parameters (DeltaH(++)(obs) = 35.0 +/- 1.1 kcal/mol, DeltaS(++)(obs) = 13 +/- 3 eu) were measured for the reductive elimination of methane from 1 in both benzene-d(6) and toluene-d(8). A lower energy process (DeltaH(++)(scr) = 26 +/- 1 kcal/mol, DeltaS(++)(scr) = 1 +/- 4 eu) scrambles hydrogen atoms of 1 between the methyl and hydride positions, as confirmed by monitoring the equilibration of kappa(3)-Tp(Me)()2Pt(IV)(CH(3))(2)D (1-d(1)()) with its scrambled isotopomer, kappa(3)-Tp(Me)2Pt(IV)(CH(3))(CH(2)D)H (1-d(1'). The sigma-methane complex kappa(2)-Tp(Me)2Pt(II)(CH(3))(CH(4)) is proposed as a common intermediate in both the scrambling and reductive elimination processes. Kinetic results are consistent with rate-determining dissociative loss of methane from this intermediate to produce the coordinatively unsaturated intermediate [Tp(Me)2Pt(II)(CH(3))], which reacts rapidly with solvent. The difference in activation enthalpies for the H/D scrambling and C-H reductive elimination provides a lower limit for the binding enthalpy of methane to [Tp(Me)2Pt(II)(CH(3))] of 9 +/- 2 kcal/mol.

An organometallic route to mono and bimetallic Pt and Pt-Pd catalysts supported on magnesium oxide: thermoanalytical investigation and catalytic behavior in MCP conversion

Abstract The utilization of organometallic complexes of palladium and platinum to form mono and bimetallic catalysts on basic magnesium oxide support was studied and rationalized. Thermoanalytical data in hydrogen flow suggested the uselessness of volatile, fluorinated organometallic precursors for platinum catalysts, because the strong chemical interaction on the surface, occurring during CVD, prevents the subsequent conventional reductive elimination process to take place. Conventional solvent impregnation of acetylacetonate complexes was instead successful. Chemical interaction of the organometallic complex with basic surface sites of the MgO support was occurring already in the deposition step, resulting in an even surface distribution of the metal precursor, and the formation of bimetallic Pt-Pd sites. Alloy formation between platinum and palladium in the bimetallic catalyst was then proposed and studied using methylcyclopentane conversion between 350 and 500 °C as test reaction.

Cyclopentadienyl substituent effects on reductive elimination reactions in group 4 metallocenes: kinetics, mechanism, and application to dinitrogen activation.

The rate of reductive elimination for a family of zirconocene isobutyl hydride complexes, Cp(CpR(n)())Zr(CH(2)CHMe(2))H (Cp = eta(5)-C(5)Me(5), CpR(n)() = substituted cyclopentadienyl), has been measured as a function of cyclopentadienyl substituent. In general, the rate of reductive elimination increases modestly with the incorporation of sterically demanding substituents such as [CMe(3)] or [SiMe(3)]. A series of isotopic labeling experiments was used to elucidate the mechanism and rate-determining step for the reductive elimination process. From these studies, a new zirconocene isobutyl hydride complex, Cp' '(2)Zr(CH(2)CHMe(2))(H) (Cp' ' = eta(5)-C(5)H(3)-1,3-(SiMe(3))(2)), was designed and synthesized such that facile reductive elimination of isobutane and activation of dinitrogen was observed. The resulting dinitrogen complex, [Cp' '(2)Zr](2)(mu(2), eta(2),eta(2)-N(2)), has been characterized by X-ray diffraction and displays a bond length of 1.47 A for the N(2) ligand, the longest observed in any metallocene dinitrogen complex. Solution magnetic susceptibility demonstrates that [Cp' '(2)Zr](2)(mu(2), eta(2), eta(2)-N(2)) is a ground-state triplet, consistent with two Zr(III), d(1) centers. Mechanistic studies reveal that the dinitrogen complex is derived from the reaction of N(2) with the resulting cyclometalated zirconocene hydride rather than directly from reductive elimination of alkane.

Trends in the Unimolecular Reactions of Triaryl Pnictogen Radical Cations Ar3E•+ (E = N, P, As, Sb, Bi): Reductive Elimination versus E−C Bond Cleavage

The unimolecular reactions of the molecular ions M•+ of the triphenyl pnictogens (C6H5)3E (1, E = N; 2, E = P; 3, E = As; 4, E = Sb; 5, E = Bi) have been investigated using mass-analyzed ion kinetic energy (MIKE) spectrometry to select ions of low internal excess energy. Molecular ions of triphenylamine 1 both of high and low internal energy prefer fragmentation by losses of one and two H atoms, which proceeds by a well-known reaction between two phenyl ligands resulting in fragment ions of an azafluorene structure. In contrast, the molecular ions of the heavier triphenyl pnictogens 3, 4, and 5 dissociate at high and low internal energies almost completely by generating ions C6H5E•+ (B•+; E = As, Sb, Bi). Ionized triphenyl phosphane 2 is intermediate, showing loss of H as the main reaction at low internal energy. The ions B•+ (E = As, Sb, Bi) are generated from molecular ions of low internal energy in a one-step process without ions (C6H5)2E+ (A+; E = As, Sb, Bi) being intermediates. The formation of B•+ by successive cleavages of the relatively weak E−Caryl bonds and sequential losses of two phenyl radicals, which is discussed in the literature, is definitely excluded. Direct formation of B•+ from M•+ entails reductive elimination of C6H5E•+ under ligand coupling to yield biphenyl as the neutral product. Biaryl ions have been detected earlier in 70 eV mass spectra of triaryl pnictogens, and in the case of tris(4-ethylphenyl)arsane 6 and 4-methylphenylbisphenylarsane 7, the formation of biaryl-derived ions is the main reaction in the MIKE spectra of the molecular ions, giving positive evidence for the reductive elimination process. Formation of B•+ at low and high excess energies with exclusion of the formation of intermediate A+ requires a fast and effortless rearrangement of the molecular ions into the structure of a complex which is well prepared for biaryl loss. It is assumed that this complex contains the biphenyl moiety and the fragment C6H5E rather loosely bound to one of the benzene rings. The fast isomerization of the heavier triaryl pnictogen radical cations explains also the puzzling phenomenon known for a long time that in the case of 3, 4, and 5 the appearance energy AE of ions B•+, generated by loss of two aryl radicals, is distinctly below the AE of ions A+, generated by loss of only one aryl radical.

Kinetics and mechanism for reduction of the anticancer prodrug trans,trans,trans-[PtCl2(OH)2(c-C6H11NH2)(NH3)] (JM335) by thiols.

The reduction of the platinum(IV) prodrug trans,trans,trans-[PtCl2(OH)2(c-C6H11NH2)(NH3)] (JM335) by L-cysteine, DL-penicillamine, DL-homocysteine, N-acetyl-L-cysteine, 2-mercaptopropanoic acid, 2-mercaptosuccinic acid, and glutathione has been investigated at 25 degrees C in a 1.0 M aqueous perchlorate medium with 6.8 < or = pH < or = 11.2 using stopped-flow spectrophotometry. The stoichiometry of Pt(IV):thiol is 1:2, and the redox reactions follow the second-order rate law -d[Pt(IV)]/dt = k[Pt(IV)][RSH]tot, where k denotes the pH-dependent second-order rate constant and [RSH]tot the total concentration of thiol. The pH dependence of k is ascribed to parallel reductions of JM335 by the various protolytic species of the thiols, the relative contributions of which change with pH. Electron transfer from thiol (RSH) or thiolate (RS-) to JM335 is suggested to take place as a reductive elimination process through an attack by sulfur at one of the mutually trans chloride ligands, yielding trans-[Pt(OH)2(c-C6H11NH2)(NH3)] and RSSR as the reaction products, as confirmed by 1H NMR. Second-order rate constants for the reduction of JM335 by the various protolytic species of the thiols span more than 3 orders of magnitude. Reduction with RS- is approximately 30-2000 times faster than with RSH. The linear correlation log(kRS) = (0.52 +/- 0.06)-pKRSH--(2.8 +/- 0.5) is observed, where kRS denotes the second-order rate constant for reduction of JM335 by a particular thiolate RS- and KRSH is the acid dissociation constant for the corresponding thiol RSH. The slope of the linear correlation indicates that the reactivity of the various thiolate species is governed by their proton basicity, and no significant steric effects are observed. The half-life for reduction of JM335 by 6 mM glutathione (40-fold excess) at physiologically relevant conditions of 37 degrees C and pH 7.30 is 23 s. This implies that JM335, in clinical use, is likely to undergo in vivo reduction by intracellular reducing agents such as glutathione prior to binding to DNA. Reduction results in the immediate formation of a highly reactive platinum(II) species, i.e., the bishydroxo complex in rapid protolytic equilibrium with its aqua form.

A Highly Active Catalyst for the Room-Temperature Amination and Suzuki Coupling of Aryl Chlorides.

A unique combination of steric and electronic properties appears to determine the effectiveness of phosphanyl-substituted biphenyls as ligands in palladium-catalyzed aminations and Suzuki coupling of aryl chlorides at room temperature [Eq. (1)]. The oxidative addition step is greatly accelerated, and transmetalation (or Pd-N bond formation) and reductive elimination processes are facilitated. Use of these ligands allows for Suzuki coupling at very low catalyst loadings (as little as 10(-6) mol % Pd). R"=cyclohexyl, tert-butyl.

5,5′-Diuracilyl Species from Uracil and [AuCl4]: Nucleobase Dimerization Brought about by a Metal

Not only UV radiation can bring about the dimerization of the pyrimidine nucleobase uracil, a metal ion can as well! The reaction proceeds by a reductive elimination process of two cis-oriented uracil entities, each bonded to AuIII through C5 [Eq. (a)]. R/R′=H/CH3, CH3/CH3, H,C5H9O4

5,5′-Diuracilyl Species from Uracil and [AuCl4]−: Nucleobase Dimerization Brought about by a Metal

Not only UV radiation can bring about the dimerization of the pyrimidine nucleobase uracil, a metal ion can as well! The reaction proceeds by a reductive elimination process of two cis-oriented uracil entities, each bonded to Au(III) through C5 [Eq. (a)]. R/R'=H/CH(3), CH(3)/CH(3), H,C(5)H(9)O(4)

An Energetically Feasible Mechanism for the Activation of the C−H Bond by the 16-Electron CpM(PH3)(CH3)+ (M = Rh, Ir) Complex. A Theoretical Study

The reaction mechanism for the activation of C−H bonds by coordinatively unsaturated CpM(PH3)(CH3)+ (Cp = cyclopentadienyl; M = Rh, Ir) has been investigated by ab initio molecular orbital methods. Of the two possible mechanisms, an oxidative addition−reductive elimination process (path 1) and a σ-bond metathesis mechanism through a four-center transition state (path 2), only the former is found for the 16-electron Ir cation, while the Rh case might adopt the latter. The reaction trajectory of path 1 for the approach of CpM(PH3)(CH3)+ to methane and the transition state structure can be predicted on the basis of a frontier molecular orbital model that determines the orientation of attack of the CpM(PH3)(CH3)+ fragment on a doubly occupied canonical fragment molecular orbital of methane. From which, four kinds of reaction paths (paths A, B, C, and D) can be deduced due to the asymmetric nature of CpM(PH3)(CH3)+. Both MP2 and QCISD results suggest that path A, where the methane C−H bond breaks on the ancill...

A Thermal Reductive-Elimination Route to Perbutylated Cyclopolystannanes

Thermolysis of dibutyl(2-ethoxyethyl)stannane (4) in heptane at 150 °C quantitatively provides the perbutylated cyclopolystannanes (Bu2Sn)5 (1) and (Bu2Sn)6 (2). Trapping experiments reveal that this formal reductive-elimination process proceeds in a stepwise manner, involving the generation of a trivalent tin intermediate that then undergoes an unprecedented β-elimination reaction.

Electronic Structure and Photoelectron Spectroscopy of the Monomeric Uranium(III) Alkyl [η5-(CH3)5C5]2UCH[Si(CH3)3]2,

The ground state configuration and the electronic structure of the title compound have been investigated by relativistic effective core potential configuration interaction ab initio calculations and He I/He II UV photoelectron spectroscopy. It has been found that the 4A‘‘ [(a‘)1 (a‘‘)1 (a‘)1] state, associated with the 5f3 uranium configuration, represents the molecular ground state and is close in energy to the higher-lying 4A‘‘ (5f2 6d1) state. The comparison of the present photoelectron data and theoretical results with those reported for analogous lanthanide complexes indicates close similarities in metal−ligand bonding between the 4f and 5f M(III) organometallics. The relative stability of the 5f3 versus 5f2 6d1 uranium ion configuration correlates with the inherent chemical stability of U(III) organometallics, compared to that of the Th(III) (6d1) analogues. The easier M(IV) → M(III) reduction for U(IV) relative to Th(IV), the numerous examples of reductive elimination processes in U(IV) organometallic chemistry, and the greater Th−R versus U−R experimental homolytic bond disruption energies in cyclopentadienylactinide(IV) alkyls can all be rationalized in terms of the differing electronic stabilities of the U(III) and Th(III) ground states.

Competitive Substitution and Electron Transfer in Reactions between Haloamminegold(III) and Halocyanoaurate(III) Complexes and Thiocyanate.

Kinetics for reactions between thiocyanate and trans-Au(CN)(2)Cl(2)(-), trans-Au(CN)(2)Br(2)(-), and trans-Au(NH(3))(2)Cl(2)(+) in an acidic, 1.00 M perchlorate aqueous medium have been studied by use of conventional and diode-array UV/vis spectroscopy and high-pressure and sequential-mixing stopped-flow spectrophotometry. Initial, rapid formation of mixed halide-thiocyanate complexes of gold(III) is followed by slower reduction to Au(CN)(2)(-) and Au(NH(3))(2)(+), respectively. This is an intermolecular process, involving attack on the complex by outer-sphere thiocyanate. Second-order rate constants at 25.0 degrees C for reduction of trans-Au(CN)(2)XSCN(-) are (6.9 +/- 1.1) x 10(4) M(-)(1) s(-)(1) for X = Cl and (3.1 +/- 0.7) x 10(3) M(-)(1) s(-)(1) for X = Br. For reduction of trans-Au(CN)(2)(SCN)(2)(-) the second-order rate constant at 25.0 degrees C is (3.1 +/- 0.1) x 10(2) M(-)(1) s(-)(1) and the activation parameters are DeltaH() = (55 +/- 3) x 10(2) kJ mol(-)(1), DeltaS() = (-17.8 +/- 0.8) J K(-)(1) mol(-)(1), and DeltaV() = (-4.6 +/- 0.5) cm(3) mol(-)(1). The activation volume for substitution of one chloride on trans-Au(NH(3))(2)Cl(2)(+) is (-4.5 +/- 0.5) cm(3) mol(-)(1), and that for reduction of trans-Au(NH(3))(2)(SCN)(2)(+) (4.6 +/- 0.9) cm(3) mol(-)(1). The presence of pi-back-bonding cyanide ligands stabilizes the transition states for both substitution and reductive elimination reactions compared to ammine. In particular, complexes trans-Au(CN)(2)XSCN(-) with an unsymmetric electron distribution along the X-Au-SCN axis are reduced rapidly. The observed entropies and volumes of activation reflect large differences in the transition states for the reductive elimination and substitution processes, respectively, the former being more loosely bound, more sensitive to solvational changes, and probably not involving any large changes in the inner coordination sphere. A transition state with an S-S interaction between attacking and coordinated thiocyanate is suggested for the reduction. The stability constants for formation of the very short-lived complex trans-Au(CN)(2)(SCN)(2)(-) from trans-Au(CN)(2)X(SCN)(-) (X = Cl, Br) by replacement of halide by thiocyanate prior to reduction can be calculated from the redox kinetics data to be K(Cl,2) = (3.8 +/- 0.8) x 10(4) and K(Br,2) = (1.1 +/- 0.4) x 10(2).

Stereoselective Synthesis of (±)-α-Kainic Acid Using Free Radical Key Reactions

Thiol-mediated free radical isomerization of a deliberately substituted but-3-enyl isocyanide 12a, and n-Bu(3)SnH/AIBN-mediated free radical cyclization of a deliberately substituted but-3-enyl isothiocyanate 22, afforded, respectively, the (ethylthio)pyrroline 13a and the thiopyroglutamates 5 and 23. Reduction, protection, and deprotection of these heterocyclic compounds afforded proline derivatives 6 and 25 which contain all the structural elements of alpha-kainic acid (1) except the C-2 acetic acid moiety. These intermediates were stereospecifically converted into (+/-)-alpha-kainic acid using a new method of temporary sulfur connection. Accordingly, CH(2)CO(2)Me is linked to the chiral isopropenyl anchor and then intramolecularly connected to the pyrrolidine ring and eventually disconnected from its anchor by a sequential reductive double elimination process in which the isopropenyl double bond is restored.

Insight into the Chemical Mechanism of Thymidylate Synthase-Catalyzed Reaction Through the Evaluation of Chemical Models: The Role of C6 Sulfhydryl Addition During the Reductive Elimination Step of the Reaction 1

Thymidylate synthase catalyzes the last step of the de novo synthesis of thymidine-5′-monophosphate (TMP), which has long been a target for the development of effective anticancer agents. Model compounds (15, 16, 17) were used to study the effect of C6 nucleophilic addition on the reductive elimination step of the TS-catalyzed reaction. Results suggest that C6 addition facilitates the reductive elimination of the H 2folate moiety of the ternary intermediate (3). Therefore, the reaction pathway (pathway (b)) with the participation of C6 sulfhydryl addition during the reductive elimination process is the energetically favored process. Consequently, the elimination of the cysteine sulfhydryl group from the C6 position is the last step of the reaction before the dissociation of the products from the enzyme.

Volume Profile Analysis of Oxidative Addition to Palladium(II) and Reductive Elimination from Palladium(IV)

The oxidative addition of MeI to Pd(II) in the complex PdMe2(bpy) to produce PdIMe3(bpy) was studied as a function of [MeI] and pressure. The DV* of -11.9 +/- 0.6 cm3 mol-' for the addition process underlines the validity of the proposed SN2 mechanism in the literature. The reductive elimination from PdIMe3(bpy) to form PdIMe(bpy) and C2H6 was studied as a function of pressure and [NaI]. The complex was prepared in situ via oxidative addition of Me1 to the Pd(II) complex. DV* is +17 +/- 1 cm3/mol for the reductive elimination process. If NaI is added to the Pd(IV) compound, the rate slows down, but it did not affect the activation volume. The large positive value of DV* for the elimination reaction suggests bond cleavage and/or the partial reduction from Pd(IV) to Pd(II) in the transition state. A volume profile for the overall oxidative addition and reductive elimination reactions is presented.

Molecular approach to the study of the mechanisms of alkyl reactions on metal surfaces

The surface chemistry of alkyl species adsorbed on solid transition metal surfaces is contrasted here against the behavior of analog organometallic systems. The several methods developed in recent years for the clean production of alkyl surface moieties on well characterized metal surfaces are described, and the main decomposition pathways observed after thermal activation of those alkyl species, namely, elimination of both hydride and methyl groups from either the alpha or the beta position, reductive elimination processes related to hydrogenation and to carbon—carbon coupling steps, and insertion, homolysis, and displacement reactions, are discussed. A brief outlook on the future of this field is presented.

Synthese von Phosphaalkenclustern durch reduktive Phosphinidenfragmentierung zweizähniger Halogenphosphane RXP— CH2 — PXR mit Fe2(CO)9 / Synthesis of Phosphaalkene Clusters by Reductive Phosphinidene Fragmentation of Bidentate Halogenphosphines RXP—CH2—PXR with Fe2(CO)9

Reaction of halogen functional methylenebisphosphines 1 XRP–CH2–PRX (X = Cl, Br) with excess Fe2(CO)9 affords μ3-phosphinidene clusters (5) containing phosphaalkene ligands R–P=CH2. The fragmentation of the P–C–P skeletons in 1 proceeds stepwise, phosphide complexes 2 and novel Fe3 clusters 3 with RP–CH2–PR bridging units being formed as intermediates of the oxidative addition reductive elimination process. The X-ray structural analysis for 5b (R = NEt2) reveals an Fe3(CO)9PR butterfly core to which the phosphaalkene ligand R–P=CH2 (P=C bond length 1.766(4) A) is coordinated in a μ3,η2-manner. In case of methylenebisphosphines 1 with bulky substituents (R = 2,4,6-iPr3C6H2) the phosphinidene fragmentation of the P–C–P skeleton is accompanied by the formation of 2,3-dihydrobenzo[b]-phosphole ligands.

Reactions of acyl(carbonyl)ruthenium(II) and acyl(carbonyl)iron(II) complexes with amines. Preparation of novel propionyl(carbamoyl)ruthenium(II) complexes

Treatment of Ru(COEt)Cl(CO)(PPh 3) 2 ( 1) with secondary amines (R 2NH) under pressure of CO and / or ethylene gives propionyl-carbamoyl complexes Ru(COEt)(CONR 2)(CO)(PPH 3) 2 (NR 2 = NEt 2 ( 4a), N(CH 2) 4CH 2 ( 4b), NMe, ( 4c)) together with the ammonium salt R 2NH 2Cl. Complexes 4a–c have been isolated as pale yellow crystals and characterized by means of NMR and IR spectroscopy and elemental analysis. Reactions of Fe(COMe)I(CO) 2(PMe 3) 2 and [Fe(COMe)(CO) 3(PMe 3) 2]BF 4 with nucleophiles (HNEt 2, LiNMe 2, EtOH (in conjunction with Et 3N) and NaOMe) give the corresponding acetamides and acetic acid esters. The carbonyl(propionyl)ruthenium complex 1 in solution under CO pressure was found to undergo nucleophilic attack of secondary amines on the coordinated CO ligand to give isolable acyl(carbamoyl)ruthenium complexes 4 in a parallel behavior with the previously reported acyl(carbonyl) palladium complexes [4g,h]. However, the isolated acyl(carbamoyl)ruthenium complexes differ in their behavior from the palladium analogs in their inactivity to release α-keto amide. The exact reason for the different behavior is not clear. A possible explanation for the reluctance of reductive elimination from the acyl(carbamoyl)ruthenium complex is that the acyl and the carbamoyl ligands are situated at unfavorable sites for a concerted reductive elimination to occur. In a theoretical treatment of reductive elimination of two organic groups from a five-coordinated nickel complex, it has been discussed that (i) the organic ligands both situated at equatorial positions in a trigonal-bipyramidal complex are symmetrically forbidden to undergo the reductive elimination process, and (ii) kinetic barriers for pseudorotation to bring the concerned organic ligands to axial and equatorial sites are very high [13]. A similar argument might be advanced in the present case but we would rather defer from advancing the discussion further until more bis-acyl type complexes are prepared and their behavior examined.

An unusual reduction of ethylene occurring during the thermal decomposition of alkalides and electrides.

Alkalides and electrides thermally decompose by a reductive elimination process leading to the formation of ethylene and a ring opened complexant which has lost an ethylenic unit. Surprisingly, gas phase nmr also shows the formation of ethane and butane. We postulate that these compounds arise from a reduction of the first-formed ethylene by the alkalide or electride.