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The reaction of [Rh(CO)2Cl]2 with CF3C≡CCF3 gives a fluorocarbon-rhodium complex of approximate formula [RhCl(CO)2or 3(C4F6)]n,xH2O,yC6H6. The complex is an intermediate in the formation of tetrakis(trifluoromethyl)cyclopentadienone from CF3C≡CCF3 and CO in the presence of[Rh(CO)2Cl]2. The molecular structure of the complex remains obscure despite extensive study of its spectroscopic and chemical properties. The major products formed in the reactions of the complex with σ-cyclopentadienylthallium and with triphenylphosphine are (η- C5H5)2Rh2(CO)2(CF3C2CF3)and Rh(CO)Cl(PPh3)2 respectively.

The reactions of several diynes MeC≡C(CH2)nC≡CMe, n = 2-4, with (η- C5H5)Co(CO)2 and Fe(CO)5 have been compared. A p-benzoquinone complex, (η-C5H5)Co[(C8H10)2(CO)2], and three isomers of the cyclopentadienone complex, (η-C5H5)Co[(C8H10)2CO], are formed in the reaction of (η- C5H5)Co(CO)2 with octa-2,6-diyne. In each complex, the ligand is formed by intermolecular cyclization of two diynes with inclusion of CO. The corresponding reactions with nona-2,7-diyne and deca-2,8-diyne give complexes (η-C5H5)Co[(C9H12)CO] and (C5H5)Co[(C10H14)CO] in which a bicyclic cyclopentadienone has been formed by intramolecular condensation of the diyne. Intramolecular cyclization is also achieved when all three diynes are treated with Fe(CO)5. The reactions with octa- 2,6-diyne and deca-2,8-diyne give metallodiene complexes, Fe2(CO)6(diyne), in which the ferracyclopentadiene ring is fused to either a 4- or 6-membered ring. With nona-2,7-diyne, a cyclopentadienone complex of formula Fe(CO)3[(C10H14)CO] is isolated. In the reactions with Fe(CO)5,organic products of the type (diyne)2, (diyne)3 and [(diyne)CO]2 are also isolated.

The effect of the lanthanide shift reagents, Eu(fod)3 and Pr(fod)3, on the nuclear magnetic resonance spectra of some (η4-cyclopentadienone)(η- cyclopentadienyl)cobalt complexes has been investigated as an aid to structure determination in this series. The lanthanides complex with the lone pairs of the carbonyl group. Pseudocontact shifts are observed for hydrogens attached to each ring and for hydrogen atoms in substituents on the cyclopentadienone. With Eu(fod)3, contact shifts are also observed for the cyclopentadienone ring hydrogens.

The reactions of (η-C5H5)Co(CO)2 with the diynes hexa-2,4-diyne and 1,4- diphenylbutadiyne give three isomers of the cyclopentadienone complexes (C5H5)Co[(RC2C2R)2CO], R = Me or Ph, and two isomers of the tris-alkyne complexes (C5H5)2Co2(RC2C2R)3CO, R = Me or Ph. Organic products of formula (RC2C2R)3, R = Me or Ph, (MeC2C2Me)5, and (PhC2C2Ph)3CO have been isolated also. Two isomers of (RC2C2R), were separated and were identified as the 1,2,4-(R)3-3,5,6-(C2R)3- and the 1,3,5-(R)3-2,4,6-(C2R)3-benzenes. The compound (PhC2C2Ph)3CO is believed to be tris(phenylethynly)triphenylcycloheptatrienone, and (MeC2C2Me)5 is probably a polycyclic aromatic compound. Thermal degradation of the complexes (C5H5)2CO2(RC2C2R)3CO gives the substituted benzenes (RC2C2R)3. The reaction of (η-C5H5)Rh(CO)2 and hexa-2,4-diyne gives the cyclopentadienone complex(C5H5)Rh[(MeC2C2Me)2CO] and the cycloheptatrienone complex (C5H5)Rh[(MeC2C2Me)3CO].Two isomers of the substituted benzene (MeC2C2Me)3 were obtained also.

The reaction between (η-C5H5)2Rh2(CO)(CF3C2CF3)(1) and alkynes, RC=CR′, can proceed by two alternative pathways. One gives the complexes (η- C5H5)2Rh2{C4(CF3)2RR′CO} (2) in which a pentadienone unit bridges the Rh - Rh bond. The other produces the binuclear metalladiene complexes (η-C5H5)2Rh2{C4(CF3)2RR?} (3) plus the dicarbonyl complex (η-C5H5)2Rh2(CO)2(CF3C2CF3) (4). The formation of (2) is strongly favoured with the dialkylacetylenes BuC≡CBu and MeC =CR (R = Et, Pri, But). With the unsymmetrical acetylenes, two isomers of (2) are isolated. The tendency to form (3) + (4) increases when there are electron-withdrawing substituents such as CN on the alkyne, and becomes dominant when the alkyne is polar (e.g. MeC≡CR with R = Ph, CF3 or CO2Me). The reactions with MeC≡CR are highly regioselective, with only one of the two possible regioisomers being isolated in each case. This has the methyl group in the 3-position of the metalladiene ring. Unexpected products formed in the reactions with MeC≡Cet and MeC≡CPri have been characterized by X-ray crystallography. One is a 1,2- dimetallacycloheptadienone complex, (η-C5H5)2Rh2{C4(CF3)2Me(CMe2OH)CO}. The compound crystallizes with 16 molecules in the orthorhombic space group Fdd2 in a unit cell of dimensions a 31.728(15), b 27.923(14), c 9.275(5) Ǻ. The structure was solved by heavy atom methods and refined to R 0.037 based on 2644 observed reflections. The CMe2(OH) group is adjacent to the carbonyl in the bridging group. The other is a binuclear metalladiene complex (η-C5H5)2Rh2{C4(CF3)2Me( COMe )}. It crystallizes with eight molecules in the orthorhombic space group P bca in a unit cell of dimensions a 17.349(8), b 15.819(8), c 13.720(7) Ǻ. The structure was solved by heavy atom methods and refined to R 0.053 based on 3045 observed reflections above background. The acyl group is adjacent to the metal in the metalladiene ring. These two complexes are formed from (1) and impurities present in the alkynes.

A stepwise pathway for the formation of cyclopentadienone complexes (η-C5H5)Rh{C4R4CO} from (#-C5H5)Rh(CO)2 and RC≡CR has been elucidated. When solutions of (η-C5H5)Rh(CO)2 are heated, there is loss of CO and (η-C5H5),Rh2(CO)3 is formed. This reacts with alkynes to give binuclear complexes such as (η-C5H5),Rh2(CO)2(CF3C2CF3) gives (ηC5H5)2Rh2(CO)(ButC2But). Removal of CO from (η-C5H5)2Rh2(CO)2(CF3C2CF3) gives (η-C5H5)2Rh2(CO)(CF3C2CF3) and this monocarbonyl complex reacts with more alkyne, R'C≡CR', to form the bis-alkyne complex (η-C5H5)2Rh2(CO)(CF3C2CF3)(R'C2R')(R' = SiMe3) and then the pentadienone complex (η-C5H5)2Rh2{C4(CF3)2R'2CO} (R' = =Me, Me3Si, CF3). In some instances (R' = Ph, But, CO2Me), this reaction gives equimolar amounts of the metallodiene complex (η-C5H5)2Rh2{C4{CF3)2R'2} plus the dicarbonyl complex (η-C5H,)2Rh2(CO)2(CF3C2CF3). The binuclear pentadienone complexes (η-C5H5),Rh2{C4R2R'2CO) (R = CF, and R' = Me; or R = R' = Et) can be converted into mononuclear cyclopentadienone complexes (η-C5H5)Rh{C4R2R'2CO} by heating in the presence of CO or alkyne, or both.

Six organometallic complexes have been isolated from the reaction between (η-C5H5)Ir(C0)2 and hexafluorobut-2-yne at 120-160. Both the cis and trans isomers of the σ-bridging alkyne complex (η C5H5)2Ir2(C0)2(CF3C2CF3) were obtained; the cis isomer is slowly transformed to the trans isomer at 160. These complexes do not react further with alkynes. Two other products were identified as an iridiocyclobutenone complex and a iridiocyclopentadiene complex, viz.(η-C5H5){IrC(CF3)=C(CF3)CO}(CO) and (η-C5H5){IrC(CF3)=C(CF3)C(CF3)}(CO)These complexes are also inert to further reaction with hexafluorobut-2-yne, and the iridiocyclopentadiene complex could not be converted into the cyclopentadienone complex (η-C5H5)Ir{C4(CF3)4-CO). The spectroscopic properties of a product of formula (η-C5H5)Ir(CF3C2CF3)2(C4HF5) indicate it incorporates a 1-(2?,2?-difluoroethenyl)-1,2,3,4,5-pentakis(trifluoromethyl)cyclopenta-2,4-diene ligand. The final product was formulated as (η-C5H5)Ir2(C0)3(CF3C2CF3)2H and five alternativestructures are consistent with the spectroscopic data. The related reaction between (η-C5H5)Ir(C0)2 and but-2-yne at 180 gives a small amount of hexamethylbenzene plus the maleoyl complex(η-C5H5){IrC(O)(Me=C(Me)C(O)}(CO).

The reaction of hex-3-yne with (η-C5H5)Co(C0)2 gives the p-benzoquinone complex (η-C5H5)Co-[(EtC2Et)2(C0)2] and the cyclopentadienone complex (q-C5H5)Co[(EtC2Et)2CO]. The corresponding reaction with (q-C2H2)Rh(CO)2 gives the cyclopentadienone complex (η-C5H5)Rh[(EtC2Et)2C0] and a binuclear 4,6-diethylnonadien-5-one complex, (η-C5H5)2Rh2(EtC2Et)2Co. The 1H N.M.R. spectra of all complexes have been analysed, in some instances with the aid of partial decoupling experiments. An analysis of the 13C N.M.R. spectra of the two cyclopentadienone complexes is also given.

Various alkynes (EtC2Et, MeO2CC2CO2Me, CF3C2CF3, PhC2Ph, C6F5C2C6F5, PhC2Me, PhC2C6-F5, PhC2CO2Me) react with (η-C5Me5)2Rh2(μ-CO)2 in acetone at room temperature; no reaction was observed with ButC2But. The σ-bridging alkyne complex, trans-(η-C5Me5)2Rh2(CO)2(μ-η1:η1C6F5C2C6F5), was obtained from the reaction with C6F5C2C6F5. With the other alkynes, dimetallaeneone complexes, (η-C5Me5)2Rh2(μ-CO){μ-η2:η2-C(O)C2RR′}, are formed. Some of these 'eneone' complexes co-exist with (η- C5Me5)2Rh2(CO)2(μ-η1:η1-RC2R) in the solid state (RC2R = PhC2C6F5) and/or in solution (EtC2Et, CF3C2CF3, PhC2C6F5); others (MeO2CC2CO2Me, PhC2Ph, PhC2Me, PhC2CO2Me) exist exclusively as (η-C5Me5)2Rh2(μ-CO){μ-η2:η2- C(O)C2RR′} in both the solid and solution states. The geometry of the bridging group in (η-C5Me5)2Rh2(μ-CO){μ-η2:η2-C(O)C2(CF3)2} has been determined from an X-ray diffraction study. The compound crystallizes with four molecules in the monoclinic space group P21/n in a unit cell of dimensions a 9.451(4), b 15.287(5), c 18.821(8)Ǻ, β 98.66(5)°. The structure was solved by conventional heavy atom methods and refined to R 0.066 based on 4356 observed reflections above background. The structure contains a metalla-eneone ring, Rh -C(=O)-C(CF3)=C(CF3), with the alkene bond η2-attached to the second rhodium atom. Variable temperature N.M.R . measurements establish that the complexes (η- C5Me5)2Rh2(μ-CO){μ-η2:η2-C(O)C2R2}(R = CF3 or CO2Me) are fluxional in solution. Facile cleavage of a C(O)-C(R) bond enables the metalla-eneone ring to shift rapidly from one rhodium atom to the other. Other products formed in the reactions between (η-C5Me5)2Rh2(μ-CO)2 and RC2R′ include. (η-C5Me5) Rh {C4(CF3)4CO}, (η-C5Me5) Rh (η4-C6R6) (R = CF3 or CO2Me), (η-C5Me5)2Rh2-(C4R2R′2) (R = R′ = CO2Me; or R, R′ = Ph, C6F5), (η- C5Me5)2Rh2(CO2C2Ph2), (η-C5Me5)- Rh (C4Ph4CO2), (η-C5Me5)2Rh2(CO)2{C4(CF3)4}, (η-C5Me5)2Rh2(CO)(μ-CO){COC4(C6F5)4} and C6R3R′3 (R = R′ = Ph or CO2Me; R = Ph and R′ = Me). Reactions between (η-C5Me5)2-Co2(μ-CO)2 and alkynes at room temperature or above yield mononuclear cyclopentadienone complexes (η-C5Me5)Co{C4R4CO}(R = Me, CF3 or C6F5), and the mononuclear arene complex (η-C5Me5)Co{C6(CF3)6}.

The reactions between (η-C5H5)Co(CO)2 and MeC≡CR (R = Bu, Pri) at 120° gave the cyclopentadienone complexes (η-C5H5)Co[C4Me2R2CO] (2) and small amounts of the p-benzoquinone complexes(η-C5H5)Co[C4Me2R2(CO)2] (1); all possible isomers of both complexes were obtained. For R = But, the only products isolated were two isomers of the cyclopentadienone complex (2). The reactions between (η-C5H5)Rh(CO)2 and MeC=CR at 160° gave the cyclopentadienone complexes(η-C5H5)Rh[C4Me2R2CO] (2), and small amounts of the p-benzoquinone complexes (η-C5H5)Rh-[C4Me2R2(CO)2] (1) and of the binuclear complexes (η-C5H5)2Rh2(MeC2R)2CO (3). With R = But, three isomers of (2), two isomers of (1) and three isomers of (3) were identified. The products obtained with R = Pri were three isomers of (2) and three isomers of (3). With R = But, three isomers of(2) and a very small amount of one of the isomers of (3) were separated. Comparisons of these reactions have shown that increasing the bulk of R results in a decrease in the total yields of products, a decrease in the range of products, and a change in the distribution of the isomers (M = Co only).

Halides of tin, lead, phosphorus, arsenic, antimony, and bismuth have been treated with solutions of lithium tetraethylaluminate, and alkylation of the group IV and VB elements was observed in every instance. Alkyls of the form MEt4 (M=Sn, Pb) or MEt3 (M=P, As, Sb, or Bi) were isolated from the reaction mixtures. Side reactions, which affect the yields of these alkyls, are discussed.

The reactions of bis(cyclopentadienyl)titanium(IV) dichloride with sodium lead triethyl and with lithium tin triethyl have been investigated. Unstable solid products are formed. The reaction of liquid ammonia with bis(cyclopentadienyl)titanium(IV) dichloride has also been studied.

Treatment of dodecacarbonyltetracobalt with the conjugated diynes RC≡CC≡CR (R = CH3, C6H5) yields complexes of stoicheiometry [Co2(CO)6]2- (RC2C2R). The same complexes are obtained from octacarbonyldicobalt and the appropriate diyne. A similar type of complex was obtained from para-(C6H5C2)2C6H4 and Co4(CO)12. Surprisingly, this complex was not isolated on reaction of the diyne with Co2(CO)8. The infrared, nuclear magnetic resonance, and mass spectra of the complexes are given, and the probable structures of the compounds are deduced from these spectroscopic properties.

Two new organocobalt complexes, Co2(CO)4(CF3C2CF3)3 and Co2(CO)4(CF3C3H)2- CF3C2CF3, have been isolated from the appropriate reactions of hexafluorobut-2-yne with octacarbonyldicobalt and of 3,3,3- trifluoropropyne with μ-hexafluorobut-2-yne-hexacarbonyldicobalt. The probable structures of these compounds are discussed in light of their infrared and nuclear magnetic resonance spectra. The direct formation of complexes of the type Co3(CO)9CCH2R has been established in the reactions of several terminal alkynes, RC2H (R = H, CF3, C6H5), with octacarbonyldicobalt. The spectroscopic properties of the products so obtained are given.

No abstract available.

The reaction at 160 of dicarbonyl(η-cyclopentadienyl)cobalt with each of the terminal alkynes phenylacetylene, t-butylacetylene, propyne, and 3,3,3-trifluoropropyne has been studied. The reactions give p(disubstituted cyclopentadienone)-η-cyclopenta-dienylcobalt complexes as the major products; two or three isomers of each cyclo- pentadienonecobalt complex are formed. The arrangement of the substituents in each isomer has been assigned on the basis of electronic, infrared, nuclear magnetic resonance, and mass spectral data. Attempts to rationalize the distribution of isomers are based on considerations of electronic and steric effects.

The thermal decomposition of Co2(CO)6(PhC2Ph) has been investigated in detail. Differential scanning calorimetry was used to determine the most suitable temperature range for the study. At 180, Co2(CO)6(PhC2Ph) decomposes to form cobalt, carbon monoxide, tetraphenylcyclopentadienone, hexaphenylbenzene, and other organic compounds. Variation in the temperature, the time, and the solvent used for the degradation reaction causes significant changes in the yields of the organic products. An investigation of the effects of adding stoichiometric amounts of free alkyne, tetra-phenylcyclopentadienone, and hexaphenylbenzene has been initiated in an attempt to understand the degradation mechanism.

In tetrahydrofuran at -45 and in diethyl ether at 20, the reaction of α-bromo- 2,3,4,5,6-pentafluorotoluene with lithium tetrahydroaluminate yields 2,3,4,5,6-penta-fluorotoluene. In tetrahydrofuran at 20, the same reaction occurs initially but the pentafluorotoluene then reacts further with LiAlH4. LiAlH4 attacks the para-fluorine atom of 2,3,4,5,6- pentafluorotoluene to form 2,3,5,6-tetrafluorotoluene and the fluoro- carbon-alane complex LiAl(C6F4CH3)H2F. The reaction between LiAlH4 and C6F5CH3 is complete after 0.5 hr at 65. In turn, 2,3,5,6- tetrafluorotoluene reacts with LiAlH4 in refluxing tetrahydrofuran to form the fluorocarbon-alane complexes LiAl(C6F4CH3)nH4-n, n = 1-3. The fluorocarbon-aluminium compounds have not been isolated from solution but were characterized by quantitative determination of the products of hydrolysis and by 1H and 19F N.M.R. spectroscopy.

The reaction of lithium tetrahydroaluminate with chloropentafluorobenzene yields mainly p-chlorotetrafluorobenzene. The nature of the solvent influences the formation of other fluorocarbon compounds in the reaction. p-Chlorotetrafluoro-benzene reacts further with LiAlH4 in tetrahydrofuran, but not in diethyl ether, to give predominantly 1-chloro-2,3,5-trifluorobenzene and 1-chloro-2,3,6- trifluorobenzene. In turn, the trifluorobenzene compounds react with LiAlH4 in tetrahydrofuran to give mainly 1-chloro-2,5-difluorobenzene. The major products are formed by a combination of (i) direct nucleophilic displacement of fluorine in the chloropolyfluorobenzene compounds by hydride, and (ii) hydrolysis of the compounds LiAl(C6F4Cl)H2F, LiAl(C6F3HCl)H2F, and LiAl(C6F2H2Cl)H2F. The fluorocarbon- aluminium compounds have not been isolated from solution but they were characterized by quantitative determination of the products of hydrolysis and by 1H and 19F N.M.R. spectroscopy.

The thermally initiated reaction of hexafluorobut-2-yne with (π-C5H5)Rh(CO)2 has been studied in detail, and it is found that the nature and yields of the products are sensitive to the reaction conditions. The known complexes (π-C5H5)Rh-[(C4F6)2CO] and (π-C5H5)Rh(C4F6)3 and the new organorhodium complexes (π-C5H5)2Rh2(CO)2(C4F6), (.π-C5Hs)3Rh3(C4F6)2, (π-C5H5)2Rh2(CO)(C4F6)2, and (π-C5H5)3Rh3(CO)(C4F6) have been isolated from the reaction system. Each organorhodium complex has been characterized by elementary and mass spectral analysis, and reasonable structures for all complexes have been predicted from the appropriate i.r. and N.M.R. data. The monoalkyne complex (π-C5H5)2Rh2(CO)2(C4F6) is an intermediate in the formation of the other organorhodium complexes.

Reaction of lithium tetrahydroaluminate with hexafluorobenzene yields pentafluorobenzene. Pentafluorobenzene reacts further with LiAlH4 to give 1,2,4,5-tetrafluorobenzene. The products are formed by a combination of (i) reduction (hydride for fluoride replacement) of the fluoroaromatic compound, and (ii) hydrolysis of one of the compounds LiAl(C6F4H)H2F or LiAl(C6F5)H2F that are formed in the reactions. These competing reactions take place to a similar extent and are much faster in tetrahydrofuran than in diethyl ether. In tetrahydrofuran, 1,2,4,5-tetrafluorobenzene is metalated by LiAlH4. The compounds LiAl(C6F4H)H3, LiAl(C6F4H)2H2, and LiAl(C6F4H)3H are proposed as products of the reaction. The fluorocarbon-aluminium compounds have been characterized by quantitative determination of the products of hydrolysis and by 1H and 19F N.M.R. spectroscopy.

The complex Co4(CO)10(CF3C2CH3) is formed at room temperature from dodecacarbonyltetracobalt and 1,1,1-trifluorobut-2-yne. Another monoalkyne complex Co2(CO)6(CF3C2CH3) has been prepared from octacarbonyldicobalt and 1,1,1-trifluorobut-2-yne at room temperature. Treatment with triphenylphosphine converts the complex into Co2(CO)4[P(C6H5)3]2(CF3C2CH3). At 150, reaction of Co2(CO)6(CF3C2CH3) and 1,1,1-trifluorobut-2-yne gives a small amount of a purple complex which is believed to be Co2(CO)4(CF3C2CH3)3. Similar reactions involving Co2(CO)4(CF3C2CH3) and the alkynes hexafluorobut-2-yne and 3,3,3-trifluoropropyne give the complexes Co2(CO)4(CF3C2CH3)(CF3C2CF3)2 and Co2(CO)4(CF3C2CH3)(CF3C2H)2. Spectroscopic studies have led to an assignment of the substitution pattern in these latter complexes. Tris-alkyne complexes were not isolated from similar reactions between 1,1,1-trifluorobut-2-yne and the complexes Co2(CO)6(CF3C2CF3) and Co2(CO)6(CF3C2H). Three isomers of the π-cyclopentadienone-π-cyclopentadienylcobalt complex, [(CF3C2CH3)2CO]Co(π-C5H5), were obtained from (π-C6H6)Co(CO)2 and 1,1,1-trifluorobut-2-yne after U.V. irradiation for several days. The isomers vary in the arrangement of the substituents attached to the cyclopentadienone ring. All reactions involving 1,1,1-trifluorobut-2-yne have been compared with similar reactions involving the related alkynes hexafluorobut-2-yne and but-2-yne.

π-Cyclopentadienone-π-cyclopentadienyloobalt complexes have been prepared from reactions of π-oyclopentadienyldicarbonylcobalt and the alkynes bis(pentafluorophenyl)acetylene and 2,3,4,5,6-pentafluorodiphenylacetylene. Spectroscopic data indicate that the complex derived from the latter alkyne has an unsymmetrical arrangement of the substituents in the cyclopentadienone ring. It is formulated as 2,4-bis(pentafluorophenyl)-3,5-diphenylcyclopentadienone-π-cyclopentadienyl-cobalt. A related cyclopentadienone complex, π-tetrakis(pentafluorophenyl)cyclopenta-dienone-π-cyclopentadienylrhodium has been prepared from π-cyclopentadienyl-dicarbonylrhodium and bis(pentafluorophenyl)acetylene. Similar organorhodium complexes could not be isolated from reactions of π-C5H5Rh(CO)2 with diphenylacetylene and 2,3,4,5,6-pentafluorodiphenylacetylene. These compounds could, however, be prepared indirectly by the in situ treatment with thallous cyclopentadienide of the cyclopentadienone complexes formed in reactions of [Rh(CO)2Cl]2 with RC=CR' (R = phenyl, R' = phenyl or pentafluorophenyl). Like its cobalt analogue, π-bis(pentafluorophenyl)diphenylcyclopentadienone-.π-cyclopentadienyl- rhodium has an unsymmetrical arrangement of the substituents in the ring.

Treatment of dodecacarbonyltetracobalt with several fluorocarbon alkynes has given complexes of stoicheiometry Co4(CO)10,(alkyne). For comparison, analogous complexes of the related hydrocarbon alkynes have also been prepared. Infrared, nuclear magnetic resonance, and mass spectra of the complexes are given and the probable structure of the complexes deduced. The reaction of both fluorocarbon and hydrocarbon alkynes with the cluster carbonyl compounds Co3(CO)9CY (Y = CH3, C6H5, CO2CH3) has also been investigated. The products obtained in these reactions include substituted benzenes and the two organocobalt complexes Co2(CO)6(alkyne) and Co2(CO)4(alkyne)3. The probable mode of formation of these compounds is discussed. The role played by the various complex types in the reactions of alkynes with cobalt carbonyls is also considered.

The new organocobalt complex CO2(CO)4(CF3C2CF3)2(CF3C2H) has been isolated from the reaction of hexafluorobut-2-yne with p-trifluoropropyne-hexacarbonyldicobalt. In addition, a second isomer of the known complex CO2(CO)4(CF3C2CF3)2(CF3C2H)2 has been isolated from the reaction of 3,3,3-tri-fluoropropyne with p-hexafluorobut-2-yne-hexacarbonyldicobalt. A detailed study of the 1H and 19F N.M.R. spectra of these and the related complexes Co2(C0)4- (CF3C2CF3)3 and CO2(CO)4(CF3C2H)3 has led to an assignment of the substituent arrangement in all of these complexes.

Treatment of pentacarbonyliron with pentafluorophenylacetylene has given the stable complex tricarbonyl-2,5-bis(pentafluorophenyl)cyclopentadienoneiron. There is no evidence of the formation of other structural isomers. The complex is also formed from pentafluorophenylaoetylene and nonacarbonyldiiron or dodecacarbonyltriiron. Two alkyne-cobalt complexes have been isolated from the interaction of octacarbonyldicobalt and pentafluorophenylacetylene. One of these is a bridging alkyne complex of molecular stoicheiometry Co2(CO)6(C6F6CCH); the second is a complex of formula Co3(CO)9(CCH2C6F5). The infrared and nuclear magnetic resonance spectra of the complexes are given, and the probable structures of the compounds are deduced from these spectroscopic properties.

Treatment of pentacarbonyliron with 3,3,3-trifluoropropyne, CF3C≡CH, has given the stable complex tricarbonylbis(trifluoromethyl)cyclopentadi- enoneiron. Although a disubstituted cyclopentadienone can exist as three structural isomers, only one metal complex has been isolated. The interaction of octacarbonyldicobalt and 3,3,3-trifluoropropyne has given two metal complexes, one of which is a bridging alkyne complex of molecular stoicheiometry Co2(CO)6(CF3CCH); the other, of formula Co2(CO)4(CF3CCH)3, is shown to have a metal-metal bridging unit which is formed by condensation of three alkyne groups. Infrared, nuclear magnetic resonance, and mass spectra of these complexes are given, and the structures of the compounds described.

Treatment of solutions of lithium tetrahydroaluminate with bromopenta- fluorobenzene, C6F5Br, or iodopentafluorobenzene, C6F5I, yields perfluorophenyl-aluminium compounds. The thermally stable complex lithium tris(pentafluorophenyl)bromoaluminate, LiAl(C6F5)3Br, has been isolated. Similar reactions between lithium tetrahydroaluminate and perfluoroalkyl iodides are discussed. These reactions are known to yield thermally unstable perfluoroalkyl-aluminium compounds, and the present paper reports an investigation of the possible use of solutions of these compounds as perfluoroalkylating reagents. Although perfluoro- alkyl groups can be transferred from aluminium to tin and lead, the reactions are complicated and cannot be considered as useful synthetic pathways to perfluoroalkyl-tin or -lead compounds.