Robert N. Haszeldine

Organic reactions involving transition metals III. The palladium(II)-catalysed dimerization of olefinic compounds☆

Abstract The palladium(II)-catalysed dimerization of olefins has been investigated. The olefinic compounds, ethylene, propene, n-butenes, methyl acrylat, and styrene, have been successfully dimerized, and the pairs of olefinic compounds, ethylene and propene, propene and 1-butene, ethylene and cyclopentene, ethylene and methyl acrylate, ethylene and styrene, and methyl acrylate and styrene successfully codimerized, using dichlorobis(benzonitrile)palladium or palladium dichloride as catalyst. In all cases, high proportions of straight-chain dimers are formed, and olefin-isomerization is a closely associated feature of the reaction. A mechanism involving a hydridopalladium(II) compound as the catalytically active species is suggested.

Metal carbonyl chemistry : XIV. Reactions of rhodium carbonyls with ligands☆

Abstract Dodecacarbonyltetrarhodium [Rh 4 (CO) 12 ] reacts with phosphine and phosphite ligands under an atmosphere of nitrogen to give the compounds Rh 4 (CO) 10 L 2 , Rh 4 (CO) 9 L 3 and Rh 4 (CO) 8 L 4 [where L = Ph 3 P or P(OCH 2 ) 3 CEt (ETPO) 1 ] in which the metal atom cluster is retained. Under similar conditions hexadecacarbonyl-hexarhodium [Rh 6 (CO) 16 ] reacts with Ph 3 P, P(OCH 2 ) 3 CEt or P(OMe) 3 to give complexes of the type Rh 6 (CO) 10 L 6 . When the reaction of either Rh 4 (CO) 12 or Rh 6 (CO) 16 with the ligands Ph 3 P or Ph 3 As is carried out in the presence of carbon monoxide, breakdown of the metal clusters occurs to give the bridged compounds L 2 (CO)Rh(CO) 2 Rh(CO)L 2 (where L = Ph 3 P or Ph 3 As) in high yields; reaction of Rh 4 (CO) 12 with n-Bu 3 P under similar conditions gives the compound [(n-Bu 3 P) 3 -(CO)Rh] 2 . Dodecacarbonyltetrarhodium has also been shown to react with PhC 2 Ph or CF 3 C 2 CF 3 to give the compounds Rh 4 (CO) 10 (RC 2 R) (R = CF 3 or Ph). Some of these ligand-substituted rhodium carbonyls have been shown to be extremely active hydroformylation catalysts for 1-alkenes.

Organosilicon chemistry: XI. The stereochemistry of Ir(H)Cl(SiR3)CO(PPh3)2, and the trans-influence of substituted silyl, germyl, and stannyl groups☆

The infrared spectra of the complexes Ir(X)Y(SiR3)CO(PPh3)2 (X = H, D; Y = Cl, Br; SiR3 = SiF3, SiCl3, Si(OEt)3. SiCl2Me, SiClMe2) show that the structure involves the trans-pairs of ligands (Ph3P, Ph3P), (X, CO) and Y, SiR3). From the variation in the metal—chlorine stretching frequencies in these complexes and in related platinum(II) complexes, the following trans-influence series are deduced: SiF3≈SiCl3<SiCl2Me<Si(OEt)3 ⪡ SiClMe2; SiCl3 < SiCl2H < SiClH2 < SiH3 ⪡ SiMe3; GeClH2 ⪡ GeMe3; SnMe3 ⪡ GeMe3≈SiMe3; SnCl3 ⪡ SnMe3≈SiCl3.

Organosilicon chemistry : XXX. Homogeneous catalysis by iridium(I) complexes of the reaction between silanes and alcohols or dideuterium

Abstract The complexes IrX(CO)L2, IrCl(N2)(PPh3)2, [IrCl(C8H14)2]2, and IrClL2 (X = halide, L = tertiary phosphine or arsine) are excellent catalysts for the reactions of HSiR3 (R = Ph, Et, OEt) with R′OH (R′ = Et, Me). With IrX(CO)L2 the reactionis inhibited by an excess of HSiR3 and by the product, H2. The proposed mechanism involves intermediate formation of ClSiR3 by elimination from the silyl complex IrHX(SiR3)(CO)L2. The iridium(I) complex IrH(CO)L2, also formed in this step, reacts with HCl in the catalytic cycle or with H2 or HSiR3 in the inhibition reactions. The exchange reaction of HSiR3 (R = OEt, Et) with D2 is catalysed by IrCl(CO)(PPh3)2 or IrH3(CO)(PPh3)2, and probably has a similar mechanism. Catalysis of the HSiR3-R′OH reaction by the other iridium(I) complexes probably involves direct attack by the alcohol on the coordinated silyl group of the intermediate IrHCl(SiR3)L2.

Organosilicon chemistry : XXVII. Silyl—ruthenium(IV) complexes

Silyl—ruthenium(IV) complexes, RuH3(SiR3)Ln, (R3 = F3, MeF2, Cl2Me, (OEt)3, ClMe2, HPh2, MePh2, Ph3; L = PPh3, AsPh3, P(C6H4Me-p)3;n = 2, 3) are formed by reaction of an excess of HSiR3 with RuH2L4, RuHClL2, RuCl2L3, or RuCl3(AsPh3)3. The chloro complexes react with concurrent formation of ClSiR3. With HSiMe3 or HSiEt3, RuCl2(PPh3)s is reduced to RuHCl(PPh3)3 and no silyl complexes are formed; these silanes do not react with RuH2(PPh3)4. Complexes of the type RuH2X(SiR3)L3 (X = Cl, I) are obtained by reaction of the chlororuthenium(II) complexes with HSiCl3, or of RuH3[Si(OEt)3](PPh3)3 with CDCl3 or I2. The complexes RuH3(SiR2)L3 undergo silyl exchange or H—D exchange with HSiR3′ or D2.

Organophosphorus chemistry. Part 19. Free-radical addition of dialkyl phosphites to polyfluoro-olefins

Abstract An improved procedure for the peroxide-catalysed addition of dialkyl phosphites to tetrafluoroethylene is described, and the reactions of diethylphosphite with chlorotrifluoroethylene, 1,1-difluoroethylene,perfluoropropene, and 3,3,3-trifluoropropene have been investigated and found to yield diethyl 2-chloro-1,1,2-trifluoroethylphosphonate, diethyl 2,2-difluoroethylphosphonate, an 80:20 mixture of diethyl 2 H -hexafluoro- n -propylphosphonate and diethyl 1 H -hexafluoropropyl-2-phosphonate, and diethyl 3,3,3-trifluoropropyl-1-phosphonate, respectively.

Metal carbonyl chemistry IV. The preparation of cobalt and rhodium carbonyls by reductive carbonylation with pentacarbonyliron

Abstract Octacarbonyldicobalt has been obtained in 40% yield from the reaction of cobaltous chloride and pentacarbonyliron; other cobalt salts are less effective in this reaction. The similar reaction of either anhydrous RhCl3 or [Rh(CO)2Cl]2 with pentacarbonyliron has been found to give high yields of Rh6(CO)16 even at atmospheric pressure at the reflux temperature of methanol. Carbonylation of [Rh(CO)2Cl]2 with carbon monoxide in the presence of Ullmann copper-bronze powder or silver can be controlled to give either Rh6(CO)16 or Rh4(CO)12 almost quantitatively.

Fluoro-olefin chemistry Part 20 [1]. Reaction of hexafluoropropene with alcohols

Abstract Reaction of hexafluoropropene (HFP) with a series of alcohols under thermal, photochemical or peroxide-initiated conditions affords the 1:1 adducts CF3CHFCF2CR1R2OH (R1 = H, R2 = H, Me, Prn or CF3; R1 = Me, R2 = Me or Et) in high yield via a radical chain mechanism. Adduct are not formed with the alcohols (CF3)2CHOH and CF3CHFCF2CH2OH. Other 1:1 adducts of structure CHF2CF(CF3)CH2OH and CH3(C2H3CF2CHFCF3)CH2OH are formed as minor products in the methanol and n -butanol reactions, respectively.

Reactions involving transition metals : XIX. Some reactions of perfluoronorbornadiene with low valent transition metal complexes☆

Abstract Perfluoronorbornadiene reacts with the compounds [M(PPh 3 ) 4 ] (M = Pt, Pd) and [IrCl(CO)(PMePh 2 ) 2 ] to give the adducts [(C 7 F 8 )M(PPh 3 ) 2 ] and [(C 7 F 8 )IrCl(CO)(PMePh 2 ) 2 ] in which one of the double bonds is coordinated to the metal atom. The platinum complex reacts further with [Pt(PPh 3 ) 4 ] to give [(C 7 F 8 ){Pt(PPh 3 ) 2 } 2 ] having both double bonds coordinated to a Pt atom. The carbonylmetal anions [M − ] react to form the mono-substitution products [(C 7 F 7 )M] (M = Mn(CO) 5 , Re(CO) 5 , Ir(CO) 2 (PPh 3 ) 2 , Rh(CO) 2 (PPh 3 ) 2 ), but the use of an excess of [Fe(CO) 2 (η-C 5 H 6 )] − leads to substitution of one fluorine atom on each of the double bonds. The complex having M = Mn(CO) 5 reacts with [Pt(PPh 3 ) 4 ] to afford the derivative [(C 7 F 7 ){Mn(CO) 4 (PPh 3 )}{Pt(PPh 3 ) 2 }], and the compound where M = Ir(CO) 2 (PPh 3 ) 2 undergoes an oxidative addition reaction with acetyl chloride. Oxidative coupling products have been isolated on UV irradiation of a mixture of perfluoronorbornadiene and [Fe(η 4 -CH 2 CRCHCH 2 )(CO) 3 ] (R = H, Me), and under similar conditions the reaction with Fe(CO) 5 affords [(C 7 F 8 )Fe(CO) 4 ] in very low yield.

Reactions involving transition metals: XX. A comparison of the reactions of 1,2,3,4,7,7-hexafluorobicyclo[2.2.1]heptadiene, and 2,3-bis(trimethyltin)- and 2,3-dichloro-1,4,5,6,7,7-hexafluorobicyclo[2.2.1]hepta-2,5-dienes with low valent transition metal complexes☆

1,2,3,4,7,7-Hexafluorobicyclo[2.2.1]heptadiene (1) and 2,3-bis(trimethyltin)-1,4,5,6,7,7-hexafluorobicyclo[2.2.1]hepta-2,5-diene (2) react with [M(Ph3P)4] (M = Pt, Pd) to afford air-stable adducts. 2,3-Dichloro-1,4,5,6,7,7-hexafluorobicyclo[2.2.1]hepta-2,5-diene (3) gives only [PtCl2(PPh3)2] with [Pt(Ph3P)4], but a low yield of an adduct was obtained with [Pd(PPh3)4]. The diene 1 also reacts with Fe(CO)5 to form the complex [(C7H2F6)Fe(CO)4], and with [Rh(C2H4)2(acac)] to give [(C7H2F6)Rh(acac)] in which the diene acts as a bidentate ligand. Similar products could not be isolated from the reactions of 2 and 3. A stable adduct, believed to be [{C7F6(SnMe3)2}Rh(CO)2(μ-Cl)2Rh(CO)2] has been isolated from the reaction between 2 and [Rh(CO)2Cl]2. This adduct reacts with PPh3 to give the bridge-cleavage product [{C7F6(SnMe3)2}RhCl(CO)(PPh3)2]. Reaction of 1 with [Rh(CO)2Cl]2 gives an unstable adduct which could not be isolated, and 2 does not react at room temperature. The chloro derivative 3 reacts with [PdCl2(PhCN)2] to give the adduct [(C7F6Cl2)PdCl(PhCN)], but 1 and 2 do not react under similar conditions. Stable substitution products [(C7F6R2)M] (R = H, M = Fe(CO)2(η-C5H5); R = SnMe3, M = Fe(CO)2(η-C5H5), Mn(CO)5, Ir(CO)2(PPh3)2, Rh(CO)2(PPh3)2; R = Cl, M = Ir(CO)2(PPh3)2, Rh(CO)2(PPh3)2) have been isolated from the reactions of the dienes with carbonylmetal anions. Insertion of the CHCH bond occurs when 1 is heated with [MnMe(CO)5] to give [{C7F6H2C(O)Me}Mn(CO)4], and this, on reaction with either PPh3 or [Pt(PPh3)4], gives [(C7F6H2COMe)Mn(CO)4PPh3].