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  • 1
    ISSN: 0947-6539
    Keywords: allyl complexes ; butadienes ; C-C coupling ; rhodium ; vinylidene complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the first part of this work, a general method for the preparation of aryl, methyl, vinyl and alkynyl(vinyl-idene)rhodium(I) complexes trans-[Rh(R')-(=C=CHR)(PiPr3)2] (8-14, 18-22) and trans-[Rh(R')(=C=CMe2)(PiPr3)2] (16, 17) from the corresponding chloro(vinyl-idene) derivatives and Grignard reagents is described. Whilst compounds 8 and 10-13 react with pyridine to give trans-[Rh(C≡CR)(py)(PiPr3)2] (23-25) by elimination of R'H, treatment of 8-11, 16, and 18 with carbon monoxide yields the square-planar η1-vinyl and η1-butadienylrhodiumcarbonyl complexes trans-[Rh{η1-(Z)-C(R')=CHR}(CO)(PiPr3)2] (27-32). The reaction of 8 or 18 with methyl or tert-butylisocyanide leads stereoselectively to the isocyaniderhodium(I) compounds trans- [Rh{η1-(Z)-C(R)=CHPh}(CNR') (PiPr3)2] (33-35). Acid-induced cleavage of the rhodium-carbon σ bond of 27, 30, or 31 with CH3CO2H gives trans-[Rh(η1-O2CCH3)-(CO)(PiPr3)2] (38) and the corresponding olefin or diene, respectively. In the absence of a Lewis base such as pyridine, CO, or CNR', compounds 18-20 rearrange in benzene at 40-50 °C to afford the isomeric π-allyl complexes [Rh(η3-1-RC3H4)(PiPr3)2] (40-42) almost quantitatively. The vinyl(vinylidene) compounds 11 and 12 also undergo an intramolecular rearrangement that leads to the η3-2,3,4-butadienyl- or to the alkynyl(ethene)rhodium(I) isomers, depending on the reaction conditions. In an analogous manner to the η1-vinyl-and η1-butadienyl(carbonyl) derivatives 27, 30, and 31, the π-allyl and π-butadienyl complexes also react with acetic acid to give [Rh(η1-O2CCH3)(PiPr3)2] (47) and the respective olefin.
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  • 2
    ISSN: 0947-6539
    Keywords: carbene complexes ; C—C coupling ; diazo compounds ; ligand effects ; rhodium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic methodology to obtain square-planar carbenerhodium(I) complexes of the general composition trans-[RhCl(=CRR′)(L)2] where L is a tertiary phosphane, arsane, or stibane has been developed. The starting material trans-[RhCl(C2H4)(SbiPr3)2] (3) reacts with diazoalkanes RR′CN2 [RR′ = Ph2, Ph(C6H4X), (C6H4X)2, Ph(CF3), C12H8] under mild conditions to give the compounds trans-[RhCl(=CRR′)(SbiPr3)2] (4-11) almost quantitatively. On treatment of 3 with EtO2CCHN2 and PhC(N2)C(O)R, the olefinrhodium and diazoalkanerhodium compounds trans-[RhCl{(E)-C2H2(CO2Et)2}(SbiPr3)2] (12) and trans-[RhCl{N2C(R)C(O)Ph}(SbiPr3)2] (13, 14) are obtained instead of carbene complexes. Displacement of the SbiPr3 ligands in 4 (R = R′ = Ph) by PiPr3, PiPr2Ph, PiPrPh2, PPh3, PPh2Me, AsiPr3, and SbEt3 leads to the corresponding carbene complexes trans-[RhCl-(=CPh2)(L)2] (15-21) in high yields. The results of the X-ray crystal structure analyses of 4 and 15 (L = PiPr3) illustrate that the different donor - acceptor properties of SbiPr3 and PiPr3 have little influence on the Rh—C bond length. The reactions of 4 and 15 with CO and CNtBu afford, by metal-assisted C—C coupling, diphenylketene Ph2C=C=O (23) and the corresponding imine Ph2C=C=NtBu (26). On treatment of 4 and 15 with ethene, however, two different olefinic products, 3,3-diphenyl-1-propene (31) and 1,1-diphenyl-1-propene (32), are formed. Compound 15 reacts with KBr, NaOPh, and NaC5H5 by substitution of the chloride to give trans-[RhBr(=CPh2)-(PiPr3)2] (33), trans-[Rh(OPh)(=CPh2)-(PiPr3)2] (34) and [C5H5Rh(=CPh2)-(PiPr3)] (35), and with HCl by oxidative addition to yield [RhCl2(CHPh2)-(PiPr3)2](36).
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  • 3
    ISSN: 0947-6539
    Keywords: antimony ; arene complexes ; diene complexes ; rhodium ; ylides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first representatives of phosphino(stibino)methanes R2PCH2Sb-R′2 (3-5) with bulky alkyl or cycloalkyl groups R and R′ were prepared in two steps from Ph3SnCH2I via the isolated stannylated phosphanes Ph3SnCH2PR2 (1, 2) as intermediates. X-ray structural analysis of 5 (R = C6H11, R′ = tBu) reveals that the lone pairs and the substituents R and R′ at phosphorus and antimony and the hydrogen atoms of the CH2 bridge adopt staggered conformations. Treatment of [{C8H12RhCl}2] with 3-5 affords the neutral compounds [Rh-Cl(η4-C8H12)(κ-P-R2PCH2SbR′2)] (6-8), of which 7 and 8 react with CH3MgI to give the corresponding methylrhodium derivatives [RhCH3(η4-C8H12)(κ-P-R2-PCH2SbR′2)] (9, 10). Cationic complexes [Rh(η4-C8H12)(η2-P,Sb-R2PCH2SbR′2)]-X (X = PF6: 11a, 12a, 13; X = BPh4: 11b, 12b) containing the phosphino(stibino)methanes as chelating ligands were obtained either from [{C8H12RhCl}2], R2PCH2SbR′2 and MX, or (for 13) from 8 and AgPF6. Compound 12a (R = iPr, R′ = tBu) was characterized by X-ray crystallography. The PF6 salts 11a, 12a, and 13 react with CH2N2 by insertion of CH2 into the Rh-Sb bond to yield the complexes 14-16, the first examples of transition-metal compounds with Sb ylides as ligands. Treatment of BPh4 salts 11b and 12b with H2 gives the half-sand-wich-type complexes [(η6-C6H5BPh3)Rh(κ2-P,Sb-R2PCH2SbR′2)] (17, 18), in which the tetraphenylborate is coordinated like a substituted arene to the metal center.
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  • 4
    ISSN: 0009-2940
    Keywords: Rhodium complexes ; Molecular structure ; square-planar ; Hydrogenation reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(triisopropylphosphane)rhodium Dichloride: Formation and StructureThe mononuclear rhodium(II) complex trans-[RhCl2(PiPr3)2] (4) has been obtained from [RhCl(PiPr3)2]n (3) and CCl4. The X-ray structural analysis of 4 reveals a square-planar coordination at the metal center. Reaction of 4 with H2 leads to the formation of the monohydrido compound [RhHCl2(PiPr3)2] (7) which on further treatment with H2 in the presence of Na[N(SiMe3)2] gives the dihydride [RhH2Cl(PiPr3)2] (8). Complex 7 has also been prepared from 3 and HCl.
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  • 5
    ISSN: 0009-2940
    Keywords: Phospha- and arsaalkene rhodium complexes ; Metalla heterocycle containing RhAs3 ; Rhodium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CH2=PPH and CH2=AsPh as Ligands Coordinated to Rhodium. Crystal and Molecular Structure of C5Me5Rh(η2-CH2PPh)(CO) and C5Me5(CO)Rh(AsPh)3C5Me5RhCH2I(CO)I (1) reacts with excess LiPHPh or LiAsHPh to give the complexes C5Me5Rh(η2-CH2EPh)(CO) (2: E = P; 3: E = As). The C—P bond length of the coordinated phosphaalkene in 2 is 174.0(4) pm and thus ca. 10 pm shorter than that of a C—P single bond. On standing in solution, the new heterocycle C5Me5(CO)Rh(AsPh)3 (4) is formed from 3. The X-ray analysis of 4 shows that the bonding distances and angles in the central nonplanar RhAs3 four-membered ring are very similar to thos in cyclo-(AsCF3)4.
    Notes: C5Me5RhCH2I(CO)I (1) reagiert mit überschüssigem LiPHPh oder LiAsHPh zu den Komplexen C5Me5Rh(η2-CH2EPh)(CO) (2: E = P; 3: E = As). Der C—P-Abstand des koordinierten Phosphaalkens in 2 ist mit 174.0(4) pm um ca. 10 pm kürzer als der einer C—P-Einfachbindung. Beim Stehenlassen in Lösung entsteht aus 3 teilweise der Heterocyclus C5Me5(CO)Rh(AsPh)3 (4), von dem die Struktur bestimmt wurde. Die Bindungsabstände und -winkel in dem zentralen, nicht planaren RhAs3-Vierring sind denen in cyclo-(AsCF3)4 sehr ähnlich.
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  • 6
    ISSN: 0009-2940
    Keywords: Cyclopentadienyl anion, substituted ; Cobalt complexes ; Rhodium complexes ; Iridium complexes ; Bis(cyclopentadienyl)methane dianion as bridging ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V[1]. - Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand*The lithium and sodium salts of the [C5H5CH2C5H4]- anion, 1 and 2, react with [Co(CO)4I], [Rh(CO)2Cl]2, and [Ir(CO)3Cl]n to give predominantly the mononuclear complexes [(C5H5-CH2C5H4)M(CO)2] (3, 5, 7) together with small amounts of the dinuclear compounds [CH2(C5H4)2][M(CO)2]2 (4, 6, 8). The 1H- and 13C-NMR spectra of 3, 5, and 7 prove that the CH2C5H5 substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)4I], [Rh(CO)2Cl]2, and [C5H5TiCl3] the heteronuclear complexes [CH2(C5H4)2][M(CO)2][M′(CO)2] (11-13) and [CH2(C5H4)2]-[Ir(CO)2][C5H5TiCl2] (17) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH2(C5H4)2][M(CO)(μ-CO)M′(CO)] (14, 15). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH2(C5H4)2][Rh2(CO)2(μ-CO)] (16).
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  • 7
    ISSN: 0009-2940
    Keywords: Dinuclear rhodium and iridium complexes ; Bis(cyclopentadienyl)methane dianion as bridging ligand ; Substitution and bridge-splitting reactions ; Rhodium complexes ; Iridium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(cyclopentadienyl)methane-Bridged Dinuclear Complexes, IV[1].  -  Synthesis, Structure, and Reactivity of Dinuclear Rhodium and Iridium Complexes in the Oxidation State +I and +III with the Bis(cyclopentadienyl)methane Dianion as Bridging LigandThe rhodium compounds [CH2(C5H4)2][Rh(L)(C2H4)]2 (2, 4) were prepared from [RhCl(L)(C2H4)]2 (1, 3) and CH2(C5H4)2Li2 in 92 and 73% yield, respectively. The reaction of 4 with Cl2, Br2, and I2 led to the almost quantitative formation of the dihalogeno derivatives [CH2(C5H4)2][RhX2(PiPr3)]2 (6-8), which on treatment with excess NaBH4 and methanol gave the dihydride [CH2(C5H4)2][RhH2(PiPr3)]2 (10). From [RhCl(C8H14)2]2 (12), PiPr3, and CH2(C5H5)2 the chloro(hydrido)rhodium complex [CH2(C5H4)2][RhH(Cl)(PiPr3)]2 (13) was obtained. Protonation of 10 with CF3CO2H in the presence of NH4PF6 gave the PF6 salt of the hydrido-bridged cation {[CH2(C5H4)2]-[RhH(PiPr3)]2(μ-H)}+ (14) of which the crystal structure was determined. In solution, fluxional behavior of the cation was observed. The dimethyl compound [CH2(C5H4)2][Rh(CH3)2-(PiPr3)]2 (17), prepared from 6, 7, or 8 and LiCH3 or CH3MgI in 80% yield, reacted with CF3CO2H at  -  78° C to give the tri-fluoroacetato derivative 18; this on treatment with P(OMe)3 and dmpe formed the dicationic complexes 19 and 20, respectively. The dinuclear iridium compounds [CH2(C5H4)2]-[Ir(olefin)2]2 (26, 27) and [CH2(C5H4)2][Ir(C8H12)]2 (28) were prepared from [IrCl(L)2]2 (23-25) and CH2(C5H4)2Li2 and used for the synthesis of {[CH2(C5H4)2][IrX2]2}n (29, 30). Compounds 29 and 30 served as starting materials for the preparation of the dinuclear derivatives [CH2(C5H4)2][IrX2(L)]2 (31-34) and {[CH2(C5H4)2][IrBr2]2(μ-dipy)} (35) and finally also for the dihydrido complex [CH2(C5H4)2][IrH2(PiPr3)]2 (36).
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  • 8
    ISSN: 0009-2940
    Keywords: Rhodium complexes ; Alkyne complexes ; Insertion reactions ; Alkyl isocyanides ; Metallacycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclopentadienyl complexes [C5H5Rh(RC≡CR′)(SbiPr3)] (5-8), which were prepared from trans-[RhCl-(RC≡CR′)(SbiPr3)2] (1-4) and NaC5H5 and which contain a labile Rh-SbiPr3 bond, reacted with CO and CNR″ (R″ = Me, tBu) to give the carbonyl and isocyanide derivatives [C5H5Rh(RC≡CR′)(CO)] (9-11) and [C5H5Rh(RC≡CR′)-(CNR″)] (12-16), respectively. On treatment of 12 (R = R′ = Ph; R″ = Me) with SbiPr3, the metallacyclobutene complex [C5H5Rh{κ2(C,C}-C( = NMe)CPh=CPh}(SbiPr3)] (17) was formed; it reacts with excess CNMe or CNtBu to yield the metallacyclopentenes [C5H5Rh{κ2(C,C)-C(=NMe)CPh=CPhC-(=NR)}(CNR)] (18, 19). Similar compounds 20-23 containing a five-membered RhC4 metallacycle were prepared either from [C5H5Rh(RC≡CR′)(SbiPr3)] (7, 8) or [C5H5Rh-(PhC≡CPh)(CNtBu)] (14) and excess isocyanide. The crystal and molecular structures of 17 and 18 (R = Me) have been determined.
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