RESUMEN
Reactions of the pentaruthenium cluster complexes Ru5(µ5-C)(CO)15 (5), Ru5(µ5-C)(CO)14[µ-η2-OâC(NMe2)](µ-H) (6), and Ru5(µ5-C)(CO)15Cl(µ-H) (7) with ethyne (C2H2) in the presence of Me3NO yielded the zwitterionic complexes Ru5(µ5-C)(CO)13[µ-η2-CHCH(NMe3)] (8), Ru5(µ5-C)(CO)13[µ-η2-OâC(NMe2)](η1-E-CHâCH(NMe3)(µ-H) (9), and Ru5(µ5-C)(CO)13Cl[η1-E-CHâCH(NMe3)](µ-H) (11). Each product contains a positively charged trimethylammonioethenyl ligand, CHâCH(+NMe3), that is derived from a 2-trimethylammonioethenide, -CHâCH(+NMe3), zwitterion that formally has a positive charge on the nitrogen atom and a negative charge on the terminal enyl carbon atom. The trimethylammonioethenyl ligand, CHâCH(+NMe3) in 8 is a η2-ligand that bridges a Ru-Ru bond on a basal edge of the square-pyramidal Ru5 cluster by a combination of σ + π cooordination of the ethenyl group. Compounds 9 and 11 each contain a η1-terminally coordinated [η1-E-CHâCH(+NMe3)] ligand with an E stereochemistry at the CâC double bond in open Ru5 cluster complexes. Compound 9 was decarbonylated to yield the compound Ru5(µ5-C)(CO)12[µ-η2-OâC(NMe2)][µ-η2-CHâCH(NMe3)](µ-H) (10) containing a η2-bridging CHCH(+NMe3) ligand. Compound 10 was converted back to 9 by the addition of CO. Two zwitterionic products, Ru5(µ5-C)(CO)14[η1-E-CHâCH(NMe3)] (12) and Ru5(µ5-C)(CO)15[η1-E-CHâCH(NMe3)] (13), were obtained by the addition of CO to 8. Compound 12 is an intermediate en route to 13. Compound 12 contains a terminally coordinated η1-E-CHâCH(+NMe3) ligand on one of the basal Ru atoms of a square-pyramidal Ru5 cluster. Compound 13 also contains a terminally coordinated η1-E-CHâCH(+NMe3) ligand on the wing-tip bridging Ru atom of a butterfly Ru4C cluster. Treatment of 6 with methyl propiolate (HC≡CCO2Me) yielded the zwitterionic complex Ru5(µ5-C)(CO)13[µ-η2-OâC(NMe2)][η1-E-(MeO2C)CâC(H)NMe3](µ-H) (14) that is structurally similar to 9 but contains a η1-E-(MeO2C)CâC(H)(+NMe3) ligand. Compound 14 eliminated the NMe3 group to yield the compounds Ru5(µ5-C)(CO)13[µ-η2-OâC(NMe2)][µ-η2-(MeO2C)HCâCH] (15) which contains a bridging methoxycarbonyl-substituted alkenyl ligand and the known compound Ru5(µ5-C)(CO)13[µ-η2-OâC(NMe2)](HNMe2)(µ-H) (16).
RESUMEN
Ru5(µ5-C)(CO)15, 1, has been found to activate CH bonds in the vinyl group of polar vinyl olefins, methyl acrylate (MA), and vinyl acetate (VAc), through a cluster opening process to yield the complexes Ru5(µ5-C)(CO)14[η2-OâC(OMe)CHâCH](µ-H), 2, and Ru5(µ5-C)(CO)14[η2-(MeCO2)CâCH2](µ-H), 4, respectively. The site of CH activation is dependent on the olefin substituent. In 2, the site of CH activation is the ß-carbon atom of the vinyl group, while in 4 the CH activation has occurred exclusively at the α-carbon atom of the vinyl group. Compound 2 can be further decarbonylated to yield the complex Ru5(µ5-C)(CO)13[µ-η3-OâC(OMe)CHCH](µ-H), 3, which contains a η3-bridging acryloyl ligand. Compound 2 reacts with ethylene in the presence of Me3NO to yield three new Ru5 products: Ru5(µ5-C)(CO)13[η4-1- anti,3- syn-{OâC(OMe)}C(H)C(H)C(H)Me](µ-H), 5, Ru5(µ5-C)(CO)12(C2H4)[µ-η3- OâC(OMe)C(H)C(H)](µ-H), 6, and Ru5(µ5-C)(CO)13[η4- anti-OâC(OMe)H2CHCHCH2](µ-H), 7. Compounds 5 and 7 are isomers containing substituted η3-allyl ligands formed by the coupling of the ethylene to the CH-activated ß-carbon atom of the acryloyl ligand accompanied by some metal-mediated H-shifts. Compound 6 contains an uncoupled π-coordinated ethylene ligand. Compound 7 was isomerized to 5 thermally at 80 °C. Compound 4 reacts with ethylene in the presence of Me3NO to yield two new Ru5 products: Ru5(µ5-C)(CO)13[η4-1,1- anti- syn-[(O2CMe)C(Me)CHCH2](µ-H), 8, and Ru5(µ5-C)(CO)13[η4-1- anti-CH(Me)C(O2CMe)(CH2)](µ-H), 9. Compounds 8 and 9 both contain substituted η3-allyl ligands formed by the coupling of the ethylene to the CH-activated α-carbon atom of the vinyl acetyl ligand. Compound 8 was isomerized to 9 thermally at 80 °C. All new products were characterized structurally by single-crystal X-ray diffraction analyses.
RESUMEN
Reactions of Re2(CO)8(µ-C6H5)(µ-H), 1, with naphthalene and anthracene have yielded the first multiply-CH activated arene products through the reductive elimination of benzene from 1 and multiple oxidative-additions of the dirhenium octacarbonyl grouping to these polycyclic aromatic compounds under very mild conditions. In addition, compound 1 was found to react with itself to yield the bis-Re2-metalated C6H4 bridged compound Re2(CO)8(µ-H)(µ-1,µ-3-C6H4)Re2(CO)8(µ-H), 3. Reaction of 1 with naphthalene yielded two doubly CH activated isomers, Re2(CO)8(µ-H)(µ-η2-1,2-µ-η2-3,4-C10H6)Re2(CO)8(µ-H), 4, 41% yield, and Re2(CO)8(µ-H)(µ-η2-1,2-µ-η2-5,6-C10H6)Re2(CO)8(µ-H), 5, via the mono CH activated intermediate Re2(CO)8(µ-η2-C10H7)(µ-H), 2. Compound 4 contains two Re2(CO)8(µ-H) groups on one C6 ring formed by CH activations at the 2- and 4-positions. Compound 5 contains two Re2(CO)8(µ-H) groups; one formed by CH activation at the 2-position on one C6 ring and the other formed by CH activation at the 6-position (or centrosymmetrically related 2'-position) on the second C6 ring. The Re2(CO)8(µ-H) groups are coordinated to the C6 rings by binuclear σ + π coordination to two adjacent carbon atoms in the rings. Compound 1 reacts with anthracene to yield the mono-CH activated compound Re2(CO)8(µ-η2-1,2-C14H9)(µ-H), 6, and two doubly CH activated compounds, Re2(CO)8(µ-H)(µ-η2-1,2-µ-η2-3,4-C14H8)Re2(CO)8(µ-H), 7, and Re2(CO)8(µ-H)(µ-η2-1,2-µ-η2-5,6-C14H8)Re2(CO)8(µ-H), 8. Compounds 7 and 8 are isomers that are structurally similar to 4 and 5. Compounds 7 and 8 can also be obtained in good yields from the reaction of 6 with 1. In the presence of a 5/1 ratio of 1/anthracene, a small amount (5% yield) of the tetra-substituted anthracene product [Re2(CO)8(µ-H)]4(µ-η2-1,2-µ-η2-3,4-µ-η2-5,6-µ-η2-7,8-C14H6), 9, was formed. Compound 9 contains four σ + π coordinated Re2(CO)8(µ-H) groups formed by oxidative additions of the CH bonds of anthracene to the Re2(CO)8 groups at the 2, 4, 6, and 8 positions of the three ring system. Molecular orbital calculations have been performed for all new compounds in order to develop an understanding of the bonding of the ring systems to the Re2(CO)8(µ-H) groups. All new compounds were characterized by single-crystal X-ray diffraction analyses.
RESUMEN
The reaction of Re2(CO)8(µ-C6H5)(µ-H) (1) with thiophene in CH2Cl2 at 40 °C yielded the new compound Re2(CO)8(µ-η2-SC4H3)(µ-H) (2), which contains a bridging σ-π-coordinated thienyl ligand formed by the activation of the C-H bond at the 2 position of the thiophene. Compound 2 exhibits dynamical activity on the NMR time scale involving rearrangements of the bridging thienyl ligand. The reaction of compound 2 with a second 1 equiv of 1 at 45 °C yielded the doubly metalated product [Re2(CO)8(µ-H)]2(µ-η2-2,3-µ-η2-4,5-C4H2S) (3), formed by the activation of the C-H bond at the 5 position of the thienyl ligand in 2. Heating 3 in a hexane solvent to reflux transformed it into the ring-opened compound Re(CO)4[µ-η5-η2-SCC(H)C(H)C(H)][Re(CO)3][Re2(CO)8(µ-H)] (4) by the loss of one CO ligand. Compound 4 contains a doubly metalated 1-thiapentadienyl ligand formed by the cleavage of one of the C-S bonds. When heated to reflux (125 °C) in an octane solvent in the presence of H2O, the new compound Re(CO)4[η5-µ-η2-SC(H)C(H)C(H)C(H)]Re(CO)3 (5) was obtained by cleavage of the Re2(CO)8(µ-H) group from 4 with formation of the known coproduct [Re(CO)3(µ3-OH)]4. All new products were characterized by single-crystal X-ray diffraction analyses.
RESUMEN
Hydrocarbamoylation of C2H2 by N, N-dimethylformamide (DMF) to N, N-dimethylacrylamide was effected by a series of cluster-opening reactions with Ru5(µ5-C)(CO)15 (1). The reaction of 1 with DMF yielded the new complexes Ru5(µ5-C)(CO)14(µ-η2-OâCNMe2)(µ-H) (2) and a minor coproduct Ru5(µ5-C)(CO)13(HNMe2)(µ-η2-OâCNMe2)(µ-H) (3) by a cluster-opening activation of the formyl C-H bond of DMF. Compound 3 was obtained from 2 by a further reaction with DMF. Compound 3 reacted with C2H2 (1 atm, 70 °C) to yield Ru5(µ5-C)(CO)13(µ-η3-OâCNMe2CHCH)(µ-H) (4) by the addition and coupling of C2H2 to the bridging dimethylformamido ligand. Compound 4 contains a σ-π-coordinated, dimethylformamido-substituted vinyl ligand that bridges a Ru-Ru edge of an open Ru5C cluster. The formamido group is also coordinated to one of the metal atoms. The addition of CO (1 atm, 25 °C) to 4 yielded the CO adduct Ru5(µ5-C)(CO)14(η2-OâCNMe2CHâCH)(µ-H) (5) containing a chelating dimethylacrylamido ligand, which released dimethylacrylamide by the reductive elimination of a C-H bond upon a further addition of CO (400 psi, 125 °C) with the re-formation of 1. All of the products were characterized by single-crystal X-ray diffraction analyses.
RESUMEN
Multiple aromatic CH activations by a dirhenium complex have provided meta-related dimetallated arene rings in the complexes Re2(CO)8(µ-H)(µ-η2-1,2-µ-η2-3,4-C14H8)Re2(CO)8(µ-H), 3 and Re2(CO)8(µ-H)(µ-η1-1,µ-η1-3-C6H4)Re2(CO)8(µ-H), 4. Both products were characterized structurally by single crystal X-ray diffraction and DFT molecular orbital analyses.