Dirhenium Carbonyl Complexes Research Articles

C – C coupling of alkynes to the CH2 group in a 1-phosphonioethenyl ligand in a zwitterionic dirhenium carbonyl complex

Reactions of the zwitterionic dirhenium complex Re2(CO)8[μ-η2-1-C(CH2)(PMePh2)], 3 with the terminal alkynes, HCC(OEt) and HCCPh, have yielded two new isomeric ethoxy-substituted dirhenium complexes, Re2(CO)7[µ-η3-C(H)C(OCH2CH3)CH2C(PMePh2)], 5 and Re2(CO)7[µ-η3-C(OCH2CH3)C(H)CH2C(PMePh2)], 6 and one phenyl-substituted dirhenium complex Re2(CO)7[µ-η3-C(H)CPhCH2C(PMePh2)], 7, respectively, with each containing a bridging, substituted 1-phosphonio-3,4-butenyl ligand formed by loss of CO and the addition and coupling of one alkyne to the CH2 group of the 1-phosphonioethenyl ligand in 3. The bridging 1-phosphonio-3,4-butenyl ligand in compound 6 exhibits a dynamical “flip-flop” exchange for the phosphonio-3,4-butenyl ligand between the two rhenium atoms that leads to an averaging of the inequivalent protons on its methylene group that is rapid on the NMR timescale. When heated to 70oC, compound 5 was converted to two new compounds: Re2(CO)6(µ-H)[µ-η4-C(H)C(OCH2CH3)CHC(PMePh2)], 8, by loss of a CO ligand and a CH activation at the CH2 group in its C(H)C(OCH2CH3)CH2C(+PMePh2) ligand and an isomer Re2(CO)6(PMePh2)[µ-η4-C(H)C(OCH2CH3)CHCH], 9. Compound 9 was also obtained from 8 by heating to 80 °C for 5 days by shifting the PMePh2 group from its phosphonium carbon atom in 8 to one of the rhenium atoms to become a PMePh2 ligand in 9 and then shifting the hydrido ligand back to the same carbon atom to form a bridging η4-2-ethoxybutadiendiyl, [C(H)C(OCH2CH3)CHCH], ligand. All new products were characterized structurally by single-crystal X-ray diffraction analyses.

Synthesis and Chemistry of Ammonioethenyl and Phosphonioethenyl Ligands in Zwitterionic Dirhenium Carbonyl Complexes.

New zwitterionic dirhenium carbonyl complexes containing ammonioethenyl and phosphonioethenyl ligands have been synthesized and studied. The reaction of Re2(CO)10 with C2H2 and Me3NO yielded the dirhenium complex Re2(CO)9(NMe3) (6) and the new zwitterionic complex Re2(CO)9[η1-E-2-CH═CH(NMe3)] (7). Compound 6 was characterized structurally and was found to have a NMe3 ligand in an equatorial coordination site cis to a long Re-Re single bond, Re-Re = 3.0938(2) Å. Compound 7 can be obtained from the reaction of 6 with ethyne (C2H2) formally by the insertion of ethyne into the Re-N bond to the NMe3 ligand. Compound 7 contains a 2-trimethylammonioethenyl ligand, -CH═CH(+NMe3), that is formally a zwitterion having a positive charge on the nitrogen atom and a negative charge on the terminal carbon atom. When coordinated to rhenium by the terminal ethenyl carbon atom, the negative charge on the -CH═CH(+NMe3) carbon atom is formally transferred to the rhenium atom. The reaction of Re2(CO)10 with C2H2 and NEt3 in the presence of Me3NO yielded the new dirhenium complex Re2(CO)9[η1-E-2-CH═CH(NEt3)] (8) together with some 6 and 7. Compound 8 is structurally similar to 7, but it contains a NEt3 group in the ammonioethenyl ligand in the place of the NMe3 group in 7. Reactions of 7 with PMePh2 and PPh3 yielded the zwitterionic 2-arylphosphonioethenyl-coordinated dirhenium carbonyl complexes, Re2(CO)9[η1-E-2-CH═CH(PPh2Me)] (9a) and Re2(CO)9[η1-E-2-CH═CH(PPh3)] (9b), and the zwitterionic 1-phosphonioethenyl ligand in the dirhenium carbonyl complexes, Re2(CO)9[η1-1-C(PPh2Me)(═CH2)] (10a), Re2(CO)8[μ-η2-1-C(PPh2Me)(═CH2)] (11a), and Re2(CO)8[[μ-η2-1-C(PPh3)(CH2)] (11b). Compound 10a was converted to 11a and the new compound Re2(CO)7(μ-H)[μ-η2-1-(CH2C)P(Ph)(Me)(o-C6H4)], (12) by decarbonylation using Me3NO. Compound 12 contains an ortho-metalated phenyl ring. The new products 6,7, 8, 9b, 10a, 11a, 11b and 12 were characterized structurally by single-crystal X-ray diffraction analyses.

Reductive coupling of diisopropylcarbodiimide by a dirhenium carbonyl complex

The reaction of Re2(CO)8(μ-H)[μ-η2-C(H) = C(H)Bun] with N,N′-diisopropylcarbodiimide yielded the new rhenium diamidinate complex [Re(CO)4]2[(μ-C2(N{iPr})4], 2, in 59% yield that was formed by the reductive coupling of two of carbodiimide molecules at the central carbon atom. The diamidinate ligand is nonplanar and four iminyl nitrogen atoms are coordinated to two Re(CO)4 groups in two chelating groups that have formed five-membered rings. Density functional molecular orbital analyses were used to explain the bonding of the diamidinate ligand to the two rhenium atoms. A second product Re2(CO)8(μ-OH)(μ-H), 3 was obtained from the reaction of N,N′-diisopropylcarbodiimide and Re2(CO)8(μ-C6H5)(μ-H), 1. Compound 3 was subsequently found to be a product of the reaction of 1 with traces of H2O in the original reaction and was independently obtained in 60% yield from the reaction of 1 with H2O. Compound 3 contains a bridging hydroxo ligand and a bridging hydrido ligand across the Re–Re bond between two mutually bonded Re(CO)4 groups. Both new compounds were characterized structurally by single-crystal X-ray diffraction analysis.

High variety of coordination modes of π-conjugated phospholes in dinuclear rhenium carbonyls. Fluxional behavior of σ,π-complexes

A variety of dirhenium carbonyl complexes containing π-conjugated phosphole derivatives were obtained from reaction of [Re2(CO)8(CH3CN)2] with each of the following phospholes: 2,5-bis(2-thienyl)-1-phenylphosphole (btpp), 2,5-bis(2-pyridyl)-1-phenylphosphole (bpypp) and 1,2,5-triphenylphosphole (tpp). The π-conjugated phospholes were found to behave as two-, four- or six-electron donor ligands via σ or σ-π interactions with the metal centers, presenting bridging or chelating coordination modes as determined by spectroscopic methods and single crystal X-ray diffraction analysis. Metal-metal bond cleavage was evidenced when btpp was used, leading to a mono-substituted mononuclear complex. Variable-temperature 1H NMR studies for σ,π-complexes showed a fluxional behavior due to the restricted rotation around the PC and CC bonds of the 1,2,5-trisubstituted phosphole ring.

Multiple Aromatic C-H Bond Activations by an Unsaturated Dirhenium Carbonyl Complex.

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.

Synthesis, characterization and catalytic activities of rhenium carbonyl complexes bearing pyridine-alkoxide ligands

Thermal treatment of Re2(CO)10 with pyridine-alkoxide ligands PyC(CH2)4OH (LaH) and PyCR1R2OH (R1 = CH3, R2 = C6H5 (LbH); R1 = H, R2 = C6H5 (LcH); R1 = H, R2 = 4-CH3C6H4 (LdH); R1 = H, R2 = 4-OMeC6H4 (LeH); R1 = H, R2 = 4-ClC6H4 (LfH); R1 = H, R2 = 4-CF3C6H4 (LgH)) respectively in refluxing xylene generated a series of dirhenium carbonyl complexes [PyC(CH2)4O]2 [Re(CO)3]2 (1a) and (PyCR1R2O)2 [Re(CO)3]2 (R1 = CH3, R2 = C6H5 (1b); R1 = H, R2 = C6H5 (1c); R1 = H, R2 = 4-CH3C6H4 (1d); R1 = H, R2 = 4-OMeC6H4 (1e); R1 = H, R2 = 4-ClC6H4 (1f); R1 = H, R2 = 4-CF3C6H4 (1g)). Complexes 1a−1g were characterized by NMR spectroscopy, elemental analyses and FT-IR spectroscopy. Furthermore, the molecular structures of complexes 1a, 1d and 1g were determined by single crystal X-ray diffraction analysis. In the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxyl) as co-oxidant and molecular oxygen (ambient air) as terminal oxidant, these dirhenium carbonyl complexes showed moderate catalytic activity for aerobic oxidation of secondary alcohols.

Multiple C-H Bond Activations and Ring-Opening C-S Bond Cleavage of Thiophene by Dirhenium Carbonyl Complexes.

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.

Multiple aromatic C-H bond activations by a dirhenium carbonyl complex.

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.

Formyl C-H activation in N,N-Dimethylformamide by a dirhenium carbonyl complex

The reaction of Re2(CO)8[μ-η2-C(H)=C(H)Bun](μ-H), 1 with N,N-dimethylformamide (DMF) at 70 C for 6 h has yielded three new compounds: Re2(CO)8(μ-η2-O=CNMe2)(μ-H), 2, (16% yield), Re2(CO)7(NHMe2)(μ-η2-O=CNMe2)(μ-H), 3, (30% yield), Re2(CO)9(NHMe2), 4 (14% yield). Compounds 2 and 3 contain a C,O-η2-bridging formamido (O=CNMe2) ligand and a bridging hydrido ligand that were formed by the elimination of hexene from 1 and the oxidative addition of the formyl C-H bond of the DMF to the dirhenium group of 1. Compound 3 also contains an NHMe2 ligand that was apparently formed by the decarbonylation of DMF and the transfer of the formyl hydrogen atom to the NMe2 group. Compound 4 contains a similarly formed NHMe2 ligand. Compound 2 was also obtained by the reaction of 3 with CO and compound 3 was obtained by the reaction of 2 with DMF. Compound 4 was obtained independently in a high yield by the reaction of Re2(CO)9(NCMe) with NHMe2. Compounds 2, 3 and 4 were characterized structurally by single-crystal X-ray diffraction analyses.

Facile cleavage of a phenyl group from SbPh 3 by dirhenium carbonyl complexes

The complex Re 2(CO) 8[μ-η 2-C(H) C(H)Bu n ](μ-H) ( 1) reacts with SbPh 3 at 68 °C to yield the new σ-phenyl dirhenium complex Re 2(CO) 8(SbPh 3)(Ph)(μ-SbPh 2) ( 4) in 72% yield. Compound 4 contains two rhenium atoms held together by a bridging SbPh 2 ligand. One rhenium atom contains a σ-phenyl group. The other rhenium atom contains a SbPh 3 ligand. Compound 4 was also obtained in 34% yield from the reaction of Re 2(CO) 10 with SbPh 3 in the presence of UV–Vis irradiation together with some monorhenium products: HRe(CO) 4SbPh 3 ( 5), Re(Ph)(CO) 4SbPh 3 ( 6) and fac-Re(Ph)(CO) 3(SbPh 3) 2 ( 7) in low yields. Complex 4 is split by reaction with an additional quantity of SbPh 3 to yield the monorhenium SbPh 3 complexes 6, 7 and mer-Re(Ph)(CO) 3(SbPh 3) 2 ( 8) that contain a σ-phenyl ligand. When 4 was treated with hydrogen, the phenyl ligand was eliminated as benzene and the dirhenium complexes Re 2(CO) 8(μ-SbPh 2)(μ-H) ( 10), and Re 2(CO) 7(SbPh 3)(μ-SbPh 2)(μ-H) ( 11), were formed that contain a bridging hydrido ligand. The doubly SbPh 2-bridged dirhenium complex Re 2(CO) 7(SbPh 3)(μ-SbPh 2) 2 ( 9) that has no metal–metal bond was also formed in these two reactions.

μ-Chloro-(μ-dicyclohexylphosphanido)bis[tricarbonyl(triphenylphosphine)rhenium

This is the first crystallographically characterized dirhenium carbonyl complex to contain one chloro and one phosphido bridge.

Catalytic Cyclooligomerization of Thietane by Dirhenium Carbonyl Complexes.

Catalytic Cyclooligomerization of Thietane by Dirhenium Carbonyl Complexes.

Reactions of a Dicarboxylate-Substituted Allene with Activated Dirhenium Carbonyl Complexes

The compound Re(CO)4[C(CH2CO2Me)C(H)CO2Me], 1, was obtained in 83% yield when a mixture of Re2(CO)9(NCMe) and MeO2C(H)CCC(H)CO2Me in a hexane solution was heated to reflux for 1.5 h. The addition of one hydrogen atom to the allene grouping was shown to be derived from adventitious water. The reaction of 1 with PMe2Ph yielded the derivative fac-Re(CO)3(PMe2Ph)[C(CH2CO2Me)C(H)CO2Me], 2, in 98% yield. The reaction of Re2(CO)8(PMe2Ph)(NCMe) with MeO2C(H)CCC(H)CO2Me yielded two isomeric products mer-Re2(CO)6(PMe2Ph)[μ-η3-η1-MeO2C(H)CCC(H)CO2Me], 3 (31%), and fac-Re2(CO)6(PMe2Ph)[μ-η3-η1-MeO2C(H)CCC(H)CO2Me], 4 (22%), which contain bridging η3-η1-MeO2C(H)CCC(H)CO2Me dicarboxylateallene ligands and small amounts of three mononuclear nuclear products: fac-Re(CO)3(PMe2Ph)[MeO2CCH2CC(H)CO2Me], 2 (8%), mer-Re(CO)3(PMe2Ph)(MeO2CCH2CCHCO2Me), 5 (5%), and a trace of 1. The carbonyl oxygen atom of one of the carboxylate groups is coordinated to one of the metal atoms in 3 and 4. Compound 3 slowly isomerizes to 4 at 25 ...

Ring-Opening Insertion of a Substituted Dithiazole-3-thione into the Re−Re Bond in a Dirhenium Carbonyl Complex

The reaction of the complex Re{sub 2}(CO){sub 9}(NCMe) with 5-((ethoxycarbonyl)amino)-1,2,4-dithiazole-3-thione (1) has yielded the series of complexes Re(CO){sub 4}[{mu}-S{sub 2}CNC(N(H)CO{sub 2}Et)S]Re(CO){sub 5} (2; 8% yield), Re(CO){sub 4}[{mu}-S{sub 2}CNC(NHCO{sub 2}Et)S]Re(CO){sub 4} (3; 14% yield), and Re(CO){sub 4}[{mu}-S{sub 2}CNHC(NCO{sub 2}Et)S]Re(CO){sub 4} (4; 27% yield) by the ring-opening insertion of 1 into the rhenium-rhenium bond of Re{sub 2}(CO){sub 9}(NCMe). The sulfur-sulfur bond in 1 was also cleaved. Two mononuclear rhenium complexes, Re(CO){sub 4}[S{sub 2}CNHCSNH(CO{sub 2}Et)] (5; 14% yield) and Re(CO){sub 4}[SCNC(NHCO{sub 2}Et)SCSN] (6; 6% yield), were also isolated and characterized. Compounds 3 and 4 are isomers that exist in an equilibrium at room temperature. The isomerization of 3 to 4 and vice versa is catalyzed by the presence of pyridine. Each of the complexes 2-6 as well as the starting material 1 was characterized by a single-crystal X-ray diffraction analysis. 16 refs., 6 figs., 3 tabs.

Catalytic Cyclooligomerization of Thietane by Dirhenium Carbonyl Complexes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic Cyclooligomerization of Thietane by Dirhenium Carbonyl ComplexesRichard D. Adams and Stephen B. FalloonCite this: Organometallics 1995, 14, 4, 1748–1755Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April 1995https://doi.org/10.1021/om00004a030RIGHTS & PERMISSIONSArticle Views120Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (983 KB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts

Transformation of alkenyl-N-arylthioamido ligands into quinoline-2-thiolate ligands in dirhenium carbonyl complexes

Irradiation of the alkenyl-N-arylthioamide complexes Re(CO)[sub 4][(E)-HC=C(CO[sub 2]Me)C=N-(C[sub 6]H[sub 4]-p- R)S] Re(CO)[sub 4], 1a-c, R = H, Me, Cl, in the presence of iodine yielded a mixture of four products: Re[sub 2](CO)[sub 7][[mu]-2-S-3-CO[sub 2]Me-6-RNC[sub 9]H[sub 4]] ([mu]-I), 2a-c, R = H, Me, Cl; Re(CO)[sub 4][(E)-HC=C-(CO[sub 2]Me) C=N(C[sub 6]H[sub 4]-p-R)S]Re[sub 2](CO)[sub 7]([mu]-I), 3a-c, R = H, Me, Cl;Re(CO)[sub 4][(E)-HC=C(CO[sub 2]Me)C-(NHC[sub 6]H[sub 4]-p- R)=S] B Re(CO)[sub 4](I), 4a-c, R = H, Me, Cl;Re(CO)[sub 4](2-S-3-CO[sub 2]Me-6-RNC[sub 9]H[sub 4]), 5a-c, R = H, Me, Cl, with compounds 5 being the major products. Compounds 2a-c, 4a-c, and 5a-c are new. Compounds 4a-c were also obtained from the reaction of 1a-c with HI. UV irradiation of 1b in the absence of iodine yielded the compounds Re[sub 2](CO)[sub 8][[mu]-2-S-3-CO[sub 2]Me-6-MeNC[sub 9]H[sub 4]] ([mu]-H) , 6b, Re[sub 2](CO)[sub 7][[mu]-2-S-3-CO[sub 2]Me-6-MeNC[sub 9]H[sub 4]]([mu]-H) , 7b, and 5b, while UV irradiation of 6b yielded 7b and 5b plus Re[sub 3](CO)[sub 12]([mu]-H)[sub 3]. UV irradiation of 2b in the presence of CO yielded 5b plus Re[sub 2](CO)[sub 8]([mu]-I)[sub 2]. UV irradiation of 3b also yielded 2b, 5b, and some 7b. Treatment of 7b with iodine yielded 2b. Finally, from the UV irradiation of 5b the dimer [Re(CO)[sub 3](2-S-3-CO[sub 2]Me-6-MeNC[sub 9]H[sub 4])][submore » 2], 8b, was obtained in 57% yield. Complexes 2b, 4c, 5b, 6b, 7b, and 8b were characterized by single crystal X-ray diffraction analyses. The compounds 2 and 5-8 all contain substituted quinoline-2-thiolate ligands formed by the coupling of one of the carbon atoms of the aryl ring to the hydrogen-substituted carbon atom of the alkeny group. Crystal data are provided. 11 refs., 6 figs., 7 tabs.« less

Studies of the coupling of aryl isothiocyanates to bridging alkyne ligands in dirhenium carbonyl complexes

Reactions of the lightly stabilized dimetalated olefin complex Re(CO)[sub 4][trans-[mu]-HC=C(CO[sub 2]Me)]Re(CO)[sub 4](NCMe) (1) with aryl isothiocyanates have yielded a series of complexes having the general formula Re(CO)[sub 4][(E)-HC=C(CO[sub 2]Me)CN(Ar)=S]Re(CO)[sub 4] (2a, Ar = p-tolyl; 2b, Ar = Ph; 2c, Ar = p-chlorophenyl). Compounds 2a-c were formed by the loss of NCMe from 1 and the addition and insertion of one isothiocyanate molecule into one of the metal-carbon bonds to form a thioamido group that is chelated to one of the rhenium atoms. When heated to 98[degrees]C, complexes 2a-c were decarbonylated and converted into the dimeric complexes [Re-(CO)[sub 4](E)-HC=C(CO[sub 2]ME)CN(Ar)=S]Re(CO)[sub 3] B[sub 2] (3a, Ar = p-tolyl; 3b, Ar = Ph; 3c, Ar = Ph; 3c, Ar = p-chlorophenyl), in which the sulfur atoms of the thioamido groups bridge the two metal atoms. Decarbonylation of 2a-c at 80[degree]C in the presence of [Re(CO)[sub 4]([mu]-I)] B[sub 2] yielded the trirhenium complexes Re(CO)[sub 4][[mu]-(E)-HC=C(CO[sub 2]Me)CN(Ar)=S]Re[sub 2](CO)[sub 7] ([mu]-I) (4a, Ar = p-tolyl; 4b, Ar = Ph; 4c, Ar = p-chlorophenyl). 12 refs., 4 figs., 7 tabs.

Synthesis and properties of bridging siloxyl ligands in dirhenium carbonyl complexes

Synthesis and properties of bridging siloxyl ligands in dirhenium carbonyl complexes

Facile alkyne coupling reactions in dirhenium carbonyl complexes

The complex (OC)[sub 4]Re[trans-[mu]-HC=C(CO[sub 2]Me)]Re(CO)[sub 5] (1) was converted to the reactive acetonitrile complex (OC)[sub 4]Re[trans-[mu]-HC=C(CO[sub 2]Me)]Re(CO)[sub 4](NCMe) (2) by reaction with Me[sub 3]NO in acetonitrile. Under an atmosphere of CO, complex 2 reacts with HC[triple bond]CO[sub 2]Me in refluxing CH[sub 2]Cl[sub 2] to yield the new complexes (OC)[sub 4]Re[[mu]-C(H)=C(CO[sub 2]Me)C(H)=C(CO[sub 2]Me)]-Re(CO)[sub 5] (3; 11%) and (OC)[sub 4]Re[C(H)=C(CO[sub 2]Me)C(H)=C(CO[sub 2]Me)C(H)= C(CO[sub 2]Me)]Re(CO)[sub 4] (4a,b; 49%, existing in solution as a mixture of isomers) by the head-to-tail coupling of two and three HC[equivalent to]CCO[sub 2]Me molecules, respectively. In the absence of CO only compound 4 and a small amount of the new compound [ovr Re(CO)[sub 4][C[sup 6]H[sub 2](CO][sub 2]Me)(CO[sub 2]Me)[sub 2]] (5;6%) were obtained. Complex 3 was converted into 4 by reaction with additional HC[equivalent to]CCO[sub 2]Me in the presence of Me[sub 3]NO. When heated to 98[degrees]C, 4 was transformed into 5 in 22% yield. Three of the products, 3, 4a, and 5 were characterized crystallographically. In complex 3 the two linked HC[equivalent to]CCO[sub 2]Me groups form a four-carbon chain between the metal-containing groups. One of the carboxylate substituents is also coordinated to form a five-membered metallacyclic ring. In complex 4a the metal-containing groups are joined by a six-carbon chain formedmore » from the three alkynes, and two of the carboxylate groups are coordinated to form five- and six-membered metallacyclic rings. The six-carbon chain in 4 was transformed into a 2,4,6-tris(methoxycarbonyl)phenyl group that is [sigma]-coordinated to the metal atom and also has one of its carboxylate groups coordinated. 10 refs., 3 figs., 6 tabs.« less

The carbonylation of [Re 2(μ-O 2CCH 3)X 2 (μ-dmpm) 3]PF 6 (X = Cl OR Br; dmpm = Me 2PCH 2PME 2) involving a switch in the binding of two of the dmpm ligands from bridging to chelating

The reactions of the triply bonded complexes [Re 2(μ-O 2CCH 3)X 2(μ-dmpm) 3] PF 6 (X = Cl or Br; dmpm = Me 2PCH 2PMe 2) with CO in deoxygenated acetone/HPF 6(aq) mixtures afford the unusual dirhenium(II) carbonyl complexes [Re 2(μ-X) 2(μ-dmpm) (CO) 2(dmpm) 2(H 2PO 4) 2 in which the ReRe bond is very long [2.918(2) Å for X = Cl]. These reactions are accompanied by the switch of two of the bridging dmpm ligands to a chelating mode.