Oxidative dehydrodimerization of rhenium vinylidene complex (η5-C5H5)(CO)2ReCC(H)Ph: two competitive routes of coupling of σ-phenylethynyl intermediate [(η5-C5H5)(CO)2ReCCPh]. X-ray structures of rhenium mononuclear (η5-C5H5)(CO)2ReCC(H)Ph and binuclear [(η5-C5H5)(CO)2Re]2(μ2-CC(Ph)CCPh) vinylide... (original) (raw)
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Oxidative dehydrodimerization of rhenium vinylidene complex (? 5-C 5H 5)(CO) 2Re C C(H)Ph: two compe
Developments in Petroleum Science, 2004
The oxidation of the rhenium vinylidene complex (g 5-C 5 H 5)(CO) 2 Re@C@C(H)Ph (2) with one equivalent of AgBF 4 or (C 5 H 5) 2 FeBF 4 leads to the radical cation [(g 5-C 5 H 5)(CO) 2 Re@C@C(H)Ph] +Å (2 +Å) which undergoes dehydrodimerization only in the presence of triethylamine affording a mixture of the binuclear compounds (g 5-C 5 H 5)(CO) 2 Re@C@C(Ph)C(Ph)@C@Re (CO) 2 (g 5-C 5 H 5) (6, 55%) and [(g 5-C 5 H 5)(CO) 2 Re] 2 (l 2-C@C(Ph)CBCPh) (9, 22%). Both 6 and 9 are believed to arise via competitive C b-C b and C b-Re couplings of the intermediate r-phenylethynyl radicals [(g 5-C 5 H 5)(CO) 2 ReACBCPh] Å (5 Å). The former process directly yields 6 and the latter one produces 9 after reductive elimination and a 1,2-shift of the metal containing moiety. The enthalpies of C b-C b (À30.3 kcal/mol) and C b-Re (+0.3 kcal/mol) coupling processes estimated by DFT calculations are in accordance with the 6:9 ratio observed. The electrochemical behavior of 2, 6, 9 was studied by cyclic voltammetry. The X-ray structures of 2 and 9 are reported.
Organometallics, 1989
The reaction of bis(dimethy1phosphino)methane with R u~( C O )~~ under CO pressure at 120 "C leads to the quantitative formation of the binuclear ruthenium complex R~, ( d m p m )~( C O )~ Although this complex was previously unreported, the s ectroscopic data and X-ray crystallographic analysis [ P l space group, a = 10.569 (2) A, b = 11.964 (2) i, c = 12.232 (4) A, LY = 77.22 (2)O, = 77.53 (3)O, y = 75.14 (3)O, V = 1437 (1) A3, 2 = 21 show that it has a structure analogous to that found for related bmucleatmg diphosphines. The reaction of R~~( d m p m ) , ( C O )~ with acids such as HBF4 occurs rapidly and leads t o quantitative protonation of the metal-metal bond forming [HRuz(dmpm),(CO),]BF4. The reaction with diphenylacetylene occurs at 90 "C in toluene leading t o R U~(~~~~)~( C O )~( C~H & C C~H~) , which was shown to contain a az-bridging acetylene ligand by X-ray crystallograph [m1/a space group, a = 13.140 (3) A, b = 15.157 (4) A, c = 16.280 (3) A, p = 92.56 (2)O, V = 3239 (2) i3, 2 = 41. Although the analogous product can be isolated by treating R~~( d m p m )~( C O )~ c2 c10 m A. Ligand-Metal-Ligand C(ll)-R~(l)-C(l2) 100.6 (2) C(22)-Ru(2)-C(21) 101.4 (2) C(ll)-Ru(l)-C(OA) 99.8 (2) C(22)-Ru(2)-C(OB) 99.3 (2) C(ll)-R~(l)-P(l2) 88.6 (2) C(22)-Ru(Z)-P(22) 90.8 (2) C(ll)-Ru(l)-P(ll) 90.2 (2) C(22)-Ru(2)-P(21) 88.0 (2) C (1 l)-Ru( l)-Ru(2) 167.3 (1) C (22)-Ru(2)-Ru( 1) 167.1 (2) C(12)-Ru(l)-C(OA) 159.3 (2) C(2l)-Ru(2)-C(OB) 159.0 (2) C(12)-Ru(l)-P(12) 92.6 (2) C(2l)-Ru(Z)-P(22) 91.8 (2) C(l2)-R~(l)-P(ll) 91.9 (2) C(21)-Ru(2)-P(21) 93.4 (2) C(12)-Ru(l)-Ru(2) 91.8 (2) C(21)-Ru(Z)-Ru(l) 91.3 (2) C(OA)-Ru(l)-P(12) 84.5 (1) C(OB)-Ru(2)-P(22) 91.4 (1) C(OA)-Ru(l)-P(ll) 91.4 (1) C(OB)-Ru(2)-P(21) 83.8 (1) C(OA)-Ru(l)-Ru(2) 68.1 (1) C(OB)-Ru(2)-Ru(l) 68.2 (1) P(l2)-R~(l)-P(ll) 175.49 (5) P(22)-Ru(2)-P(21) 174.84 (5) P(12)-Ru(l)-Ru(2) 93.75 (4) P(22)-Ru(2)-Ru(l) 86.52 (4) P(ll)-Ru(l)-Ru(2) 86.53 (4) P(21)-Ru(2)-Ru(l) 93.55 (4) B. Metal Carbonyls and Other Ligands Ru(l)-P(ll)-C(l) 116.1 (2) Ru(2)-P(21)-C(l) 114.1 (2) Ru(l)-P(12)-C(2) 114.2 (2) Ru(2)-P(22)-C(2) 116.4 (2) Ru(l)-C(ll)-O(ll) 177.3 (5) Ru(2)-C(22)-0(22) 177.2 (4) R~(l)-C(12)-0(12) 177.7 (5) Ru(2)-C(21)-0(21) 178.7 (5) Ru(l)-C(OA)-C(OB) 112.2 (3) Ru(2)-C(OB)-C(OA) 111.5 (3) Ru(l)-C(OA)-C(lA) 125.5 (3) Ru(2)-C(OB)-C(lB) 124.4 (3) C(lA)-C(OA)-C(OB) 122.3 (4) C(1B)-C(0B)-C(0A) 124.0 (4) P(ll)-C(l)-P(21) 109.9 (2) P(12)-C(2)-P(22) 110.5 (2)
Organometallics, 1999
Reaction of Cp*Re(CO) 2 I 2 with methylcopper affords cis-Cp*Re(CO) 2 (Me)I, which converts to the trans isomer on prolonged reaction or in the presence of neutral alumina. The X-ray structure of the trans isomer has been determined. The related chloro complexes Cp*Re-(CO) 2 (Me)Cl and Cp*Re(CO) 2 (p-tolyl)Cl are formed in the photolyses of compounds 3 and 1 (below) in CCl 4 . Photolysis of Cp*Re(CO) 2 (Me)R (R ) p-tolyl (1), Ph (2), Me (3)) in the presence of CO has been carried out in hydrocarbons, CCl 4 , and benzene-d 6 . In hydrocarbons, 1 and 2 produce Cp*Re(CO) 3 , CH 4 , and either toluene or benzene, respectively; 3 produces Cp*Re-(CO) 3 and CH 4 . In benzene-d 6 1 gave CH 3 D and toluene-4-d, and 3 gave mainly CH 3 D. These results are consistent with a general scheme involving successive homolysis of the metalmethyl and metal-aryl bonds to give methyl and aryl radicals that abstract H or D from the solvent and carbonylation of the rhenium dicarbonyl fragment. Products known or expected to arise from further photolysis of Cp*Re(CO) 3 in benzene-d 6 , such as Cp* 2 Re 2 (CO) 3 , Cp* 2 Re 2 (CO) 5 , and Cp*Re(CO) 2 (η 2 -C 6 D 6 ), were also found. Photolysis of 1 in CCl 4 in the presence or absence of CO gave CH 3 Cl and Cp*Re(CO) 2 (p-tolyl)Cl, but no p-chlorotoluene, indicating the preferential homolysis of the Re-Me bond and the rapid scavenging of the subsequent radicals by the chlorinated solvent. Photolysis of the dimethyl complex 3 gave CH 3 Cl and some evidence of a small amount of Cp*Re(CO) 2 (Me)Cl, but the major rhenium product was Cp*Re(CO) 2 Cl 2 , consistent with the more facile homolysis of both Re-Me bonds in 3. Production of small amounts of CH 2 D 2 (in benzene-d 6 ) and CH 4 and CH 2 Cl 2 (in CCl 4 ) are discussed in terms of a competing pathway. Notably, in none of these photolyses were there observed other than trace amounts of products such as p-xylene, which would be expected to be major products if reductive elimination were to occur.
Journal of The American Chemical Society, 2006
Anodic oxidation of the important half-sandwich compound CoCp(CO)2, 1, has been studied under gentle electrolyte conditions, e.g., chlorinated hydrocarbons with weakly coordinating anion (WCA) supporting electrolyte anions. The 17-electron cation 1 + produced at E1/2(1) ) 0.37 V vs FeCp2 0/+ undergoes a surprising reaction with neutral 1 to form the dimer radical cation [Co2Cp2(CO)4] + , 2 + , which has a metalmetal bond unsupported by bridging ligands. The dimer radical is oxidized at a slightly more positive potential (E1/2 ) 0.47 V) to the corresponding dication 2 2+ . Observation of the oxidation of 2 + is without precedent in confirming a radical-substrate (R-S) dimerization process by direct voltammetric detection of the R-
Journal of The American Chemical Society, 2002
Anodic oxidation of the important half-sandwich compound CoCp(CO)2, 1, has been studied under gentle electrolyte conditions, e.g., chlorinated hydrocarbons with weakly coordinating anion (WCA) supporting electrolyte anions. The 17-electron cation 1 + produced at E1/2(1) ) 0.37 V vs FeCp2 0/+ undergoes a surprising reaction with neutral 1 to form the dimer radical cation [Co2Cp2(CO)4] + , 2 + , which has a metalmetal bond unsupported by bridging ligands. The dimer radical is oxidized at a slightly more positive potential (E1/2 ) 0.47 V) to the corresponding dication 2 2+ . Observation of the oxidation of 2 + is without precedent in confirming a radical-substrate (R-S) dimerization process by direct voltammetric detection of the R-
Radical Pathways in Reactions of Transition Metal Organometallic Compounds
Annals of the New York Academy of Sciences, 1980
Nearly all transition metal organometallic compounds are spin-paired, closedshell, ground-state molecules. For the most part, they obey the so-called 18-electron rule, which means that the sum of valence shell electrons from the metal atom, and the electrons that may be considered as donated from the ligands in the u interaction with the metal, totals 18. It has long been recognized that coordinative unsaturation at the metal is a prerequisite for many of the most important reaction processes involving transition metal organometallic species. Loss of a ligand, e.g., CO, or a valence tautomeric equilibrium (e.g., q3-CsH5 C I q1-C3H5), results in formation of a 16-electron species in so1ution.t