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 Re(CO) with CH and MeNO yielded the dirhenium complex Re(CO)(NMe) () and the new zwitterionic complex Re(CO)[η--2-CH═CH(NMe)] (). Compound was characterized structurally and was found to have a NMe ligand in an equatorial coordination site to a long Re-Re single bond, Re-Re = 3.

"Broken-hearted" carbon bowl electron shuttle reaction: energetics and electron coupling.

Unprecedented one-step C[double bond, length as m-dash]C bond cleavage leading to opening of the buckybowl (π-bowl), that could provide access to carbon-rich structures with previously inaccessible topologies, is reported; highlighting the possibility to implement drastically different synthetic routes to π-bowls in contrast to conventional ones applied for polycyclic aromatic hydrocarbons. Through theoretical modeling, we evaluated the mechanistic pathways feasible for π-bowl planarization and factors that could affect such a transformation including strain and released energies. Through employment of Marcus theory, optical spectroscopy, and crystallographic analysis, we estimated the possibility of charge transfer and electron coupling between "open" corannulene and a strong electron acceptor such as 7,7,8,8-tetracyanoquinodimethane.

Synthesis, Structures, and Transformations of Bridging and Terminally-Coordinated Trimethylammonioalkenyl Ligands in Zwitterionic Pentaruthenium Carbido Carbonyl Complexes.

Reactions of the pentaruthenium cluster complexes Ru(μ-C)(CO) (), Ru(μ-C)(CO)[μ-η-O═C(NMe)](μ-H) (), and Ru(μ-C)(CO)Cl(μ-H) () with ethyne (CH) in the presence of MeNO yielded the zwitterionic complexes Ru(μ-C)(CO)[μ-η-CHCH(NMe)] (), Ru(μ-C)(CO)[μ-η-O═C(NMe)](η--CH═CH(NMe)(μ-H) (), and Ru(μ-C)(CO)Cl[η--CH═CH(NMe)](μ-H) (). Each product contains a positively charged trimethylammonioethenyl ligand, CH═CH(NMe), that is derived from a 2-trimethylammonioethenide, CH═CH(NMe), zwitterion that formally has a positive charge on the nitrogen atom and a negative charge on the terminal enyl carbon atom. The trimethylammonioethenyl ligand, CH═CH(NMe) in is a η-ligand that bridges a Ru-Ru bond on a basal edge of the square-pyramidal Ru cluster by a combination of σ + π cooordination of the ethenyl group.

Zwitterionic Ammoniumalkenyl Ligands in Metal Cluster Complexes. Synthesis, Structures, and Transformations of Zwitterionic Trimethylammoniumalkenyl Ligands in Hexaruthenium Carbido Carbonyl Complexes.

Ru(μ-C)(CO), , has been shown to react with CH when activated by MeNO to yield the complexes RuC(CO)(μ-η-CHNMe), , and RuC(CO)(μ-η-CHNMe), , containing a bridging 2-trimethylammoniumethenyl (CHNMe) ligand and a triply bridging 4-trimethylammoniumbutadienyl (CHNMe) ligand, respectively. Complexes and are formally zwitterionic by virtue of the positive charge on the nitrogen atom and a negative charge that must be assigned formally to the Ru cluster. Compound added CO at room temperature to yield the compound RuC(CO)(η--CHNMe), , that contains a terminally coordinated zwitterionic 2-trimethylammoniumethenyl ligand.

Selective Activation of CH Bonds in Polar Vinyl Olefins and Coupling of Ethylene to the Activated Carbon Atoms in Pentaruthenium Complexes.

Ru(μ-C)(CO), 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 Ru(μ-C)(CO)[η-O═C(OMe)CH═CH](μ-H), 2, and Ru(μ-C)(CO)[η-(MeCO)C═CH](μ-H), 4, respectively. The site of CH activation is dependent on the olefin substituent. In 2, the site of CH activation is the β-carbon atom of the vinyl group, while in 4 the CH activation has occurred exclusively at the α-carbon atom of the vinyl group.

Multiple activations of CH bonds in arenes and heteroarenes.

The activation of CH bonds in arenes and heteroarenes has attracted considerable attention in recent years. Examples of the activation of two or more CH bonds in arenes or heteroarenes are rare. In recent studies it has been found that certain polynuclear metal carbonyl complexes, such as Re(CO)(μ-CH)(μ-H), 1 and Os(CO)(NCMe), can react two or more times with selected arenes and heteroarenes through a series of CH activations to yield interesting new multiply-CH activated arenes and heteroarenes and can lead to the opening of ring systems in the case of heteroarenes.

Activation of Heteroaromatic C-H Bonds in Furan and 2,5-Dimethylfuran.

The reaction of Re(CO)(μ-CH)(μ-H) (1) with furan in CHCl at 40 °C yielded two new isomeric dirhenium compounds, Re(CO)(μ-η-2,3-CHO)(μ-H) (2) and Re(CO)(μ-η-3,2-CHO)(μ-H) (3), which contain a bridging (σ + π)-coordinated furyl ligand formed by activation of the C-H bond at the 2 and 3 positions of furan, respectively. Compound 3 is the first example of a compound formed by C-H bond activation at the 3 position of a furan ring. Compound 3 was isomerized to 2 by heating to 80 °C for 7 days.

Multiple C-H Bond Activations in Corannulene by a Dirhenium Complex.

The reaction of Re (CO) (μ-C H )(μ-H), 1 with corannulene (C H ) yielded the product Re (CO) (μ-H)(μ-η -1,2-C H ), 2 (65 % yield) containing a Re metalated corannulene ligand formed by loss of benzene from 1 and the activation of one of the CH bonds of the nonplanar corannulene molecule by an oxidative-addition to 1. The corannulenyl ligand has adopted a bridging η -σ+π coordination to the Re (CO) grouping. Compound 2 reacts with a second equivalent of 1 to yield three isomeric doubly metalated corannulene products: Re (CO) (μ-H)(μ-η -1,2-μ-η -10,11-C H )Re (CO) (μ-H), 3 (35 % yield), Re (CO) (μ-H)(μ-η -2,1-μ-η -10,11-C H )Re (CO) (μ-H), 4 (12 % yield), and Re (CO) (μ-H)(μ-η -1,2-μ-η -11,10-C H )Re (CO) (μ-H), 5 (12 % yield), by a second CH activation on a second rim double bond on the corannulene molecule.

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

Reactions of Re(CO)(μ-CH)(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-Re-metalated CH bridged compound Re(CO)(μ-H)(μ-1,μ-3-CH)Re(CO)(μ-H), 3. Reaction of 1 with naphthalene yielded two doubly CH activated isomers, Re(CO)(μ-H)(μ-η-1,2-μ-η-3,4-CH)Re(CO)(μ-H), 4, 41% yield, and Re(CO)(μ-H)(μ-η-1,2-μ-η-5,6-CH)Re(CO)(μ-H), 5, via the mono CH activated intermediate Re(CO)(μ-η-CH)(μ-H), 2.

Correction: Multiple cluster CH activations and transformations of furan by triosmium carbonyl complexes.

Correction for 'Multiple cluster CH activations and transformations of furan by triosmium carbonyl complexes' by Richard D. Adams et al., Chem.

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

The reaction of Re(CO)(μ-CH)(μ-H) (1) with thiophene in CHCl at 40 °C yielded the new compound Re(CO)(μ-η-SCH)(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 [Re(CO)(μ-H)](μ-η-2,3-μ-η-4,5-CHS) (3), formed by the activation of the C-H bond at the 5 position of the thienyl ligand in 2.

Formation of N, N-Dimethylacrylamide by a Multicenter Hydrocarbamoylation of CH with N, N-Dimethylformamide Activated by Ru(μ-C)(CO).

Hydrocarbamoylation of CH by N, N-dimethylformamide (DMF) to N, N-dimethylacrylamide was effected by a series of cluster-opening reactions with Ru(μ-C)(CO) (1). The reaction of 1 with DMF yielded the new complexes Ru(μ-C)(CO)(μ-η-O═CNMe)(μ-H) (2) and a minor coproduct Ru(μ-C)(CO)(HNMe)(μ-η-O═CNMe)(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.

Multiple cluster CH activations and transformations of furan by triosmium carbonyl complexes.

Reaction of Os3(CO)10(NCMe)2 with the triosmium furyne complex Os3(CO)9(μ3,η2-C4H2O)(μ-H)2, 1 yielded the bis-triosmium complex 2 containing a bridging furyenyl ligand by CH activation at the uncoordinated C-C double bond. Heating 2 led to additional CH activation with formation of the first furdiyne C4O ligand in the complex Os3(CO)9(μ-H)2(μ3-η2-2,3-μ3-η2-4,5-C4O)Os3(CO)9(μ-H)2, 3. The furdiyne ligand in 3 was subsequently ring-opened and decarbonylated to yield products 4 and 5 containing novel bridging C3 ligands.

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.

Synthesis and Reactivity of Electronically Unsaturated Dirhenium Carbonyl Compounds Containing Bridging Gold-Carbene Groups.

The electronically unsaturated compounds Re(CO)[μ-Au(NHC)](μ-Ph), 1, and Re(CO)[μ-Au(NHC)], 2, were obtained from the reaction of Re(CO)[μ-η-C(H)═C(H)Bu](μ-H) with MeAu(NHC), NHC = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene. Compound 1 was converted to the new compound Re(CO)[μ-Au(NHC)](μ-H), 3, by reaction with H. Addition of CO to 3 yielded the new compound Re(CO)[Au(NHC)](μ-H), 4, which contains a terminally coordinated Au(NHC) group on one of the rhenium atoms, and the hydrido ligand was shifted to bridge the Re-Au bond.

Opening of Carborane Cages by Metal Cluster Complexes: The Reaction of a Thiolate-Substituted Carborane with Triosmium Carbonyl Cluster Complexes.

The reaction of Os3(CO)10(NCMe)2 with closo-o-(1-SCH3)C2B10H11 has yielded the complex Os3(CO)9[μ3-η(3)-C2B10H9(SCH3)](μ-H)2, 1, by the loss of the two NCMe ligands and one CO ligand from the Os3 cluster and the coordination of the sulfur atom and the activation of two B-H bonds with transfer of the hydrogen atoms to the cluster. Reaction of 1 with a second equivalent of Os3(CO)10(NCMe)2 yielded the complex Os3(CO)9(μ-H)[(μ3-η(3)-1,4,5-μ3-η(3)-6,10,11-C2B10H8S(CH3)]Os3(CO)9(μ-H)2, 2, that contains two triosmium triangles attached to the same carborane cage. The carborane cage was opened by cleavage of two B-C bonds and one B-B bond.

Cage Opening of a Carborane Ligand by Metal Cluster Complexes.

The reaction of Os3 (CO)10 (NCMe)2 with closo-o-C2 B10 H10 has yielded two interconvertible isomers Os3 (CO)9 (μ3 -4,5,9-C2 B10 H8 )(μ-H)2 (1 a) and Os3 (CO)9 (μ3 -3,4,8-C2 B10 H8 )(μ-H)2 (1 b) formed by the loss of the two NCMe ligands and one CO ligand from the Os3 cluster. Two BH bonds of the o-C2 B10 H10 were activated in its addition to the osmium cluster. A second triosmium cluster was added to the 1 a/1 b mixture to yield the complex Os3 (CO)9 (μ-H)2 (μ3 -4,5,9-μ3 -7,11,12-C2 B10 H7 )Os3 (CO)9 (μ-H)3 (2) that contains two triosmium triangles attached to the same carborane cage.

Binuclear Aromatic C-H Bond Activation at a Dirhenium Site.

The electronically unsaturated dirhenium complex [Re2(CO)8(μ-H)(μ-Ph)] (1) has been found to exhibit aromatic C-H activation upon reaction with N,N-diethylaniline, naphthalene, and even [D6]benzene to yield the compounds [Re2(CO)8(μ-H)(μ-η(1)-NEt2C6H4)] (2), [Re2(CO)8(μ-H)(μ-η(2)-1,2-C10H7)] (3), and [D6]-1, respectively, in good yields. The mechanism has been elucidated by using DFT computational analyses, and involves a binuclear C-H bond-activation process.

The Addition of Gold and Tin to Bismuth-Triiridium Carbonyl Complexes.

The reaction of Ir3(CO)9(μ3-Bi) with PhAu(NHC) (1), where NHC = 1,3-bis(2,6-diisopropylphenylimidazol-2-ylidene), has yielded the compound Ir3(CO)8(Ph)(μ3-Bi)[μ-Au(NHC)] (2) by the loss of one CO ligand and the oxidative addition of the Au-C (phenyl) bond of 1 to one of the iridium atoms. The Au(NHC) group bridges one of the Ir-Bi bonds of the cluster. On the basis of X-ray crystal structural analysis and molecular orbital and quantum theory of atoms in molecules calculations, the Au-Bi interaction was determined to be substantial and is comparable in character to the Ir-Bi and Ir-Ir bonds in this cluster.

Host-guest behavior of a heavy-atom heterocycle Re4(CO)16(μ-SbPh2)2(μ-H)2 obtained from a palladium-assisted ring opening dimerization of Re2(CO)8(μ-SbPh2)(μ-H).

The heavy-atom heterocycle Pd[Re2(CO)8(μ-SbPh2)(μ-H)]2 (5) has been synthesized by the palladium-catalyzed ring-opening cyclodimerization of the three-membered heterocycle Re2(CO)8(μ-SbPh2)(μ-H) (3). The Pd atom occupies the center of the ring. The Pd atom in 5 can be removed reversibly to yield the palladium-free heterocycle [Re2(CO)8((μ-SbPh2)(μ-H)]2 (6).

Facile C-H bond formation by reductive elimination at a dinuclear metal site.

The electronically unsaturated dirhenium complex [Re2(CO)8(µ-AuPPh3)(µ-Ph)] (1) was obtained from the reaction of [Re2(CO)8{µ-η(2)-C(H)=C(H)nBu}(µ-H)] with [Au(PPh3)Ph]. The bridging {AuPPh3} group was replaced by a bridging hydrido ligand to yield the unsaturated dirhenium complex [Re2(CO)8(µ-H)(µ-Ph)] (2) by reaction of 1 with HSnPh3. Compound 2 reductively eliminates benzene upon addition of NCMe at 25 °C.

Two-dimensional bimetallic carbonyl cluster complexes with new properties and reactivities.

The new electron-rich, anionic, planar cluster complex [IrRu(6)(CO)(23)](-), 5, isolated as a PPN salt, PPN = [Ph(3)PNPPh(3) ](+), has been synthesized and characterized crystallographically. The complex exhibits unusual absorption and emission properties. Computational analyses have been performed to explain its metal-metal bonding and electronic properties.

Tetrarhena-heterocycle from the palladium-catalyzed dimerization of Re2(CO)8(μ-SbPh2)(μ-H) exhibits an unusual host-guest behavior.

The six-membered heavy atom heterocycles [Re(2)(CO)(8)(μ-SbPh(2))(μ-H)](2), 5, and Pd[Re(2)(CO)(8)(μ-SbPh(2))(μ-H)](2), 7, have been prepared by the palladium-catalyzed ring-opening cyclo-dimerization of the three-membered heterocycle Re(2)(CO)(8)(μ-SbPh(2))(μ-H), 3. The palladium atom that lies in the center of the heterocycle 7 was removed to yield 5. The palladium removal was found to be partially reversible leading to an unusual example of host-guest behavior.

Systematic differences between healthcare professionals and poison information staff in the severity scoring of pesticide exposures.

Context: Severity scores are used in triage and for data comparison in cases of poisoning. Exposure severity scores have not been generally validated and their utilization by healthcare staff other than specialists in poison information (SPIs) is untested.

Objective: To compare the poisoning severity grading allocated in pesticide exposure cases by healthcare professional enquirers and poison information staff.

Osmium-bismuth complexes from the reaction of Os3(CO)11(NCMe) with BiPh3.

Five new compounds were obtained from the reaction of Os(3)(CO)(11)(NCMe), 1, with BiPh(3) in hexane solution at reflux. These have been identified as Os(2)(CO)(8)(mu-BiPh), 2, Os(CO)(4)Ph(2), 3, Os(4)(CO)(14)(mu-eta(3)-O=CC(6)H(5))(mu(4)-Bi), 4, Os(4)(CO)(15)Ph(mu(4)-Bi), 5, and Os(5)(CO)(19)Ph(mu(4)-Bi), 6. Cleavage of the phenyl groups from the BiPh(3) was the dominant reaction pathway.