Structure of a Highly Unsaturated Anionic Tetrahydridononacarbonyltrirhenate Cluster

Abstract

The reaction between H4Re4(CO)12 and N,N-dimethylformamide (DMF) in chloroform yields [H4Re3(CO)9]-[Re(CO)3(DMF)3]+, 1, quantitatively. The X-ray structure of 1 reveals that the three Re atoms in the 44-e anionic cluster [H4Re3(CO)9]- form an isosceles triangle. Two hydrides bridge the two long Re−Re single-bonded edges, and another two hydrides bridge the Re−Re double-bonded edge. There is a coordinative unsaturation site on the rhenium atom not involved in the Re−Re double bond. However, the anionic cluster associates face-to-face antiprismatically with another identical unit to form a dimer in which there are donor−acceptor interactions between the hydrides bridging the Re−Re double bonds and the coordinative unsaturation sites on the other clusters. The anionic cluster reacts rapidly with donor ligand L (CO, Py, PPh3, CH3CN) to form [H4Re3(CO)9L]-. In CD2Cl2 solution at 183 K, [H4Re3(CO)9]- has a hydride NMR pattern of 3:1 and a carbonyl group 13C NMR pattern of 6:3. These NMR spectra as well as their VT NMR results and IR spectra in the solid state and solution are consistent with a solution structure of [Re3(μ3-H)(μ2-H)3(CO)9]- in which two double bonds are delocalized over the rhenium triangle.

Structure and Properties of a Novel Square-Pyramidal Cluster: Heptahydridopentadecacarbonylpentarhenate Dianion

“…The reaction between H 4 Re 4 (CO) 12 and N,N-dimethylformamide (DMF) yields [H 4 Re 3 (CO) 9 -][Re(CO) 3 (DMF) 3 + ] (1) quantitatively. 4 In chloroform or dichloromethane solution with This DMF-coordinated cluster, with its extra ligand coordinated to the rhenium atom not connected to others by a Re-Re double bond, is isostructural with H 4 Re 3 (CO) 10 -7 and H 4 Re 3 (CO) 9 (PPh 3 ) -. 8 It was found that the chloroform solution of 1 with a DMF concentration of 0.13 M turned from yellow to reddish yellow on standing for 24 h at 298 K. A yellow crystalline precipitate, 2, can be obtained from this solution.…”

“…Formation of the Novel Square-Pyramidal Anionic Cluster H 7 Re 5 (CO) 1 5 2- . The reaction between H 4 Re 4 (CO) 12 and N , N -dimethylformamide (DMF) yields [H 4 Re 3 (CO) 9 - ][Re(CO) 3 (DMF) 3 + ] ( 1 ) quantitatively . In chloroform or dichloromethane solution with high DMF concentration (>1 M), 1 does not undergo any cluster skeletal transformation, because the anionic cluster H 4 Re 3 (CO) 9 - is coordinated by DMF: This DMF-coordinated cluster, with its extra ligand coordinated to the rhenium atom not connected to others by a Re−Re double bond, is isostructural with H 4 Re 3 (CO) 10 - and H 4 Re 3 (CO) 9 (PPh 3 ) - …”

“…3 In the solid state, the structure of [H 4 Re 3 (CO) 9 -][Re(CO) 3 -(DMF) 3 + ] indicates that the unusual trirhenium anionic cluster possesses a metal-metal double bond and a coordinatively unsaturated site on the other rhenium atom not involved in the double bond. 4 To stabilize this highly unsaturated anionic cluster, two clusters are associated antiprismatically to form a dimer in which a hydride bridging the double bond is located in the area of the coordinatively unsaturated site of the other associated cluster. The solution structure of H 4 Re 3 (CO) 9is completely different from that in the solid state.…”

“…We are particularly interested in unsaturated rhenium clusters, which exhibit interesting chemistry. For example, H 4 Re 4 (CO) 12 , − which has a tetrahedral geometry with two delocalized double bonds and four face-bridging hydrides, reacts readily with various donor ligands, including common coordinating solvents such as acetone, THF, DMF, and various alcohols. The reaction between H 4 Re 4 (CO) 12 and methanol follows a clean fifth-order reaction (first order in H 4 Re 4 (CO) 12 and fourth order in methanol), as reported in our previous paper .…”

A Methyl Group Bridging on Three Metal Atoms. Solid-State and Solution Structural Characterization of the [Re3(μ-H)3(μ3-CH3)(CO)9]-Anion

“…The μ 2 -bridging coordination is much more common 7 and often involves agostic interactions . In triangular clusters it has been observed in [Os 3 (μ-H)(μ-HCH 2 )(CO) 10 ] 9 and in [Re 3 (μ-CH 3 ) 3 (CH 3 ) 6 (PEt 2 Ph) 2 ] …”