Diphosphine-induced thiolate-bridge scission of [Re(CO)3(μ,κ2-S,N-thpymS)]2 (thpymS = 1,4,5,6-tetrahydropyrimidine-2-thiolate): Structural and computational studies of configurational isomers of [Re(CO)3(κ2-S,N-thpymS)]2(μ,κ1,κ1-dppe)

Publication date: Available online 7 July 2018Source: Journal of Organometallic ChemistryAuthor(s): Md Rassel Moni, Shishir Ghosh, Shaikh M. Mobin, Derek A. Tocher, Graeme Hogarth, Michael G. Richmond, Shariff E. KabirAbstractReactions of binuclear [Re(CO)3(μ,κ2-S,N-thpymS)]2 (1) with diphosphines have been investigated. At 298 K, dppm reacts to give mononuclear [Re(CO)3 (κ1-dppm) (κ2-S,N-thpymS)] (2) through a phosphine-promoted scission of the dithiolate bridges that leaves one of the phosphine moieties free (dangling). Refluxing 2 in toluene leads to CO loss and formation of dinuclear [Re2(CO)4 (μ-dppm) (μ,κ2-S,N-thpymS)2] (3) whose rhenium centers are bridged by two thiolate groups and the dppm ligand. Treatment of 1 with dppe at room temperature furnishes [Re(CO)3(κ2-S,N-thpymS)]2(μ,κ1,κ1-dppe) (4) where each phosphine center ligates the respective d6-ML5 rhenium fragment. Complex 4 exists as two distinct configurational isomers (4a and 4b) that have been isolated and the solid-state structures characterized crystallographically. The principal difference in the stereoisomeric products is the orientation of the two [Re(CO)3 (κ2- S,N-thpymS)] moieties at the anti-staggered Newman projection involving the P-C-C-P backbone of the dppe ligand. Both stereoisomers retain their identity in solution at ambient temperatures but equilibrate to a 1:1 mixture upon heating at 363 K for 1 h. The reaction of 1 with dppe in toluene at 383 K affords [Re(CO)2 (κ1-dppe)...

Source: Journal of Organometallic Chemistry - July 8, 2018 Category: Chemistry Source Type: research