Synthesis and reactions of dimolybdenum(II,II), diruthenium(II,III) and dicopper(II,II) complexes containing unsaturated aliphatic carboxylate bridging ligands: X-ray crystal structure of [Ru 2(μ-O 2C(CH 3)Cz.dbnd&2;CH 2) 4Cl

Abstract

Metathesis reactions were used to prepare dimolybdenum(II,II), diruthenium (II,III) and dicopper(II,II) tetra-μ-carboxylato complexes containing unsaturated aliphatic carboxylate ligands (O 2CR) {R 1 = HC:CH 2, R 2 = (CH 3)C:CH 2, R 3 = H 2CHC:CH 2, R 4 = C 7H 9, R 5 = C 8H 11}. The X-ray crystal structure of [Ru 2(μ-O 2C(CH 3)C:CH 2) 4Cl] ( 9) shows that there are two independent centrosymmetric Ru 2L 4 dimers in the unit cell, bridged by chlorine atoms to form an infinite polymeric chain. Principal dimensions are RuRu 2.287(1) and 2.290(1) Å, RuCl 2.555(2) and 2.572(2) Å, RuClRu 118.29(7)°. The terminal ethylene (:CH 2) and methyl (CH 3) groups of the ligand are mutually disordered. The bicyclo[2.2.1]hept-5-ene-2-carboxylato complexes [Mo 2(μ-O 2CR 4) 4] ( 3), [Ru 2(μ-O 2CR 4) 4Cl] ( 8) and [Cu 2(μ-O 2CR 4) 4] · 2H 2O ( 14) were also synthesized by the Diels-Alder [4+21] cycloaddition reaction of cyclopentadiene with the respective propenoato complexes, [Mo 2(μ-O 2CR 1) 4] · 0.5H 2O ( 2), [Ru 2(μ-O 2CR 1) 4Cl] · 2HO 2CR 1 ( 7) and [Cu2(μ-O 2CR 1) 4] · 2H 2O ( 13). The bicyclo[2.2.1]hept-5-ene-2-methyl-2-carboxylato complex, [Ru 2(μ-O 2CR 5) 4Cl] ( 10), was prepared by a similar cycloaddition route from [Ru 2(μ-O 2CR 2) 4Cl] ( 9). No Diels-Alder adducts were formed when cyclopentadiene was reacted with [Mo 2(μ-O 2CR 2) 4] · 0.5H 2O ( 4), [Cu 2(μ-O 2CR 2) 4] · 2H 2O, [Cu 2(μ-O 2CR 3) 4] · 2H 2O and [Ru 2(η-O 2CR 3) 4Cl] ( 11).