Tetra-tert-butyl-pentafulvalen als Ligand in zweikernigen Molybdänkomplexen: cis-Anordnung ohne Metall-Metall-bindung

Abstract

Reaction of 1,1′,3,3′-tetra-tert-butyl-5-′-pentafulvalenedipotassium ( 1) with hexacarbonylmolybdenum leads to hexacarbonyl-dipotassium(1,1′,3,′-tetra-tert-butyl-5,5′-pemtafulvalene)dimolybdate ( 2), which on further treatment with stoichiometric amounts of iodomethane yields the hexacarbonyldimethyl(1,1′-3,3′-tetra-tert-butyl-5,5′-pentafulvalene)dimolybdenum, (η 5 : η 5- tBu 4C 10H 4)Mo 2(CO) 6-(CH) 3) 2 ( 3). Compound 3 is obtained as yellow needles and brownish cube-like crystals, and it is characterized by 1H-NMR, 13C-NMR, IR, and MS data. The cubes crystallize in the space group C2/ c with four molecules in the unit cell. Each molecule consists of two tricarbonylmethyl(cyclopentadienyl) molybdenum units which are connected by a central CC-bond, twisted against each other by 64.8° and bent by 25.8°. Due to the steric requirements of the tertbutyl substituents in the fulvalene ligand, 3 should be formed only from cis-configurated 2.