Synthesis, Characterization, and Structural Studies of Transition Metal Open Fulvalene Complexes

Abstract

Starting from the 3-methylpentadienyl anion, a route to 3,8-dimethyl-1,3,5,7,9-decapentaene has been devised. This pentaene reacts readily with Co(C5H5)(C2H4)2 or [Ru(C5Me5)Cl]4 (2 and 0.5 equiv, respectively) to yield the expected (η4,η4‘-decapentaene)dimetal complexes, in which the two external diene fragments of the pentaene are each coordinated to a metal center, leaving the central CC bond uncoordinated. Subsequent respective two-electron oxidation or reduction then leads to (η5,η5‘-dimethyldecapentaene)ML n species (ML n = Co(C5H5)+ or Ru(C5Me5)). The first three complexes have been found to exist as mixtures of two isomers, and structural studies have confirmed the natures of the two open fulvalene (η5,η5‘) complexes. A related reaction, involving the reduction of [V(C5H5)Cl(PMe3)2]2 and the pentaene with magnesium, has been found to lead to a similar η5,η5‘ complex for which ML n = V(C5H5)(PMe3). Its structural nature has also been confirmed through a diffraction study.

Syntheses and characterization of the edge-bridged open metallocenes M(C8H11)2 (C8H11 = cyclooctadienyl; M = Ti, V, Cr or Fe) †

“…33 Spectroscopic data were obtained as previously described. 34 The 1 H and 13 C NMR spectra were obtained at 300 and 75 MHz, respectively. For the 13 C NMR spectra the peaks were not precisely integrated, but numbers of carbon atoms are presented in accord with their assignments.…”

Solid state structure of (pentamethylcyclopentadienyl)(2,4-dimethylpentadienyl)iron, Fe(C5Me5)(2,4-C7H11), and its incorporation into silica aerogels

“…As well, there is the possibility that a (pentamethylcyclopentadienyl)iron bromide tetramer or other oligomer is responsible for its stability; (pentamethylcyclopentadienyl)ruthenium halide complexes are isolable and synthetically useful starting materials for preparing Ru(C5Me5)(pentadienyl) complexes [19][20][21][22][23][24][25][26][27][28][29][30][31]. In the second step the pentadienyl ligand is expected to be incorporated by a conventional anion metathesis with the remaining bromide ligand.…”