Aldol condensation reactions of [Co(η4-C4Ph4){η5-C5H4C(O)CH3}]

(η4-Tetraarylcyclobutadiene)(η5-formylcyclopentadienyl)cobalt(I) complexes: Facilities to finetune the electron-donating capability in dipolar organometallics

“…Both of the complexes 1c and 1e display very similar Co-C distances, which are slightly shorter for the cobalt-cyclobutadiene (CBD) unit (198.4(3)-199.0(3) pm for 1c and 197.7(8)-200.4(7) pm for 1e) than for the cobalt-cyclopentadienyl coordination (205.4(4)-207.6(4) pm for 1c and 205.6(8)-207.9(8) pm for 1e) ( Table 1). The structural data of the sandwich core of 1c and 1e are quite comparable to other molecular structures of (g 4 -cyclobutadiene)(g 5 -cyclopentadienyl)cobalt(I) complexes reported in the literature [9][10][11][12][13][14][15]. The difference in Co-C bond lengths suggests a stronger cobalt bonding to the CBD ligand than to the C 5 -ring ligand, which is in agreement with theoretical calculations (see below) [14,15].…”

“…13 4.2.2. (g 4 -Tetraphenylcyclobutadiene) (g 5 -formylcyclopentadienyl)cobalt(I) (1b) [8,10] Tris(triphenylphosphine)cobalt(I) chloride (1.88 g, 2 mmol) in toluene (10 mL), formylcyclopentadienyl sodium (232 mg, 0.20 mmol) in THF (5 mL …”

The preparation, spectroscopy, structure and electrochemistry of some [Co(η4-C4Ph4)(η5-C5H4R)] complexes

“…The UV/Visible spectra of most of 5e12 are very similar to that of [Co(h 4 -C 4 Ph 4 )(h 5 -C 5 H 5 )] which shows a very intense absorption band below 250 nm, a strong band at 274 nm and a very weak band at 412 nm [35]. Thus when the C 5 H 4 -C a carbon atom is sp 3 hybridised, the observed spectrum is the summation of the [Co(h 4 -C 4 Ph 4 )(h 5 -C 5 H 4 e)] and eR parts e.g.…”

Synthesis, reactivity and structural studies of (η5-methylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt and its derivatives

“…The steric hindrance of the tetraphenylcyclobutadiene moiety in coming in the way of the reactivity of the Cp ring as indicated in the attempted lithiation of the non-methylated analogue of 1 [13]. The preparation of the acetyl derivative was therefore carried out by introducing the acetyl group on the sodium salt of methylcyclopentadienyl [14][15][16] and then reacting it with CoCl(PPh 3 ) 3 and diphenylacetylene (Scheme 2).…”