100813-52-3Relevant academic research and scientific papers
Reactions of cyclopropenyl cations with tricarbonylnitrosylferrate(1-), tetracarbonylcobaltate(1-), and octacarbonyldicobalt. Synthesis and conformational and configurational stabilities of η3-cyclopropenyl and η3-oxocyclobutenyl complexes of iron and cobalt. Crystal and molecular structure of Fe(η-C3Ph2-t-Bu)(CO)2(NO)
Hughes, Russell P.,Lambert, James M. J.,Whitman, David W.,Hubbard, John L.,Henry, William P.,Rheingold, Arnold L.
, p. 789 - 797 (2008/10/08)
The cyclopropenyl salt [C3Ph2-t-Bu][BF4] reacts with [Co2(CO)8] to give the cyclopropenylcobalt complex [Co(η3-C3Ph2-t-Bu)(CO)3] (10b) and the unsymmetrically substituted oxocyclobutenyl compound [Co-(η3-C3Ph2-t-BuCo)(CO)3] (8b). The reaction of tri-teri-butylcyclopropenyl tetrafluoroborate, [C3-t-Bu3][BF4], with [PPN][Co(CO)4] affords both the cyclopropenyl complex [Co(η3-C3-t-Bu3)(CO)3] (10c) and the oxocyclobutenyl compound [Co(η3-C3-t-Bu3CO)(CO)3] (8c). Reaction of the previously reported cyclopropenyl complex [Co(η3-C3Ph3)(CO)3] (10a) with tertiary phosphite or phosphine ligands does not lead to ring expansion to give the oxocyclobutenyl ligand but affords only the products of CO substitution, [Co(η3-C3Ph3)(CO)2L] (L = P (OPh)3, PPh3, PMe2Ph; 12a-c). Reactions of a variety of cyclopropenyl salts, [C3Ph2R][BF4] (R = Ph, H, Me, t-Bu), with [PPN][Fe(CO)3(NO)] afford both the cyclopropenyliron complexes [Fe(η3-C3Ph2R)(CO)2(NO)] (15a-d) and the oxocyclobutenyl compounds [Fe(η-C3Ph2RCO)-(CO)2(NO)] (13a-d). Only the unsymmetrically substituted isomers of compounds 13b-d are formed. In contrast, reaction of [PPN][Fe(CO)3NO] with [C3-t-Bu3][BF4] affords only the cyclopropenyl complex [Fe(η3-C3-t-Bu3)(CO)2(NO)] (15e) in high yield. Variable-temperature 13C NMR studies on these cyclopropenyl compounds demonstrate that rotation about the metal-C3 ring axis is fast on the NMR time scale at -80°C, as predicted by theory. The cyclopropenyl-iron skeleton in complex 20 is configurationally stable on the NMR time scale, with no evidence for scrambling of diastereotopic sites via a metallacyclobutadiene intermediate. The value of 1J(C-H) for the cyclopropenyl carbon atom of complex 15b is 232 Hz, consistent with approximately sp hybridization for the carbon orbital of the C-H bond. This hybridization is also consistent with that exhibited by the organic tetrahedrane 4. The molecular structure of 15d has been determined by a single-crystal X-ray diffraction study. It crystallizes in the orthorhombic space group Pbca with a = 8.686 (2) A?, b = 15.869 (4) A?, c = 28.53 (1) A?, and Z = 8. The structure of 15d confirms the η3-cyclopropenyl bonding, and bond distances are compared to those found in the organic tetrahedrane 4.
