175086-48-3Relevant academic research and scientific papers
Pentamethylcyclopentadienyl imido compounds of chromium
Danopoulos, Andreas A.,Wilkinson, Geoffrey,Sweet, Tracy K. N.,Hursthouse, Michael B.
, p. 271 - 282 (2007/10/03)
The interaction of the pentamethylcyclopentadienylchromium(III) complex 2 with alkyl- and aryl-lithium amido compounds, LiNHR, gave products whose nature depends on the reactants and on reaction conditions.For the aryl (R) 2,6-i-Pr2C6H3 both 1 and 2 2 were obtained, whereas LiNH(C6H11) gave 2 5.Use of R = 2,4,6-t-Bu3C6H2 gave 3.The unisolable chromium(III) intermediate can be trapped by interaction of 2 and LiNHR (R = 2,6-i-Pr2C6H3) in the presence of diphenylacetylene to give Cr(η-C5Me5)(NR)(PhCCPh) 6.A comparable reaction but using LiNHt-Bu gave only the dimer (η-C5Me5)BrCr(μ-NHt-Bu)2Cr(Nt-Bu)(NHt-Bu) 7.Trapping by various other ligands failed but the interaction in the presence of 2,6-xylyl isocyanide gave a chromium(III) chelate 8 of a quinoline diamide where an isopropyl group has been removed from the original C6H3i-Pr2 moiety.The crystal structures of 1-7 and 8 have been determined.The triply bridged complex 1, which has a confacial bitetrahedral structure (assuming C5Me5 takes one co-ordination site) has a Cr(III)...Cr(III) distance of 2.649(5) Angstroem (average over two molecules), whilst the doubly bridged (Cr(III))2 complexes 2 and 3, each of which is centrosymmetric, have Cr(III)...Cr(III) distances of 2.591(1 ) and 2.564(1) Angstroem.In compound 5, also showing centrosymmetric bis(imido) bridging, the Cr(IV)...Cr(IV) distance is 2.974(5) Angstroem, In 6 the acetylene is symmetrically bihapto and the imido function bonds in a linear manner.Compound 7 has dissimilar chromium atoms, formally assigned as Cr(III), Cr(IV), with bridging amido functions.The Cr...Cr distance is 2.936(2) Angstroem.
