84050-91-9Relevant academic research and scientific papers
Nucleophilic addition of N,N-dimethylaniline to the (cyclobutadiene)nitrosyldicarbonyliron cation: A kinetic and structural study
Calabrese, Joseph C.,Ittel, Steven D.,Choi, Hyung Soo,Davis, Steven G.,Sweigart, Dwight A.
, p. 226 - 229 (1983)
The electrophilic aromatic substitution reaction between N,N-dimethylaniline and the cyclobutadiene ring in [(C4H4)Fe(CO)2NO]PF6 yields the η3-cyclobutenyl complex [(Me2NC6H4C4H 4)Fe(CO)2NO] (2). Spectroscopic studies suggest that substitution occurs exclusively at the carbon para to the NMe2 group and that the product has exo stereochemistry. A kinetic study in acetonitrile showed the reaction to be second order overall with the following activation parameters: ΔH? = 11.2 ± 1.5 kcal; ΔS? = -31 ± 5 cal deg-1 mol-1. A mechanism is suggested that involves initial π-complex formation followed by rate-determining conversion to a σ complex. A single-crystal X-ray analysis of 2 at -100°C showed that it crystallizes in the monoclinic space group P21/c with a = 16.690 (2) A?, b = 6.310 (1) A?, c = 26.716 (3) A?, β = 96.46 (1)°, Z = 8, R = 0.036, and Rw = 0.044. The structure confirms the exo attack of the N,N-dimethylaniline para carbon on the coordinated cyclobutadiene. The bond distances and angles in the cyclobutenyl group are similar to previously reported structures. The dihedral angle between the enyl plane (C7, C4, C5) and the nonbonded plane (C5, C6, C7) is 26.5° (Figure 1).
