Syntheses and X‐Ray Crystal Structures of 2‐Aminoindenes and Aminocymantrenes

Abstract

AbstractSubstituted 2‐aminoindenes have been synthesized in almost quantitative yields by reactions of amines such as methylpiperazine, trimethylethylenediamine, 1,4‐diaza‐cycloheptane and N,N′‐dimethylethylenediamine with 2‐indanone. The 2‐aminoindenes can be deprotonated and reacted with BrMn(CO)3(Py)2 to produce the respective aminoindenyl‐cymantrenes in yields between 55–70%. The X‐ray crystal structures of 2‐(methylpiperazine)indenyl‐cymantrene 5 (P1, a = 12.667(3) Å, b = 16.630(3) Å, c = 17.382(3) Å, α = 72.70(3)°, β = 74.59(3)°, γ = 88.66(3)°, V = 3364.1(12) Å 3, Z = 8, R1(2σ(I)) = 4.02%, wR2(2σ(I)) = 10.30%) and the HClO4 adduct of 2‐(trimethylethylenediamine)‐indenyl‐cymantrene 6 (Cc, a = 23.722(5) Å, b = 6.9080 Å, c = 13.264 Å, β = 111.77(3)°, V = 2018.6(7) Å 3, Z = 4, R1(2σ(I)) = 2.94%, wR2(2σ(I)) = 7.90%) were determined. In both complexes the indenyl‐carbon bonded to nitrogen displays significantly longer bonds to manganese [223.5(3)–225.8(3) pm] than the other four carbon atoms [213.3(3)–219.1(3) pm]. The short indenyl‐nitrogen bonds of 136.2(4) and 137.8(4) pm are indicative of a substantial multiple bond character. The complexation of Zn2+ by the nitrogen atoms of 6 results in significant shifts of the CO stretching frequencies.