Synthesis and Structural Characterization of Spiro(fluorene-9,4′-imidazolidine)-2′,5′-dione and (9H-Fluorene-9-yl)urea

Abstract

Alkaline hydrolysis of spiro(fluorene-9,4′-imidazolidine)-2′,5′-dione, 2 resulted in ring opening leading to (9H-fluorene-9-yl) urea, 3. The crystal structures 2 and 3 have been determined. Compound 2 crystallizes in the orthorhombic space group P212121 with a = 7.2596(9) A, b = 9.4497(14) A, c = 17.304(3) A and Z = 4 while compound 3 crystallizes in the monoclinic space group P21/c with a = 4.6171(3) A, b = 14.4713(9) A, c = 16.9762(14) A, β = 95.385(7)° and Z = 4. Both molecules have very similar bond lengths and angles pattern, even after the hydantoin ring opening. The 9H-fluorene moiety is nearly planar with rms of 0.007 and 0.032 A for 2 and 3. The angle between the mean planes of the 9H-fluorene and the hydantoin or carbamide moieties is 86.92(4)° and 71.07(4)° respectively. In both structures N–H···O hydrogen bonds connect molecules into the chains along a. The X-ray molecular structure and IR spectra for 2 and 3 are compared with those calculated by the density functional theory method. Alkaline hydrolysis of spiro(fluorene-9,4′-imidazolidine)-2′,5′-dione resulted in a ring opening product namely (9Н-fluorene-9-yl) urea.