Abstract
The title compound, C70H70N8O4Se2, is a spiro bicyclic diselenide, made up of two [SeC6H4CH=N-N(CO)C6H4(C)C6H3NEt2(O)C6H3NEt2] units related by a twofold crystallographic symmetry element bis-ecting the diselenide bond. The compound crystallizes in a non-centrosymmetric polar space group (tetra-gonal, P b2) and the structure was refined as an inversion twin. The two diethyl amine groups and their attached phenyl groups of the xanthene ring are disordered over two orientations, with occupancies of 0.664 (19)/0.336 (19) and 0.665 (11)/0.335 (11), respectively. The dihedral angles between the mean planes of the central isoindoline and the phenyl rings are 26.8 (2) and 2.5 (4)°, respectively. The mean plane of the central xanthene ring forms dihedral angles of 2.0 (5), 8.8 (5), 1.7 (5) and 7.9 (6)° with the peripheral phenyl rings. The isoindoline and xanthene rings subtend a dihedral angle of 89.8 (2)°. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯O hydrogen bond generating an S(6) ring motif. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds together with C-H⋯π (ring) inter-actions, forming a three-dimensional network. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (68.1%), C⋯H/H⋯C (21.2%) and O⋯H/H⋯O (8.7%) contacts. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6 - 31 G(d) level is compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was used to determine the energy gap and the mol-ecular electrostatic potential (MEP) of the compound was investigated.
Highlights
Been reported with interesting intra- and intermolecular interactions (Saravanan et al, 2021)
The Se–Se unit is coplanar with both phenyl rings but the Se–aryl planes are essentially perpendicular to each other [C—Se—Se—C torsion angle of À88.9 (3)]
The diethyl amine groups and their attached phenyl groups (C16–C21, N3/C18–C20/C22–C25 and C26– C31, N4/C32–C35) of the xanthene rings are disordered over two conformations with occupancies of 0.664 (19)/0.336 (19) and 0.665 (11)/0.335 (11), respectively
Summary
Diaryl diselenides and aryl selenolates have been previously used as ligand precursors for the synthesis of transition-metal complexes (Khandelwal & Gupta, 1989; Gupta & Parihar, 1995, 1998; Gupta et al, 1998). The formation of spirobicyclic diselenides is rare and to the best of our knowledge, not reported in the literature. There are very few reports of the formation of selenospirocyclic derivatives which have been structurally characterized (Singh et al, 2011; Shi et al, 2010). The synthetic and structural studies of various diselenides (see section 4, Database survey) are known in the literature, to the best of our knowledge, a synthesis and structural data have not yet been published for the title compound. We report the crystal structure, DFT and Hirshfeld surface analysis of 2,200({[(1E,10E)-(diselanediyl)bis(2,1-phenylene)]bis(methaneylylidene)}bis(azaneylylidene))bis[30,60-bis(diethylamino)-4a’,9a’dihydrospiro[isoindoline-1,90-xanthen]-3-one], isolated from the condensation of rhodamine B hydrazide with bis(o-formylphenyl)diselenide. The isoindoline (N2/C8/ C9/C14/C15) and xanthene (O2/C21/C16/C15/C31/C26) rings are essentially perpendicular to each other [dihedral angle of 89.8 (6)]
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