화학공학소재연구정보센터
Chemical Engineering Journal, Vol.226, 113-122, 2013
Organometallic Sn(II) catalyzing adducts of substituted benzaldehydes
This paper reports about the electrospray ionization mass spectrometric and quantum chemical study of unique coupling reaction of dihydroxybenzaldehydes in strong basic medium, which in the presence of (SnCl4)-Cl-IV yielded series of condensation products through the homo Dies-Alder reaction of the bicyclohexyl-4,6,4',6'-tetraene-2,3,2',3'-tetraone (2). In contrast to the known coupling reaction products catalyzing by diversity of Cu-I/Cu-II, Ag-I-, Au-0/Au-III/Au-I-, Zn-II-, Pd-0/Pd-III/Pd-II- and/or Pt-II-organometallics, yielding the substituted biphenyls, benzo-[c]-cromenes, condensation products of 5,6,11, 12-tetraoxo-tricyclo[6.2.2.02,7]dodeca-3,9-diene-1,4-dicarbaldehyde (14) type from 2,3-dihydroxybenzaldehyde particularly, and/or substituted aldehydes by Reimer-Tiemann reaction, in the presence of SnIV- Cl-4, the formation of above dimeric adducts is chiefly process, explained with Sn-IV -> Sn-II redox process. The known product 14 is obtained at trace concentrations, producing further dimeric 5,6,11,12,5',6',11',12'-octaoxo-[4,4']bi[tricyclo[6.2.2.02,7]dodecyl]-3,9,3',9'-tetraene-1,1'-dicarbaldehyde adduct (15). The catalyzing organometallic precursor is a binuclear Se-complex (I), where the metal ion is bonded covalently in Cl-Sn-C manner. A second metal ion is bidentately coordinated to adjacent O=C- groups, forming a five membered chelate ring. The Cl- and OH--terminal ligands completed the SnO3Cl chromophore. The experimentally evidenced complex I exhibited a significant thermodynamics stability of Delta G = -52996.80 kcal mol(-1), a value different than Delta(Delta G) =vertical bar 52945 vertical bar kcal mol(-1) towards the corresponding quantities of other structurally proposed analogous of Sn-II, Sn-IV or Sn-II/Sn-IV organometallics II-IV on the base of the MS elemental compositions and isotopic shapes. (C) 2013 Elsevier B.V. All rights reserved.