REACTION OF IMIDAZOLE-2-SELONE DERIVATIVES WITH DIIODINE - SYNTHESIS,STRUCTURAL AND SPECTROSCOPIC CHARACTERIZATION OF THE ADDUCT 1,1'-BIS(3-METHYL-4-IMIDAZOLIN-2-SELONE)METHANE BIS(DIIODINE) AND OF THE 1ST EXAMPLES OF I-SE-I HYPERVALENT SELENIUM-COMPOUNDS - 1,3-DIMETHYL-4-IMIDAZOLIN-2-YLIUM DIIODO SELENANIDE AND 1,2-BIS(3-METHYL-4-IMIDAZOLIN-2-YLIUM DIIODO SELENANIDE)-ETHANE BIS(DICHLOROMETHANE)

The reactions of 1,3-dimethyl-4-imidazolin-2-selone, 1, and 1,2-bis(3- methyl-4-imidazolin-2-selone)ethane, 3, with I2 give rise to the new s table hypervalent 10-Se-3 compounds: 1,3-dimethyl-4-imidazolin-2-ylium diiodo selenanide, I, and 1,2-bis(3-methyl-4-imidazolin-2-ylium diiod o selenanide)ethane bis(dichloromethane), III, characterized by the li near I-Se-I arrangement. Crystals of I are monoclinic [a = 12.648(6), b = 10.084(6), c = 8.624(7) angstrom; beta = 97.08(2)-degrees; Z = 4; space group P2(1)/c; R = 0.0393]. Crystals of III are monoclinic [a = 16.737(6), b = 8.286(7), c = 19.755(6) angstrom; beta = 98.68(2)-degre es; Z = 4; space group C2/c; R = 0.0305]. The corresponding reaction u sing 1,1'-bis(3-methyl-4-imidazolin-2-selone)methane, 2, produces inst ead the adduct 1,1'-bis(3-methyl-4-imidazolin-2-selone) methane bis(di iodine), II, where two linear Se-I-I groups are present. Crystals of I I are monoclinic [a = 16.144(2), b = 10.825(2), c = 23.196(4) angstrom ; beta = 111.14(1)-degrees; Z = 8; space group C2/c; R = 0.0427]. The Se-I distances in II are comparable with those found in I and III, and the I-I distances are close to the mean value found in triiodides. An alogously to the I-Se-I and I-I-I- cases, a three centre-two electron (3c-2e) axial orbital deficient bonding scheme is proposed to describe the bonding in the triatomic Se-I-I linear group. Electronic spectra of II agree with the proposed MO scheme better than with the Charge-Tr ansfer complex description. FT-IR and FT-Raman spectra of I, II and II I show that Se-I-I and I-Se-I groups give rise to vibrational bands at very similar frequencies and moreover they fall very close to those f ound for several asymmetric triiodides. These results indicate that bo th the electronic and vibrational spectra cannot be conclusive for the identification of the products. Moreover, the reported results show t hat in the reaction of diiodine with similar selenoamidic donors, no p redictable products are obtained.