SYNTHESIS AND MULTINUCLEAR (1H,13C, 15N, 29Si, 11B and 119Sn) NMR STUDIES OF ORGANOTIN AND ORGANOSILICON DERIVATIVES

Khadija, Shahid (2006) SYNTHESIS AND MULTINUCLEAR (1H,13C, 15N, 29Si, 11B and 119Sn) NMR STUDIES OF ORGANOTIN AND ORGANOSILICON DERIVATIVES. Doctoral thesis, Quaid-i-Azam University Islamabad.

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Abstract

This thesis consists of two parts (A and B) of the research work. Part A contains the synthesis and 1, 1-organoboration of various alkynylsilanes and part B includes the synthesis and characterization of organotin carboxylates. Silanes of the type C1Me2SiC≡CR/C1MeHSiC≡CR (R = nBu, CH2NMe2, Me3Si) [1-4], HC12SiC≡CR (R = nBu, Me3Si) [5,6], HMe2SiC≡CR (R = CH2NMe2) [7], symmetrically substituted di-alkynyl silanes Me2Si(C≡CR)2/MeHSi(C≡CR)2 (R = CH2NMe2) [8,9], unsymmetrically substituted di-alkynyl silanes Me2Si(C≡CR12/MeHSi(C≡CR)2 (R = nBu, CH2NMe2, Me3Si) [10-13], Cl2HSiC≡CR (R ≡ CH2NMe2) [14], ClHSi(C≡CR) (R = CH2NMe2) [15], unsymmetrically substituted C1HSi(C≡CRR1) (C=CR1) (R = CH2NMe2, R1 = nBu, CH2NMe2, Me3Si) [17, 18], as well as symmetrically substituted trialkyl silanes HSi(C≡CR)3 (R = CH2NMe2) [16] were prepared and treated with BEt3. Unsymmetrically substituted trialkynyl silanes HSi(C≡CR) (C≡CR1) (R = CH2NMe2 and R1 = nBu, CH2NMe2, Me3Si) [19, 20], and silanes with tri and dichloro function C13SiC≡CR (R = nBu) [21], C12Si(C≡CR)2 (R = nBu) [22] were prepared and their reactivity towards triethylborane, BEt3, was studied. Unsymmetrically substituted tri-/dialkynyl silanes were synthsized in order to find out which Si-C≡ bond is attacked preferably by BEt3. In case of mono-alkynyl silanes, the final products of 1, 1-ethylboration were alkenes [23a, b, 24b, 25a, b, 26b, 28a, 29b, 30b, 31a, band 67]. The 1, 1-ethylboration of alkyn-1-yl-chloro(methyl)silanes, Me2Si(C1)-C≡C-R (1) and Me(H)Si(C1)-C≡C-R (2) [R = nBu, CH2NMe2] requires harsh reaction conditions (-20 days boiling in triethylborane), and leads to alkenes in which the boryl and silyl groups occupy cis (E)-isomers: 23a, 23b, 25a, 25b) or trans positions (Z)-isomers in smaller quantities: 24b and 26b). The alkenes are destabilized in the presence of SiH(C1) and CH2NMe2 units (25b, 26b). NMR data indicate hyper coordinated silicon by intramolecular N-Si coordination in 23b and 25b, by which, at the same time, weak Si-C1-B bridges. The 1,l-ethylboration of dichloro(hexyn-1-y1) silane, C12Si(H)-C≡C-Bu, affords selectively an alkene which is the first example with dialkylboryl and dichlorosilyl groups in eis-positions at the C≡C bond. The analogous reaction of dichloro(trimethylsilylethynyl)silane, C12(H)Si-C≡C-Si Me3, leads to a 4:1 mixture of alkenes, in one of which the boryl groups are in trans-positions. The alkenes were characterized by a consistent set of NMR data. As well as in case of 1,1-ethylboration of di- and trialkylsilanes the final products, sila-2,4-cyclopentadienes (siloles) [32, 33, 36-43, 47, 49, 50, 52-56, 59-68] were obtained respectively bearing a diethylboryl group in 3- or 4-position. If the CH2NMe2 and the boryl group are in neighboured positions, the Me2N group is always coordinated to the boron atom. Side products and intermediates 34, 35, 45 and 46, 48, 51, 57, 58, containing an electron-deficient Si-H-B bridge could be detected by NMR spectroscopy. Azoles [69, 70] were prepared for synthesis of heterocyclic compounds [71-82] with reaction of alkenes. The molecular structure of tricyclic compound 76 has also been determined by the single crystal X-ray analysis. On the other hand 1, l-ethylboration of alkyne, C12Si(C≡CR)2, gives interesting results due to cleavage of Et2BH. The proposed structures of all products, side products and intermedidates follow from a consistent set of multinuclear magnetic resonance data 1H, 11B, 13C and 29Si NMR), IR and Mass spectrometry. In part B, organotin (IV) derivatives of the general formulae R2SnL2 and R3SnL where R = Me, n-Bu, n-Oct, Ph and Bz have been synthesized in 1:2 and 1:1 molar ratio by using acids HL 1-HL10 (prepared by the mixing of different anhydrides with different anilines). The synthesis of these complexes has been achieved by either reaction of organotin halides R2SnC12/R3SnCl or organotin oxide R2SnO with triethylammonium salt of 4-(2,5-Dioxo-2,5-dihydro-lH-pyrrol-l-yl)benzoic acid (HL1) or aniline derived acids (H2 -HL10). The coordination around tin in solid as well as in solution has been proposed on the basis of spectroscopic results. The crystal structure of the HL1, C10H8BrNO3, establishes that condensation of 4-bromoaniline with maleic anhydride gives the title compound at room temperature. There are strong intermolecular hydrogen bonding. The carboxyl groups adopt an anti-planar conformation and participate in intramolecular bonding. These complexes were characterized by elemental analyses, infrared, multinuclear 1H, 13C, 119Sn) NMR and Mass spectrometry. Biological screenings were performed in order to establish their biological activity. These complexes were also tested against different bacteria and fungi to determine their toxicity. LD50 data were also calculated using the Brine Shrimp method. Insecticidal and antileishminial activity was performed for selective complexes by contact toxicity method

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: nmr studies, organotin, organosilicon, organoboron, silanes, ligand
Subjects: Q Science > QD Chemistry
Depositing User: Muhammad Khan Khan
Date Deposited: 08 Sep 2016 04:03
Last Modified: 08 Sep 2016 04:03
URI: http://eprints.hec.gov.pk/id/eprint/1077

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