Synthetic applications of p block anions

• Main Author: Davies, M. K.
• Published: University of Cambridge 1997
• Subjects: 546
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598378

Chapter 1 surveys the chemistry and reactivity of Group 14 and relevant Group 15 complexes and introduces the analogies which exist between the well-established ligand behaviour of non-metallic systems and the configuration of donor functionality present in a range of main group metallo-organic compounds. Chapter 2 initially looks at the reactivity of the anion [Sn {μ-N=C(<SUP>t</SUP>Bu)Ph}<SUB>3</SUB>]<SUP>-</SUP>, towards a variety of metals with the aim of using this complex as a tripodal ligand. However, the reaction of [Sn{μ-N=C(<SUP>t</SUP>Bu)Ph}<SUB>3</SUB>Li.THF] with [CuCl] results in ligand transfer of one of the imido groups, to form [Cu{μ-N=C(<SUP>t</SUP>Bu)Ph}]<SUB>4</SUB>.THF] and the presence of PPh<SUB>3</SUB> fails to block this transfer, thus [Cu{μ-N=C(<SUP>t</SUP>Bu)Ph}]<SUB>4</SUB>.2PPh<SUB>3</SUB>-THF is produced. The reaction of [Cp<SUB>2</SUB>Sn] with [2-LiPy] (2-Py = Pyridyl), formed from [<SUP>n</SUP>BuLi] with [2-PyBr], yields the Sn(IV) product [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>LiBr.0.5THF]. Investigations of this compound demonstrate the efficacy of the [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>] moiety as a robust neutral ligand. The reaction of [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>LiBr.0.5THF] with CuCl<SUB>2</SUB> yields the Cu(I) product [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>CuBr.0.5THF]. However, an attempt to extend this reactivity to AgNO<SUB>3</SUB> results in anion exchange, producing [<SUP>n</SUP>BuSn(2-Py)<SUB>3</SUB>LiNO<SUB>3</SUB>]. The Pb(II) complex [Pb(2-Py)<SUB>3</SUB>Li.THF] was synthesised from the reaction of [2-LiPy] with [Cp<SUB>2</SUB>Pb]. In Chapter 3, two alternative reaction pathways are identified in the nucleophilic substitution reactions of Group 14 metallocenes with lithiated primary amines [RNHLi]. These are exemplified by the synthesis of the primary tris(amido)stannate [(MANH)Sn(μ-NHMA)<SUB>2</SUB>Li.2THF] obtained from the reaction of [Cp<SUB>2</SUB>Sn] with [(MA)NHLi] (MA = 2-MeOC<SUB>6</SUB>H<SUB>4</SUB>), and the cubanes [ENCy<SUB>4</SUB>] [E = Sn, Pb ; Cy = C<SUB>6</SUB>H<SUB>11</SUB>] are prepared from [CyNHLi] and [Cp<SUB>2</SUB>E]. The later furnishes a new route to Group 14 imido cubanes. A study of the effects of two potent nucleophiles in the same molecule, [PhCH<SUB>2</SUB>N(Li)CH<SUB>2</SUB>)]<SUB>2</SUB>, with [Cp<SUB>2</SUB>Sn] was undertaken, yielding the dimer [{PhCH<SUB>2</SUB>N(CH<SUB>2</SUB>)<SUB>2</SUB>NCH<SUB>2</SUB>Ph}Sn]<SUB>2</SUB>.