Sara J. Kidd

Templating and Selection in the Formation of Macrocycles Containing [{P(μ-NtBu)2}(μ-NH)]n Frameworks: Observation of Halide Ion Coordination

Amination of [ClP(micro-NtBu)](2) (1) using NH(3) in THF gives the cyclophospha(III)zane dimer [H(2)NP(micro-NtBu)](2) (2), in good yield. (31)P NMR spectroscopic studies of the reaction of 1 with 2 in THF/Et(3)N show that almost quantitative formation of the cyclic tetramer [[P(micro-NtBu)](2)(micro-NH)](4) (3) occurs. The remarkable selectivity of this reaction can (in part) be attributed to pre-organisation of 1 and 2, which prefer cis arrangements in the solid state and solution. The macrocycle 3 can be isolated in yields of 58-67 % using various reaction scales. The isolation of the major by-product of the reaction (ca. 0.5-1 % of samples of 3), the pentameric, host-guest complex [[P(micro-NtBu)(2)](2)(micro-NH)](5)(HCl).2 THF] (4.2 THF), gives a strong indication of the mechanism involved. In situ (31)P NMR spectroscopic studies support a stepwise condensation mechanism in which Cl(-) ions play an important role in templating and selection of 3 and 4. Amplification of the pentameric arrangement occurs in the presence of excess LiX (X=Cl, Br, I). In addition, the cyclisation reaction is solvent- and anion-dependent. The X-ray structures of 2 and 4.2 THF are reported.

Synthesis and structure of [{As(NtBu)3}2Li6] containing an [As(NtBu)3]3− trianion

Abstract Attempts to prepare the [As(NtBu)3]3− trianion by the reaction of As(NMe2)3 with [tBuNHLi]n (1:3 monomer equiv.) proved unsuccessful. However, if the reaction is carried out with an excess of tBuNH2 (3 equiv.) the target complex [{As(NtBu)3}2Li6] (1) is obtained. This is the first example of a complex containing an [As(NR)3]3− trianion.

[ButNHP(μ-NBut)2PNH2], a novel building block for neutral and anionic polycyclic main group arrangements

The novel precursor [ButNHP(μ-NBut)2PNH2] (1) provides easy access to polycyclic main group systems; reaction with Sb(NMe2)3 gives the tricyclic species {[ButNHP(μ-NBut)2- P}2{Me2NSb(μ-N)}2] (2), whereas reaction with an excess of BunLi results in elimination of LiNH2 and the formation of the co-complex [{ButNP(μ-NBut)2P}2 N]Li3 (BunLi)2, (3), containing the unprecedented [{ButNP(μ-NBut)2P}2 N]3− trianion.

Synthesis, structures and coordination behaviour of [As(NR)3]3− trianions

Re-examination of the X-ray structure of the imido As(III) complex previously formulated as [{As(NtBu)3}2Li6]·benzene (1·benzene) indicates that the disorder within the [{As(NtBu)3}2Li6] cage can be better explained by the molecular formulae [{As(NtBu)3}2Li6]·[LiNHtBu]6 or [{As(NtBu)3}Li3·(tBuNHLi)3]. The syntheses and X-ray structures of the new complexes [{As(N(2-MeO-C6H4)3)}2Li6·2TMEDA] (3) and [As{N(2-py)}3·LiN(2-py)·3thf]2·2thf (4·2thf), containing [As(NR)3]3− anions, are reported. Attempts to prepare the heteroleptic trianion [As(NCy)2(NCH2Ph)]3−via reaction of the arsazane dimer [CyNHAs(μ-NCy)]2 (5) with PhCH2NHLi (1 ∶ 6 equivalents) led to the unexpected formation of Zintl compounds containing the As73− anion. The X-ray structure of [As7Li3·3(CyNH2)·3thf] 6 is also reported.

Cooperative cation and anion coordination by a bifunctional imidophosphorane ligand framework; syntheses and structures of [LiCl{ButNHP)μ-NBut)2PNH(2-py)}3] and [{ButNP(μ-NBut)2PN(2-py)}Li2·{Li(ButN)2P}]

The neutral ligand [ButNHP(μ-NBut)2PNH(2-py)] and its dilithiate [{ButNP(μ-NBut)2PN(2-py)}Li 2] exhibit a parallel ability to coordinate cations and anions, as revealed in the structures of the tris-solvate [LiCl{ButNHP(μ-NBut)2PNH(2-py) }3] 1 and the unusual co-complex [{ButNP(μ-NBut)2PN(2-py)}Li 2·{Li(ButN)2P}] 2.

The synthesis and structure of [Sn(NMe2)3Li]∞; an unsolvated polymeric tris(amido)stannate

Abstract The reaction of Sn(NMe2)2 with LiNMe2 (1:1 equiv.) gives [Sn(NMe2)3Li]∞ (1). The complex is the simplest tris(amido)stannate to be structurally characterised and the first in which there is no Lewis base solvation of the alkali metal cation; as a result a polymeric structure is obtained in which the stannate anions are involved in bidentate and monodentate coordination of the Li+ cations.

The tetrameric macrocycle [{P(μ-NtBu)}2NH]4

The 1∶1 reaction of the symmetrical dimers [ClP(μ-NtBu)]21 and [H2NP(μ-NtBu)]22 in thf–Et3N gives the tetrameric macrocycle [{P(μ-NtBu)}2NH]43 (67%); consisting of four P2(μ-NtBu)2 rings linked by endo N–H groups.

The paramagnetic, heterometallic manganese cubanes [{E2(NCy)4}(MnCp)2] (Cy = C6H11, Cp = C5H5, E = As, Sb)

The heterometallic cubanes [{E2(NCy)4}(MnCp)2] (E = Sb 1, As 2; Cy= C6H11, Cp= C5H5) are the first examples of complexes in which a paramagnetic metal ion has been incorporated into a p block ligand framework.

Geometric control of cage architecture; observation of ligand-selective behaviour in the structures of [{As2(NCy)4}2M4] (M = Na, Cu; Cy = C6H11)

The structure of [{As2(NCy)4}2Cu4] reveals a dramatic change in the metal coordination mode compared to that found in the Sb analogue [{Sb2(NCy)4}2Cu4], resulting in the distortion of the Cu4 core from a square-planar to a butterfly shape and providing the first illustration of ligand-selective cage modification in such heterobimetallic species; in contrast the square-planar Na4 arrangement found in [{Sb2(NCy)4}2M4] (M = Na, Cu, Ag) is retained in [{As2(NCy)4}2Na4].

Synthesis and structure of [(ButN)P(μ-NBut)2P(PCy)Li2·thf]2; an unusual cage compound containing an amido/phosphido functionalised [(ButN)P(μ-NBut)2P(PCy)]2− dianion (Cy = C6H11)

The reaction of [(ButNH)P(μ-NBut)2PCl] (1) with CyPHLi and BunLi in toluene gives [(ButN)P(μ-NBut)2P(PCy)Li2 ·thf]2 (2), an unusual aggregate containing the first example of a phosphine-functionalised cyclodiphosphazane anion [(ButN)P(μ-NBut)2P(PCy)]2− .