The imido cage complex [Sb2Li2{ N(C6H11)}4]2, synthesised by the condensation reaction of dimeric [Sb(NMe& { p-N(CcH1l)}]Z with [LiNH(CGHll)ln (1 : 1 monomer equiv.) consists of an Sb4Li4N8 polyhedral core which can be viewed as being constructed from two interlocked 'broken' cubes.Recently we showed that the reactions of SbClx(NMe2)3-x ( x = 0-2) with various organic acids, containing 0 and N centres, gave two possible outcomes depending on the reaction solvent employed and on the particular organic acid and Sb reagent used.1.2 Surprisingly, we found that the reactions of SbCI,(NMe2)3-, ( x = 1 and 2) with organic acids in Et2O gave dimeric complexes in which Me2NH, produced as a gaseous byproduct, acts as a Lewis base donor to Sb.1 In contrast, the reactions of Sb(NMe2)3 with 1 equivalent of a primary amine (RNH?) in toluene lead to dimeric complexes, [Sb(NMe2)(y-NR)I2, in which no Me2NH ligation of Sb occurs.2 Significantly, these complexes are themselves potential metallating reagents since they contain dimeric Sb2N2 cores in which two reactive Me2N groups are retained. We have also shown recently that 'mixed-metallation' reactions of Sb(NMe2)3 can be used to prepare heterometallic complexes.3 The polynuclear Sb-amido anion complex Li[Sb3{N(C6H11)}4-(NMe2)*J is produced by the metallation reaction of Sb(NMe& with Li+[Sb{NH(C6H11)}4]-(2: 1 equiv.) and the cage complex [Sb(LiNCH2CH2Ph)3(thf)]2 is the product of the reaction of Sb(NMe& with [LiNHCH&H2Ph],(1 : 3 monomer equiv .) .3

Ph 3 PAgCtCPh] 4 ‚3.5THF (2) can be prepared by the reaction of CpAgPPh 3 (1) with lithium phenylacetylide (1:1 equiv). Similarly [Me 3 PAgCtCSiMe 3 ] ∞ (4) can be prepared by the reaction of CpAgPMe 3 (3) and lithium (trimethylsilyl)acetylide (1:1 equiv). Both complexes have been characterized by elemental analyses, solid-state IR spectroscopy, 1 H and 31 P NMR spectroscopy, and low-temperature X-ray diffraction studies. The structure of 2 consists of a tetranuclear "flat-butterfly" core, with the two "hinge" silver atoms σ-bonded to two acetylide fragments, which then π-complex the apical Ag(PPh 3 ) 2 fragments. In 4, the smaller steric bulk of the phosphine employed allows this complex to crystallize as a polymer. Rather than being constructed from simple [R 3 PAg(acetylide)] units, both 2 and 4 are formed by the aggregation of (acetylide) 2 Agand Ag(PR 3 ) 2 + fragments. The preparation of complexes 2 and 4 demonstrates the synthetic utility of nucleophilic substitution of CpAgPR 3 in the synthesis of Ag organometallics. The different structural alternatives adopted by 2 and 4 point to the steric bulk of the phosphine ligands being the major influence on the structure of Ag acetylide complexes.

Successive metalation of primary amines, first with nBuLi and then with Sb(NMe2)3, has enabled the preparation of the heterometallic complexes 1 and 2. Neutra [Ph(CH2)2N(H)Li]n and ionic Li[Sb(cyNH)4] occur as the intermediates in the formation of 1 and 2, respectively. equation image

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