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A series of calix[5]arene bismuth(III) and antimony(III) mono- and bimetallic complexes were synthesized and fully characterized by NMR, X-ray, IR, mp, UV-Vis and elemental analysis. Reaction of p-tert-butylcalix[5]arene (tBuC5(H)5) trianionic salts M'3.tBuC5(H)2 (M'=Li, Na, K) with MCl3 (M=Bi, Sb) yielded monometallic complexes [Bi{tBuC5(H)2}] 1 and [Sb{tBuC5(H)2}] 2, respectively. 1H NMR spectra of both complexes showed two remaining OH groups available for further reactivity. Alternatively, complexes 1 and 2 can be obtained by reacting tBuC5(H)5 in a 1:1 ratio with M(OtBu)3, but the yields are lower. When the tBuC5(H)5 lower rim monobenzyl ether [tBuC5(Bn)(H)4] is treated in a 1:1 ratio with Bi(OtBu)3, the monometallic complex [Bi{tBuC5(Bn)(H)}]2 3 is prepared. If, however, [tBuC5(Bn)(H)4] reacts with Sb(NMe2)3 or Sb(OtBu)3 in a 1:2 ratio the production of the bimetallic complex [Sb2O{tBuC5(Bn)}] 4 is observed. p-Benzylcalix[5]arene (BnC5(H)5) reacts with excess Bi(OtBu)3 to produce the bimetallic complex [Bi2O{BnC5(H)}]2 5. 1H NMR spectra of 5 display patterns characteristic for a cone conformer in solution. Treatment of calix[5]arene [HC5(H)5] with one equivalent of Bi[N(SiMe3)2]3 or with 0.75 equivalents of Sb(NMe2)3 yields bimetallic complexes [Bi2O{HC5(H)}] 6 and [Sb2O{HC5(H)}] 7, respectively. The reactivity of monometallic complexes 1 and 2 was tested in order to investigate the availability of their remaining OH groups. Treatment of 1 with Bi(OtBu)3 at ambient temperature yields bimetallic complex [Bi2O{tBuC5(H)}]2 8 while the reaction of complex 2 with Sb(OtBu)3 in a 1:1 ratio produces complex [Sb2O{tBuC5(H)}] 9. The crystal structures of the monometallic bismuth complexes 1 and 3 display dimeric units with the calixarene ligands in distorted cone and "paco-in" conformations, respectively. Complexes 4, 7 and 9 are all monomeric units, displaying [(RO)2Sb]2(micro-O) cores and the calixarene ligands in 1,2-alternate conformation. The dimeric units of bimetallic complexes 5 and 8 contain Bi4O2(OR)8 core structures that force the calixarene ligands to adopt a flattened cone conformation.

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The reaction of the monosodium salt of p-tert-butylcalix[4]arene (But)C4) with 2 equivalents of SbCl3 provides ButC4(SbCl)2 and the first bismuth calixarene complex was prepared by treatment of p-tert-butylcalix[8]arene (ButC8) with Bi[N(SiMe3)2]3 in toluene.

The synthesis, complete characterization, and solid state structural and solution conformation determination of calix[n]arenes (n = 4, 6, 8) is reported. A complete series of X-ray structures of the alkali metal salts of calix[4]arene (HC4) illustrate the great influence of the alkali metal ion on the solid state structure of calixanions (e.g., the Li salt of monoanionic HC4 is a monomer; the Na salt of monoanionic HC4 forms a dimer; and the K, Rb, and Cs salts exist in polymeric forms). Solution NMR spectra of alkali metal salts of monoanionic calix[4]arenes indicate that they have the cone conformation in solution. Variable-temperature NMR spectra of salts HC4.M (M = Li, Na, K, Rb, Cs) show that they possess similar coalescence temperatures, all higher than that of HC4. Due to steric hindrance from tert-butyl groups in the para position of p-tert-butylcalix[4]arene (Bu(t)C4), the alkali metal salts of monoanionic Bu(t)C4 exist in monomeric or dimeric form in the solid state. Calix[6]arene (HC6) and p-tert-butylcalix[6]arene (Bu(t)C6) were treated with a 2:1 molar ratio of M(2)CO(3) (M = K, Rb, Cs) or a 1:1 molar ratio of MOC(CH(3))(3) (M = Li, Na) to give calix[6]arene monoanions, but calix[6]arenes react in a 1:1 molar ratio with M(2)CO(3) (M = K, Rb, Cs) to afford calix[6]arene dianions. Calix[8]arene (HC8) and p-tert-butylcalix[8]arene (Bu(t)()C8) have similar reactivity. The alkali metal salts of monoanionic calix[6]arenes are more conformationally flexible than the alkali metal salts of dianionic calix[6]arenes, which has been shown by their solution NMR spectra. X-ray crystal structures of HC6.Li and HC6.Cs indicate that the size of the alkali metal has some influence on the conformation of calixanions; for example, HC6.Li has a cone-like conformation, and HC6.Cs has a 1,2,3-alternate conformation. The calix[6]arene dianions show roughly the same structural architecture, and the salts tend to form polymeric chains. For most calixarene salts cation-pi arene interactions were observed.

The synthesis and full characterization (mp, NMR, UV/vis, FTIR, and elemental analysis) of 13 bismuth aryloxides are reported. We have prepared bismuth aryloxides with alkyl, aryl, and allylic substituents on the aryl rings. Eleven of these bismuth aryloxides have been characterized with single crystal X-ray diffraction methods. Bismuth-donor interactions (donor = aryl, methoxy) are observed in several cases. Three unexpected bismuth oxo aryloxides (6c, 9c, 11c) were also isolated. Complex C(77)H(102)Bi(4)Br(6)O(8) (6c) results from apparent C-H activation and Bi-C bond formation as a sideproduct in the synthesis of Bi(O-2,6-(i)Pr(2)-4-BrC(6)H(2))(3) (6). Cluster 9c has a Bi(32)O(56) core, and cluster C(90)H(90)Bi(4)Li(2)O(12) (11c) is the second lithium bismuth oxo cluster reported to date.

The reaction of BiCl(3) with the lithium salt of o-di-tert-butylphenol under nitrogen forms organic oxidation products rather than the expected Bi(OAr)(3) complex, and bismuth disproportionation products. Likewise, the decomposition of Bi(III) aryloxides Bi(O-2,6-(i)Pr(2)C(6)H(3))(3) and ClBi(O-2,4,6-(t)Bu(3)C(6)H(2))(3) leads to corresponding organic oxidation products. These reactions can be explained by Bi-O bond homolysis to form unstable Bi(II) radicals, analogous to a fundamental step suggested to intervene in the SOHIO process.

Organic azides are commonly used in transition metal chemistry as sources of :NR moieties to form metal imido complexes.['-31 When a metal-metal bond is exposed to an organic azide, for example, the product is usually a complex with a bridging imido g r 0~p . I~. 51 However, in spite of the frequent use of this methodology, little mechanistic information is available on either the mono-16. ' I or binuclear versions ofthis reaction. In this paper we report: a) that both azides and diazo compounds add smoothly, and without N, loss, to the polarized metalmetal bond in an early-late heterobinuclear (ELHB) complex, to yield new heterobinuclear adducts that have very similar solid-state structures; b) the diazo compound adduct is inert to both heat and light, but thermolysis of the azide complexes leads smoothly to N, and the corresponding ELHB bridging imido complexes; c) studies involving isotope labeling, kinetics, and substituent effects reveal a mechanism in which electron-withdrawing substituents stabilize the transition state for imido complex formation.Addition of phenyl azide to [Cp,Zr(p-NtBu)IrCp*] (I)[', resulted in immediate formation of dark green 2 in 75 '41 yield ( Fig. 1). Similarly. addition of ethyl diazoacetate to 1 produced the dark green diazo adduct 3 in 59% yield. Both reactions proceed without loss of N,. X-ray diffraction studies of 2 and 3 have been carried out, and their solid-state structures are remarkably similar.[". ' I 1 As shown in Figure 1, both are end-on (terminal) adducts, and the terminal nitrogen atom and phenyl or carboxylate groups are oriented anti to one another. The phenyl azido ligand of 2, the diazo ligand of 3, and the heteronuclear cores in both complexes are planar, and in both molecules the IrZrN, core and RXN, fragments lie in the same plane. The nitrogen--nitrogen distances in 2 are intermediate between single-and double-bond distances, showing some electron delocalization across the ligand. Likewise, the N2-N3-N4 angle is 11 1" rather than the 120" that would be expected for an sp2 nitrogen center. In 3 the N-N distance (1.30 A) is shorter than that of a typical single bond, consistent with electron deiocalization, but the N2-N3-C25 angle of 119" is closer to the sp2 standard. The C25-N3 bond length of 1.33 A is also indicative of some delocalization (for example, C-N of pyridine is 1.338 A). There is no sign of the formation of the more sterically hindered isomers in either compound.[12-'71 Irradiation of azide adduct 2 and diazo adduct 3 in a quartz vessel for 12 hours at room temperature led to only a trace of the product formed by nitrogen loss. Complex 3 also did not under-