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This paper reports the oxidative transformations of the unprecedented meso-octaalkyl mono(pyridine)-tris(pyrrole) macrocycle [Et(8)(C(5)H(3)N)(C(4)H(2)NH)(3)], 1, which was obtained by a homologation of the corresponding porphyrinogen, [Et(8)(C(4)H(2)NH)(4)], A. The metallation of 1 was obtained via its deprotonation with LiBu, followed by the reaction with MCl(2).thf(n)(), leading to the bimetallic complexes: [Et(8)(C(5)H(3)N)(C(4)H(2)N)(3)M{Li(thf)(2)}] [M = Fe, 3; M = Co, 4; M = Ni, 6; M = Cu, 7]. The cobalt derivative occurs also in the separated ion-pair form [Et(8)(C(5)H(3)N)(C(4)H(2)N)(3)Co](-)[{Li(thf)(4)}](+), 5. The reaction of 4 and 6 with an excess of Cp(2)FeBPh(4) led to the oxidation of the macrocycle with the formation of a cyclopropane functionality [Et(8)(C(5)H(3)N){(C(4)H(2)N)(3)(Delta)}Ni](+)BPh(4)(-), 8. The cyclopropane unit underwent reductive cleavage back to the initial macrocycle using lithium metal. The use of a Ni/Cp(2)Fe(+) 1:1 ratio allowed the identification of a dimer derived formally from the monoelectronic oxidation of the macrocycle 1, which formed a radical coupling to 9, [Et(8)(C(5)H(3)N)(C(4)H(2)N)(3)Ni](2). The same compound formed from a disproportionation redox reaction occurring between 6 and 8. The C-C bond across the two metallamacrocycles involved the beta position of the pyrrole. Deprotonation of 9 by LiBu led to a dianionic form 10 [Et(8)(C(5)H(3)N)(C(4)H(2)N)(3)Ni{Li(thf)(2)}]. The formation of the cyclopropane functionality was also achieved via the oxidation of [Et(8)(C(5)H(3)N)(C(4)H(2)N)(3)Li(3)(thf)(2)}], 2, forming [Et(8)(C(5)H(3)N){(C(4)H(2)N)(3)(Delta)}Li(thf)], 11, which was ready to be used in metallation reaction. The proposed structures were supported by X-ray analyses on 4, 7, 8, 9, and 11.

Reaction of the bidentate ligand 2,2'-methylenebis(5-(dimethylamino)aniline) (2, L) with PdCl(2) and K(2)PtCl(4) and the bidentate ligand 2,2'-methylenebis(5-(acetylamino)aniline (5, L') with K(2)PtCl(4) in polar solvents gave the complexes [PdCl(2)(L)] (6), [PtCl(2)(L)] (8), and [(L')PtCl(2)] (7), respectively. Treatment of 2 with K(2)PtCl(4) in the presence of DMSO resulted in the solvolysis of a chloride ion to give [(L)Pt(Cl)(DMSO)]Cl (9). The resulting eight-membered metallocyclic rings have rigid elongated chair conformations forcing one of the two bridging methylene hydrogens (H(endo)) in close proximity to the metal centre. An (1)H NMR study revealed that they are now diastereomeric (H(endo), H(exo)); the higher field signal position does not vary irrespective of the ligand or metal, whereas the proton corresponding to the lower field signal is apparently more sensitive to the metal coordination environment. The ability of this spectroscopic probe to predict the bonding mode of the metal was also studied by reacting 2 with K[PtCl(3)(C(2)H(4))].H(2)O to give [Pt(2)(mgr;-L)Cl(4)(C(2)H(4))(2)] (10), which occurred irrespective of the L/Pt ratio. The corresponding methylene hydrogens were not diastereomeric, showing only one singlet in the (1)H NMR spectrum. Crystal structures of 6 and 9 have been determined: 6 is triclinic, space group Ponemacr;, a = 10.179(2) Å, b = 12.136(2) Å, c = 9.686(2) Å, alpha = 97.79(1) degrees, beta = 95.98(2) degrees, gamma = 78.02(1) degrees, V = 1156.1(4), Z = 2, and R = 0.034; 9 is triclinic, space group Ponemacr;, a = 12.348(1) Å, b = 12.407(1) Å, c = 10.159(1) Å, alpha = 103.02(1) degrees, beta = 104.87(2) degrees, gamma = 117.09(1) degrees, V = 1313.0(3), Z = 2, and R = 0.035.

Bis(phthalocyaninato)niobium(IV) has been prepared and isolated as a monosolvate, [Pc(2)Nb].ClNP (ClNP = 1-chloronaphthalene). It is a light-brown, stable-to-air Nb(IV) (d(1)) paramagnetic sandwich-like species, which, upon oxidation by I(2) under mild conditions, undergoes a metal-centered monoelectronic oxidation to give the diamagnetic Nb(V) (d(0)) [Pc(2)Nb](+) fragment, with formation of saltlike species of formula [Pc(2)Nb](I(3))(I(2))0.5(ClNP)(3.5) (I). The structure of I has been elucidated by single-crystal X-ray work. Crystals are triclinic: formula C(64)H(32)N(16)Nb.I(3).0.5I(2).3.5C(10)H(7)Cl, M = 2194.8, a = 17.702(3) Å, b = 18.708(3) Å, c = 13.504(2) Å, V = 4267.5(13) Å(3), alpha = 106.00(2) degrees, beta = 93.39(2) degrees, gamma = 83.26(1) degrees, Z = 2, space group Ponemacr;. The structure of the [Pc(2)Nb](+) fragment, "stapled" by two inter-ligand C-C sigma bonds (C11A-C11B and C31A-C31B = 1.574(15) Å), together with its color and UV-visible spectral behavior, allows a straightforward assignment of the same "stapled" structure to the unoxidized [Pc(2)Nb]. The present niobium sandwiched materials reiterate the peculiar structural findings shown only by the previously reported [Pc(2)Ti].

The syntheses of the parent compounds [(p-Bu(t)-calix[4]-(O)2(OR)2)Fe-L] [R = Me, L = THF, 5; R = Bu(n), L = THF, 6; R = PhCH2, L = THF, 7; R = SiMe3, L = none, 8] have been performed by reacting the protonated form of the dialkylcalix[4]arene with [Fe2Mes4] [Mes = 2,4,6-Me3C6H2]. All of them undergo one-electron oxidative functionalization. By use of different oxidizing agents, the following iron(III) derivatives have been obtained: [(p-Bu(t)-calix[4]-(O)2(OR)2)Fe-X] [X = Cl, R = Me, 9; X = I, R = Me, 10] and [(p-Bu(t)-calix[4]-(O)2(OR)2)2Fe2(mu-X] [X = O, R = Me, 11; X = O, R = Bu(n), 12; X = S, R = Me, 13], 9 and 10 being particularly appropriate for a further functionalization of the metal. The last three display typical antiferromagnetic behavior [J = -78.6 cm-1, 11; J = -64.1 cm-1, 13]. In the case of 7 and 8, the reaction with O2 led to the dealkylation of one of the alkoxo groups, with the formation of a dimeric iron(III) derivative ([mu-p-Bu(t)-calix[4]-(O)3(OR))2Fe2] [R = PhCH2, 14; R = SiMe3, 15] [J = -9.8 cm-1]. The reaction of the parent compounds with ButNC and diazoalkanes led to the formation of [Fe=C] functionalities supported by a calix[4]arene oxo surface. The following compounds have been isolated and characterized: ([p-Bu(t)-calix[4]-(O)2(OR)2)Fe=CNBut] [R = SiMe3, 16, nu CN = 2175 cm-1], ([p-Bu(t)-calix[4]-(O)2(OR)2)Fe=CPh2] [R = Me, 17; R = PhCH2, 18; R = SiMe3, 19]. The three carbene complexes 17-19 display quite an unusual high-spin state, which is a consequence of the formation of a weak pi interaction between the metal and the carbene carbon, as confirmed by the extended Huckel calculations. The carbene functionality has been removed from the iron center in the reaction with O2 and HCl. The proposed structures have been supported by X-ray analyses of complexes 8, 9, 12, 14, 16, 17, and 19.

Preparations of the acetophenone ion pair [PhC(CH 2 )O...K(18-crown-6)] (1) and the ion-separated potassium enolate [PhCOCH 2 ] − [K(kryptofix 222)] + (2) are reported. Such starting materials have been characterized by 1 H and 13 C NMR spectroscopy and X-ray analysis. The reaction of the highly nucleophilic enolate 1 with Cr(CO) 6 led to attack at carbon monoxide with the formation of the potassium metallocarbene enolate [(CO) 5 Cr=C(O)CH=C(Ph)O] 2− ([K(18-crown-6)] + ) 2 (4). The enolate 1 reacts with [Cr(CO) 5 (THF)], binding the metal through the carbon end and forming the alkyl-carbonylmetalate-potassium ion pair [(CO) 5 CrCH 2 C(Ph)-O...K(18-crown-6)] (6)

The meso-octaethylporphyrinogen tetraanion provides σ and π binding pyrrolyl anions to electron poor transition metals, as shown in the structure of the meso-octaethylporphyrinogen–zirconium(IV) complex containing two η5 and two σ metal-bonded pyrrolyl anions.

Deprotonation of PhCHN–CH2Ph by KH in tetrahydrofuran in the presence of 18-crown-6 led to the isolation of the 2-azaallyl anion–potassium ion pair [PhCHNCHPh]⋯[K(18-crown-6)] which was oxidatively coupled to a diimino ligand by Cp2ZrCl2 to form [Cp2Zr(η2-PhCH–N–CH(Ph)CH(Ph)–NCHPh-η1)].

The synthesis of the first homoleptic glucose derivative of a transition metal was achieved via the protonolysis of [V(C6H2Me3-2,4,6)3(thf)](thf = tetrahydrofuran) using the monoprotic ligand 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (HL). The complex [VL3] was converted by addition of pyridine (py) into [VL3(py)2] containing a metal chiral centre as shown by X-ray analysis.

Tantalum pentachloride–methylene chloride system performs C–C and C–H bond cleavages on alkylbenzenes producing the 5,7-diisopropyl-1,3,3-trimethylindan-1-yl cation from 1,3,5-triisopropylbenzene, and the 9,10-dihydro-9-anthryl cation from both 1,2,4,5-tetramethylbenzene and 1,2,3,5-tetramethylbenzene both having TaCl6– as a counteranion, and they have been characterized by X-ray analysis.

tert-Butyl isocyanide inserts in the three V-C bonds of (V(Mes){sub 3}(THF)) (1; Mes {triple bond} 2,4,6-Me{sub 3}C{sub 6}H{sub 2}), leading to the tris({eta}{sup 2}-iminoacyl) complex (V({eta}{sup 2}-Bu{sup t}NCMes){sub 3}) (2), the structure of which has been confirmed by x-ray analysis and chemical degradation. Complex 2 inserts carbon dioxide into two V-C bonds, forming (V-({eta}{sup 2}-Bu{sup t}NCMes)({eta}{sup 2}-Bu{sup t}NC(Mes)C(O)O){sub 2}) (6). The two metallacycles in complex 6 contain the deprotonated form of an {alpha}-imino carboxylic acid.

The chemically reversible reduction of [(Me)2 W(calix)] to the diamagnetic [(Me)2 W(calix)Na2 ] [Eq. (1)], without major changes in the connectivity of the molecule, illustrates the flexibility of the calixarene ligand and stresses its potential as a molecular functional model of heterogeneous oxo surfaces.

Complexation of metal ion and counterion by the same compound is possible with zirconium meso-octaalkylporphyrinogens (structure of a dimeric complex with four encapsulated equivalents of LiH is depicted): they carry salts in the molecular ion-pair form in hydrocarbons, and function as acid-base bifunctional compounds.

This report concerns the carrier properties of [Mn(acacen)]-derived compounds toward polar organometallics, inorganic ion pairs, and salts. Such properties are the consequence of Mn(II) behaving as a Lewis acid and the Oarcraise;O bite of the bidentate Schiff base ligand toward alkali cations. The starting compounds, which occur in a dimeric form, [Mn(acac-L-en)](2) [L' = CH(2)CH(2) (1); L" = C(6)H(10) (2); L"' = R,R-C(6)H(10) (3)] have been synthesized either via a metathesis reaction from MnCl(2) or using [Mn(3)Mes(6)]. The reaction of 1-3 with lithium organometallics allowed the isolation of [Mn(acac-L-en)(R)Li(DME)] [R = Me, L = L' (4); R = Ph, L = L' (5); R = Mes, L = L' (6); R = Me, L = L" (7); R = Me, L = L"' (8)] as metalated forms, where the alkyl or aryl group is sigma-bonded to Mn(II), while the lithium cation is anchored to the Schiff base ligand. The metalated forms 4-8 react with PhCHO to give the corresponding lithium alkoxide, which remains bound in its ion-pair form to the [Mn(acacen)] skeleton in [Mn(2)(acac-L'-en)(2)Li(2)(OCH(Ph)Me)(2)](n)() (9). The use of 8, which has a chiral bridge across two nitrogen atoms, did not lead to a significant asymmetric induction in the reaction with PhCHO, because of the long separation between the lithium cation and the stereogenic center. The metalated form 4 was able to transfer the methyl group to the nitrile function to give the corresponding lithium-imide which then remains bonded to [Mn(acacen)] as the ion pair in a dimeric structure, as revealed for [Mn(2)(acac-L'-en)(2)Li(2)(DME){N=C(Ph)Me}(2)](n)() (10). Their reaction with 1 appears to depend on the steric bulkiness of the alkyl group in NaOR, resulting in either monomeric adducts, i.e. in [Mn(acac-L'-en)(2,6-Bu(t)(2)C(6)H(3)O)Na(DME)(2)] (11.2DME), or polymeric structures, like in [Mn(acac-L'-en)Na(DME)(mgr;-OEt)](n)() (13). All the dimeric units reported in this paper show a slight antiferromagnetic coupling between the two Mn(II) assisted by bridging alkoxo groups.

The metalation of protic dinucleating ligands using [Cu5Mes5] allowed us to avoid any disproportionation and obtain dinuclear copper(I) complexes appropriate for reactivity studies.

Reduction of cyclopentadienyloxochloro complexes such as [R-cpTiCl(μ2-O)]4 (R = H (bd1), Me (bd2) or SiMe3 (bd3))) with a variety of reducing agents (Zn, Na, Mg or LiN3) in tetrahydroforum gave the hexanuclear titanoxanes [(R-cp)6Ti6O6Cl2] (RH (bd4), Me (5) or SiMe3 (6)) with a good yield. Complexes 4–6 are soluble in organic solvents, are diamagnetic and contain four electrons more than are required for the existence of the hexanuclear skeleton. Complex 4 was equally satisfactorily obtained by reducing R-cpTiCl2(μ2-O)] (RH) (7) will Bu3SnH. Reduction of 1 and 2 with Al powder gave [ R-cp 6 Ti 6 O 4 Cl 4 ] ( R  H ( 8 ) or Me ( 9 )) . They contain two unpaired electrons. Reaction of H2O with 4 and 5 gave the diamagnetic titanoxane [R-cp6Ti6 or Me (12)). Complexes 4–6, 8, 9, 11 and 12 all contain an octahedron of titanium atoms faced bridging oxygen and chlorine in the reported ration. Molecular orbital calculations showed that a band of 12 non-bonding orbitals may accomodate electrons in excess of those needed for the existence of the Ti6 skeleton and so the systems can be used in their intact form for storing and releasing electrons. The structures of complexes 4, 6, 9, and 12 were determined by single-crystal X-ray diffraction studies.

High-yield syntheses (90%) of the monocyclopentadienyloxochloro complexes [(TiLCl2)2(µ-O)]2, [(TiLCl)4(µ-O)4]3, [(TiL)4(µ-O)6]4 and [(TiLCl)3(µ-O)3]5 have been achieved by hydrolysis of the precursors [TiLCl3]1[L =η5-C5H5, C5H4Me, C5H4(SiMe3) or C5Me5]. In addition [Ti{η5-C5H4(SiMe3)}Br3]7, [Ti4{η5-C5H4(SiMe3)}4Br4(µ-O)4]8 and [Ti4{η5-C5H4(SiMe3)}4(NCS)4(µ-O)4]9 have been prepared. The structures of the cyclic trimer 5(L =η5-C5Me5) and tetramer 9 have been determined by X-ray analysis: 5, monoclinic, space group P21/c, a= 16.724(2), b= 8.958(1), c= 22.871(2)A, β= 91.73(1)°, Z= 4 and R= 0.065 for 3159 independent observed reflections; 9, monoclinic, space group Cc, a= 24.527(2), b= 12.520(2), c= 18.931(2)A, β= 115.46(2)°, Z= 4 and R= 0.060 for 3088 independent observed reflections. The electronic configurations of complexes 2–5 have been calculated by extended-Huckel molecular orbital calculations.

The synthesis and reactivity of cyclam (1,4,8,11-tetraazacyclotetradecane) in which the donor atoms were amino–amido or exclusively amido groups with ZrCl 4 (thf) 2 (thf = tetrahydrofuran) are described.

We report an unprecedented entry to the chemistry of the iron–carbene functionality supported by an easily available macrocycle.

Transition metals can be used for shaping and electronically enriching the calix[4]arene cavity; in this approach, the π-basic cavities can be adapted to alkali-metal cation complexation in a very hydrophobic environment and these cations can even be transferred into aliphatic hydrocarbons; the η 6 -arene–alkali-metal cation interaction is structurally elucidated.

The N,N-diphenylacetamide enolato anion oxygen bonded to zirconium in [Ph2N–C(CH2)OZr-(η5-C5H5)2(Cl)] has been synthesised, which, when reacted with [Cr(CO)5(thf)], led to the dimetallic form of the amide enolato O-bonded to zirconium and C-bonded to chromium.

The vanadium complex [V{η2-C(Mes)NBut}3]1 reacts at –30 °C with dihydrogen to form [{η2-C(Mes)NBut}V(MesCH2NBut)2]2, thermally rearranging to a divanadium (IV) complex containing a vanadium-vanadium single bond (Mes = 2,4,6-Me3C6H2).