Synthesis and study of hexanuclear molybdenum clusters containing thiolate ligands

Four hexanuclear molybdenum chloride cluster complexes containing terminal thiolate ligands have been synthesized and fully characterized. (Bu 4N) 2[Mo 6Cl 8(SEt) 6] was prepared by reacting Na 2[Mo 6Cl 8(OMe) 6] with an excess of ethanethiol in refluxing tetrahydrofuran. (PPN) 2[Mo 6Cl 8(SBu) 6], (Bu 4N) 2[Mo 6Cl 8(SBn) 6], and (Bu 4N) 2[Mo 6Cl 8(SNC 8H 6) 6] (C 8H 6NS (-) = 3-indolylthiolate) were subsequently prepared in the reaction of [Mo 6Cl 8(SEt) 6] (2-) with an excess of HSR (R = Bu, Bn or 3-indolyl). Single crystal X-ray diffraction analyses were performed on two of these complexes: (PPN) 2[Mo 6Cl 8(SEt) 6].Et 2O, crystallizes in the triclinic space group P1 with a = 12.3894(11), b = 13.7651(12), c = 15.0974(13), alpha = 103.975(2), beta = 99.690(2), gamma = 98.062(2), and Z = 1; (PPh 3Me) 2[Mo 6Cl 8(SBn) 6].2NO 2CH 3, also crystallizes in the P1 space group with a = 12.1574(16), b = 13.4441(17), c = 14.2132(18), alpha = 89.654(2), beta = 88.365(2), gamma = 71.179(2), and Z = 1. Our studies demonstrate that [Mo 6Cl 8(SEt) 6] (2-) displays luminescent properties and that the same complex undergoes substitution reactions with different thiols, as well as reaction with electrophilic reagents such as MeI.     

Self-assembly of diorganotin(IV) moieties and 2-pyrazinecarboxylic acid: syntheses, characterizations and crystal structures of monomeric, polymeric or trinuclear macrocyclic compounds

A series of diorganotin(IV) compounds of the type [R(2)Sn(pca)Cl](3)(R = CH(3); (n)Bu; C(6)H(5); C(6)H(5)CH(2); Hpca = 2-pyrazinecarboxylic acid), R(2)Sn(pca)(2)(mH(2)O)xnH(2)O (m= 1: R = CH(3), n= 2, R =(n)Bu, n= 0; m= 0, n= 0: R =(n)Bu, C(6)H(5), C(6)H(5)CH(2)) and (Et(3)NH)(+)[R(2)Sn(pca)(2)Cl](-)xmH(2)O (m= 0: R = CH(3), (n)Bu, C(6)H(5)CH(2); m= 1: R = C(6)H(5)) have been obtained by reactions of 2-pyrazinecarboxylic acid with diorganotin(iv) dichloride in the presence of sodium ethoxide or triethylamine. All compounds were characterized by elemental, IR and NMR spectra analyses. Except for compounds, and, the others were also characterized by X-ray crystallography diffraction analyses, which revealed that compounds and were trinuclear macrocyclic structures with six-coordinate tin(IV) atoms, compounds and were monomeric structures with seven-coordinate tin(IV) atoms, compounds and were polymeric chain structures with seven-coordinate tin(IV) atoms and compounds and were stannate with seven-coordinate tin(IV) atoms.     

Group 5 imido complexes derived from diamido-pyridine ligands

Reaction of the vanadium(V) imide [V(NAr)Cl(3)(THF)] (Ar = 2,6-C(6)H(3)(i)()Pr(2)) with the diamino-pyridine derivative MeC(2-C(5)H(4)N)(CH(2)NHSiMe(2)(t)()Bu)(2) (abbreviated as H(2)N'(2)N(py)) gave modest yields of the vanadium(IV) species [V(NAr)(H(3)N'N' 'N(py))Cl(2)] (1 where H(3)N'N' 'N(py) = MeC(2- C(5)H(4)N)(CH(2)NH(2))(CH(2)NHSiMe(2)(t)()Bu) in which the original H(2)N'(2)N(py) has effectively lost SiMe(2)(t)()Bu (as ClSiMe(2)(t)()Bu) and gained an H atom. Better behaved reactions were found between the heavier Group 5 metal complexes [M(NR)Cl(3)(py)(2)] (M = Nb or Ta, R = (t)()Bu or Ar) and the dilithium salt Li(2)[N(2)N(py)] (where H(2)N(2)N(py) = MeC(2-C(5)H(4)N)(CH(2)NHSiMe(3))(2)), and these yielded the six-coordinate M(V) complexes [M(NR)Cl(N(2)N(py))(py)] (M = Nb, R = (t)()Bu 2; M = Ta, R = (t)()Bu 3 or Ar 4). The compounds 2-4 are fluxional in solution and undergo dynamic exchange processes via the corresponding five-coordinate homologues [M(NR)Cl(N(2)N(py))]. Activation parameters are reported for the complexes 2 and 3. In the case of 2, high vacuum tube sublimation afforded modest quantities of [Nb(N(t)()Bu)Cl(N(2)N(py))] (5). The X-ray crystal structures of the four compounds 1, 2, 3, and 4 are reported.     

Titanium and niobium imido complexes stabilized by heteroscorpionate ligands

The reaction of [Ti(NR)Cl(2)(py)(3)](R = (t)Bu, p-tolyl, 2,6-C(6)H(3)(i)Pr(2)) with [{Li(bdmpza)(H(2)O)}(4)][bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate] and [{Li(bdmpzdta)(H(2)O)}(4)][bdmpzdta = bis(3,5-dimethylpyrazol-1-yl)dithioacetate] affords the corresponding complexes [Ti(NR)Cl(kappa(3)-bdmpzx)(py)](x = a, R = (t)Bu 1, p-tolyl 2, 2,6-C(6)H(3)(i)Pr(2) 3; x = dta, R =(t)Bu 4, p-tolyl , 2,6-C(6)H(3)(i)Pr(2) 6), which are the first examples of imido Group 4 complexes stabilized by heteroscorpionate ligands. The solid-state X-ray crystal structure of 1 has been determined. The titanium centre is six-coordinate with three fac-sites occupied by the heteroscorpionate ligand and the remainder of the coordination sphere being completed by chloride, imido and pyridine ligands. The complexes are 1-6 fluxional at room temperature. The pyridine ortho- and meta-proton resonances show evidence of dynamic behaviour for this ligand and variable-temperature NMR studies were carried out in order to study their dynamic behaviour in solution. The complexes [Nb(NR)Cl(3)(py)(2)](R = (t)Bu, p-tolyl, 2,6-C(6)H(3)(i)Pr(2)) reacted with [{Li(bdmpza)(H(2)O)}(4)] and (Hbdmpze)[bdmpze = 2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide], the latter with prior addition of (n)BuLi, to give the complexes [Nb(NR)Cl(2)(kappa(3)-bdmpzx)](x = a, R =(t)Bu 7, p-tolyl 8, 2,6-C(6)H(3)(i)Pr(2) 9; x = e, R = (t)Bu 10, p-tolyl 11, 2,6-C(6)H(3)(i)Pr(2)) 12 and these are the first examples of imido Group 5 complexes with heteroscorpionate ligands. The structures of these complexes have been determined by spectroscopic methods.     

Gold complexes with potentially tri- and tetradentate phosphinothiolate ligands

Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- = 2-(N,N-dimethylaminomethyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3-SH-2-R-3)2 (H2L1a, R = SiMe3; H2L1b, R = H) and P(C6H4-SH-2)3 (H3L2) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different oxidation states, +1 and +3, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl4]-. A dinuclear complex having two Au(III) centers can be isolated from the reaction of [Au(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained, which contains a three-coordinate gold atom. Comparatively short gold-gold distances have been found in the dinuclear complexes (2.978(2) and 3.434(1) A). They are indicative of weak gold-gold interactions, which is unusual for gold(III).     

Synthesis, spectral and thermal studies of some organotin(IV) derivatives of 5-amino-3H-1,3,4-thiadiazole-2-thione

Some tri- and diorganotin(IV) compounds of the general formula, RnSnL4-n (where n=2, R=Me, n-Bu and Ph; n=3, R=Me, n-Bu, n-Pr and Ph; HL=5-amino-3H-1,3,4-thiadiazole-2-thione) have been synthesized by the reaction of RnSnCl4-n (where n=2 or 3, R=Me, n-Bu, n-Pr and Ph) and the sodium salt of the ligand. Oct2SnL2 was obtained by the reaction of Oct2SnO with HL in a 1:2 molar ratio under azeotropic removal of water. The bonding and coordination behavior in these derivatives are discussed on the basis of IR, Far-IR, multinuclear (1H, 13C and 119Sn) NMR and 119Sn M?ssbauer spectroscopic studies. These investigations suggest that in all the compounds the ligand acts as monoanionic bidentate coordinating through ring N(3) and exocyclic S. Thermal studies of five compounds, viz., Ph3SnL, Me2SnL2, n-Bu2SnL2, Oct2SnL2 and Ph2SnL2 have been carried out in the temperature range 25-1000 degrees C using TG, DTG and DTA techniques under an atmosphere of dry nitrogen.     

Organometallic gold(III) compounds as catalysts for the addition of water and methanol to terminal alkynes

Different inorganic and organometallic gold(III) and gold(I) complexes have been tested in the addition of water and methanol to terminal alkynes. Anionic and neutral organometallic gold(III) compounds can efficiently mediate these reactions in neutral media in refluxing methanol. The compounds are added in catalytic amounts (1.6-4.5 mol % with respect to the alkyne). Thus, compounds of the general formula Q[AuRCl(3)], Q[AuR(2)Cl(2)], [AuRCl(2)](2), and [AuR(2)Cl](2) (Q = BzPPh(3)(+), PPN: N(PPh(3))(2)(+) or N(Bu)(4)(+); R = C(6)F(5) or 2,4,6-(CH(3))(3)C(6)H(2)) seem to behave as Lewis acids in nucleophilic additions to triple bonds. Some intermediates could be detected in the stoichiometric reaction between [Au(C(6)F(5))(2)Cl](2) and phenylacetylene that was followed by variable temperature (1)H, (19)F[(1)H], COSY (19)F[(1)H]-(19)F[(1)H], and (2)H[(1)H] NMR experiments. Compound [Au(C(6)F(5))(2)Cl](2) is also able to catalyze the hydration of phenylacetylene at room temperature. A plausible mechanism for the hydration reaction has been proposed.     

Diimine-acetylide compounds of ruthenium: the structural and spectroscopic effects of oxidation

The reaction of Ru(Me(2)bipy)(PPh(3))(2)Cl(2) 1 with terminal alkynes HCCR in the presence of TlPF(6) leads to the formation of the vinylidene compounds [Ru(Me(2)bipy)(PPh(3))(2)Cl(=C=CHR)][PF(6)] (2) (2a, R = Bu(t); 2b, R = p-C(6)H(4)-Me; 2c, R = Ph). These compounds decompose in oxygenated solution to form the carbonyl compound [Ru(Me(2)bipy)(PPh(3))(2)Cl(CO)][PF(6)] (3), and may be deprotonated by K(2)CO(3) to give the ruthenium(II) terminal acetylide compounds Ru(Me(2)bipy)(PPh(3))(2)Cl(CC-R) (4) (4a, R = Bu(t); 4b, R = p-C(6)H(4)-Me; 4c, R = Ph). Cyclic voltammetry shows that 2a-c may also be reductively dehydrogenated to form 4a-c. 4a-c are readily oxidized to their ruthenium(III) analogues [4a](+)-[4c](+), and the changes seen in their UV/visible spectra upon performing this oxidation are analyzed. These show that whereas the UV/visible spectra of 4a-c show MLCT bands from the ruthenium atom to the bipyridyl ligand, those of [4a](+)-[4c](+) contain LMCT bands originating on the acetylide ligands. This is in agreement with the IR and ESR spectra of [4a](+)-[4c](+). The X-ray crystal structures of the redox pair 4a and [4a][PF(6)()] have been determined, allowing the bonding within the metal-acetylide unit to be analyzed, and an attempt is made to determine Lever electrochemical parameters (E(L)) for the vinylidene and acetylide ligands seen herein. Room temperature luminescence measurements on 4a-c show that the compounds are not strongly emissive.     

A general and modular synthesis of monoimidouranium(IV) dihalides

The conproportionation reaction between the dimeric diimidouranium(V) species [U(N(t)Bu)(2)(I)((t)Bu(2)bpy)](2) ((t)Bu(2)bpy = 4,4'-di-tert-butyl-2,2'-bipyridyl) and UI(3)(THF)(4) in the presence of additional (t)Bu(2)bpy yields U(N(t)Bu)(I)(2)((t)Bu(2)bpy)(THF)(2) (2), an unprecedented example of a monoimidouranium(IV) dihalide complex. The general synthesis of this family of uranium(IV) derivatives can be achieved more readily by adding 2 equiv of MN(H)R (M = Li, K; R = (t)Bu, 2,6-(i)PrC(6)H(3), 2-(t)BuC(6)H(4)) to UX(4) in the presence of coordinating Lewis bases to give complexes with the general formula U(NR)(X)(2)(L)(n) (X = Cl, I; L = (t)Bu(2)bpy, n = 1; L = THF, n = 2). The complexes were characterized by (1)H NMR spectroscopy and single-crystal X-ray diffraction analysis of compounds 2 and {U[N(2,6-(i)PrC(6)H(3))](Cl)(2)(THF)(2)}(2) (4). (The X-ray structures of 5 and 6 are reported in the Supporting Information.)     

DNA Binding Studies and Evaluation of Electrochemical Parameters of New Tri-and Di-Organotin(IV) Complexes of 4-(1H-Indol-3-yl)butanoic Acid

New triorganotin(IV) [R₃SnL where R = Me (1), Bu (2), Ph (3)] and diorganotin(IV) [R₂SnL₂, where R = Me (4), Bu (5), Ph (6)] derivatives of 4-(1H-indol-3-yl)butanoic acid (HL) were prepared and characterized by FT-IR and ¹H and ¹³C NMR spectroscopy. Interaction between DNA and selected compounds was studied by UV-Vis spectroscopy and viscometry. The binding constants calculated on the basis of the accumulated data reveal the following order of binding strength: compound 2 > 1 > 5 > 4. Electrochemical parameters such as diffusion coefficient and charge transfer coefficient are evaluated with cyclic voltammetry. The results demonstrate that diorganotin(IV) complexes are characterized by higher diffusion coefficient than triorganotin(IV) analogues. In case of triorganotin(IV) complexes, the lower coordination number allows a solvent to interact with Sn(IV) center and hence decreases the rate of diffusion.

     

Electrochemical study of nickel complexes in Ziegler-type catalytic systems

Conclusions By electrochemical methods, it was shown that -organonickel complexes stabilized by organoaluminum compounds are present in homogeneous three-component systems consisting of NiX₂ (X=Cl or acac), an organophosphorus activator [PR₃, P(OR)₃, where R=Et, i-Pr, Bu,Ph], and an organoaluminum reducing agent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1293–1295, June, 1984.     

Synthesis,Properties, Structure and Reactivity of Sodium 2,3,4,5-Tetra- tert -butylcyclopentaphosphanide

The reaction between Na, t BuPCl 2 , and PCl 3 in thf gives Na[ cyclo -( t Bu 4 P 5 )] ( 1 ). 1 reacts with PCl 3 to yield ( cyclo - t Bu 3 P 4 ) t BuPCl ( 2 ), and with a proton source, such as HCl, NH 4 Cl, or t BuCl, to give cyclo - t Bu 4 P 5 H ( 3 ). The reaction of 1 with [MCl 2 (PRR' 2 ) 2 ] (M = Ni; R = R' = Et; M = Pd, Pt, R = Ph, R' = Me) gives [Ni{ cyclo -( t Bu 3 P 5 )}(PEt 3 ) 2 ] ( 4 ), [Pd{ cyclo -( t Bu 4 P 5 )} 2 ] ( 5 ), and [PtCl{ cyclo -( t Bu 3 P 4 ) t BuP}(PPhMe 2 )] ( 6 ). 1-6 were characterized by 31 P{ 1 H} NMR spectroscopy, and 1 and 4-6 were also characterized by X-ray crystallography.     

Binding and redox properties of iron(II) bonded to an oxo surface modeled by calix[4]arene

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 Hückel 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.     

Synthetic and structural studies of donor-functionalized alkoxy derivatives of gallium

The synthesis of a range of alkyl/chloro-gallium alkoxide and amido/alkoxide compounds was achieved via a series of protonolysis and alcoholysis steps. The initial reaction involved the synthesis of [Me(Cl)Ga{N(SiMe(3))(2)}](2) (1) via methyl group transfer from the reaction of GaCl(3) with two equivalents of LiN(SiMe(3))(2). Reaction of 1 with varying amounts of ROH resulted in the formation of [Me(Cl)Ga(OR)](2) (2, R = CH(2)CH(2)OMe; 3, CH(CH(3))CH(2)NMe(2)), [Me(Cl)Ga{N(SiMe(3))(2)}(μ(2)-OR)Ga(Cl)Me] (4, R = CH(2)CH(2)NMe(2)), or [MeGa(OR)(2)] (5, R = CH(CH(3))CH(2)NMe(2)). Compound 4 represents an intermediate in the formation of dimeric complexes, of the type [Me(Cl)Ga(OR)](2), when formed from compound [Me(Cl)Ga{N(SiMe(3))(2)}](2). A methylgallium amido/alkoxide complex [MeGa{N(SiMe(3))(2)}(OCH(2)CH(2)OMe)](2) (6) was isolated when 2 was further reacted with LiN(SiMe(3))(2). In addition, reaction of 2 with HO(t)Bu resulted in a simple alcohol/alkoxide exchange and formation of [Me(Cl)Ga(O(t)Bu)](2) (7). In contrast to the formation of 1, the in situ reaction of GaCl(3) with one equivalent of LiN(SiMe(3))(2) yielded [Cl(2)Ga{N(SiMe(3))(2)}](2) in low yield, where no methyl group transfer has occurred. Reaction of alcohol with [Cl(2)Ga{N(SiMe(3))(2)}](2) was then found to yield [Cl(2)Ga(OR)](2) (8, R = CH(2)CH(2)NMe(2)), and further reaction of 8 with LiN(SiMe(3))(2) yielded the gallium amido alkoxide complex, [ClGa{N(SiMe(3))(2)}(OR)](2) (9, R = CH(2)CH(2)NMe(2)), similar to 6. The structures of compounds 4, 5, 7, and 8 have been determined by single-crystal X-ray diffraction.     

Synthesis, structures, and olefin polymerization capability of vanadium(4+) imido compounds with fac-N3 donor ligands

One-pot reactions of V(NMe2)4 with a range of primary alkyl- and arylamines RNH2 and Me3SiCl afforded the corresponding five-coordinate vanadium(4+) imido compounds V(NR)Cl2(NHMe2)2 [R = 2,6-C6H3(i)Pr2 (1a, previously reported), 2-C6H4(t)Bu (1b), 2-C6H4CF3 (1c), (t)Bu (1d), Ad (Ad = adamantyl, 1e)]. The crystal structures of 1b (two diamorphic forms) and 1c featured N-H...Cl hydrogen-bonded chains. Reaction of 1a-e with the neutral face-capping, N3 donor ligands TACN (TACN = 1,4,7-trimethyltriazacyclononane) or TPM [TPM = tris(3,5-dimethylpyrazolyl)methane] gave the corresponding six-coordinate complexes V(NR)(TACN)Cl2 (2a-e) and V(NR)(TPM)Cl2 (3a-e). The X-ray structures of 2b, 2c, 2d, 3b, 3c, and 3e were determined. When activated with methylaluminoxane, certain of the complexes V(NR)(TPM)Cl2 (3) formed moderately active ethylene polymerization catalysts, whereas none of the compounds V(NR)(TACN)Cl2 (2) were active.     

(Fluoren-9-ylidene)methanedithiolato complexes of gold: synthesis, luminescence, and charge-transfer adducts

Piperidinium 9H-fluorene-9-carbodithioate and its 2,7-di-tert-butyl-substituted analogue [(pipH)(S(2)CCH(C(12)H(6)R(2)-2,7)), R = H (1a), t-Bu (1b)] and 2,7-bis(octyloxy)-9H-fluorene-9-carbodithioic acid [HS(2)CCH(C(12)H(6)(OC(8)H(17))(2)-2,7), 2] and its tautomer [2,7-bis(octyloxy)fluoren-9-ylidene]methanedithiol [(HS)(2)C=C(C(12)H(6)(OC(8)H(17))(2)-2,7), 3] were employed for the preparation of gold complexes with the (fluoren-9-ylidene)methanedithiolato ligand and its substituted analogues. The gold(I) compounds Q(2)[Au(2)(mu-kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)], where Q(+) = PPN(+) or Pr(4)N(+) for R = H (Q(2)4a) or Q(+) = Pr(4)N(+) for R = OC(8)H(17) [(Pr(4)N)(2)4c], were synthesized by reacting Q[AuCl(2)] with 1a or 2 (1:1) and excess piperidine or diethylamine. Complexes of the type [(Au(PR'3))(2)(mu-kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)] with R = H and R' = Me (5a), Et (5b), Ph (5c), and Cy (5d) or R = t-Bu and R' = Me (5e), Et (5f), Ph (5g), and Cy (5h) were obtained by reacting [AuCl(PR'(3))] with 1a,b (1:2) and piperidine. The reactions of 1a,b or 2 with Q[AuCl(4)] (2:1) and piperidine or diethylamine gave Q[Au(kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)] with Q(+) = PPN(+) for R = H [(PPN)6a], Q(+) = PPN(+) or Bu(4)N(+) for R = t-Bu (Q6b), and Q(+) = Bu(4)N(+) for R = OC(8)H(17) [(Bu(4)N)6c]. Complexes Q6a-c reacted with excess triflic acid to give [Au(kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(kappa(2)-S,S-S(2)CCH(C(12)H(6)R(2)-2,7))] [R = H (7a), t-Bu (7b), OC(8)H(17) (7c)]. By reaction of (Bu(4)N)6b with PhICl(2) (1:1) the complex Bu(4)N[AuCl(2)(kappa(2)-S,S-S(2)C=C(C(12)H(6)(t-Bu)(2)-2,7))] [(Bu(4)N)8b] was obtained. The dithioato complexes [Au(SC(S)CH(C(12)H(8)))(PCy(3))] (9) and [Au(n)(S(2)CCH(C(12)H(8)))(n)] (10) were obtained from the reactions of 1a with [AuCl(PCy(3))] or [AuCl(SMe(2))], respectively (1:1), in the absence of a base. Charge-transfer adducts of general composition Q[Au(kappa(2)-S,S-S(2)C=C(C(12)H(6)R(2)-2,7))(2)].1.5TCNQ.xCH(2)Cl(2) [Q(+) = PPN(+), R = H, x = 0 (11a); Q(+) = PPN(+), R = t-Bu, x = 2 (11b); Q(+) = Bu(4)N(+), R = OC(8)H(17), x = 0 (11c)] were obtained from Q6a-c and TCNQ (1:2). The crystal structures of 5c.THF, 5e.(2)/(3)CH(2)Cl(2), 5g.CH(2)Cl(2), (PPN)6a.2Me(2)CO, and 11b were solved by X-ray diffraction studies. All the gold(I) complexes here described are photoluminescent at 77 K, and their emissions can be generally ascribed to LMMCT (Q(2)4a,c, 5a-h, 10) or LMCT (9) excited states.     

Selective syntheses of iron-imide-sulfide cubanes, including a partial representation of the Fe-S-X environment in the FeMo cofactor

The dinuclear precursors Fe(2)(N(t)Bu)(2)Cl(2)(NH(2)(t)Bu)(2), [Fe(2)(N(t)Bu)(S)Cl(4)](2-), and Fe(2)(NH(t)Bu)(2)(S)(N{SiMe(3)}(2))(2) allowed the selective syntheses of the cubane clusters [Fe(4)(N(t)Bu)(n)(S)(4-n)Cl(4)](z) with [n, z] = [3, 1-], [2, 2-], [1, 2-]. Weak-field iron-sulfur clusters with heteroleptic, nitrogen-containing cores are of interest with respect to observed or conjectured environments in the iron-molybdenum cofactor of nitrogenase. In this context, the present iron-imide-sulfide clusters constitute a new class of compounds for study, with the Fe(4)NS(3) core of the [1, 2-] cluster affording the first synthetic representation of the corresponding heteroligated Fe(4)S(3)X subunit in the cofactor.     

Investigations on the interaction of dichloroaluminum carboxylates with Lewis bases and water: an efficient road toward oxo- and hydroxoaluminum carboxylate complexes

A series of dichloroaluminum carboxylates [Cl(2)Al(O(2)CR)](2) (were R = Ph (1a), (t)Bu (1b), CHCH(2) (1c) and C(11)H(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H(2)O performed. Compounds [Cl(2)Al(O(2)CR)](2) and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl(2)Al(O(2)CR)](2) equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl(2)Al(λ(2)-O(2)CR)(py-Me)(2)] [R = Ph (3a), (t)Bu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H(2)O in THF-toluene solution lead to oxo carboxylates [(Al(3)O)(O(2)CR)(6)(THF)(3)] [AlCl(4)] [where R = Ph (4a(THF)), (t)Bu (4b(THF)), and C(11)H(23) (4d(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl)(2)(OH)(O(2)CC(2)H(3))(2) (THF)(4)][AlCl(4)] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al(2)(OH)(O(2)C(t)Bu)(2)(MeCN)(6)][AlCl(4))(3)] (6). All compounds were characterized by elemental analysis, (1)H, (27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a(THF), 4b(THF), 4b(py-Me'), 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H(2)O and neutral donor ligands.     

Ionic iron(iii) complexes of bis(phenol)-functionalized imidazolium cations: synthesis, structures and catalysis for aryl Grignard cross-coupling of alkyl halides

A series of bis(phenol)-functionalized imidazolium salts, 1,3-bis(4,6-di-R(1)-2-hydroxybenzyl)-2-R(2)-4,5-di-R(3)-imidazolium chlorides H(3)L(n)Cl (R(1) = (t)Bu, R(2) = R(3) = H, H(3)L(1)Cl, 1; R(1) = CH(3), R(2) = R(3) = H, H(3)L(2)Cl, 2; R(1) = (t)Bu, R(2) = H, R(3) = Cl, H(3)L(3)Cl, 3; R(1) = (t)Bu, R(2) = CH(3), R(3) = H, H(3)L(4)Cl, 4), were used to produce a novel series of ionic iron(iii) complexes [H(3)L(n)][FeX(4)] (n = 1, X = Cl, 5; n = 2, X = Cl, 6; n = 3, X = Cl, 7; n = 4, X = Cl, 8; n = 1, X = Br, 9; n = 3, X = Br, 10). All of the complexes were characterized by Raman spectroscopy and electrospray ionization mass spectrometry. Elemental analysis and X-ray crystallography were also used. All of the complexes were non-hygroscopic and air-stable, with five of them existing as solids (5, 7-10) and one as an oil (6) at room temperature. A preliminary catalytic study on the cross-coupling reactions of aryl Grignard reagents with primary and secondary alkyl halides bearing β-hydrogens, revealed that all of the ionic iron(iii) complexes exhibited good to excellent catalytic activity. Complexes 5, 6 and 8 exhibited optimal activity, whereas 7, 9 and 10 showed only moderate activity. Furthermore, by simply decanting the cross-coupling product in the ether layer, complexes 5 and 6 could be reused in at least seven successive runs without significant loss in catalytic activity.     

Preparation and substitution chemistry of [Bu4N]2[W6Cl8(p-OSO2C6H4CH3)6]. A useful precursor for pseudohalide, acetate, and organometallic complexes containing the [W6Cl8](4+) core

The tosylate (p-toluenesulfonate) cluster [Bu4N]2[W6Cl8(p-OSO2C6H4CH3)6] (1) has been prepared and characterized by IR and NMR spectroscopy, elemental analysis, and an X-ray crystal structure. This cluster complex is shown to be a useful starting material for the preparation of pseudohalide clusters, [Bu4N]2[W6Cl8(NCQ)6] (Q = O (2), S (3), and Se (4)), in high yields. Cluster 1 also serves as a precursor to the new cluster compounds: [Bu4N]2[W6Cl8(O2CCH3)6] (5), [Bu4N]2[W6Cl8((mu-NC)Mn(CO)2(C5H5))6] (6), [W6Cl8((mu-NC)Ru(PPh3)2(C5H5))6][ p-OSO2C6H4CH3]4 (7), and [W6Cl8((mu-NC)Os(PPh3)2(C5H5))6][ p-OSO2C6H4CH3]4 (8). X-ray crystal structures are reported for 1, 4, and 5.