Synthesis of luminescent gold(I) and gold(III) complexes with a triphosphine ligand

We have synthesized and characterized a series of trinuclear gold(I) complexes [(AuX)(3)(mu-triphos)] (triphos = bis(2-diphenylphosphinoethyl)phenylphosphine; X = Cl 1, Br 2, I 3, C(6)F(5) 4) and di- and trinuclear gold(III) complexes [[Au(C(6)F(5))(3)](n)(mu-triphos)] (n = 2 (5), 3 (6)). The crystal structure of 6 [[Au(C(6)F(5))(3)](3)(mu-triphos)] has been determined by X-ray diffraction studies, which show the triphosphine in a conformation resulting in very long gold-gold distances, probably associated with the steric requirements of the tris(pentafluorophenyl)gold(III) units. Complex 6 crystallizes in the triclinic space group P(-1) with a = 12.7746(16) A, b = 18.560(2) A, c = 21.750(3) A, alpha = 98.215(3) degrees, beta = 101.666(3) degrees, gamma = 96.640(3) degrees, and Z = 2. Chloride substitutions in complex 1 afford trinuclear gold(I) complexes [(AuX)(3)(mu-triphos)] (X = Fmes (1,3,5-tris(trifluoromethyl)phenyl) 7, p-SC(6)H(4)Me 8, SCN 9) and [Au(3)Cl(3)(-)(n)()(S(2)CNR(2))(n)(mu-triphos)] (R = Me, n = 3 (10), 2 (12), 1 (14); R = CH(2)Ph, n = 3 (11), 2 (13), 1 (15)). The luminescence properties of these complexes in the solid state have been studied; at low temperature most of them are luminescent, including the gold(III) derivative 6, with the intensity and the emission maxima being clearly influenced by the nature and the number of the ligands bonded to the gold centers.     

Au(2)Tl(2)(C(6)Cl(5))(4)].(CH(3))(2)C=O: a luminescent loosely bound butterfly cluster with a Tl(I)-Tl(I) interaction

By reaction of NBu(4)[Au(C(6)Cl(5))(2)] with TlPF(6) in acetone the complex [Au(2)Tl(2)(C(6)Cl(5))(4)].(CH(3))(2)C=O is obtained, which shows a butterfly type arrangement of metals through short Au(I)-Tl(I) and Tl(I)-Tl(I) interactions. The last one is likely to be responsible for its luminescence behavior.     

Synthesis and structural characterization of PHP[(C(5)Me(4))(2)], a monodentate chiral phosphine derived from intramolecular C-C coupling of tetramethylcyclopentadienyl groups: an evaluation of steric and electronic properties

The chiral monodentate phosphine PhP[(C(5)Me(4))(2)] is readily obtained by oxidation of the lithium complex Li(2)[PhP(C(5)Me(4))(2)] with I(2), which couples the two cyclopentadienyl groups to form a five-membered heterocyclic ring. The steric and electronic properties of PhP[(C(5)Me(4))(2)] have been evaluated by X-ray diffraction and IR spectroscopic studies on a variety of derivatives, including Ph[(C(5)Me(4))(2)]PE (E = S, Se), Cp*MCl(4)[P[(C(5)Me(4))(2)]Ph] (M = Mo, Ta), Ir[P[(C(5)Me(4))(2)]Ph](2)(CO)Cl, and CpFe(CO)[PhP[(C(5)Me(4))(2)]]Me. For comparison purposes, derivatives of the related phospholane ligand PhP[Me(2)C(4)H(6)] have also been investigated, including Ph[Me(2)C(4)H(6)]PS, Ir[Ph[Me(2)C(4)H(6)]](2)(CO)Cl, Ir[Ph[Me(2)C(4)H(6)]](2)(CO)Me, Ir[PPh[Me(2)C(4)H(6)]](COD)(Cl), and Pd[P[Me(2)C(4)H(6)]Ph][eta(2)-C(6)H(4)C(H)(Me)NMe(2)]Cl. The steric and electronic properties of PhP[(C(5)Me(4))(2)] are determined to be intermediate between those of PPh(2)Me and PPh(3). Thus, the crystallographic cone angles increase in the sequence PPh(2)Me (134.5 degrees) < PhP[(C(5)Me(4))(2)] (140.2 degrees) < PPh(3) (148.2 degrees), while the electron donating abilities decrease in the sequence PPh(2)Me > PhP[(C(5)Me(4))(2)] > PPh(3). Finally, PhP[(C(5)Me(4))(2)] has a smaller cone angle and is less electron donating than the structurally similar phosphine, PhP[Me(2)C(4)H(6)].     

Insertion reactions into Pd[bond]O and Pd[bond]N bonds: preparation of alkoxycarbonyl,carbonato, carbamato,thiocarbamate, and thioureide complexes of palladium(II)

Mononuclear palladium hydroxo complexes of the type [Pd(N[bond]N)(C(6)F(5))(OH)] [(N[bond]N = 2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me(2)bipy), 1,10-phenanthroline (phen), or N,N,N',N'-tetramethylethylenediamine (tmeda)] have been prepared by reaction of [Pd(N[bond]N)(C(6)F(5))(acetone)]ClO(4) with KOH in methanol. These hydroxo complexes react, in methanol, with CO (1 atm, room temperature) to yield the corresponding methoxycarbonyl complexes [Pd(N[bond]N)(C(6)F(5))(CO(2)Me)]. Similar alkoxycarbonyl complexes [Pd(N[bond]N)(C(6)F(5))(CO(2)R)] (N[bond]N = bis(3,5-dimethylpyrazol-1-yl)methane); R = Me, Et, or (i)Pr) are obtained when [Pd(N[bond]N)(C(6)F(5))Cl] is treated with KOH in the corresponding alcohol ROH and CO is bubbled through the solution. The reactions of [Pd(N[bond]N)(C(6)F(5))(OH)] (N[bond]N = bipy or Me(2)bipy) with CO(2), in tetrahydrofuran, lead to the formation of the binuclear carbonate complexes [(N[bond]N)(C(6)F(5))Pd(mu-eta(2)-CO(3))Pd(C(6)F(5))(N[bond]N)]. Complexes [Pd(N[bond]N)(C(6)F(5))(OH)] react in alcohol with PhNCS to yield the corresponding N-phenyl-O-alkylthiocarbamate complexes [Pd(N[bond]N)(C(6)F(5))[SC(OR)NPh]]. Similarly, the reaction of [Pd(bipy)(C(6)F(5))(OH)] with PhNCO in methanol gives the N-phenyl-O-methylcarbamate complex [Pd(bipy)(C(6)F(5))[NPhC(O)OR]]. The reactions of [(N[bond]N)Pd(C(6)F(5))(OH)] with PhNCS in the presence of Et(2)NH yield the corresponding thioureidometal complexes [Pd(N[bond]N)(C(6)F(5))[NPhCSNR(2)]]. The crystal structures of [Pd(tmeda)(C(6)F(5))(CO(2)Me)], [Pd(2)(Me(2)bipy)(2)(C(6)F(5))(2)(mu-eta(2)-CO(3))].2CH(2)Cl(2), and [Pd(tmeda)(C(6)F(5))[SC(OMe)NPh]] have been determined.     

High-nuclearity Pt-Tl-Fe complexes: structural, electrochemistry, and spectroelectrochemistry studies

A series of heteropolynuclear Pt-Tl-Fe complexes have been synthesized and structurally characterized. The final structures strongly depend on the geometry of the precursor and the Pt/Tl ratio used. Thus, the anionic heteroleptic cis-configured [cis-Pt(C(6)F(5))(2)(C≡CFc)(2)](2-) and [Pt(bzq)(C≡CFc)(2)](-) (Fc = ferrocenyl) complexes react with Tl(+) to form discrete octanuclear (PPh(3)Me)(2)[{trans,cis,cis-PtTl(C(6)F(5))(2)(C≡CFc)(2)}(2)] (1), [PtTl(bzq)(C≡CFc)(2)](2) (5; bzq = benzoquinolate), and decanuclear [trans,cis,cis-PtTl(2)(C(6)F(5))(2)(C≡CFc)(2)](2) (3) derivatives, stabilized by both Pt(II)···Tl(I) and Tl(I)···η(2)(alkynyl) bonds. By contrast, Q(2)[trans-Pt(C(6)F(5))(2)(C≡CFc)(2)] (Q = NBu(4)) reacts with Tl(+) to give the one-dimensional (1-D) anionic [(NBu(4)){trans,trans,trans-PtTl(C(6)F(5))(2)(C≡CFc)(2)}](n) (2) and neutral [trans,trans,trans-PtTl(2)(C(6)F(5))(2)(C≡CFc)(2)](n) (4) polymeric chains based on [PtFc(2)](2-) platinate fragments and Tl(+) (2) or [Tl···Tl](2+) (4) units, respectively, connected by Pt(II)···Tl(I) and secondary weak κ-η(1) (2) or η(2) (4) alkynyl···Tl(I) bonding. The formation of 1-4 is reversible, and thus treatment of neutral 3 and 4 with PPh(3)MeBr causes the precipitation of TlBr, returning toward the formation of the anionic 1 and 2' (Q = PPh(3)Me). Two slightly different pseudopolymorphs were found for 2', depending on the crystallization solvent. Finally, the reaction of the homoleptic [Pt(C≡CFc)(4)](2-) with 2 equiv of Tl(+) affords the tetradecanuclear sandwich type complex [Pt(2)Tl(4)(C≡CFc)(8)] (6). Electrochemical, spectroelectrochemical, and theoretical studies have been carried out to elucidate the effect produced by the interaction of the Tl(+) with the Pt-C≡CFc fragments. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) of 1-5 reveal that, in general, neutralization of the anionic fragments increases the stability of the fully oxidized species and gives higher E(1/2) (Fc) values than those observed in their precursors, increasing with the number of Pt-Tl bonding interactions. However, the electronic communication between Fc groups is reduced or even lost upon Tl(+) coordination, as confirmed by electrochemical (CVs and DPVs voltammograms, 1-5) and spectroelectrochemical (UV-vis-NIR, 2-4) studies. Complexes 2 and 4 still display some electronic interaction between the Fc groups, supported by the presence of an IVCT band in their UV-vis-NIR spectra of oxidized species and additional comparative DFT calculations with the precursor [trans-Pt(C(6)F(5))(2)(C≡CFc)(2)](2-) and complex 3.     

Synthesis of carbaalane halogen derivatives

The carbaalane halogen derivatives [(AlX)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (X = F (9), Cl (7), Br (10), I (11)) were prepared in toluene from [(AlH)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (6) and BF(3).OEt(2), BX(3) (X = Br, I), Me(3)SnF, and Me(3)SiX (X = Cl, Br, I), respectively. A partially halogenated product [(AlH)(2)(AlX)(4)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (12) (X = Cl (approximately 40%), Br (approximately 60%)) was obtained from 5 and impure BBr(3). [(AlH)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (5) was converted to [(AlX)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (X = F (13), Cl (14), Br (15), I (16)) using BF(3).OEt(2) and Me(3)SiX (X = Cl, Br, I), respectively. The X-ray single-crystal structures of 11.C(6)H(6), 12.3C(7)H(8), 13.6C(7)H(8), and 15.4C(7)H(8) were determined. Compounds 7 and 9-11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and 6 by the halides with different reagents.     

A series of dinuclear homo- and heterometallic complexes with two or three bridging sulfido ligands derived from the tungsten tris(sulfido) complex [Et(4)N][(Me(2)Tp)WS(3)] (Me(2)Tp = hydridotris(3,5-dimethylpyrazol-1-yl)borate)

The generation of heterobimetallic complexes with two or three bridging sulfido ligands from mononuclear tris(sulfido) complex of tungsten [Et(4)N][(Me(2)Tp)WS(3)] (1; Me(2)Tp = hydridotris(3,5-dimethylpyrazol-1-yl)borate) and organometallic precursors is reported. Treatment of 1 with stoichiometric amounts of metal complexes such as [M(PPh(3))(4)] (M = Pt, Pd), [(PtMe(3))(4)(micro(3)-I)(4)], [M(cod)(PPh(3))(2)][PF(6)] (M = Ir, Rh; cod = 1,5-cyclooctadiene), [Rh(cod)(dppe)][PF(6)] (dppe = Ph(2)PCH(2)CH(2)PPh(2)), [CpIr(MeCN)(3)][PF(6)](2) (Cp = eta(5)-C(5)Me(5)), [CpRu(MeCN)(3)][PF(6)], and [M(CO)(3)(MeCN)(3)] (M = Mo, W) in MeCN or MeCN-THF at room temperature afforded either the doubly bridged complexes [Et(4)N][(Me(2)Tp)W(=S)(micro-S)(2)M(PPh(3))] (M = Pt (3), Pd (4)), [(Me(2)Tp)W(=S)(micro-S)(2)M(cod)] (M = Ir, Rh (7)), [(Me(2)Tp)W(=S)(micro-S)(2)Rh(dppe)], [(Me(2)Tp)W(=S)(micro-S)(2)RuCp] (10), and [Et(4)N][(Me(2)Tp)W(=S)(micro-S)(2)W(CO)(3)] (12) or the triply bridged complexes including [(Me(2)Tp)W(micro-S)(3)PtMe(3)] (5), [(Me(2)Tp)W(micro-S)(3)IrCp][PF(6)] (9), and [Et(4)N][(Me(2)Tp)W(micro-S)(3)Mo(CO)(3)] (11), depending on the nature of the incorporated metal fragment. The X-ray analyses have been undertaken to clarify the detailed structures of 3-5, 7, and 9-12.     

1,4-dicyanobenzene as a scaffold for the preparation of bimetallic actinide complexes exhibiting metal-metal communication

Reaction of two equivalents of [(C(5)Me(4)Et)(2)U(CH(3))(Cl)] (6) or [(C(5)Me(5))(2)Th(CH(3))(Br)] (7) with 1,4-dicyanobenzene leads to the formation of the novel 1,4-phenylenediketimide-bridged bimetallic organoactinide complexes [{(C(5)Me(4)Et)(2)(Cl)U}(2)(mu-{N==C(CH(3))-C(6)H(4)-(CH(3))C==N})] (8) and [{(C(5)Me(5))(2)(Br)Th}(2)(mu-{N==C(CH(3))-C(6)H(4)- (CH(3))C==N})] (9), respectively. These complexes were structurally characterized by single-crystal X-ray diffraction and NMR spectroscopy. Metal-metal interactions in these isovalent bimetallic systems were assessed by means of cyclic voltammetry, UV-visible/NIR absorption spectroscopy, and variable-temperature magnetic susceptibility. Although evidence for magnetic coupling between metal centers in the bimetallic U(IV)/U(IV) (5f(2)-5f(2)) complex is ambiguous, the complex displays appreciable electronic communication between the metal centers through the pi system of the dianionic diketimide bridging ligand, as judged by voltammetry. The transition intensities of the f-f bands for the bimetallic U(IV)/U(IV) system decrease substantially compared to the related monometallic ketimide chloride complex, [(C(5)Me(5))(2)U(Cl){-N==C(CH(3))-(3,4,5-F(3)-C(6)H(2))}] (11). Also reported herein are new synthetic routes to the actinide starting materials [(C(5)Me(4)Et)(2)U(CH(3))(Cl)] (6) and [(C(5)Me(5))(2)Th(CH(3))(Br)] (7) in addition to the syntheses and structures of the monometallic uranium complexes [(C(5)Me(4)Et)(2)UCl(2)] (3), [(C(5)Me(4)Et)(2)U(CH(3))(2)] (4), [(C(5)Me(4)Et)(2)U{-N==C(CH(3))-C(6)H(4)-C==N}(2)] (10), and 11.     

Synthesis and reactivity of dimeric Ar'TlTlAr' and trimeric (Ar"T1)3 (Ar', Ar" = bulky terphenyl group) thallium(I) derivatives: Tl(I)-Tl(I) bonding in species ligated by monodentate ligands

The synthesis and characterization of three new organothallium(I) compounds are reported. Reaction of (Ar'Li)(2) (Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-Pr(i)(2))(2)) and Ar"Li (Ar" = C(6)H(3)-2,6-(C(6)H(3)-2,6-Me(2))(2)) with TlCl in Et(2)O afforded (Ar'Tl)(2) (1) and (Ar' 'Tl)(3) (2). The "dithallene" 1 is the heaviest group 13 dimetallene and features a planar, trans-bent structure with Ar'Tl-Tl = 119.74(14) degrees and Tl-Tl = 3.0936(8) A. Compound 2 is the first structurally characterized neutral, three-membered ring species of formula c-(MR)(3) (M = Al-Tl; R = organo group). The Tl(3) ring has Tl-Tl distances in the range ca. 3.21-3.37 A as well as pyramidal Tl geometries. The Tl-Tl bonds in 1 and 2 are outside the range (2.88-2.97 A) of Tl-Tl single bonds in R(2)TlTlR(2) compounds. The weak Tl-Tl bonding in 1 and 2 leads to their dissociation into Ar'Tl and Ar' 'Tl monomers in hexane. The Ar'Tl monomer behaves as a Lewis base and readily forms a 1:1 donor-acceptor complex with B(C(6)F(5))(3) to give Ar'TlB(C(6)F(5))(3), 3. Adduct 3 features an almost linear thallium C(ipso)-Tl-B angle of 174.358(7) degrees and a Tl-B distance of 2.311(2) A, which indicates strong association. Treatment of 1 with a variety of reagents resulted in no reactions. The lower reactivity of 1 is in accord with the reluctance of Tl(I) to undergo oxidation to Tl(III) due to the unreactive character of the 6s(2) electrons.     

Catenation control in the two-dimensional coordination polymers based on tritopic carboxylate linkers and azamacrocyclic nickel(II) complexes

Four new coordination polymer frameworks, namely [(NiL(1))(3)(BTB)(2)]·6H(2)O, [(NiL(2))(3)(BTB)(2)]·6H(2)O, [(NiL(3))(3)(BTB)(2)]·6H(2)O and [(NiL(2))(3)(BTC)(2)]·10.25H(2)O (L(1) = 1,4,8,11-tetraazacyclotetradecane, L(2) = 3-methyl-1,3,5,8,12-pentaazacyclotetradecane, L(3) = 3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane, BTC(3-) = benzene-1,3,5-tricarboxylate, BTB(3-) = 4,4',4'-benzene-1,3,5-triyl-tribenzoate) were prepared in water-N,N-dimethylformamide solutions. The molecular and crystal structures of these compounds are compared to the related coordination polymers formed by nickel(II) macrocyclic cations to examine the effect of carboxylate linker size on the framework architecture. Luminescent properties of the complexes based on the BTB(3-) bridging ligand are also discussed.     

Scandium and yttrium metallocene borohydride complexes: comparisons of (BH4)1- vs. (BPh4)1- coordination and reactivity

The synthetically accessible borohydride complexes (C(5)Me(4)H)(2)Ln(THF)(BH(4)) and (C(5)Me(5))(2)Ln(THF)(BH(4)) (Ln = Sc, Y) were examined as precursors alternative to the heavily-used tetraphenylborate analogs, [(C(5)Me(4)H)(2)Ln][BPh(4)] and [(C(5)Me(5))(2)Ln][BPh(4)], employed in LnA(2)A'/M reduction reactions (A = anion; M = alkali metal) that generate "LnA(2)" reactivity and form reduced dinitrogen complexes [(C(5)R(5))(2)(THF)(x)Ln](2)(μ-η(2):η(2)-N(2)) (x = 0, 1). The crystal structures of the yttrium borohydrides, (C(5)Me(4)H)(2)Y(THF)(μ-H)(3)BH, 1, and (C(5)Me(5))(2)Y(THF)(μ-H)(2)BH(2), 2, were determined for comparison with those of the yttrium tetraphenylborates, [(C(5)Me(4)H)(2)Y][(μ-Ph)(2)BPh(2)], 3, and [(C(5)Me(5))(2)Y][(μ-Ph)(2)BPh(2)], 4. The complex (C(5)Me(4)H)(2)Sc(μ-H)(2)BH(2), 5, was synthesized and structurally characterized for comparison with (C(5)Me(5))(2)Sc(μ-H)(2)BH(2), 6, [(C(5)Me(4)H)(2)Sc][(μ-Ph)BPh(3)], 7, and [(C(5)Me(5))(2)Sc][(μ-Ph)BPh(3)], 8. Structural information was also obtained on the borohydride derivatives, (C(5)Me(4)H)(2)Sc(μ-H)(2)BC(8)H(14), 9, and (C(5)Me(5))(2)Sc(μ-H)(2)BC(8)H(14), 10, obtained from 9-borabicyclo(3.3.1)nonane (9-BBN) and (C(5)Me(4)R)(2)Sc(η(3)-C(3)H(5)), where R = H, 11; Me, 12. The preference of the metals for borohydride over tetraphenylborate binding was shown by the facile displacement of (BPh(4))(1-) in 3, 4, 7, and 8 by (BH(4))(1-) to make the respective borohydride complexes 1, 2, 5, and 6. These results are consistent with the fact that the borohydrides are not as useful as precursors in A(2)LnA'/M reductions of N(2). An unusual structural isomer of [(C(5)Me(4)H)(2)Sc](2)(μ-η(2):η(2)-N(2)), 13', was isolated from this study that shows the variations in ligand orientation that can occur in the solid state.     

Synthesis of chromium(0) and molybdenum(0) bis (eta(6)-arene) derivatives and their monoelectronic oxidation to [M(eta(6)-arene)(2)](+) cations

M(eta(6)-arene)(2) species (M = Cr, arene = 1,3,5-Me(3)C(6)H(3); M = Mo, arene = 1,3,5-Me(3)C(6)H(3), 1,3,5-(i)Pr(3)C(6)H(3)), have been prepared by a modified Fischer-Hafner synthesis or by metal vapour techniques. The reaction of Cr(eta(6)-1,3,5-Me(3)C(6)H(3))(2) with the fulvene derivatives pentacarbomethoxycyclopentadiene (pcmcpH), 1-benzoyl-6-hydroxy-6-phenylfulvene (dbcpH), or 1-benzoyl-3-nitro-6-hydroxy-6-phenylfulvene (dbncpH) proceeds with evolution of dihydrogen and formation of the ionic derivatives [Cr(eta(6)-1,3,5-Me(3)C(6)H(3))(2)][E], where E = pcmcp, dbcp, or dbncp. Mo(eta(6)-arene)(2) derivatives (arene = toluene, 1,3,5-Me(3)C(6)H(3), 1,3,5-(i)Pr(3)C(6)H(3)) are oxidized to [Mo(eta(6)-arene)(2)](+) by pcmcpH. The crystal and molecular structures of [M(eta(6)-1,3,5-R(3)C(6)H(3))(2)][pcmcp] (M = Cr, R = Me; M = Mo, R = Me, (i)Pr) have been solved by X-ray single crystal diffraction.     

Photosensitive azobispyridine gold(I) and silver(I) complexes

The neutral and cationic dinuclear gold(I) compounds [(μ-N-N)(AuR)(2)] (N-N = 2,2'-azobispyridine (2-abpy), 4,4'-azobispyridine (4-abpy); R = C(6)F(5), C(6)F(4)OC(12)H(25)-p, C(6)F(4)OCH(2)C(6)H(4)OC(12)H(25)-p) and [(μ-N-N){Au(PR(3))}(2)](CF(3)SO(3))(2) (N-N = 2-abpy, 4-abpy, R = Ph, Me) have been obtained by displacement of a weakly coordinated ligand by an azobispyridine ligand. The corresponding silver(I) dinuclear [(μ-2-abpy){Ag(CF(3)SO(3))(PPh(3))}(2)] and polynuclear [{Ag(CF(3)SO(3))(4-abpy)}(n)] compounds have been obtained. The molecular structures of [(μ-2-abpy){Au(PPh(3))}(2)](CF(3)SO(3))(2) and [(μ-4-abpy){Au(PMe(3))}(2)](CF(3)SO(3))(2) have been confirmed by X-ray diffraction studies and feature linear gold(I) centers coordinated by pyridyl groups, and non-coordinated azo groups. In contrast the X-ray structure of [(2-abpy){Ag(CF(3)SO(3))(PPh(3))}(2)] shows tetracoordinated silver(I) centers involving chelating N-N coordination by pyridyl and azo nitrogen atoms. The gold(I) compounds with a long alkoxy chain do not behave as liquid crystals, and decompose before their melting point. The soluble gold(I) derivatives are photosensitive in solution and isomerize to the cis azo isomer under UV irradiation, returning photochemically or thermally to the most stable initial trans isomer. The silver(I) derivative [(2-abpy){Ag(CF(3)SO(3))(PPh(3))}(2)] also photoisomerizes in solution under UV irradiation, showing that its solid state structure, which would block isomerization by azo coordination, is easily broken. These processes have been monitored by UV-vis absorption and (1)H NMR spectroscopy. All these compounds are non-emissive in the solid state, even at 77 K.     

Synthesis and alkali metal ion-binding properties of a chromium(III) triacetylide complex

A simple triacetylide complex of chromium(III) is synthesized for use as a potential precursor to metal-dicarbide clusters. Reaction of Me(3)SiCCLi with [(Me(3)tacn)Cr(CF(3)SO(3))(3)] (Me(3)tacn = N,N',N"-trimethyl-1,4,7-triazacyclononane) in THF generates [(Me(3)tacn)Cr(CCSiMe(3))(3)], which subsequently reacts with Bu(4)NF to supply [(Me(3)tacn)Cr(CCH)(3)] as an air-stable orange solid. The crystal structure of this unprecedented triacetylide complex reveals octahedral coordination of the chromium center, with linear Cr-C(triple bond)C bond angles and C(triple bond)C bond distances essentially identical to the corresponding distance in acetylene. Crystallization of the complex from a DMF solution containing K(CF(3)SO(3)) leads to the sandwich complex ([(Me(3)tacn)Cr(CCH)(3)](2)K)(+), in which the K(+) ion is coordinated in a side-on fashion by each of the six C(triple bond)C units. With the larger Cs(+) cation, a triangular ([(Me(3)tacn)Cr(CCH)(3)](3)Cs)(+) complex is instead observed. The magnetic properties of these alkali metal complexes are indicative of weak antiferromagnetic exchange between Cr(III) centers, with J = -0.8 and -0.3 cm(-1), respectively.     

Unprecedented cage-carbon to cage-boron NMe(3) transfer in a monocarbon Molybdenacarborane

The reagent Li(2)[7-NMe(3)-nido-7-CB(10)H(10)] reacts with [Mo(CO)(3)(NCMe)(3)] in THF-NCMe (THF = tetrahydrofuran) to give a molybdenacarborane intermediate which, upon oxidation by CH(2)[double bond]CHCH(2)Br or I(2) and then addition of [N(PPh(3))(2)]Cl, gives the salts [N(PPh(3))(2)][2,2,2-(CO)(3)-2-X-3-NMe(3)-closo-2,1-MoCB(10)H(10)] (X = Br (1) or I (2)). During the reaction, the cage-bound NMe(3) substituent is transferred from the cage-carbon atom to an adjacent cage-boron atom, a feature established spectroscopically in 1 and 2, and by X-ray diffraction studies on several of their derivatives. When [Rh(NCMe)(3)(eta(5)-C(5)Me(5))][BF(4)](2) is used as the oxidizing agent, the trimetallic compound [2,2,2-(CO)(3)-7-mu-H-2,7,11-[Rh(2)(mu-CO)(eta(5)-C(5)Me(5))(2)]-closo-2,1-MoCB(10)H(9)] (10) is formed, the NMe(3) group being lost. Reaction of 1 in CH(2)Cl(2) with Tl[PF(6)] in the presence of donor ligands L affords neutral zwitterionic compounds [2,2,2-(CO)(3)-2-L-3-NMe(3)-closo-2,1-MoCB(10)H(10)] for L = PPh(3) (4) or CNBu(t) (5), and [2-Bu(t)C[triple bond]CH-2,2-(CO)(2)-3-NMe(3)-closo-2,1-MoCB(10)H(10)] (6) when L = Bu(t)C[triple bond]CH. When 1 is treated with CNBu(t) and X(2), the metal center is oxidized, and in the products obtained, [2,2,2,2-(CNBu(t))(4)-2-Br-3-X-closo-2,1-MoCB(10)H(10)] (X = Br (7), I (8)), the B-NMe(3) bond is replaced by B-X. In contrast, treatment of 2 with I(2) and cyclo-1,4-S(2)(CH(2))(4) in CH(2)Cl(2) results in oxidative substitution of the cluster and retention of the NMe(3) group, giving [2,2,2-(CO)(3)-2-I-3-NMe(3)-6-[cyclo-1,4-S(2)(CH(2))(4)]-closo-2,1-MoCB(10)H(9)] (9). The unique structural features of the new compounds were confirmed by single-crystal X-ray diffraction studies upon 6, 7, 9 and 10.     

Reduction of dinitrogen with an yttrium metallocene hydride precursor, [(C5Me5)2YH]2

Treatment of [(C(5)Me(5))(2)YH](2), 1, with KC(8) under N(2) in methylcyclohexane generates the unsolvated reduced dinitrogen complex, [(C(5)Me(5))(2)Y](2)(μ-η(2):η(2)-N(2)), 2, and extends the range of yttrium and lanthanide LnZ(2)Z'/M (Z = monoanion; M = alkali metal) dinitrogen reduction reactions to (Z')(-) = (H)(-). The hydride complex, 1, is unique in this reactivity compared to other alkane-soluble yttrium metallocenes, [(C(5)Me(5))(2)YX](x) {X = [N(SiMe(3))(2)](-), (Me)(-), (C(3)H(5))(-), and (C(5)Me(5))(-)} which did not generate 2 when treated with KC(8). [(C(5)Me(5))(2)LnH](x)/KC(8)/N(2) reactions with Ln = La and Lu did not give isolable dinitrogen complexes. Complex 2 and the unsolvated lutetium analogue, [(C(5)Me(5))(2)Lu](2)(μ-η(2):η(2)-N(2)), 3, were obtained using benzene as a solvent and [(C(5)Me(5))(2)Ln][(μ-Ph)(2)BPh(2)] as precursors with excess KC(8). Complex 2 functions as a reducing agent with PhSSPh to form [(C(5)Me(5))(2)Y(μ-SPh)](2), 4, in high yield.     

K(6)Tl(2)Sb(3), a zintl phase with a novel heteroatomic (1)(infinity)[Tl4Sb(6)(12-)] chain

The title compound with heteratomic anionic chains [Tl(4)Sb(6)(12)(-)] has been discovered in the K-Tl-Sb system. The phase is obtained from a range of compositions near K(3)TlSb(1.5) following reaction first at 750-850 degrees C and then at 550 degrees C for one week or more. It crystallizes in the monoclinic system in space group C2/c, Z = 8, a = 9.951(1) A, b = 17.137(3) A, c = 19.640(6) A, and beta = 104.26(3) degrees. Swing-like (Tl(4)Sb(6))(12)(-) units consisting of alternating Sb and Tl atoms in four- and eight-membered rings are linked through Tl-Tl bonds to form infinite one-dimensional chains along a. EHTB calculations and resistivity measurements show that the compound is a semiconductor.     

Unusual reactivity of a sterically hindered diphosphazane ligand, EtN{P(OR)(2)}(2), (R = C(6)H(3)(Pr(I))(2)-2,6) towards (eta(3)-allyl)palladium precursors

The reactivity of (eta(3)-allyl)palladium chloro dimers [(1-R-eta(3)-C(3)H(4))PdCl](2) (R = H or Me) towards a sterically hindered diphosphazane ligand [EtN{P(OR)(2)}(2)] (R = C(6)H(3)(Pr(i))(2)-2,6), has been investigated under different reaction conditions. When the reaction is carried out using NH(4)PF(6) as the halide scavenger, the cationic complex [(1-R-eta(3)-C(3)H(4))Pd{EtN(P(OR)(2))(2)}]PF(6) (R = H or Me) is formed as the sole product. In the absence of NH(4)PF(6), the initially formed cationic complex, [(eta(3)-C(3)H(5))Pd{EtN(P(OR)(2))(2)}]Cl, is transformed into a mixture of chloro bridged complexes over a period of 4 days. The dinuclear complexes, [(eta(3)-C(3)H(5))Pd(2)(mu-Cl)(2){P(O)(OR)(2)}{P(OR)(2)(NHEt)}] and [Pd(mu-Cl){P(O)(OR)(2)}{P(OR)(2)(NHEt)}](2) are formed by P-N bond hydrolysis, whereas the octa-palladium complex [(eta(3)-C(3)H(5))(2-Cl-eta(3)-C(3)H(4))Pd(4)(mu-Cl)(4)(mu-EtN{P(OR)(2)}(2))](2), is formed as a result of nucleophilic substitution by a chloride ligand at the central carbon of an allyl fragment. The reaction of [EtN{P(OR)(2)}(2)] with [(eta(3)-C(3)H(5))PdCl](2) in the presence of K(2)CO(3) yields a stable dinuclear (eta(3)-allyl)palladium(I) diphosphazane complex, [(eta(3)-C(3)H(5))[mu-EtN{P(OR)(2)}(2)Pd(2)Cl] which contains a coordinatively unsaturated T-shaped palladium center. This complex exhibits high catalytic activity and high TON's in the catalytic hydrophenylation of norbornene.     

Ability of a Au(III)-N unit to bond two aurophilically interacting gold(I) centers

The monohapto neutral 2-(diphenylphosphino)aniline (PNH(2)) complexes [Au(C(6)F(5))(2)X(PNH(2))] (X = C(6)F(5) (1), Cl (2)) have been obtained from [Au(C(6)F(5))(3)(tht)] or [Au(C(6)F(5))(2)(micro-Cl)](2) and PNH(2), and the cationic [Au(C(6)F(5))(2)(PNH(2))]ClO(4) (3) has been similarly prepared from [Au(C(6)F(5))(2)(OEt(2))(2)]ClO(4) and PNH(2) or from 2 and AgClO(4). The neutral amido complex [Au(C(6)F(5))(2)(PNH)] (4) can be obtained by deprotonation of 3 with PPN(acac) (acac = acetylacetonate) or by treatment of the chloro complex 2 with Tl(acac). It reacts with [Ag(OClO(3))(PPh(3))] or [Au(OClO(3))(PPh(3))] to give the dinuclear species [Au(C(6)F(5))(2)[PNH(MPPh(3))]]ClO(4) (M = Ag (5), Au (6)). The latter can also be obtained by reaction of equimolar amounts of 3 and [Au(acac)(PPh(3))]; when the molar ratio of the same reagents is 1:2, the trinuclear cationic complex [Au(C(6)F(5))(2)[PN(AuPPh(3))(2)]]ClO(4) (7) is obtained. The crystal structures of complexes 2-4 and 7 have been established by X-ray crystallography; the last-mentioned displays an unusual Au(I)-Au(III) interaction.     

Coordination and reductive chemistry of tetraphenylborate complexes of trivalent rare earth metallocene cations, [(C5Me5)2Ln][(μ-Ph)2BPh2

The reactivity of the tetraphenylborate salts of the rare earth metallocene cations [(C(5)Me(5))(2)Ln][(μ-Ph)(2)BPh(2)] (Ln = Y, 1; Sm, 2) has been investigated with substrates that undergo reduction with f element complexes to probe metal-substrate interactions prior to reduction. Results with NaN(3), 1-adamantyl azide, acetone, benzophenone, phenanthroline, pyridine, azobenzene, and phenazine are described. Not only were coordination complexes isolated, but substrate reduction by (BPh(4))(-) was also observed. Complex 1 reacts with NaN(3) to form the azide [(C(5)Me(5))(2)YN(3)](x), 3, which crystallizes as [(C(5)Me(5))(2)Y(μ-N(3))](3), 4, when obtained from 1 and 1-adamantyl azide. The samarium analogue [(C(5)Me(5))(2)SmN(3)](x), 5, can be produced similarly from 2 and NaN(3) and crystallized from MeCN as [(C(5)Me(5))(2)Sm(NCMe)(μ-N(3))](3), 6, and {[(C(5)Me(5))(2)Sm(μ-N(3))][(C(5)Me(5))(2)Sm(NCMe)(μ-N(3))]}(n), 7. Complexes 1 and 2 react with stoichiometric amounts of acetone and benzophenone to form the ketone adducts [(C(5)Me(5))(2)Ln(OCMe(2))(2)][BPh(4)] (Ln = Y, 8; Sm, 9) and [(C(5)Me(5))(2)Ln(OCPh(2))(2)][BPh(4)] (Ln = Y, 10; Sm, 11), respectively. Phenanthroline (phen) coordinates to 1 to form [(C(5)Me(5))(2)Y(phen)][BPh(4)], 12. Complexes 1 and 2 react with pyridine (py) to form [(C(5)Me(5))(2)Ln(py)(2)][BPh(4)], (Ln = Y, 13; Sm, 14). Complexes 3, 8, 10, and 12 can also be made from the solvated cation [(C(5)Me(5))(2)Y(THF)(2)][BPh(4)]. The reaction of 1 with PhNNPh yields the diamagnetic adduct [(C(5)Me(5))(2)Y(PhNNPh)][BPh(4)], 15, which transforms in benzene to the radical anion complex (C(5)Me(5))(2)Y(PhNNPh), 16, via a one electron reduction by (BPh(4))(-). Complex 1 similarly reacts with phenazine (phz) to produce the first rare earth phenazine radical anion complex {[(C(5)Me(5))(2)Y](2)(phz)}{BPh(4)}, 17. Further reduction of phenazine by (BPh(4))(-) in 17 yields [(C(5)Me(5))(2)Y](2)(phz), 18, which contains the common (phz)(2-) dianion. The reduction of fluorenone by (BPh(4))(-) is also reported.