Synthesis and characterization of a series of rubidium alkoxides and rubidium-titanium double alkoxides

This report investigates the structural aspects of the products isolated from the reactions of a series of titanium alkoxides [[Ti(OR)4]n n = 2, OR = OCH2C(CH3)3 (ONep) (1); n = 1, OC6H3(CH3)2-2,6 (DMP) (2)] with rubidium alkoxides [[Rb(OR)]infinity where OR = (ONep) (3), (DMP) (4), and OC6H3(CH(CH3)2)2-2,6 (DIP) (5)]. The resultant double alkoxides were determined by single crystal X-ray diffraction to be [Rb(mu-ONep)4(py)Ti(ONep)]2 (6), [Rb(mu-DMP)Ti(DMP)4]infinity (7), and [Rb(mu-DMP)2(mu-ONep)2Ti(ONep)]infinity (8). Compound 1 is the previously reported dinculear species with trigonal bipyramidal Ti metal centers whereas compound 2 is a monomer with a tetrahedral Ti center. Suitable X-ray quality crystals of 3 were not isolated. Compounds 4 and 5 demonstrate extended polymeric networks with Rb coordination ranging from two to five utilizing terminal mu- and mu3-OR ligands and pi-interactions of neighboring OAr ligands. The double alkoxide 6 revealed a simple tetranuclear structure with mu-ONep acting as the bridge, terminal ONep ligands on the Ti, and one terminal py on the Rb. For 7 and 8, the pi-interaction facilitated the formation of extended polymeric systems. All complexes were further characterized by FT-IR and multinuclear NMR spectroscopy.     

Synthesis and characterization of a family of structurally characterized dysprosium alkoxides for improved fatigue-resistance characteristics of PDyZT thin films

Using either an ammoniacal route, the reaction between DyCl3, Na0, and HOR in liquid ammonia, or preferentially reacting Dy(N(SiMe3)2)3 with HOR in a solvent, we isolated a family of dysprosium alkoxides as [Dy(mu-ONep)2(ONep)]4 (1), (ONep)2Dy[(mu3-ONep)(mu-ONep)Dy(ONep)(THF)]2(mu-ONep) (2), (ONep)2Dy[(mu3-ONep)(mu-ONep)Dy(ONep)(py)]2(mu-ONep) (3), [Dy3(mu3-OBut)2(mu-OBut3(OBut)4(HOBut)2] (4), [Dy3(mu3-OBut)2(mu-OBut)3(OBut)4(THF)2] (5), [Dy3(mu3-OBut)2(mu-OBut)3(OBut)4(py)2] (6), (DMP)Dy(mu-DMP)4[Dy(DMP)2(NH3)]2 (7), [Dy(eta6-DMP)(DMP)2]2 (8), Dy(DMP)3(THF)3 (9), Dy(DMP)3(py)3 (10), Dy(DIP)3(NH3)2 (11), [Dy(eta6-DIP)(DIP)2]2 (12), Dy(DIP)3(THF)2 (13), Dy(DIP)3(py)3 (14), Dy(DBP)3(NH3) (15), Dy(DBP)3 (16), Dy(DBP)3(THF) (17), Dy(DBP)3(py)2 (18), [Dy(mu-TPS)(TPS2]2 (19), Dy(TPS)3(THF)3 (20), and Dy(TPS)3(py)3 (21), where ONep = OCH2CMe3, OBut) = OCMe3, DMP = OC6H3(Me)(2)-2,6, DIP = OC6H3(CHMe2)(2)-2,6, DBP = OC6H3(CMe3)(2)-2,6, TPS = OSi(C6H5)3, tol = toluene, THF = tetrahydrofuran, and py = pyridine. We were not able to obtain X-ray quality crystals of compounds 2, 8, and 9. The structures observed and data collected for the Dy compounds are consistent with those reported for its other congeners. A number of these precursors were used as Dy dopants in Pb(Zr0.3Ti0.7)O3 (PZT 30/70) thin films, with compound 12 yielding the highest-quality films. The resulting Pb0.94Dy0.04(Zr0.3Ti0.7)O3 [PDyZT (4/30/70)] had similar properties to PZT (30/70), but showed substantial resistance to polarization reversal fatigue.     

Series of comparable dinuclear group 4 neo-pentoxide precursors for production of pH dependent group 4 nanoceramic morphologies

A series of similarly structured Group 4 alkoxides was used to explore the cation effect on the final ceramic nanomaterials generated under different pH solvothermal (SOLVO) conditions. The synthesis of [Ti(μ-ONep)(ONep)(3)](2) (1, ONep = OCH(2)C(CH(3))(3)) and {[H][(μ-ONep)(3)M(2)(ONep)(5)(OBu(t))]} where M = Zr (2) and Hf (3, OBu(t) = OC(CH(3))(3)) were realized from the reaction of M(OBu(t))(4) (M = Ti, Zr, Hf) and H-ONep. Crystallization of 1 from py led to the isolation of [Ti(μ-ONep)(ONep)(3)](2)(μ-py) (1a) whereas the dissolution of 2 or 3 in py yielded {(μ(3)-O)(μ(3)-OBu(t))[(μ-ONep)M(ONep)(2)](3)} M = Zr (2a) and Hf (3a). The structurally similar congener set of 1-3 was used to investigate variations of their resultant nanomaterials under solvothermal conditions at high (10 M KOH), low (conc. (aq) HI), and neutral (H(2)O) pH conditions. Reproducible nanodots, -squares, and -rods of varied aspect ratios were isolated based on cation and the reaction pH. The hydrolysis products were reasoned to be the "seed" nucleation sites in these processes, and studying the hydrolysis behavior of 1-3 led to the identification of [Ti(6)(μ(3)-O)(7)(μ-O)(μ-ONep)(2)(ONep)(6)](2) (1b) for 1 but yielded 2a and 3a for 2 and 3, respectively. A correlation was found to exist between these products and the final nanomaterials formed for the acidic and neutral processes. The basic route appears to be further influenced by another property, possibly associated with the solubility of the final nanoceramic material.     

Hydrolysis of tin(II) neo-pentoxide: syntheses, characterization, and X-ray structures of [Sn(ONep)(2)](infinity), Sn(5)(mu(3)-O)(2)(mu-ONep)(6), and Sn(6)(mu(3)-O)(4)(mu-ONep)(4) where ONep = OCH(2)CMe(3)

The reaction of [Sn(NMe(2))(2)](2) (1) with 4 equiv of HOCH(2)CMe(3) (HONep) leads to the isolation of [Sn(ONep)(2)](infinity) (2). Each Sn atom is four coordinated with mu-ONep ligands bridging the metal centers; however, if the free electrons of the Sn(II) metal center are considered, each Sn center adopts a distorted trigonal bipyramidal (TBP) geometry. Through (119)Sn NMR experiments, the polymeric compound 2 was found to be disrupted into smaller oligomers in solution. Titration of 2 with H(2)O led to the identification of two unique hydrolysis products characterized by single-crystal X-ray diffraction as Sn(5)(mu(3)-O)(2)(mu-ONep)(6) (3) and Sn(6)(mu(3)-O)(4)(mu-ONep)(4) (4). Compound 3 consists of an asymmetrical molecule that has five Sn atoms arranged in a square-based pyramidal geometry linked by four basal mu-ONep ligands, two facial mu(3)-O, and two facial mu-ONep ligands. Compound 4 was solved in a novel octahedral arrangement of six Sn cations with an asymmetric arrangement of mu(3)-O and mu-ONep ligands that yields two square base pyramidal and four pyramidal coordinated Sn cations. These compounds were further identified by multinuclear ((1)H, (13)C, (17)O, and (119)Sn) solid-state MAS and high resolution, solution NMR experiments. Because of the complexity of the compounds and the accessibility of the various nuclei, 2D NMR experiments were also undertaken to elucidate the solution behavior of these compounds. On the basis of these studies, it was determined that while the central core of the solid-state structures of 3 and 4 is retained, dynamic ligand exchange leads to more symmetrical molecules in solution. Novel products 3 and 4 lend structural insight into the stepwise hydrolysis of Sn(II) alkoxides.     

Chemistry of a novel family of tridentate alkoxy tin(II) clusters

The chemical interconversions observed for a novel family of trihydroxymethyl ethane (THME-H(3)) ligated Sn(II) compounds have been determined using single-crystal X-ray and (119)Sn NMR experiments. (mu-THME)(2)Sn(3) (1) was isolated from the reaction of 3 equiv of [Sn(NR(2))(2)](2) (R = SiMe(3)) with 4 equiv of THME as a unique trinuclear species capped above and below the plane of Sn atoms by two THME ligands. Upon reaction with "Sn(NR(2))(2)", compound 1 rearranged to yield another novel molecule [(mu-THME)Sn(2)(NR(2))](2) (2). Compound 2 could also be formed directly from the stoichiometric mixture of THME-H(3) and [Sn(NR(2))(2)](2). Further studies revealed that 1 would also rearrange in the presence of Sn(OR)(2) to form [(mu-THME)Sn(2)(mu-OR)](2) [OR = OMe (3), OCH(2)Me (4), OCH(2)CH(Me)CH(2)CH(3) (5), OCH(2)CMe(3) (6, ONep), OC(6)H(5) (7, not structurally characterized), OC(6)H(4)Me-3 (8), OC(6)H(4)Me-2 (9), OC(6)H(3)(Me)(2)-2,6 (10), OC(6)H(3)(CHMe(2))(2)-2,6 (11). Additionally, 3-11 could by synthesized from the reaction of 2 and the appropriate H-OR. (119)Sn solution NMR studies of 2-11, in THF-d(8), indicate that an equilibrium between the parent complex and its disassociation products (1 and the free parent Sn alkoxy or amide precursor) exists at room temperature. This is a likely reason behind the ease of interconversion observed for 1. The generality of this exchange was further verified through the reaction of 1 with [Ti(mu-ONep)(ONep)(3)](2), which led to the isolation of (mu-ONep)(2)Sn(3)(mu-THME)(2)Ti(ONep)(2) (12). For 12, the solid-state structure was maintained in solution with no indication of an equilibrium.     

Controlled synthesis of a structurally characterized family of sterically constrained heterocyclic alkoxy-modified titanium alkoxides

The reaction of [Ti(mu-ONep)(ONep)3]2 (ONep = OCH2C(CH3)3) with a series of heterocyclic methanol derivatives [tetrahydrofurfuryl alcohol (H-OTHF), thiophene methanol (H-OTPM), or 2-pyridylcarbinol (H-OPy)-collectively termed H-OR*], led to the isolation of a novel family of OR*-substituted titanium alkoxide precursors. Independent of the initial stoichiometry for the H-OTHF reaction, a monosubstituted, dinuclear species was isolated as [(ONep)3Ti(muc-OTHF)]2 (1). For 1, each Ti was octahedrally (Oh) bound by three terminal ONep ligands, one bidentate bridging OTHF ligand (muc-OTHF), and an oxygen from the other muc-OTHF ligand. For the OTPM derivatives, the product was identified as [(ONep)3Ti(mu-OTPM)]2 (2). For this ligand, the soft S atom does not bind to the Ti but the O atom does act as a bridge between the two trigonal bipyramidal bound Ti metal centers. The OPy system yielded (OPy)2Ti(OR)2 independent of the OR and the stoichiometry used [OR = ONep (3), OCHMe2 (4), OCMe3 (5)]. For 3-5, the two OPy ligands chelate to the Oh-bound Ti metal center with two terminal OR ligands. Compounds 1-5 were fully characterized using a variety of analytical techniques. An initial investigation of the proposed chemical stability of the '(OPy)2Ti' moiety of 3-5 to alcoholysis exchange pathways involving (i) alkyl alcohols, (ii) aryl alcohols, (iii) substituted phenols, (iv) H-OR* derivatives, and (v) silanols proved successful through the isolation of a novel family of structurally characterized (OPy)2Ti(OR')2 (7-24) compounds.     

Phosphato, chromato, and perrhenato complexes of titanium(IV) and zirconium(IV) containing Kläui's tripodal ligand

Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL(OEt) (L(OEt)(-) = [(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)](3)](-)) in the presence of Na(3)PO(4) and Na(4)P(2)O(7) led to isolation of [(L(OEt)Ti)(3)(mu-O)(3)(mu(3-)PO(4))] (1) and [(L(OEt)Ti)(2)(mu-O)(mu-P(2)O(7))] (2), respectively. The structure of 1 consists of a Ti(3)O(3) core capped by a mu(3)-phosphato group. In 2, the [P(2)O(7)](4-) ligands binds to the two Ti's in a mu:eta(2),eta(2) fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL(OEt) and 1.5 equiv of Na(2)Cr(2)O(7) gave [(L(OEt)Ti)(2)(mu-CrO(4))(3)] (3) that contains two L(OEt)Ti(3+) fragments bridged by three mu-CrO(4)(2-)-O,O' ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L(OEt)Ti(OTf)(3)] (OTf(-) = triflate) with [n-Bu(4)N][ReO(4)] afforded [[L(OEt)Ti(ReO(4))(2)](2)(mu-O)] (4). Treatment of [L(OEt)MF(3)] (M = Ti and Zr) with 3 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(3)] (5) and [L(OEt)Zr(ReO(4))(3)(H(2)O)] (6), respectively. Treatment of [L(OEt)MF(3)] with 2 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(2)F] (7) and [[L(OEt)Zr(ReO(4))(2)](2)(mu-F)(2)] (8), respectively, which reacted with Me(3)SiOTf to give [L(OEt)M(ReO(4))(2)(OTf)] (M = Ti (9), Zr (10)). Hydrolysis of [L(OEt)Zr(OTf)(3)] (11) with Na(2)WO(4).xH(2)O and wet CH(2)Cl(2) afforded the hydroxo-bridged complexes [[L(OEt)Zr(H(2)O)](3)(mu-OH)(3)(mu(3)-O)][OTf](4) (12) and [[L(OEt)Zr(H(2)O)(2)](2)(mu-OH)(2)][OTf](4) (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L(OEt)Ti(IV) complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti(IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates.     

Structural variations of potassium aryloxides

A series of potassium aryloxides (KOAr) were isolated from the reaction of a potassium amide (KN(SiMe(3))(2)) and the desired substituted phenoxide (oMP, 2-methyl; oPP, 2-iso-propyl; oBP, 2-tert-butyl; DMP, 2,6-di-methyl; DIP, 2,6-di-iso-propyl; DBP, 2,6-di-tert-butyl) in tetrahydrofuran (THF) or pyridine (py) as the following: [([K(mu(4)-oMP)(THF)][K(mu(3)-oMP)])(5)]( infinity ) (1), [[K(6)(eta(6),mu(3)-oMP)(4)(eta(6),mu(4)-oMP)(2)(py)(4)].[K(6)(eta(6),mu(3)-oMP)(6)(eta(6)-py)(4)]]( infinity ) (2), [K(mu(3)-oPP)](4)(THF)(3) (3), [K(4)(eta(6),mu(3)-oPP)(2)(mu(3)-oPP)(2)(py)(3)]( infinity ) (4), [K(mu(3)-oBP)(THF)](6) (5), [K(6)(eta(6),mu(3)-oBP)(2)(mu(3)-oBP)(4)(py)(4)]( infinity ) (6), [K(3)(eta(6),mu(3)-DMP)(2)(mu-DMP)(THF)]( infinity ) (7), [[K(eta(6),mu-DMP)(py)](2)]( infinity ) (8), [K(eta(6),mu-DIP)]( infinity ) (9), [K(eta(6),mu-DBP)]( infinity ) (10). Further exploration of the aryl interactions led to the investigation of the diphenylethoxide (DPE) derivative which was isolated as [K(mu(3)-DPE)(THF)](4) (11) or [K(mu(3)-DPE)(py)](4).py(2) (12) depending on the solvent used. In general, the less sterically demanding ligands (oMP, oPP, oBP, and DMP) were solvated polymeric species; however, increasing the steric bulk (DIP and DBP) led to unsolvated polymers and not discrete molecules. For most of this novel family of compounds, the K atoms were pi-bound to the aryl rings of the neighboring phenoxide derivatives to fill their coordination sites. The synthesss and characterization of these compounds are described in detail.     

Novel heteroleptic heterobimetallic alkoxide complexes as facile single-source precursors for Ta(5+) doped TiO(2)-SnO(2) nanoparticles

The nanometric mixed tin-titanium oxide doped with a M(5+) cation was recently shown as a promising thermoelectric material. We report here synthesis of novel molecular precursors for above material using a convenient approach of reacting a metal chloride with a metal alkoxide. Heterometallic complexes with simple addition formula [(EtOH)(2)(OEt)(2)Ti(μ-OEt)(2)SnCl(4)] (1·EtOH) and [(EtOH)(OEt)(3)Ta(μ-OEt)(2)SnCl(4)] (2) were isolated in quantitative yield, which on recrystallization from isopropanol afforded mixed-alkoxide complexes [(Pr(i)OH)(2)(OPr(i))(2)Ti(μ-OEt)(2)SnCl(4)] (3) and [(Pr(i)OH)(OPr(i))(3)Ta(μ-OEt)(2)SnCl(4)] (4), respectively, thus indicating the robustness of the heterometallic M(μ-OEt)(2)Sn core in the solution phase. Facile conversion of these precursors to halide-free spinodal form of Ta(5+)-doped TiO(2)-SnO(2) as a potential thermoelectric material is reported.     

Titanium(IV) and zirconium(IV) sulfato complexes containing the Kläui tripodal ligand: molecular models of sulfated metal oxide surfaces

Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL(OEt) (L(OEt) (-)=[(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)}(3)](-)) afforded the mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(2)(mu-SO(4))] (2). In more concentrated sulfuric acid (>1 M), the same reaction yielded the di-mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(mu-SO(4))(2)] (3). Reaction of 2 with HOTf (OTf=triflate, CF(3)SO(3)) gave the tris(triflato) complex [L(OEt)Ti(OTf)(3)] (4), whereas treatment of 2 with Ag(OTf) in CH(2)Cl(2) afforded the sulfato-capped trinuclear complex [{(L(OEt))(3)Ti(3)(mu-O)(3)}(mu(3)-SO(4)){Ag(OTf)}][OTf] (5), in which the Ag(OTf) moiety binds to a mu-oxo group in the Ti(3)(mu-O)(3) core. Reaction of 2 in H(2)O with Ba(NO(3))(2) afforded the tetranuclear complex (L(OEt))(4)Ti(4)(mu-O)(6) (6). Treatment of 2 with [{Rh(cod)Cl}(2)] (cod=1,5-cyclooctadiene), [Re(CO)(5)Cl], and [Ru(tBu(2)bpy)(PPh(3))(2)Cl(2)] (tBu(2)bpy=4,4'-di-tert-butyl-2,2'-dipyridyl) in the presence of Ag(OTf) afforded the heterometallic complexes [(L(OEt))(2)Ti(2)(O)(2)(SO(4)){Rh(cod)}(2)][OTf](2) (7), [(L(OEt))(2)Ti(O)(2)(SO(4)){Re(CO)(3)}][OTf] (8), and [{(L(OEt))(2)Ti(2)(mu-O)}(mu(3)-SO(4))(mu-O)(2){Ru(PPh(3))(tBu(2)bpy)}][OTf](2) (9), respectively. Complex 9 is paramagnetic with a measured magnetic moment of about 2.4 mu(B). Treatment of zirconyl nitrate with NaL(OEt) in 3.5 M sulfuric acid afforded [(L(OEt))(2)Zr(NO(3))][L(OEt)Zr(SO(4))(NO(3))] (10). Reaction of ZrCl(4) in 1.8 M sulfuric acid with NaL(OEt) in the presence Na(2)SO(4) gave the mu-sulfato-bridged complex [L(OEt)Zr(SO(4))(H(2)O)](2)(mu-SO(4)) (11). Treatment of 11 with triflic acid afforded [(L(OEt))(2)Zr][OTf](2) (12), whereas reaction of 11 with Ag(OTf) afforded a mixture of 12 and trinuclear [{L(OEt)Zr(SO(4))(H(2)O)}(3)(mu(3)-SO(4))][OTf] (13). The Zr(IV) triflato complex [L(OEt)Zr(OTf)(3)] (14) was prepared by reaction of L(OEt)ZrF(3) with Me(3)SiOTf. Complexes 4 and 14 can catalyze the Diels-Alder reaction of 1,3-cyclohexadiene with acrolein in good selectivity. Complexes 2-5, 9-11, and 13 have been characterized by X-ray crystallography.     

Synthesis and characterisation of new titanium amino-alkoxides: precursors for the formation of TiO2 materials

Reaction of the amino-alkoxides HOCH(CH(2)NMe(2))(2) (Hbdmap) and HOC(CH(2)NMe(2))(3) (Htdmap) with [Ti(OR)(4)] yields a series of heteroleptic titanium alkoxides [Ti(OR)(4-n)(L)(n)] (L = bdmap, tdmap). Substitution of the monodentate alkoxide with the chelating alkoxides becomes progressively more difficult, with homogeneous products being obtained only for n = 1, 2. The structure of [Ti(OEt)(3)(bdmap)](2), a mu-OEt bridged dimer, has been determined. Hydrolysis of [Ti(OR)(2)(L)(2)], by adventitious moisture affords the dimeric oxo-alkoxides [Ti(O)(L)(2)](2), both of which have been characterised crystallographically. These two compounds have also been prepared by reaction of [Ti(NMe(2))(2)(L)(2)] with the hydrated metal salts [Zn(acac)(2).2H(2)O] and [Zn(OAc)(2).2H(2)O] using the intrinsic water molecules in these salts to react with the labile amido groups, though the former also produces Me(Me(2)N)C=C(H)C(O)Me from reaction of liberated HNMe(2) with the coordinated acac ligand, while the latter also affords the ligand exchange product [Zn(OAc)(bdmap)]. In neither case does the free dimethylamino group of [Ti(O)(L)(2)](2) coordinate a second metal. The dimeric structure of [Zn(OAc)(bdmap)](2) has been established, and the structure of the tetrameric oxo-alkoxide [Ti(O)(OPr(i))(OCH(2)CH(2)NMe(2))](4) is reported for comparison with others in this study. [Ti(OEt)(3)(bdmap)](2) has been used as a precursor in AACVD (Aerosol-Assisted Chemical Vapour Deposition) to generate amorphous TiO(2) films on glass at 440 degrees C, and TiO(2)@C nanoparticles of approximate diameter 350 nm with a carbon coating of width ca. 75 nm on heating in a sealed container at 700 degrees C.     

Single-source materials for metal-doped titanium oxide: syntheses, structures, and properties of a series of heterometallic transition-metal titanium oxo cages

Titanium dioxide (TiO(2)) doped with transition-metal ions (M) has potentially broad applications in photocatalysis, photovoltaics, and photosensors. One approach to these materials is through controlled hydrolysis of well-defined transition-metal titanium oxo cage compounds. However, to date very few such cages have been unequivocally characterized, a situation which we have sought to address here with the development of a simple synthetic approach which allows the incorporation of a range of metal ions into titanium oxo cage arrangements. The solvothermal reactions of Ti(OEt)(4) with transition-metal dichlorides (M(II)Cl(2), M = Co, Zn, Fe, Cu) give the heterometallic transition-metal titanium oxo cages [Ti(4)O(OEt)(15)(MCl)] [M = Co (2), Zn (3), Fe (4), Cu (5)], having similar MTi(4)(μ(4)-O) structural arrangements involving ion pairing of [Ti(4)O(OEt)(15)](-) anion units with MCl(+) fragments. In the case of the reaction of MnCl(2), however, two Mn(II) ions are incorporated into this framework, giving the hexanuclear Mn(2)Ti(4)(μ(4)-O) cage [Ti(4)O(OEt)(15)(Mn(2)Cl(3))] (6) in which the MCl(+) fragments in 2-5 are replaced by a [ClMn(μ-Cl)MnCl](+) unit. Emphasizing that the nature of the heterometallic cage is dependent on the metal ion (M) present, the reaction of Ti(OEt)(4) with NiCl(2) gives [Ti(2)(OEt)(9)(NiCl)](2) (7), which has a dimeric Ni(μ-Cl)(2)Ni bridged arrangement arising from the association of [Ti(2)(OEt)(9)](-) ions with NiCl(+) units. The syntheses, solid-state structures, spectroscopic and magnetic properties of 2-7 are presented, a first step toward their applications as precursor materials.     

Cube-type nitrido complexes containing titanium and alkali/alkaline-earth metals

Treatment of [[Ti(eta(5)-C(5)Me(5))(mu-NH)](3)(mu(3)-N)] with alkali-metal bis(trimethylsilyl)amido derivatives [M[N(SiMe(3))(2)]] in toluene affords edge-linked double-cube nitrido complexes [M(mu(4)-N)(mu(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)]](2) (M = Li, Na, K, Rb, Cs) or corner-shared double-cube nitrido complexes [M(mu(3)-N)(mu(3)-NH)(5)[Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)](2)] (M = Na, K, Rb, Cs). Analogous reactions with 1/2 equiv of alkaline-earth bis(trimethylsilyl)amido derivatives [M[N(SiMe(3))(2)](2)(thf)(2)] give corner-shared double-cube nitrido complexes [M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)](2)] (M = Mg, Ca, Sr, Ba). If 1 equiv of the group 2 amido reagent is employed, single-cube-type derivatives [(thf)(x)[(Me(3)Si)(2)N]M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)]] (M = Mg, x = 0; M = Ca, Sr, Ba, x = 1) can be isolated or identified. The tetrahydrofuran molecules are easily displaced with 4-tert-butylpyridine in toluene, affording the analogous complexes [(tBupy)[(Me(3)Si)(2)N]M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)]] (M = Ca, Sr). The X-ray crystal structures of [M(mu(3)-N)(mu(3)-NH)(5)[Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)](2)] (M = K, Rb, Cs) and [M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3))-N)](2)] (M = Ca, Sr) have been determined. The properties and solid-state structures of the azaheterometallocubane complexes bearing alkali and alkaline-earth metals are discussed.     

Isostructural neo-pentoxide derivatives of group 3 and the lanthanide series metals for the production of Ln2O3 nanoparticles

The synthesis and characterization of a series of neo-pentoxide (OCH2C(CH3)3 or ONep) derivatives of group 3 and the lanthanide (Ln) series' metals were undertaken via an amide/alcohol exchange route. Surprisingly, the products isolated and characterized by single-crystal X-ray diffraction yielded isostructural species for every trivalent cation studied: [Ln(mu-ONep)2(ONep)]4 [Ln=Sc (1), Y (2), La (3), Ce (4), Pr (5), Nd (6), Sm (7), Eu (8), Gd (9), Tb (10), Dy (11), Ho (12), Er (13), Tm (14), Yb (15), Lu (16)]. Compounds 3, 4, 6, and 11 have been previously reported. Within this series of complexes, the Ln metal centers are oriented in a square with each Ln-Ln edge interconnected via two mu-ONep ligands; each metal center also binds one terminal ONep ligand. NMR data of 1-3 indicate that the solid-state structure is retained in solution. FTIR spectroscopy (KBr pellet) revealed the presence of significant Ln---H-C interactions within one set of the bridging ONep ligands in all cases; the stretching frequencies of these C-H bonds appear to increase in magnitude with decrease in metal ion radius. These complexes were used to generate nanoparticles through solution hydrolysis routes, resulting in the formation of lanthanide oxide nanoparticles and rods. The emission properties of these ceramics were preliminarily investigated using UV-vis and PL measurements.     

Versatility of dithiophosphates in the syntheses of copper(I) complexes with bis(diphenylphosphino)alkanes: abstraction of chloride from dichloromethane

Reactions of [Cu(CH(3)CN)(4)]X (X = PF(6), BF(4)) with bis(diphenylphosphino)methane (dppm = Ph(2)PCH(2)PPh(2)) and ammonium dialkyldithiophosphates, (NH(4))[S(2)P(OR)(2)] (R = Et, (i)Pr), yield a series of novel Cu(I) polynuclear complexes, trinuclear [Cu(3)(mu-dppm)(3)(mu(3)-Cl){S(2)P(OEt)(2)}] (PF(6)) 1 and [Cu(3)(mu-dppm)(2){S(2)P(OR)(2)}(2)](PF(6)) (R = Et, 2; (i)Pr, 3), tetranuclear [Cu(4)(mu-dppm)(2) {S(2)P(OEt)(2)}(4)] 4, and hexanuclear [Cu(6)(mu-dppm)(2)(mu(4)-Cl){S(2)P(O(i)()Pr)(2)}(4)](BF(4)) 5. Similarly, the reaction of [Cu(2)(mu-L-L)(2)(CH(3)CN)(2)](PF(6))(2) (L-L, dppm, dppe = Ph(2)PCH(2)CH(2)PPh(2)) with (NH(4))[S(2)P(OR)(2)] yields dinuclear [Cu(2)(mu-dppm)(2){S(2)P(OR)(2)}(2)] 6 (R= (i)Pr, 6A; Et, 6B), trinuclear [Cu(3)(mu-dppe)(3)(mu-Cl)(2){S(2)P(O(i)Pr)(2)}] 9, and polymeric [Cu(mu(2)-dppe){S(2)P(OR)(2)}](n) (R = Et, 7; (i)Pr, 8) complexes. The formation of 1 and 5 involved the abstraction of chloride from dichloromethane when the Cu/S(2)P(OR)(2) ratio exceeded 1, but when ratio was 1:1, no Cl abstraction occurred, as in compound 4. Compound 9, however, was obtained as a 12% byproduct in the synthesis of 8 using a 1:1:1 ratio of Cu/dppe/S(2)P(O(i)Pr)(2). The chloride binds to Cu atoms in a mu(3)-Cl mode by capping one face of the Cu(3) triangle of cluster 1. A mu(4)-Cl caps a single tetragonal face of the trigonal prism of cluster 5, and in the cluster 9, two chlorides bond in mu(2)-Cl modes. Both clusters 2 and 3 exhibit the mu(3)-S mode of bonding for dtp ligands. Only cluster 5 exhibited close Cu...Cu contacts (2.997-3.0238 A). All of compounds were characterized by single-crystal X-ray diffraction and pertinent crystallographic data for 1, 5, and 9 are are follows: (1) C(79)H(76)ClCu(3)F(6)O(2)P(8)S(2), triclinic, P, a = 11.213(1) A, b = 14.142(1) A, c = 25.910(2) A, alpha = 95.328(2) degrees , beta = 99.594(2) degrees , gamma = 102.581(2) degrees , V = 3918.2(6) A(3), Z = 2; (5) C(74)H(100)BClCu(6)F(4)O(8)P(8)S(8), monoclinic, P2(1)/n, a = 25.198(4) A, b = 15.990(3) A, c = 25.421(4) A, beta = 106.027(3) degrees , V = 9845(3)A(3), Z = 4; (9) C(84)H(86)Cl(2)Cu(3)O(2)P(7)S(2), monoclinic, C2/c, with a = 24.965(3) A, b = 17.058(2) A, c = 20.253(2) A, beta = 95.351(4) degrees , V = 8587.4(17)A(3), Z = 4.     

Dendritic arrays of [Re6(mu3-Se)8]2+ core-containing clusters: exploratory synthesis and electrochemical studies

The reaction between the previously reported site-differentiated cluster solvate [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(MeCN)](SbF(6))(2) (1) with pyridyl-based ditopic ligands 4,4'-trimethylenedipyridine (2), 1,2-bis(4-pyridyl)ethane (3), and (E)-1,2-bis(4-pyridyl)ethene (4) afforded cluster complexes of the general formula [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(L)](SbF(6))(2) (5-7), where L represents one of the pyridyl-based ligands. Reacting these cluster complex-based ligands with the fully solvated cluster complex [Re(6)(mu(3)-Se)(8)(MeCN)(6)](SbF(6))(2) (8) produced dendritic arrays of the general formula {Re(6)(mu(3)-Se)(8)[Re(6)(mu(3)-Se)(8)(PEt(3))(5)(L)](6)}(SbF(6))(14) (9-11), each featuring six circumjacent [Re(6)(mu(3)-Se)(8)(PEt(3))(5)](2+) units bridged to a [Re(6)(mu(3)-Se)(8)](2+) core cluster by the pyridyl-based ligands. Electrochemical studies using a thin-layer electrochemical cell revealed cluster-based redox events in these cluster arrays. For 9 (L = 2), one reversible oxidation event corresponding to the removal of 7 electrons was observed, indicating noninteraction or extremely weak interactions between the clusters. For 10 (L = 3), two poorly resolved oxidation waves were found. For 11 (L = 4), two reversible oxidation events, corresponding respectively to the removal of 1 and 6 electrons, were observed with the 1-electron oxidation event occurring at a potential 150 mV more positive than the 6-electron oxidation. These electrochemical studies suggest intercluster coupling in 11 via through-bond electronic delocalization, which is consistent with electronic spectroscopic studies of this same molecule.     

Half-sandwich titanium(IV) complexes with Kläui's tripod ligand

Treatment of [Ti(O-i-Pr)(2)Cl(2)] with NaL(OEt) (L(OEt)(-) = [CpCo[P(O)(OEt)(2)](3)](-), Cp = eta(5)-C(5)H(5)) afforded [L(OEt)Ti(O-i-Pr)(2)Cl] that reacted with HCl in ether to give [L(OEt)TiCl(3)] (1). The average Ti-O and Ti-Cl distances in 1 are 1.975 and 2.293 A, respectively. Reaction of titanyl sulfate with NaL(OEt) in water followed by addition of HBF(4) afforded [L(OEt)TiF(3)] (2), the Ti-O and Ti-F distances of which are 2.020(2) and 1.792(2) A, respectively. The Zr(IV) analogue [L(OEt)ZrF(3)] (3) was prepared similarly from zirconyl nitrate, NaL(Oet), and HBF(4) in water. The Zr-O and average Zr-F distances in 3 are 2.139(2) and 1.938(2) A, respectively. Treatment of 1 with tetrachlorocatechol (H(2)Cl(4)cat) afforded [L(OEt)Ti(Cl(4)cat)Cl] (4). The average Ti-O(P), Ti-O(C), and Ti-Cl distances in 4 are 1.972, 1.926, and 2.334 A, respectively. Hydrolysis of 4 in the presence of Et(3)N yielded the mu-oxo dimer [(L(OEt))(2)Ti(2)(Cl(4)cat)(2)(mu-O)] (5). The average Ti-O(P), Ti-O(C), and Ti-O(Ti) distances in 5 are 2.027, 1.926, and 1.7977(9) A. Treatment of 1 with 1,1'-binaphthol (BINOLH(2)) in the presence of Et(3)N afforded [(L(OEt))(2)Ti(2)(mu-O)(2)(mu-BINOL)] x 2BINOLH(2) (6.2BINOLH(2)). Complex 1 is capable of catalyzing ring opening of epoxides with Me(3)SiN(3) under solvent-free conditions presumably via a Ti-azide intermediate.     

Extending the family of titanium heterometallic-oxo-alkoxy cages

Here we investigate the synthesis of high-nuclearity heterometallic titanium oxo-alkoxy cages using the reactions of metal chlorides with [Ti(OEt)(4)] or the pre-formed homometallic titanium-oxo-alkoxy cage [Ti(7)O(4)(OEt)(20)] (A). The octanuclear Ti(7)Co(II) cage [Ti(7)CoO(5)(OEt)(19)Cl] (1) (whose low-yielding synthesis we reported earlier) can be made in better yield, reproducibly by the reaction of a mixture of heptanuclear [Ti(7)O(4)(OEt)(20)] (A) and [KOEt] with [Co(II)Cl(2)] in toluene. A alone reacts with [Co(II)Cl(2)] and [Fe(II)Cl(2)] to form [Ti(7)Co(II)O(5)(OEt)(18)Cl(2)] (2) and [Ti(7)Fe(II)O(5)(OEt)(18)Cl(2)] (3), respectively. Like 1, compounds 2 and 3 retain the original Ti(7) fragment of A and the II-oxidation state of the transition metal ions (Tm). In contrast, from the reaction of [Ti(OEt)(4)] with [Cr(II)Cl(2)] it is possible to isolate [Ti(3)Cr(V)O(OEt)(14)Cl] (4) in low yield, containing a Ti(3)Cr(V) core in which oxidation of Cr from the II to V oxidation state has occurred. Reaction of [Mo(V)Cl(5)] with [Ti(OEt)](4) in [EtOH] gives the Ti(8)Mo(V)(4) cage [{Ti(4)Mo(2)O(8)(OEt)(10)}(2)] (5). The single-crystal X-ray structures of the new cages 2, 3, 4, and 5 are reported. The results show that the size of the heterometallic cage formed can be influenced by the nuclearity of the precursor. In the case of 5, the presence of homometallic Mo-Mo bonding also appears to be a significant factor in the final structure.     

Synthesis, structures and reactivity of ruthenium nitrosyl complexes containing Kläui's oxygen tripodal ligand

Ruthenium nitrosyl complexes containing the Kl?ui's oxgyen tripodal ligand L(OEt)(-) ([CpCo{P(O)(OEt)(2)}(3)](-) where Cp = η(5)-C(5)H(5)) were synthesized and their photolysis studied. The treatment of [Ru(N^N)(NO)Cl(3)] with [AgL(OEt)] and Ag(OTf) afforded [L(OEt)Ru(N^N)(NO)][OTf](2) where N^N = 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) (2·[OTf](2)), 2,2'-bipyridyl (bpy) (3·[OTf](2)), N,N,N'N'-tetramethylethylenediamine (4·[OTf](2)). Anion metathesis of 3·[OTf](2) with HPF(6) and HBF(4) gave 3·[PF(6)](2) and 3·[BF(4)](2), respectively. Similarly, the PF(6)(-) salt 4·[PF(6)](2) was prepared by the reaction of 4·[OTf](2) with HPF(6). The irradiation of [L(OEt)Ru(NO)Cl(2)] (1) with UV light in CH(2)Cl(2)-MeCN and tetrahydrofuran (thf)-H(2)O afforded [L(OEt)RuCl(2)(MeCN)] (5) and the chloro-bridged dimer [L(OEt)RuCl](2)(μ-Cl)(2) (6), respectively. The photolysis of complex [2][OTf](2) in MeCN gave [L(OEt)Ru(dtbpy)(MeCN)][OTf](2) (7). Refluxing complex 5 with RNH(2) in thf gave [L(OEt)RuCl(2)(NH(2)R)] (R = tBu (8), p-tol (9), Ph (10)). The oxidation of complex 6 with PhICl(2) gave [L(OEt)RuCl(3)] (11), whereas the reduction of complex 6 with Zn and NH(4)PF(6) in MeCN yielded [L(OEt)Ru(MeCN)(3)][PF(6)] (12). The reaction of 3·[BF(4)](2) with benzylamine afforded the μ-dinitrogen complex [{L(OEt)Ru(bpy)}(2)(μ-N(2))][BF(4)](2) (13) that was oxidized by [Cp(2)Fe]PF(6) to a mixed valence Ru(II,III) species. The formal potentials of the RuL(OEt) complexes have been determined by cyclic voltammetry. The structures of complexes 5,6,10,11 and 13 have been established by X-ray crystallography.     

Titanium alkali metal nitrido complexes

Treatment of [(Ti(eta5-C5Me5)(mu-NH))3(mu3-N)] with alkali metal bis(trimethylsilyl)amido reagents in toluene afforded the complexes [M(mu3-N)(mu3-NH)2[Ti3(mu5-C5Me5)3(mu3-N)]]2 (M = Li (2), Na, (3), K (4)). The molecular structures of 2 and 3 have been determined by X-ray crystallographic studies and show two azaheterometallocubane cores [MTi3N4] linked by metal-nitrogen bonds. Reaction of the lithium derivative 2 with chlorotrimethylsilane or trimethyltin chloride in toluene gave the incomplete cube nitrido complexes [Ti3(eta5-C5Me5)3(mu-NH)2(mu-NMMe3)(mu3-N)] (M = Si (5), Sn (6)). A similar reaction with indium(I) or thallium(I) chlorides yielded cube-type derivatives [M(mu3-N)(mu3-NH)2[Ti(eta5-C5Me5)3(mu3-N)] (M=In (7), Tl (8)).