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.     

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.     

New synthetic route for organic polyoxometallic clusters: synthetic and structural investigations on the first dumb-bell shaped polyoxozirconium hydroxide with the [Zr9(mu5-O)2(mu3-O)4(mu-O)4(mu-OH)8] core structure

A new route for organic polyoxometallic clusters describes the first dumb-bell-like organic polyoxozirconium hydroxide [[(Cp*Zr)4(mu5-O)(mu3-O)2(mu-OH)4]2Zr(mu-O)4] x 2C7H8 (2; Cp* = C5Me5) involving the treatment of the Br?nsted acidic organozirconium hydroxide [(Cp*Zr)6(mu4-O)(mu-O)4(mu-OH)8] x 2C7H8 (1) with organozirconium compounds.     

Oligomerization and oxide formation in bismuth aryl alkoxides: synthesis and characterization of Bi4(mu 4-O)(mu-OC6F5)6(mu 3-OBi(mu-OC6F5)3)2(C6H5CH3), Bi8(mu 4-O)2(mu 3-O)2(mu-OC6F5)16, Bi6(mu 3-O)4(mu 3-OC6F5)(mu 3-OBi(OC6F5)4)3, NaBi4(mu 3-O)2(OC6F5)9(THF)2, and Na2Bi4(mu 3-O)2(OC6F5)10(THF)2

Exposing [Bi(OR)3(toluene)]2 (1, R = OC6F5) to different solvents leads to the formation of larger polymetallic bismuth oxo alkoxides via ether elimination/oligomerization reactions. Three different compounds were obtained depending upon the conditions: Bi4(mu 4-O)(mu-OR)6(mu 3-OBi(mu-OR)3)2(C6H5CH3) (2), Bi8(mu 4-O)2(mu 3-O)2(mu 2-OR)16 (3), Bi6(mu 3-O)4(mu 3-OR)(mu 3-OBi(OR)4)3 (4). Compounds 2 and 3 can also be synthesized via an alcoholysis reaction between BiPh3 and ROH in refluxing dichloromethane or chloroform. Related oxo complexes NaBi4(mu 3-O)2(OR)9(THF)2 (5) and Na2Bi4(mu 3-O)2(OR)10(THF)2 (6) were obtained from BiCl3 and NaOR in THF. The synthesis of 1 and Bi(OC6Cl5)3 via salt elimination was successful when performed in toluene as solvent. For compounds 2-6 the single-crystal X-ray structures were determined. Variable-temperature NMR spectra are reported for 2, 3, and 5.     

New mu-oxo octanuclear complexes of 3d elements stabilized by dialkylcarbamato ligands. Synthesis and X-ray crystal and molecular structures

The octanuclear aggregates M(8)(mu(4)-O)(2)(O(2)CN(i)()Pr(2))(12) [M = Mn(II) 1, Co(II) 2, Ni(II) 3] have been prepared in good yields by controlled hydrolysis of the corresponding metal carbamate precursors [M(O(2)CN(i)()Pr(2))(2)](n)(). X-ray analysis has shown compounds 1-3 to be isostructural. The core of 2 contains two distorted [M(4)O] tetrahedra related by an inversion center. The hexanuclear carbamates M(6)(O(2)CNEt(2))(12) in toluene undergo a metal redistribution process with formation of the hexanuclear carbamates M'(x)M' '(6-x)(O(2)CNEt(2))(12), M' = Co, M' ' = Mn, as evidenced by mass-spectrometric data. In the presence of moisture, the mixed octanuclear carbamates Co(x)Mn(6-x)(MnO)(CoO)(O(2)CNEt(2))(12) were promptly formed and detected by DCI/MS measurements. Mass spectral data of Co(8)(mu(4)-O)(2)(O(2)CN(i)Pr(2))(12) are also reported.     

Investigating the stability of the peroxide bridge in (mu-oxo)- and bis(mu-oxo)manganese clusters

The stability of the peroxide ligand bridging two manganese ions in the trinuclear oxomanganese complex [Mn(III)(3)(mu(3)-O)(mu-O(2))(AcO)(2)(dien)(3)](2+), one of only two structurally characterized Mn clusters possessing a mu(1,2)-peroxo bridge, has been investigated using density functional theory. Although the peroxide O-O bond in the related bis(mu-oxo)-bridged complex [Mn(IV)(2)(mu-O)(2)(mu-O(2))(NH(3))(6)](2+) undergoes spontaneous cleavage upon two-electron reduction to the Mn(III)(2) dimer, calculations on the model complexes [Mn(III)(2)(mu-O)(mu-O(2))(NH(3))(8)](2+) and [Mn(III)(2)(mu-O)(mu-O(2))(NH(3))(6)(H(2)O)(2)](2+), which contain the same mu-oxo-,mu-peroxo-bridged core present in the trimer, indicate that the peroxide bridge remains intact, in agreement with experiment. Its stability can be attributed to a Jahn-Teller distortion resulting in elongation of the axial Mn-N bonds perpendicular to the Mn(2)(mu-O)(mu-O(2)) plane which in turn stabilizes the high-spin Mn(III) oxidation state. However, the difference in the energies of the bridged and cleaved peroxide structures is small (ca. 0.5 eV), the lowest energy structure depending on the nature of the terminal ligands. Calculations on the model trimer complex [Mn(III)(3)(mu(3)-O)(mu-O(2))(HCO(2))(2)(NH(3))(9)](2+) indicate that the energetic differences between the cleaved and uncleaved structures is even smaller (ca. 0.2 eV), and although the peroxo-bridge remains more or less intact, it is likely to be quite facile.     

Construction of titanasiloxanes by incorporation of silanols to the metal oxide model [(Ti(eta 5-C5Me5)(mu-O))3(mu3-CR)]: DFT elucidation of the reaction mechanism

A family of novel titanasiloxanes containing the structural unit {[Ti(eta(5)-C(5)Me(5))O](3)} were synthesized by hydron-transfer processes involving reactions with equimolecular amounts of mu(3)-alkylidyne derivatives [{Ti(eta(5)-C(5)Me(5))(mu-O)}(3)(mu(3)-CR)] (R=H (1), Me (2)) and monosilanols, R(3)'Si(OH), silanediols, R(2)'Si(OH)(2), and the silanetriol tBuSi(OH)(3). Treatment of 1 and 2 with triorganosilanols (R'=Ph, iPr) in hexane affords the new metallasiloxane derivatives [{Ti(eta(5)-C(5)Me(5))(mu-O)}(3)(mu-CHR)(OSiR(3)')] (R=H, R'=Ph (3), iPr (4); R=Me, R'=Ph (5), iPr (6)). Analogous reactions with silanediols, (R'=Ph, iPr), give the cyclic titanasiloxanes [{Ti(eta(5)-C(5)Me(5))(mu-O)}(3)(mu-O(2)SiR'(2))(R)] (R=Me, R'=Ph (7), iPr (8); R=Et, R'=Ph (9), iPr (10)). Utilization of tBuSi(OH)(3) with 1 or 2 at room temperature produces the intermediate complexes [{Ti(eta(5)-C(5)Me(5)) (mu-O)}(3)(mu-O(2)Si(OH)tBu)(R)] (R=Me (11), Et(12)). Further heating of solutions of 11 or 12 affords the same compound with an adamantanoid structure, [{Ti(eta(5)-C(5)Me(5))(mu-O)}(3)(mu-O(3)SitBu)] (13) and methane or ethane elimination, respectively. The X-ray crystal structures of 3, 4, 6, 8, 10, 12, and 13 have been determined. To gain an insight into the mechanism of these reactions, DFT calculations have been performed on the incorporation of monosilanols to the model complex [{Ti(eta(5)-C(5)H(5))(mu-O)}(3)(mu(3)-CMe)] (2 H). The proposed mechanism consists of three steps: 1) hydron transfer from the silanol to one of the oxygen atoms of the Ti(3)O(3) ring, forming a titanasiloxane; 2) intramolecular hydron migration to the alkylidyne moiety; and 3) a mu-alkylidene ligand rotation to give the final product.     

Heterobimetallic Bi(III)-Ti(IV) coordination complexes: synthesis and solid-state structures of BiTi4(sal)6(mu-OiPr)3(OiPr)4, and the cyclic isomers Bi4Ti4(sal)10(mu-OiPr)4(OiPr)4 and Bi8Ti8(sal)20(mu-OiPr)8(OiPr)8

The reaction of a 1:2 mixture of bismuth(III) salicylate with titanium(IV) isopropoxide in refluxing toluene has been investigated and found to proceed with ligand exchange to produce the new heterobimetallic complexes BiTi(4)(sal)(6)(mu-O(i)Pr)(3)(O(i)Pr)(4) (1), Bi(4)Ti(4)(sal)(10)(mu-O(i)Pr)(4)(O(i)Pr)(4) (2), and Bi(8)Ti(8)(sal)(20)(mu-O(i)Pr)(8)(O(i)Pr)(8) (3). Complex 1 is the major product, while 2 and 3 were identified as minor products from the reaction. Compound 1 is produced pure and in high yield by employing stoichiometric amounts of reagents; its crystal structure consists of a [Ti(4)(sal)(6)(O(i)Pr)(7)](3)(-) ion capped by a Bi(3+) ion. Complexes 2 and 3 exhibit cyclic ring structures of bismuth and titanium atoms showing crystallographically imposed inversion symmetry. Both structures occlude large quantities of lattice solvent. The compositional and structural parameters from the single crystal studies indicate that complexes 2 and 3 may represent sequential steps in a ligand exchange process between the two metal species, while the reactivity patterns that were observed provide clues about the solution state structure of bismuth(III) salicylate itself. The 2D COSY (1)H NMR spectrum of 1 indicates retention of the asymmetric structure in solution as evidenced by the presence of 14 diastereotopic isopropoxide methyl resonances.     

Praseodymium(III)-substituted bismuth titanate thin-film generation using metallo-organic precursors with an M-O-C skeleton and sol-gel technique and employing 4f-4f transition spectra as a probe to explore kinetic performance

A hetero-trimetallic lanthanide-substituted bismuth titanate (BLT, where lanthanide is praseodymium) with stoichiometry Pr(0.75)Bi(3.25) Ti(3)O(12) has been obtained as both highly homogenized crystalline and amorphous thin films using three different BLT precursors: (i). precursor A-(Pr(OC(3)H(7)(i))(3),Bi(OOCCH(3))(3),Ti(OC(3)H(7)(i))(4)); (ii). precursor B-(Pr(OC(3)H(7)(i))(2)(acac),Bi(OOCCH(3))(3),Ti(OC(3)H(7)(i))(3)(acac)); and (iii). precursor C-(Pr(OC(3)H(7)(i))(2)(acac),Bi(OOCCH(3))(3),Ti(OC(3)H(7)(i))(2)(acac))(2). These three BLT precursors (A, B, C) are prepared by reacting constituent monometallic precursors in the desired stoichiometry and by employing controlled acidic hydrolysis via the sol-gel method. Paramagnetic Pr(III), being a f(2) ion, gives characteristic 4f-4f transition bands (3H(4)-->3P(2), 3H(4)-->3P(1), 3H(4)-->3P(0), and 3H(4)-->1D(2)) in the visible region, the intensities of which have been found to be highly sensitive to even minor changes in the immediate coordination around Pr(III), occurring as a result of the progress of polycondensation reactions of three multicomponent BLT sols. We have used the changes with time in the intensities (represented by oscillator strengths of these four 4f-4f bands) and the magnitude and variation of the spectral parameters evaluated from the observed spectra with a view toward monitoring the sol-gel reactions of BLT precursors A, B, and C. 4f-4f transition spectra of the aliquots, withdrawn from the hydrolyzing A, B, and C sols at different time intervals, represent the changes occurring in the Pr(III) environment with the progress of sol-gel hydrolysis of BLT, and are used to investigate the kinetic performance in hydrolysis of the three precursors. Kinetics of hydrolysis of precursors A, B, and C indicate that all four f-f transition bands of Pr are almost equally sensitive to precursor hydrolysis in the order A>B>C.     

Dodecanuclear manganese(III) phosphonates with cage structures

Treatments of Mn(O(2)CR)(2) (R = Me, Ph) with NBu(4)MnO(4) in CH(3)CN or CH(3)CN/CH(2)Cl(2) in the presence of acetic acid, delta(1)-cyclohexenephosphonic acid (C(6)H(9)PO(3)H(2)), and 2,2'-bipyridine or 1,10-phenanthroline result in three novel dodecamanganese(III) clusters [Mn(12)O(8)(O(2)CMe)(6)(O(3)PC(6)H(9))(7)(bipy)(3)] (1), [Mn(12)O(8)(O(2)CPh)(6)(O(3)PC(6)H(9))(7)(bipy)(3)] (2), and [Mn(12)O(8)(O(2)CPh)(6)(O(3)PC(6)H(9))(7)(phen)(3)] (3). They have a similar Mn(12) core of [Mn(III)(12)(mu(4)-O)(3)(mu(3)-O)(5)(mu-O(3)P)(3)] with a new type of topologic structure. Solid-state dc magnetic susceptibility measurements of complexes 1-3 reveal that dominant antiferromagnetic interactions are propagated between the magnetic centers. The ac magnetic measurements suggest an S = 2 ground state for compounds 1 and 3 and an S = 3 ground state for compound 2.     

Synthesis and characterization of mixed-valent manganese phosphonate cage complexes

The reaction of phenylphosphonic acid (PhPO(3)H(2)) with the mixed-valent basic oxo-centered manganese triangle [Mn(3)O(O(2)CCMe(3))(6)(py)(3)] (1; where py=pyridine) in the presence of a suitable base gives four different manganese clusters depending on the identity of the base. The syntheses and structural characterization of [Mn(18)(mu(3)-O)(8)(PhPO(3))(14)(O(2)CCMe(3))(12)(py)(6)(H(2)O)(2)] (2), [Mn(7)(mu(3)-O)(3)(O(3)PPh)(3)(O(2)CCMe(3))(8)(py)(3)] (3), [Mn(9)Na(mu(3)-O)(4)(mu(4)-O)(2)(O(3)PPh)(2)(O(2)CCMe(3))(12)(H(2)O)(2)(H(2)O)(0.67)(Py)(0.33)] (4), and [Mn(13)(mu(3)-O)(8)(OMe)(8)(O(3)PPh)(4)(O(2)CCMe(3))(10)] (5) are described. Complexes 4 and 5 are homovalent Mn(III) cages, while 2 and 3 contain divalent, trivalent, and/or tetravalent ions. All the manganese centers are valence-localized, the octahedral Mn(III) sites being recognizable by marked Jahn-Teller distortions. The magnetic properties of compounds 2-5 have been investigated in the polycrystalline state by magnetic susceptibility and high-field magnetization measurements, which reveal that spin ground states vary from 0< or =S > or =8. AC susceptibility measurements performed on 4 and 5, in the 1.6-10.0 K ranges show the presence of out of AC susceptibility signal (chi(M)') for 4, and an effective energy barrier (U(eff)) for the re-orientation of the magnetization is found to be 17 K, but for 5, the chi(M)' maximum is found to be below 1.5 K.     

Activation of CO2 by a heterobimetallic Zr/Co complex

At room temperature, the early/late heterobimetallic complex Co((i)Pr(2)PNMes)(3)Zr(THF) has been shown to oxidatively add CO(2), generating (OC)Co((i)Pr(2)PNMes)(2)(μ-O)Zr((i)Pr(2)PNMes). This compound can be further reduced under varying conditions to generate either the Zr oxoanion (THF)(3)Na-O-Zr(MesNP(i)Pr(2))(3)Co(CO) or the Zr carbonate complex (THF)(4)Na(2)(CO(3))-Zr(MesNP(i)Pr(2))(3)Co(CO). Additionally, reactivity of the CO(2)-derived product has been observed with PhSiH(3) to generate the Co-hydride/Zr-siloxide product (OC)(H)Co((i)Pr(2)PNMes)(3)ZrOSiH(2)Ph.     

Stannylplumbylenes: bonding between tetravalent tin and divalent lead

Depending on stoichiometry, reactions of the mixed valence Sn(0)/Sn(III) compound Sn(SnAr(3))(2) (1) (Ar = C(6)H(4)(O(i)Pr)(2)-2,6) with the likewise substituted plumbylene PbAr(2) (3) afforded either the homoleptic distannylplumbylene Pb(SnAr(3))(2) (4) or the heteroleptic arylstannylplumbylene Pb(Ar)SnAr(3) (5), a valence isomer of a stannaplumbene.     

1,1,1-Tris(hydroxymethyl)propane in manganese carboxylate chemistry: synthesis, structure and magnetic properties of a mixed-valence [MnIII4MnII4] cluster featuring the novel [MnIII4MnII4(mu3-OR)6(mu2-OR)8]6+ core

The reaction between MnBr(2).4H(2)O with H(3)tmp (1,1,1-tris(hydroxymethyl)propane) in MeCN in the presence of Na(O(2)CCMe(3)) and NBu(4)Br produces the complex [Mn(8)(O(2)CCMe(3))(2)(tmp)(2)(Htmp)(4)Br(4)(H(2)O)(2)].2MeCN (1.2MeCN) in good yield. The centrosymmetric octanuclear molecule consists of four Mn(III) and four Mn(II) ions assembled together by fourteen alkoxo bridges to give a [Mn(III)(4)Mn(II)(4)(mu(3)-OR)(6)(mu(2)-OR)(8)](6+) rod-like core in which the metal centres are arranged in a planar zigzag fashion. Peripheral ligation is provided by a combination of bridging pivalate ions, terminal bromides and water molecules. Dc magnetic susceptibility measurements reveal the presence of dominant antiferromagnetic interactions leading to a spin ground state of S = 0. A rationalization of this result is attempted by structural comparison with previously reported tetranuclear manganese complexes containing the [Mn(III)(2)Mn(II)(2)(mu(3)-OR)(2)(mu(2)-OR)(4)] core in which the magnetic interactions are ferromagnetic.     

Synthesis and crystal structure of unprecedented oxo/hydroxo-bridged polynuclear gallium(III) aqua complexes

Two new polynuclear oxo/hydroxo-bridged polynuclear gallium(III) aqua complexes are obtained upon treatment of Ga(3+)(aq) with pyridine: the supramolecular compound of macrocyclic cavitand cucurbit[6]uril with gallium complex containing 32 metal atoms [Ga(32)(mu(4)-O)(12)(mu(3)-O)(8)(mu(2)-O)(7)(mu(2)-OH)(39)(H(2)O)(20)](PyH subsetC(36)H(36)N(24)O(12))(3)(NO(3))(6).53H(2)O (1) and the tridecanuclear complex [Ga(13)(mu(3)-OH)(6)(mu(2)-OH)(18)(H(2)O)(24)](NO(3))(15).12H(2)O (2). It follows that two modes of nucleation exist when Ga(3+)(aq) is hydrolyzed: one around the tetrahedral GaO(4) units (complex 1) and the other around the octahedral GaO(6) units (complex 2). This is the first time that polynuclear oxo/hydroxo-bridged aqua complexes of Ga(III) have been isolated without the use of other ligands to control or block olygomerization.     

Transfer hydrogenation processes to mu(3)-alkylidyne groups on the organotitanium oxide [Ti(3)Cp*O(3)

The photochemical treatment of mu(3)-alkylidyne complexes [[TiCp*(mu-O)](3)(mu(3)-CR)] (R=H (1), Me (2), Cp*=eta(5)-C(5)Me(5)) with the amines (2,6-Me(2)C(6)H(3))NH(2), Et(2)NH, and Ph(2)NH and the imine Ph(2)C=NH leads to the partial hydrogenation of the alkylidyne moiety that is supported on the organometallic oxide, [Ti(3)Cp*O(3)], and the formation of new oxoderivatives [[TiCp*(3)(mu-CHR)(R'NR")] (R"=2,6-Me(2)C(6)H(3), R'=H, R=H (3), Me (4); R'=R"=Et, R=H (5), Me (6); R'=R"=Ph, R=H (7), Me (8)) and [[TiCp*(mu-O)](3)(mu-CHR)(N=CPh(2))] (R=H (9), R=Me (10)), respectively. A sequential transfer hydrogenation process occurs when complex 1 is treated with tBuNH(2), which initially gives the mu-methylene [[TiCp*(mu-O)](3)(mu-CH(2))(HNtBu)] (11) complex and finally, the alkyl derivative [[TiCp*(mu-O)](3)(mu-NtBu)Me] (12). Furthermore, irradiation of solutions of the mu(3)-alkylidyne complexes 1 or 2 in the presence of diamines o-C(6)H(4)(NH(2))(2) and H(2)NCH(2)CH(2)NH(2) (en) affords [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(6)H(4)NH)] (13) and [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(2)H(4)NH)] (14) by either methane or ethane elimination, respectively. In the reaction of 1 with en, an intermediate complex [[TiCp*(mu-O)](3)(mu-CH(2))(NHCH(2)CH(2)NH(2))] (15) is detected by (1)H NMR spectroscopy. Thermal treatment of the complexes 4-10 quantitatively regenerates the starting mu(3)-alkylidyne compounds and the amine R'(2)NH or the imine Ph(2)C=NH; however, heating of solutions of 3 or 4 in [D(6)]benzene or a equimolecular mixture of both at 170 degrees C produces methane, ethane, or both, and the complex [[TiCp*(mu-O)](3)[mu(3)-eta(2)-NC(6)H(3)(Me)CH(2)]] (16). The molecular structure of 8 has been established by single-crystal X-ray analysis.     

Group 13 organoderivatives supported on a metallic oxide model

The [{TiCp*(micro-O)}3(mu3-CH)] (1) metalloligand, (Cp* = eta5-C5Me5), coordinates in a 1:1 ratio to [AlMe3] or 9-BBN to give [{Me3Al}{(mu3-O)(mu-O)2(TiCp)2(TiCp)3(mu3-CH)}](2) or [{(C8H14)B}(mu-H) {(mu3-O)(mu-O)2(TiCp*)3(mu3-CH)}](4), respectively, partial hydrolysis of 2 leads to the new hydroxo-aluminium derivative [{MeAl} {(mu-OH)(mu3-O)}2{(mu-O)2(TiCp*)3-(mu3-CH)}2](3).     

Synthesis and characterization of novel oxo-centered phosphanylzincates of potassium and cesium with a central Zn6O2P4 double-heterocubane cage

The hydrolysis reaction of K(2)(MeZn)(2)(PSitBu(3))(2) in THF/toluene solution yields the [(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)](4-) anions independent of the applied stoichiometry. If the applied molar ratio resembles the composition of the anion, [(thf)K](2)[(eta(6)-toluene)K](2)[(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)] (1) crystallizes from a mixture of THF and toluene. In the case with less water, a phosphanediylzincate moiety is bonded to this anion, and [Zn(PSitBu(3))(2)K(4)(thf)(6)](2)[(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)] (2) crystallizes. However, again the major product is 1. The same anion is also observed with larger and softer cations, and [(thf)(3)Cs(2)](2)[(MeZn)(4)Zn(2)(mu(3)-PSitBu(3))(4)(mu(4)-O)(2)] (3) is obtained if the cesium zincate is used in this reaction. In all of these compounds, the anion is a slightly distorted Zn(6)O(2)P(4) double-heterocubane cage with a central Zn(2)O(2) ring having Zn-O bond lengths of approximately 207 pm.     

Polynuclear lanthanide hydroxo complexes: new chemical precursors for coordination polymers

The synthesis of hexanuclear lanthanide hydroxo complexes by controlled hydrolysis led to polymorphic compounds. The hexanuclear entities crystallize in four different ways that depend on the extent of their hydration. The four structures can be described as hexanuclear lanthanide entities with formula [Ln(6)(mu(6)-O)(mu(3)-OH)(8)(NO(3))(6)(H(2)O)(12)](2+). Two additional NO(3)(-) ions intercalate between the hexanuclear entities in order to ensure the electroneutrality of the crystal structure. Some crystallization water molecules fill the intermolecular space. The three first families of compounds (1-3) exhibit crystal structures that have previously been reported. The fourth family of compounds (4) is described here for the first time. Its chemical formula is [Ln(6)(mu(6)-O)(mu(3)-OH)(8)(NO(3))(6)(H(2)O)(12)](NO(3))(2).2H(2)O (Ln = Gd, Er, and Y). In this paper, the chemical and thermal stabilities of the hexanuclear lanthanide compounds are reported together with the magnetic properties of the Gd(III)-containing species. To use these entities as precursors for new materials, the substitution of the nitrato groups by chloride ions has been studied. Two byproduct compounds have so been obtained: The first (compound 5) is a nitrato/chloride hexanuclear compound of chemical formula [Er(6)(mu(6)-O)(mu(3)-OH)(8)(NO(3))(6)(H(2)O)(12)](NO(3))Cl.2H(2)O. The second one (compound 6) is a polymeric compound in which the hexanuclear entities are linked by an unexpected and original N(2)O(4) bridge. Its chemical formula is [Er(6)(mu(6)-O)(mu(3)-OH)(8)(NO(3))(4)(H(2)O)(11)(OH)(ONONO(2))]Cl(3).2H(2)O. Its crystal structure can be described as the juxtaposition of chainlike molecular motifs. To the best of our knowledge, this is the first example of a coordination polymer synthesized from an isolated polylanthanide hydroxo complex.     

Large spin differences in structurally related Fe6 molecular clusters and their magnetostructural explanation

The syntheses, crystal structures, and magnetic characterizations of three new hexanuclear iron(III) compounds are reported. Known [Fe(6)O(2)(OH)(2)(O(2)CBu(t))(10)(hep)(2)] (1) is converted to new [Fe(6)O(2)(OH)(O(2)CBu(t))(9)(hep)(4)] (3) when treated with an excess of 2-(2-hydroxyethyl)-pyridine (hepH). Similarly, the new compound [Fe(6)O(2)(OH)(2)(O(2)CPh)(10)(hep)(2)] (2), obtained from the reaction of [Fe(3)O(O(2)CPh)(6)(H(2)O)(3)] with hepH, is converted to [Fe(6)O(2)(OH)(O(2)CPh)(9)(hep)(4)] (4) when treated with an excess of hepH. This can be reversed by recrystallization from MeCN. The cores of the four Fe(6) complexes all comprise two triangular [Fe(3)(mu(3)-O)(O(2)CR)(3)(hep)](+3) units connected at two of their apices by two sets of bridging ligands. However, 1 and 2 differ slightly from 3 and 4 in the precise way the two Fe(3) units are linked together. In 1 and 2, the two sets of bridging ligands are identical, consisting of one mu-hydroxo and two mu-carboxylate groups bridging each Fe(2) pair, i.e., a (mu-OH(-))(mu-O(2)CR(-))(2) set. In contrast, 3 and 4 have two different sets of bridging ligands, a (mu-OH(-))(mu-O(2)CR(-))(2) set as in 1 and 2, and a (mu-OR(-))(2)(mu-O(2)CR(-)) set, where RO(-) refers to the alkoxide arm of the hep(-) chelate. Variable-field and -temperature dc magnetization measurements establish that 1 and 2 have S = 5 ground states and significant and positive zero-field splitting parameters (D), whereas 3 and 4 have S = 0 ground states. This dramatic difference of 10 unpaired electrons in the ground state S values for near-isomeric compounds demonstrates an acute sensitivity of the magnetic properties to small structural changes. The factors leading to this have been quantitatively analyzed. The semiempirical method ZILSH, based on unrestricted molecular orbital calculations, was used to obtain initial estimates of the Fe(2) pairwise exchange interaction constants (J). These calculated values were then improved by fitting the experimental susceptibility versus T data, using a genetic algorithm approach. The final J values were then employed to rationalize the observed magnetic properties as a function of the core topologies and the presence of spin frustration effects. The large difference in ground state spin value was identified as resulting from a single structural difference between the two types of complexes, the different relative dispositions (cis vs trans) of two frustrated exchange pathways. In addition, use of the structural information and corresponding J values allowed a magnetostructural correlation to be established between the J values and both the Fe-O bond distances and the Fe-O-Fe angles at the bridging ligands.