Structural Characterization of (Arylimido)vanadium(V) Compounds with 2,6‐Difluorophenoxide Ligand

The (arylimido)vanadium(V) compound, [(p‐MeOC₆H₄N)V(OiPr)₃] was demonstrated to undergo ligand exchange reaction with one or two equivalents of 2,6‐difluorophenol, affording the (arylimido)vanadium(V) compounds, [(p‐MeOC₆H₄N)V(OiPr)₂(O‐2,6‐F₂Ph)] and [(p‐MeOC₆H₄N)V(OiPr)(O‐2,6‐F₂Ph)₂]. Their X‐ray crystallographic analyses elucidated the μ‐isopropoxido‐bridged dimeric structures, wherein each vanadium atom has a trigonal‐bipyramidal arrangement with the imido and bridging isopropoxide ligands in the apical positions. The isopropoxide ligand was selectively employed as a bridging ligand between two central vanadium atoms. On the other hand, the reaction of the (arylimido)vanadium(V) compound, [(p‐MeOC₆H₄N)VCl₃] and three equivalents of lithium 2,6‐difluorophenoxide gave the (arylimido)vanadium(V) compound, [(p‐MeOC₆H₄N)V(O‐2,6‐F₂Ph)₃]. In the crystal packing, the thus‐obtained compound showed a distorted trigonal‐bipyramidal environment at the vanadium atoms with the μ‐phenoxido‐bridged dimeric structure, wherein the 2,6‐difluorophenoxide ligand was found to serve as a bridging ligand.     

Aerobic oxidation reactions catalyzed by vanadium complexes of bis(phenolate) ligands

Vanadium(V) complexes of the tridentate bis(phenolate)pyridine ligand H(2)BPP (H(2)BPP = 2,6-(HOC(6)H(2)-2,4-(t)Bu(2))(2)NC(5)H(3)) and the bis(phenolate)amine ligand H(2)BPA (H(2)BPA = N,N-bis(2-hydroxy-4,5-dimethylbenzyl)propylamine) have been synthesized and characterized. The ability of the complexes to mediate the oxidative C-C bond cleavage of pinacol was tested. Reaction of the complex (BPP)V(V)(O)(O(i)Pr) (4) with pinacol afforded the monomeric vanadium(IV) product (BPP)V(IV)(O)(HO(i)Pr) (6) and acetone. Vanadium(IV) complex 6 was oxidized rapidly by air at room temperature in the presence of NEt(3), yielding the vanadium(V) cis-dioxo complex [(BPP)V(V)(O)(2)]HNEt(3). Complex (BPA)V(V)(O)(O(i)Pr) (5) reacted with pinacol at room temperature, to afford acetone and the vanadium(IV) dimer [(BPA)V(IV)(O)(HO(i)Pr)](2). Complexes 4 and 5 were evaluated as catalysts for the aerobic oxidation of 4-methoxybenzyl alcohol and arylglycerol β-aryl ether lignin model compounds. Although both 4 and 5 catalyzed the aerobic oxidation of 4-methoxybenzyl alcohol, complex 4 was found to be a more active and robust catalyst for oxidation of the lignin model compounds. The catalytic activities and selectivities of the bis(phenolate) complexes are compared to previously reported catalysts.     

一个二核钒配合物的合成及晶体结构：NH4[(VⅣO)2(μ2-O)(nta)2][EuⅢ(H2O)9](英)

A binuclear vanadium complex NH₄[(V^ⅣO)₂(μ₂-O)(nta)₂][Eu^Ⅲ(H₂O)₉] was synthesized by reaction of NH₃VO₃, nitrilotriacetic acid and EuCl₃ in one aqueous solution. The crystal X-ray analysis shows that the complex contains one binuclear vanadium anion [(V^ⅣO)₂(μ₂-O)(nta)2]^4- and one [Eu^Ⅲ(H₂O)₉]³⁺ cation. The molecules are built up to a three-dimensional supramolecular structure through hydrogen bonding. CCDC: 238716.     

Activation of carbodiimide and transformation with amine to guanidinate group by Ln(OAr)3(THF)2 (Ln: lanthanide and yttrium) and Ln(OAr)3(THF)2 as a novel precatalyst for addition of amines to carbodiimides: influence of aryloxide group

Reaction of Ln(OAr(1))(3)(THF)(2) (Ar(1)= [2,6-((t)Bu)(2)-4-MeC(6)H(2)] with carbodiimides (RNCNR) in toluene afforded the RNCNR coordinated complexes (Ar(1)O)(3)Ln(NCNR) (R = (i)Pr (isopropyl), Ln = Y (1) and Yb (2); R = Cy (cyclohexyl), Ln = Y (3)) in high yields. Treatment of 1 and 2 with 4-chloroaniline, respectively, at a molar ratio of 1:1 yielded the corresponding monoguanidinate complex (Ar(1)O)(2)Y[(4-Cl-C(6)H(4)N)C(NH(i)Pr)N(i)Pr](THF) (4) and (Ar(1)O)(2)Yb[(4-Cl-C(6)H(4)N)C(NH(i)Pr)N(i)Pr](THF) (5). Complexes 4 and 5 can be prepared by the reaction of Ln(OAr(1))(3)(THF)(2) with RNCNR and amine in toluene at a 1:1:1 molar ratio in high yield directly. A remarkable influence of the aryloxide ligand on this transformation was observed. The similar transformation using the less bulky yttrium complexes Y(OAr(2))(3)(THF)(2) (Ar(2) = [2,6-((i)Pr)(2)C(6)H(3)]) or Y(OAr(3))(3)(THF)(2) (Ar(3) = [2,6-Me(2)C(6)H(3)]) did not occur. Complexes Ln(OAr(1))(3)(THF)(2) were found to be the novel precatalysts for addition of RNCNR with amines, which represents the first example of catalytic guanylation by the lanthanide complexes with the Ln-O active group. The catalytic activity of Y(OAr(1))(3)(THF)(2) was found to be the same as that of monoguanidinate complex 4, indicating 4 is one of the active intermediates in the present process. The other intermediate, amide complex (Ar(1)O)(2)Ln[(2-OCH(3)-C(6)H(4)NH)(2-OCH(3)-C(6)H(4)NH(2))] (6), was isolated by protonolysis of 4 with 2-OCH(3)-C(6)H(4)NH(2). All the complexes were structurally characterized by X-ray single crystal determination.     

Synthesis, crystal structures, and properties of oxovanadium(IV)-lanthanide(III) heteronuclear complexes

A new series of oxovanadium(IV)-lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)](3)21 H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)} 8.5 H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)](0.5)}8.5 H2O (3), {[Eu(H2O)7][(VO)2(TTHA)](1.5)} 10.5 H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H(6)TTHA as structure-directing agent. X-ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2- unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2- ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2- ion. Compound 4 is an extended one-dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2- ions. For 5, the structure is further assembled into a three-dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV)-lanthanide(III) coordination polymers and thus enlarge the realm of 3d-4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions.     

A novel cationic heteropolyoxovanadium(IV) cluster functionalized with organic ligands: synthesis and characterization of the fully reduced species [Mn(II)V(IV)6O6[(OCH2CH2)2N(CH2CH2OH)]6]Cl2

The solvothermal reaction of (HOCH2CH2)3N with [(n-C4H9)4N]3[H3V10O28] and MnCl2 x 4H2O in CH3CN and CH3OH yields a novel cationic heteropolyoxovanadium(IV) cluster, [Mn(II)V(IV)6O6[(OCH2CH2)2N(CH2CH2OH)]6]2+, containing a fully reduced new cyclic [MnV6N6O18] core with the Anderson structure.     

Vanadium complexes of the N(CH2CH2S)3(3-) and O(CH2CH2S)2(2-) ligands with coligands relevant to nitrogen fixation processes

Vanadium(III) and vanadium(V) complexes derived from the tris(2-thiolatoethyl)amine ligand [(NS3)3-] and the bis(2-thiolatoethyl)ether ligand [(OS2)2-] have been synthesized with the aim of investigating the potential of these vanadium sites to bind dinitrogen and activate its reduction. Evidence is presented for the transient existence of (V(NS3)(N2)V(NS3), and a series of mononuclear complexes containing hydrazine, hydrazide, imide, ammine, organic cyanide, and isocyanide ligands has been prepared and the chemistry of these complexes investigated. [V(NS3)O] (1) reacts with an excess of N2H4 to give, probably via the intermediates (V(NS3)(NNH2) (2a) and (V(NS3)(N2)V(NS3) (3), the V(III) adduct [V(NS3)(N2H4)] (4). If 1 is treated with 0.5 mol of N2H4, 0.5 mol of N2 is evolved and green, insoluble [(V(NS3))n] (5) results. Compound 4 is converted by disproportionation to [V(NS3)(NH3)] (6), but 4 does not act as a catalyst for disproportionation of N2H4 nor does it act as a catalyst for its reduction by Zn/HOC6H3Pri2-2,6. Compound 1 reacts with NR1(2)NR2(2) (R1 = H or SiMe3; R2(2) = Me2, MePh, or HPh) to give the hydrazide complexes [V(NS3)(NNR2(2)] (R2(2) = Me2, 2b; R2(2) = MePh, 2c; R2(2) = HPh, 2d), which are not protonated by anhydrous HBr nor are they reduced by Zn/HOC6H3Pri2-2,6. Compound 2b can also be prepared by reaction of [V(NNMe2)(dipp)3] (dipp = OC6H3Pri2-2,6) with NS3H3. N2H4 is displaced quantitatively from 4 by anions to give the salts [NR3(4)][V(NS3)X] (X = Cl, R3 = Et, 7a; X = Cl, R3 = Ph, 7b; X = Br, R3 = Et, 7c; X = N3, R3 = Bu(n), 7d; X = N3, R3 = Et, 7e; X = CN, R3 = Et, 7f). Compound 6 loses NH3 thermally to give 5, which can also be prepared from [VCl3(THF)3] and NS3H3/LiBun. Displacement of NH3 from 6 by ligands L gives the adducts [V(NS3)(L)] (L = MeCN, nu CN 2264 cm-1, 8a; L = ButNC, nu NC 2173 cm-1, 8b; L = C6H11NC, nu NC 2173 cm-1, 8c). Reaction of 4 with N3SiMe3 gives [V(NS3)(NSiMe3)] (9), which is converted to [V(NS3)(NH)] (10) by hydrolysis and to [V(NS3)(NCPh3)] (11) by reaction with ClCPh3. Compound 10 is converted into 1 by [NMe4]OH and to [V(NS3)NLi(THF)2] (12) by LiNPri in THF. A further range of imido complexes [V(NS3)(NR4)] (R4 = C6H4Y-4 where Y = H (13a), OMe (13b), Me (13c), Cl (13d), Br (13e), NO2 (13f); R4 = C6H4Y-3, where Y = OMe (13g); Cl (13h); R4 = C6H3Y2-3,4, where Y = Me (13i); Cl (13j); R4 = C6H11 (13k)) has been prepared by reaction of 1 with R4NCO. The precursor complex [V(OS2)O(dipp)] (14) [OS2(2-) = O(CH2CH2S)2(2-)] has been prepared from [VO(OPri)3], Hdipp, and OS2H2. It reacts with NH2NMe2 to give [V(OS2)(NNMe2)(dipp)] (15) and with N3SiMe3 to give [V(OS2)(NSiMe3)(dipp)] (16). A second oxide precursor, formulated as [V(OS2)1.5O] (17), has also been obtained, and it reacts with SiMe3NHNMe2 to give [V(OS2)(NNMe2)(OSiMe3)] (18). The X-ray crystal structures of the complexes 2b, 2c, 4, 6, 7a, 8a, 9, 10, 13d, 14, 15, 16, and 18 have been determined, and the 51V NMR and other spectroscopic parameters of the complexes are discussed in terms of electronic effects.     

Synthesis and Crystal structure of [（Praseodymium）2（3,5—Binitro benzoyloxy）6（Dimethyl Sulfoxide）4]Complex

1 INTRODUCTION The polynuclear lanthanide complexes are specially interested and widely applied in the researches on light, electricity and magnetism[1～4], and the studies of the synthesis of polynuclear lanthanide complexes and its applications tend to be growing rapidly nowadays. Herein a report on the synthesis process and crystal structure of the title complex is presented. The crystal structure showed it is a non-electrolyte complex with one- dimensional chain. OCCOOPrOOCPr…     

Preparation, structure, and properties of tetranuclear vanadium(III) and (IV) complexes bridged by diphenyl phosphate or phosphate

Three novel tetranuclear vanadium(III) or (IV) complexes bridged by diphenyl phosphate or phosphate were prepared and their structures characterized by X-ray crystallography. The novel complexes are [{V(III)(2)(μ-hpnbpda)}(2){μ-(C(6)H(5)O)(2)PO(2)}(2)(μ-O)(2)]·6CH(3)OH (1), [{V(III)(2)(μ-tphpn)(μ-η(3)-HPO(4))}(2)(μ-η(4)-PO(4))](ClO(4))(3)·4.5H(2)O (2), and [{(V(IV)O)(2)(μ-tphpn)}(2)(μ-η(4)-PO(4))](ClO(4))(3)·H(2)O (3), where hpnbpda and tphpn are alkoxo-bridging dinucleating ligands. H(3)hpnbpda represents 2-hydroxypropane-1,3-diamino-N,N'-bis(2-pyridylmethyl)-N,N'-diacetic acid, and Htphpn represents N,N,N',N'-tetrakis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine. A dinuclear vanadium(IV) complex without a phosphate bridge, [(VO)(2)(μ-tphpn)(H(2)O)(2)](ClO(4))(3)·2H(2)O (4), was also prepared and structurally characterized for comparison. The vanadium(III) center in 1 adopts a hexacoordinate structure while that in 2 adopts a heptacoordinate structure. In 1, the two dinuclear vanadium(III) units bridged by the alkoxo group of hpnbpda are further linked by two diphenylphosphato and two oxo groups, resulting in a dimer-of-dimers. In 2, the two vanadium(III) units bridged by tphpn are further bridged by three phosphate ions with two different coordination modes. Complex 2 is oxidized in aerobic solution to yield complex 3, in which two of the three phosphate groups in 2 are substituted by oxo groups.     

The elusive vanadate (V(3)O(9))(3-): isolation, crystal structure, and nonaqueous solution behavior.

The isolation, crystal structure, and nonaqueous solution characteristics of the first trinuclear vanadate are presented. The crystal structure reveals a six-membered cyclic arrangement of alternating vanadium and oxygen atoms for the anion of [(C(4)H(9))(4)N](3)(V(3)O(9)). The (51)V NMR spectrum of this compound in CD(3)CN exhibits multiple peaks. The relative intensities of each resonance can be altered by concentration and temperature changes, the later of which are reversible. Addition of [(C(4)H(9))(4)N]Br and NaClO(4) also perturbs the equilibria between species observed. Conductivity data for [(C(4)H(9))(4)N](3)(V(3)O(9)) in CH(3)CN as a function of concentration display pronounced curvature and indicate formation of a neutral species in solution at the highest concentrations studied. Stoichiometric mixtures of [(C(4)H(9))(4)N](3)(V(3)O(9)) with the known vanadates [(C(4)H(9))(4)N](3)(HV(4)O(12)), [(C(4)H(9))(4)N](3)(V(5)O(14)), and [(C(4)H(9))(4)N](3)(H(3)V(10)O(28)) are prepared and examined by (51)V NMR. Equilibration between the various vanadates is observed and characterized. Resonances for these known vanadates, however, cannot be used to identify the peaks found for [(C(4)H(9))(4)N](3)(V(3)O(9)), alone, in solution. The existence of ion pairs in acetonitrile is the only interpretation for the solution behavior of [(C(4)H(9))(4)N](3)(V(3)O(9)) consistent with all data. As such, we can directly observe each possible ion pairing state by (51)V NMR: (V(3)O(9))(3-) at -555 ppm, [[(C(4)H(9))(4)N](V(3)O(9))] (2-) at -569 ppm, [[(C(4)H(9))(4)N](2)(V(3)O(9))](-) at -576 ppm, and [(C(4)H(9))(4)N](3)(V(3)O(9)) at -628 ppm. To the best of our knowledge, [(C(4)H(9))(4)N](3)(V(3)O(9)) presents the first case in which every possible ion paired state can be observed directly from a parent polyion. Isolation and characterization of this simple metal oxo moiety may now facilitate efforts to design functional polyoxometalates.     

Influence of hydrogen bonding on the assembly of six-membered vanadium borophosphate cluster anions: synthesis and structures of (NH4)2(C2H10N2)6[Sr(H2O)5]2[V2P2BO12](6)10H2O, (NH4)2(C3H12N2)6[Sr(H2O)4]2[V2P2BO12](6)17H2O, and (NH4)3(C4H14N2)4 5[Sr(H2O)5]2[Sr(H2O)4][V2P2BO12]6 10H2O

Three new strontium vanadium borophosphate compounds, (NH4)2(C2H10N2)6[Sr(H2O)5]2[V2P2BO12]6 10H2O (Sr-VBPO1) (1), (NH4)2(C3H12N2)6[Sr(H2O)4]2[V2P2BO12]6 17H2O (Sr-VBPO2) (2), and (NH4)3(C4H14N2)4.5[Sr(H2O)5]2[Sr(H2O)4][V2P2BO12]6 10H2O (Sr-VBPO3) (3) have been synthesized by interdiffusion methods in the presence of diprotonated ethylenediamine, 1,3-diaminopropane, and 1,4-diaminobutane. Compound 1 has a chain structure, whereas 2 and 3 have layered structures with different arrangements of [(NH4) [symbol: see text] [V2P2BO12]6] cluster anions within the layers. Crystal data: (NH4)2(C2H10N2)6[Sr(H2O)5]2[V2P2BO12]6 10H2O, monoclinic, space group C2/c (no. 15), a = 21.552(1) A, b = 27.694(2) A, c = 20.552(1) A, beta = 113.650(1) degrees, Z = 4; (NH4)2(C3H12N2)6[Sr(H2O)4]2[V2P2BO12]6 17H2O, monoclinic, space group I2/m (no. 12), a = 15.7618(9) A, b = 16.4821(9) A, c = 21.112(1) A, beta = 107.473(1) degrees, Z = 2; (NH4)3(C4H14N2)4.5[Sr(H2O)5]2[Sr(H2O)4] [V2P2BO12]6 10H2O, monoclinic, space group C2/c (no. 15), a = 39.364(2) A, b = 14.0924(7) A, c = 25.342(1) A, beta = 121.259(1) degrees, Z = 4. The differences in the three structures arise from the different steric requirements of the amines that lead to different amine-cluster hydrogen bonds.     

两个基于[Fe(bpca)(CN)3]-的一维3d-4f异金属配合物的合成和晶体结构

以[(bpca)Fe(CN)3]-(bpca=二(2-吡啶羰基)酰胺阴离子)为构筑基元,设计合成了2个新颖的3d-4f异金属配合物,{[(bpca)Fe(CN)3Pr(H2O)5]Cl2}n(1)和{[(bpca)2Fe2(CN)6Pr(H2O)6]Cl·4H2O}n(2),并测定了它们的晶体结构.化合物1的晶体属正交晶系,Pnma空间群;而化合物2属三斜晶系,P1空间群.在这2个化合物中,[(bpca)Fe(CN)3]-和[Pr(H2O)x]3 (1,x=5;2,x=6)交替排列形成一维链状结构,并通过π-π堆积作用、氢键作用及分子间短距离相互作用形成三维网络结构.     

Lithiation of tris(alkyl- and arylamido)orthophosphates EP[N(H)R]3 (E = O,S, Se): imido substituent effects and P=E bond cleavage

In the solid state, OP[N(H)Me](3) (1a) and OP[N(H)(t)Bu](3) (1b) have hydrogen-bonded structures that exhibit three-dimensional and one-dimensional arrays, respectively. The lithiation of 1b with 1 equiv of (n)BuLi generates the trimeric monolithiated complex (THF)[LiOP(N(t)Bu)[N(H)(t)Bu](2)](3) (4), whereas reaction with an excess of (n)BuLi produces the dimeric dilithium complex [(THF)(2)Li(2)OP(N(t)Bu)(2)[N(H)(t)Bu]](2) (5). Complex 4 contains a Li(2)O(2) ring in an open-ladder structure, whereas 5 embraces a central Li(2)O(2) ring in a closed-ladder arrangement. Investigations of the lithiation of tris(alkyl or arylamido)thiophosphates, SP[N(H)R](3) (2a, R = (i)Pr; 2b, R = (t)Bu; 2c, R = p-tol) with (n)BuLi reveal interesting imido substituent effects. For the alkyl derivatives, only mono- or dilithiation is observed. In the case of R = (t)Bu, lithiation is accompanied by P-S bond cleavage to give the dilithiated cyclodiphosph(V/V)azane [(THF)(2)Li(2)[((t)BuN)(2)P(micro-N(t)Bu)(2)P(N(t)Bu)(2)]] (9). Trilithiation occurs for the triaryl derivatives EP[N(H)Ar](3) (E = S, Ar = p-tolyl; E = Se, Ar = Ph), as demonstrated by the preparation of [(THF)(4)Li(3)[SP(Np-tol)(3)]](2) (10) and [(THF)(4)Li(3)[SeP(NPh)(3)]](2) (11), which are accompanied by the formation of small amounts of 10.[LiOH(THF)](2) and 11.Li(2)Se(2)(THF)(2), respectively.     

Hydrothermal syntheses and structural characterizations of organic-inorganic hybrid materials of the M(II)-ligand/vanadium oxide system (M(II) = Cu(II) and Zn(II); ligand = 2,2'-bipyridine and 2,2':6',2"-terpyridine)

Investigation into the incorporation of complex transition metal-organic units into vanadium oxide structures has resulted in the preparation of several novel composite materials. Hydrothermal reactions of V(2)O(5), 2,2'-bipyridine, an appropriate Zn or Cu starting material, and H(2)O under a variety of conditions yielded the organic-inorganic hybrid materials [[Zn(2,2'-bpy)](2)V(4)O(12)] (1) and [Cu(2,2'-bpy)V(4)O(10.5)] (2). Blocking an additional coordination site on the secondary metal center by using a tridentate organonitrogen ligand, 2,2':6',2' '-terpyridine in place of 2,2'-bipyridine, allowed the isolation of [Cu(terpy)V(2)O(6)] (3) and [[Zn(terpy)](2)V(6)O(17)] (4). The structure of 1 is a two-dimensional zinc vanadate layer, composed of rings containing four corner-sharing [VO(4)] vanadium(V) tetrahedra linked through six zinc square pyramids, with the 2,2'-bipyridine groups attached to the zinc centers and directed above and below the plane of the layer. In contrast to 1, the layer of 2 is based on a two-dimensional vanadium oxide substructure composed of vanadium(IV) square pyramids and vanadium(V) tetrahedra with copper square pyramids attached through corner-sharing interactions with vanadium tetrahedra such that the bipyridine ligands attached to the copper sites form staggered stacks above and below the plane of the layer. Compound 3 consists of one-dimensional vanadium oxide chains of corner-sharing tetrahedra linked through copper-terpyridine units into a two-dimensional bimetallic oxide of composition [CuV(2)O(6)], while the layer structure of 4 contains more complex one-dimensional vanadium oxide chains composed of fused rings of six corner-sharing vanadium oxide tetrahedra which are linked into a layer through [Zn(terpy)](2+) units.     

Structural influences of organonitrogen ligands on vanadium oxide solids. Hydrothermal syntheses and structures of the terpyridine vanadates [V2O4(terpy)2]3[V10O28], [VO2(terpy)][V4O10], and [V9O22(terpy)3

Hydrothermal reactions of the V2O5/2,2':6':2"-terpyridine/ZnO/H2O system under a variety of conditions yielded the organic-inorganic hybrid materials [V2O4(terpy)2]3[V10O28].2H2O (VOXI-10), [VO2(terpy)][V4O10] (VOXI-11), and [V9O22(terpy)3] (VOXI-12). The structure of VOXI-10 consists of discrete binuclear cations [V2O4(terpy)2]2+ and one-dimensional chains [V10O28]6-, constructed of cyclic [V4O12]4- clusters linked through (VO4) tetrahedra. In contrast, the structure of VOXI-11 exhibits discrete mononuclear cations [VO2(terpy)]1+ and a two-dimensional vanadium oxide network, [V4O10]1-. The structure of the oxide layer is constructed from ribbons of edge-sharing square pyramids; adjacent ribbons are connected through corner-sharing interactions into the two-dimensional architecture. VOXI-12 is also a network structure; however, in this case the terpy ligand is incorporated into the two-dimensional oxide network whose unique structure is constructed from cyclic [V6O18]6- clusters and linear (V3O5(terpy)3) moieties of corner-sharing vanadium octahedra. The rings form chains through corner-sharing linkages; adjacent chains are connected through the trinuclear units. Crystal data: VOXI-10, C90H70N18O42V16, triclinic P1, a = 12.2071(7) A, b = 13.8855(8) A, 16.9832(10) A, alpha = 69.584(1) degrees, beta = 71.204(1) degrees, gamma = 84.640(1) degrees, Z = 1; VOXI-11, C15H11N3O12V5, monoclinic, P2(1)/n, a = 7.7771(1) A, b = 10.3595(2) A, c = 25.715(4) A, beta = 92.286(1) degrees, Z = 4; VOXI-12, C45H33N9O22V9, monoclinic C2/c, a = 23.774(2) A, b = 9.4309(6) A, c = 25.380(2) A, beta = 112.047(1) degrees, Z = 4.     

Polynuclear vanadium complexes from thermal decomposition of [V3O(O2CPh)6(H2O)3]Cl

Solid-state decomposition of [V3O(O2CPh)6(H2O)3]Cl at 300 degrees C followed by alcoholysis of the product gives the new vanadium complexes [V6O6(PhCO2)6(CH3O)6(CH3OH)3] (1), [V6O6(PhCO2)6(C2H5O)6(C2H5OH)3] (2), [V6O6(PhCO2)6(C3H7O)6(C3H7OH)3] (3), [V6O6(PhCO2)6(C4H9O)6(C4H9OH)3] (4) and [V4O4(OCH3)6(O2CPh)2(HOCH3)2] (5). Complexes 2, 3 and 5 have been crystallographically characterised. DC magnetic susceptibility studies on complex shows antiferromagnetic coupling leading to a S = 0 spin ground state.     

Synthesis and characterization of vanadium(IV) complexes with cis-inositol in aqueous solution and in the solid-state

The complex formation of vanadium(IV) with cis-inositol (ino) and the corresponding trimethyl ether 1,3,5-trideoxy-1,3,5-trimethoxy-cis-inositol (tmci) was studied in aqueous solution and in the solid-state. With increasing pH, the formation of [VO(H-2L)], [(VO)2L2H-5]-, [VO(H-3L)]- (L = ino) or [(VO)2L2H-6]2- (L = tmci), [V(H-3L)2]2-, and [VO(H-3L)(OH)2]3- was observed. For the vanadium(IV)/ino system, [(VO)2L2H-7]3- was observed as an additional dinuclear species. The formation constants of these complexes were determined by potentiometric titrations (25 degrees C, 0.1 M KCl). In addition, the vanadium(IV)/ino system was investigated by means of UV-vis spectrophotometric methods. EPR spectroscopy and cyclic voltammetry confirmed this complexation scheme. EPR measurements indicated the formation of three distinct isomers of the non-oxo complex [V(H-3ino)2]2- in weakly basic solution. This type of isomerism, which is not observed for the vanadium(IV)/tmci system, was assigned to the ability of ino to bind the vanadium(IV) center with three alkoxo groups having either a 1,3,5-triaxial or an 1,2,3-axial-equatorial-axial arrangement. The structures of [V(H-3ino)2][K2(ino)2].4H2O (1) and [Na6V(H-3ino)2](SO4)2.6H2O (2) were determined by single-crystal X-ray analysis. In both compounds, the coordination of each ino molecule to the vanadium(IV) center via three axial deprotonated oxygen donors was confirmed. The centrosymmetric structure of the coordination spheres corresponds to an almost regular octahedral geometry with a twist angle of 60 degrees. The crystal structure of the potassium complex 1 represents an unusual 1:1 packing of [V(H-3ino)2]2- dianions and [K2(ino)2]2+ dications, in which both K+ ions have a coordination number of nine and are bonded simultaneously to a 1,3,5-triaxial and an 1,2,3-axial-equatorial-axial site of ino. In 2, the [V(H-3ino)2]2- complexes are surrounded by six Na+ counterions that are bonded to the axial alkoxo oxygens and to the equatorial hydroxy oxygens of the cis-inositolato moieties. The six Na+ centers are further interlinked by bridging sulfate ions. According to EPR spectroscopy, the D3d symmetric structure of the [V(H-3ino)2]2- anion is retained in H2O, in dimethylformamide, and in a mixture of CHCl3/toluene 60:40 v/v.     

Reaction of p-toluenesulfonylamide and M(NMe2)4 (M = Ti, V): generation of electron-deficient imido complexes of early transition metals

p-Toluenesulfonamide (p-TsNH2) was successfully employed as an imido ligand precursor in the synthesis of highly air- and moisture-sensitive titanium(IV) and vanadium(IV) complexes. Reaction of M(NMe2)4 (M = Ti, V) with TsNH2 in toluene afforded [M(micro-NTs)(NMe2)2]2 dimer complexes (M = Ti (1), V (2)). By contrast, the reaction carried out in dichloromethane led to [Ti[micro-N,O-NTs]Cl(NMe2)(NHMe2)2]2 (3) and [Ti[micro-N,O-NTs]Cl2(NHMe2)2]n (4) through solvent activation. The same reaction of M(NMe2)4/TsNH2 conducted in the presence of an excess of trimethylchlorosilane produced [V(=NTs)Cl2(NHMe2)2] (5) and [(Me2HN)Cl2Ti(micro2-N-NTs-kappa2N,O)2TiCl2(NHMe2)2] (6). Alternatively, compound 6 has also been prepared from TiCl2(NMe2)2 and TsNH2. 1 was reacted with trimethylchlorosilane to afford the amide complex [Ti[micro-N,O'-N(SiMe3)Ts-kappa3N,O,O']Cl2(NMe2)]2 (7) in which the tosylimide bond has been silylated. Compounds 1-6 represents the first examples of sulfonylimido complexes for titanium and vanadium.     

A novel series of vanadium-sulfite polyoxometalates: synthesis, structural, and physical studies

Reaction of NH4VO3 with sulfur dioxide affords the hexanuclear cluster (NH4)2(Et4N)[(V(IV)O)6(mu4-O)2(mu3-OH)2(mu3-SO3)4(H2O)2]Cl x H2O (1), and the decapentanuclear host-guest compound (Et4N)5{Cl subset [(VO)15(mu3-O)18(mu-O)3]} x 3 H2O (2). Sequential addition of magnesium oxide to an acidic aqueous solution of NH4VO3 (pH approximately 0) followed by (NH4)2SO3 resulted in the formation of either the non-oxo polymeric vanadium(IV) compound trans-(NH4)2[V(IV)(OH)2(mu-SO3)2] (3) or the polymeric oxovanadium(IV) sulfite (NH4)[V(IV)O(SO3)1.5(H2O)] x 2.5 H2O (4) at pH values of 6 and 4, respectively. The decameric vanadium(V) compound {Na4(mu-H2O)8(H2O)6}[Mg(H2O)6][V(V)10(O)8(mu6-O)2(mu3-O)14] x 3 H2O (5) was synthesised by treating an acidic aqueous solution of NH4VO3 with MgO and addition of NaOH to pH approximately 6. All the compounds were characterised by single-crystal X-ray structure analysis. The crystal structure of compound 1 revealed an unprecedented structural motif of a cubane unit [M4(mu4-O)2(mu3-OH)2] connected to two other metal atoms. Compound 3 comprises a rare example of a non-oxo vanadium(IV) species isolated from aqueous solution and in the presence of the reducing agent SO3(2-), while compound 4 represents a rare example of an open-framework species isolated at room temperature (20 degrees C). In addition to the synthesis and crystallographic studies, we report the IR and magnetic properties (for 1, 2 and 3) of these vanadium clusters as well as theoretical studies on compound 3.     

Synthesis of vanadium(III) complexes bearing iminopyrrolyl ligands and their role as thermal robust ethylene (co)polymerization catalysts

Bis(imino)pyrrolyl vanadium(III) complexes 2a-e [2,5-C(4)H(2)N(CH=NR)(2)]VCl(2)(THF)(2) [R = C(6)H(5) (2a), 2,6-Me(2)C(6)H(3) (2b), 2,6-(i)Pr(2)C(6)H(3) (2c), 2,4,6-Me(3)C(6)H(2) (2d), C(6)F(5) (2e)] and bis(iminopyrrolyl) vanadium(III) complex 4f [C(4)H(3)N(CH=N-2,6-(i)PrC(6)H(3))](2)VCl(THF) have been prepared in good yields from VCl(3)(THF)(3) by treating with 1.0 and 2.0 equivalent deprotonated ligands in tetrahydrofuran (THF), respectively. These complexes were characterized by FTIR and mass spectra as well as elemental analysis. Structures of 2c and 4f were further confirmed by X-ray crystallographic analysis. DFT calculations indicated the configurations of 2a-e with two nitrogen atoms of the chelating ligand coordinating with vanadium metal centre were more stable in energy. These complexes were employed as catalysts for ethylene polymerization at various reaction conditions. On activation with Et(2)AlCl, these complexes exhibited high catalytic activities (up to 22.2 kg mmol(-1)(V) h(-1) bar(-1)) even at high temperature, suggesting these catalysts possessed remarkable thermal stability. Moreover, high molecular weight polymer with unimodal molecular weight distributions can be obtained, indicating the polymerization took place in a single-site nature. The copolymerizations of ethylene and 1-hexene with precatalysts 2a-e and 4f were also explored in the presence of Et(2)AlCl. Catalytic activity, comonomer incorporation, and properties of the resultant polymers can be controlled over a wide range by tuning catalyst structures and reaction parameters.