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A series of new compounds has been synthesised from an electron-rich olefin derived from cyclam (A). Thus, A reacts with oxygen gas to give the syn-bis(urea) 1 and with sulfur to yield the anti-bis(thiourea) 2. The reaction of A with triflic acid furnishes the bis(imidazolium) triflate 3, which gives the monoprotonated imidazolium salt 4 upon treatment with sodium tetraphenylborate in water. Theoretical calculations (DFT) predict the diprotonated species to be energetically disfavoured, thus demonstrating the importance of hydrogen-bonding interactions. Treatment of compound 3 with silver oxide affords the di- and monoprotonated cationic salts 5a and 5b in THF and dichloromethane, respectively. The molecular structures of compounds 1, 2, 3, 4, 5a and 5b have been established by X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A series of new titanium pyridine−alkoxide complexes, [TiCp*Cl{2,6-(OCH2)2py-κ3-O,N,O}] (2), [TiCp*{2,6-(OCH2)py(CH2OH)-κ1-O}{2,6-(OCH2)2py-κ3-O,N,O}] (3), [TiCp*Me2{2-(OCH2)py-κ1-O}] (4), [TiCp*Me{2-(OCH2)py-κ1-O}2] (5), and [TiCp*(O){2-(OCH2)py-κ2-O,N})] (6), have been synthesized. All of these compounds were characterized by NMR spectroscopy. The single-crystal structures of [TiCp*Me{2,6-(OCH2)2py-κ3-O,N,O}] (1), 2, 3, and 4 were determined and revealed the presence of piano and nonpiano stool geometries. The molecular structures of 1, 2, and 3 were also studied by means of density functional theory (DFT) in an attempt to rationalize the possible reasons for the stabilization of one or other geometry., This work was supported by the Ministerio de Ciencia e Innovación (MCINN), Spain (Grant Nos. CTQ2005-08123-C02-01/BQU, CTQ2006-11845/BQU, and Consolider-Ingenio 2010 ORFEO CSD2007-00006) and the Junta de Comunidades de Castilla-La Mancha, Spain (Grant No. PCI08-0010).

A series of new tantalum-tbcp [tbcp = 2,2′-thiobis(4,6-dichlorophenolato)] and tantalum-tbop [tbop = 2,2′-thiobis(6-tert-octylphenolato)] complexes [TaCp*Cl2(κ3-tbop)] (1), [TaCp*Cl2(κ3-tbcp)] (2), [TaCp*Me2(κ3-tbop)] (3), [TaCp*Me2(κ3-tbcp)] (4), [TaCp*Me(κ3-tbop)(OTf)] (OTf = triflate) (5), [TaCp*Me(κ3-tbcp)(OTf)] (6), [TaCp*(κ3-tbop)(OTf)2] (7), and [TaCp*(κ3-tbcp)(OTf)2] (8) have been synthesized. Insertion processes into the methyl groups of complex 3 were not observed upon reaction with CO or isocyanides. In contrast, complex 4 reacted slowly with 1 equiv of xylyl isocyanide (xylyl = 2,6-dimethylphenyl) or tert-butyl isocyanide to yield complexes [TaCp*(κ2-Me2CNxylyl)(κ3-tbcp)] (9) and [TaCp*Me(κ2- MeCNtBu)(κ3-tbcp)] (10), respectively. All products were characterized by NMR spectroscopy and elemental analysis. The single-crystal structures of 2, 3, 6, and 9 were also determined.

The new tantalum siloxide complex [TaCp*Me3(OSiPh3)] (1; Cp* = η5-C5Me5) has been synthesized. The reaction of complex 1 with isocyanides yields the respective azatantalacyclopropanes [TaCp*(η2-Me2CNxylyl)Me(OSiPh3)] (2; xylyl = 2,6-dimethylphenyl) and [TaCp*(η2-Me2CNtBu)Me(OSiPh3)] (3). The molecular structure of complex 2 has been established by X-ray diffraction. Complex 2 reacts with a second mol-equiv. of 2,6-xylyl isocyanide to yield [TaCp*(Nxylyl)[N(xylyl)CMe=CMe2)(OSiPh3)] (4). The reaction of 1 with carbon monoxide gives [TaCp*(O)(OCMe=CMe2)(OSiPh3)] (5), whereas 1 reacts with B(C6F5)3 to give the corresponding cationic compound [TaCp*Me2(OSiPh3)][MeB(C6F5)3] (6). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A mesoporous silica functionalized with octyl groups had been used as the support for lipase (from Candida antarctica ) immobilization. The hydrophobicity provided by the hydrocarbon chains together with the excellent morphologic characteristics of the solid leads to high enzyme loadings in monolayer fashion. However, in this kind of systems the aqueous enzyme solution cannot easily access all the inner surface of the pores because of the highly hydrophobic nature of these surfaces. Thus, the presence of low ethanol concentration decreases the hydrophobicity of the channels and the access of enzyme seems to be significantly improved. The monolayer capacity (400–500 mg protein/g of octyl silica) increases twice compared to the corresponding immobilization in the absence of ethanol (200 mg protein/g of octyl silica). The activity of the derivatives prepared in the presence of ethanol was also significantly improved: 33,000 tributyrin units/g of catalyst at the monolayer limit, which is four- to five-fold higher than the activities of the corresponding derivatives prepared in the absence of ethanol.

The heterometallic complex [TiCp*(O(2)Bz)(2)AlMe(2)] (2) has been synthesised by reaction of [TiCp*(O(2)Bz)(OBzOH)] (1) with AlMe(3) (Cp*=eta(5)-C(5)Me(5); Bz=benzyl). Complex 1 reacts with HOTf to yield the cationic derivative [TiCp*(OBzOH)(2)]OTf (3) (HOTf=HSO(3)CF(3)). Compound 3 reacts with [{M(mu-OH)(cod)}(2)] (M=Rh, Ir; cod=cyclooctadiene) to render the early-late heterometallic complexes [TiCp*(O(2)Bz)(2){M(cod)}(2)]OTf (M=Rh (4); Ir (5)). The molecular structure of complex 4 has been established by single-crystal X-ray diffraction studies.

The titanium salycilate complex [Cp*Ti(sal)(salH)] 1 (salH 2 = salycilic acid) was synthesised by reacting Cp*TiMe 3 and salycilic acid. The molecular structure of 1 studied by X-ray shows it to be dinuclear with a carboxylate group acting as a bridge ligand. [Rh(μ-OH)COD] 2 reacts with 1 to yield the bimetallic complex 2 , or with the siloxanodiol (HOSiPh) 2 O to yield the bimetalic bis-siloxide Rh complex 3 . Carbon monoxide displaces COD in 2 and 3 to give the carbonylic complexes 4 and 5 respectively. Complex 4 can also be prepared from 2 and [Rh(acac)(CO) 2 ]. Compounds 2 , 3 , 4 and 5 can be envisaged as models of Rh complexes anchored on titania or silica. The catalytic performance of heterometallic complexes is studied in the CO hydrogenation reaction and compared to rhodium-based (Rh-based) catalysts prepared by impregnation from Rh(NO 3 ) 3 or [Rh(acac)(CO) 2 ] showing higher yields to oxygenated products.

The new tantalum dialkoxide complexes Cp*TaCl 2 (OCH 2 ) 2 py (1), trans-Cp*TaMe 2 (OCH 2 ) 2 -py (2), and cis-Cp*TaMe 2 (OCH 2 ) 2 py (3) (Cp* = η 5 -C 5 Me 5 ; (OCH 2 ) 2 py = 2,6-pyridinedimethoxide) have been synthesized. The molecular structures of complexes 1 and 2 have been studied by X-ray diffraction methods. The reaction of complex 3 with carbon monoxide renders Cp*Ta-(η 2 -Me 2 CO)(OCH 2 ) 2 py (4), while with isocyanides yields the respective azatantalacyclopropanes Cp*Ta(η 2 -Me 2 CNxylyl)(OCH 2 ) 2 py (6) (xylyl = 2,6-dimethylphenyl) and Cp*Ta(η 2 -Me 2 CN t Bu)(OCH 2 ) 2 py (7). The molecular structure of complex 4 has been established by X-ray diffraction. The coordinated ketone in 4 can be reduced to 2-propanol in the presence of water. On the other hand, compound 3 reacts with triflic acid (HOTf) to render the corresponding cationic derivative [Cp*TaMe(OCH 2 ) 2 py]OTf (8).

The early–late heterometallic complexes [TiCp∗((OCH2)2Py)(μ-O)M(COD)] (M = Rh, Ir) behave as four-electron donor ligands yielding the polynuclear cationic complexes [TiCp∗(OCH2)2 Py(μ-O){M(COD)}2]OTf (M = Rh (1), Ir (2)). The molecular structure of complex 1 has been established through an X-ray diffraction study.

A support for enzyme immobilization was prepared by functionalization of mesoporous silica with octyltriethoxysilane. The features of the surface enables the adsorption of lipase from Candida antarctica B via strong hydrophobic interactions, enhancing the stability of the adsorbed enzyme molecules. Derivatives with a high enzyme loading (200 mg protein/g of silica) can be obtained due to the high porosity and surface properties of the support while the immobilization occurs in a monolayer fashion. The lack of inactive enzyme aggregates, together with the high enzyme loading, are responsible for the high catalytic activity achieved by these species. Derivatives were prepared with different lipase loading, and the activities were tested and compared to the commercial derivative Novozym 435. The stability of the catalyst and hence its industrial applicability were tested by performing subsequent reaction cycles of acylation of ethanolamine with lauric acid in acetonitrile. Conversion was quantitative even after 15 reaction cycles.

Rhodium supported on titania-silica is modeled by 1, which was obtained from [{Cp*TiMe(μ-O2 SiPh2 )}2 ] (2) and [{Rh(OH)(cod)}2 ]. Complex 2 and its triply bridged derivative [Cp*Ti(μ-O2 SiPh2 )3 TiCp*] (3) can be envisaged as molecular models of titania-silica systems. Compounds 1-3 could potentially provide insights into the nature of the catalytically active sites in these systems; cod=1,5-cycloctadiene, Cp*=η5 -C5 Me5 .

Cp*TaCl4 reacts with X(CH2CH2SH)2 in the presence of NEt3 to yield the corresponding thiolate complexes Cp*TaCl2(SCH2CH2)2X (X = O (1), S (2)). The crystal structure of complex 2 has been determine...

Halo-alkoxide zirconocene complexes (η5-C5Me5)2ZrCl(OCH2CH2SPh) (1) and (η5-C5Me5)2ZrCl(OC6H4SH) (2) have been prepared by reaction of the corresponding zirconocene dichloride with HOCH2CH2SPh or HOC6H4SH, respectively, in the presence of NEt3. The molecular structure of 1 has been determined by X-ray diffraction studies. Alkyl- and aryl-containing species (η5-C5Me5)2ZrMe(OCH2CH2SPh) (3) and (η5-C5Me5)2ZrPh(OCH2CH2SPh) (4) were synthesised by reaction of the corresponding dialkyl or diaryl species with HOCH2CH2SPh, or by reaction of complex 1 with LiMe or LiPh, respectively. Finally, the dialkoxide complexes L2M(OCH2CH2SR)2 [L=η5-C5H5, M=Ti, R=Ph (5); L=η5-C5Me5, M=Ti, R=Ph (6); L=η5-C5Me5, M=Ti, R=Me (7)] were prepared by reaction of the appropriate dichloride and alcohol in the presence of NEt3, and (η5-C5H5)2Zr(OCH2CH2SMe)2 (8) was synthesised by reacting (η5-C5H5)2ZrMe2 with two equivalents of HOCH2CH2SMe.

The methyltitanium derivative TiCp*Me3 (Cp* = η5-C5Me5) reacted with tris(2-pyridyl)methyl alcohol, HOCPy3, to yield the alkoxide complex TiCp*Me2(OCPy3) 1. The reaction of TiCp*Me3 with di-2-pyridyl ketone, Py2CO, yielded, through an insertion process, the corresponding alkoxide derivative TiCp*Me2(OCMePy2) 2. In order to establish the co-ordination mode of the alkoxide ligand, X-ray diffraction studies were carried out on complex 2. Insertion of di-2-pyridyl ketone into a Ta–Me bond of TaCp*Me4 gave the corresponding alkoxide compound TaCp*Me3(OCMePy2) (3). Metathesis reaction of titanium and zirconium complexes MCp*Cl3 with the lithium alkoxide LiOCRPy2 led to the corresponding derivatives MCp*Cl2(OCRPy2) [M = Ti, R = Me (4) or Py (5); M = Zr, R = Me (6) or Py (7)]. In an analogous way, tantalum derivatives TaCp*Cl3(OCRPy2) [R = Me (8) or Py (9)] can also be synthesized by reaction of TaCp*Cl4 with the appropriate lithium alkoxide LiOCRPy2. The crystal structure of complex 9 has been determined by X-ray diffraction.

The reaction of Cp*TiMe3 with 3 equiv of [Ir(μ-OH)(COD)]2 affords the new heterometallic organometallic oxide Cp*Ti(μ3-O)3[Ir(COD)]3 (3). Reaction of Cp*TaMe4 with 4 equiv of [M(μ-OH)(COD)]2 (M = Rh, Ir) yields complexes Cp*Ta(μ3-O)4[M(COD)]4 [M = Rh (5), Ir (6)]. The structure of compound 5 has been determined by X-ray diffraction. Complexes 5 and 6 react with the alcohol 3-CN-4,6-Me2-2-OH−C5HN to yield the corresponding rhodium (7) or iridium (8) alkoxide complexes. The structure of complex 8 has been determined by X-ray diffraction. Reaction of [Rh(μ-OH)(COD)]2 with thiolacetic acid gives rise to a thioacetate complex [Rh(μ-SCOCH3)(COD)]2 (9).

The reaction of Cp2ZrCl2 (Cp = η5-C5H5) with 2 equiv of the lithium amide derivative LiNHC6H4-o-SMe affords the new zirconium complex Cp2Zr(NHC6H4-o-SMe)2 (2). The structure of 2 has been determined by X-ray diffraction. When the reaction is carried out in an 1:1 ratio, the complex Cp2ZrCl(NHC6H4-o-SMe) (3) is generated as the major product. Reaction of “Cp*2Zr” (Cp* = η5-C5Me5) with 2-(methylmercapto)aniline yields a hydride−amide complex Cp*2ZrH(NHC6H4) (4). Reaction of complex 2 with [RhCl(COD)]2 generates complex 3 and the new rhodium amide complex Rh(NHC6H4-o-SMe)(COD), which has been also directly synthesized by reacting [RhCl(COD)]2 with LiNHC6H4-o-SMe. Thermolysis of complex 6, at 100 °C, produces to a new rhodium thiolate complex [Rh(μ-SC6H4-o-NHMe)(COD)]2 (5). Its structure has been determined by X-ray diffraction methods. Reaction of [IrCl(COD)]2 with LiNHC6H4-o-SMe gives the iridium(III) complex Ir(Me)(SC6H4NH)(COD) (7) by oxidative addition of the S−Me bond.

The perfluorothiolate dinuclear compounds [Rh( μ -SC 6 F 5 )(COD)[ 2 1 and [Rh( μ -SC 6 F 5 )(CO) 2 [ 2 2 react with PPh 3 to give monomeric and dimeric complexes, the particular product depending upon the PR 3 /Rh ratio and reaction conditions. Reaction of 2 with 2 moles of PPh 3 renders cis - 7 and trans -[Rh( μ -SC 6 F 5 )((CO)(PPh 3 )[ 2 8 , while with 4 moles of PPh 3 trans [Rh(SC 6 F 5 )(CO)(PPh 3 ) 2 [ 10a is obtained. This latter product can otherwise be prepared by Cl metathesis from trans -[RhCl(CO(PPh 3 ) 2 [ in toluene. This same reaction in dichloromethane however yields the cis isomer 10b . When a larger excess of PPh 3 is used, a mixture of compounds 11a and 11b is formed. An X-ray crystal structure study shows trans [Rh(SC 6 F 5 )(CO)(PPh 3 ) 2 [ to exit as two polymorphs. 11a crystallises in the space group P2 1 /n of the monoclinic system with a = 12.489(1), b = 15.430(5), c = 19.719(1) A, α = γ = 90, β = 92.84(1)°, and 11b is triclinic, space group P1¯ with a = 9.764(2), b = 12.197(6), c = 17.880 A, α = 100.18(5), β = 101.92(2), γ = 113.61(2)°. Both PPh 3 ligands are mutually trans and the difference in v (CO) stretching frequencies 1989 and 1939 cm −1 , can be explained in terms of o-phenyl H…CO interactions in the latter. The [Rh( μ -SC 6 F 5 )(COD)[ 2 1 and [Rh( μ -SC 6 F 5 )(CO) 2 [ 2 2 /nPPh 3 systems have been studied as catalyst precursors for the hydroformylation of 1-heptene in toluene at 30 bar and 343 K. Selectivity towards the linear aldehyde is enhanced when dimeric complexes are used.

The thiolate−alkylzirconocene complex Cp2ZrMe(SR) (2) (Cp = η5-C5H5; SR = 4,6-dimethylpyrimidine-2-thiolate) can be prepared by reacting the corresponding dialkylmetallocene complex Cp2ZrMe2 (1) with 1 equiv of 4,6-dimethyl-2-mercaptopyrimidine. X-ray structure analysis of complex 2 revealed that the thiolate group is bonded in an η2 fashion through the sulfur and one of the nitrogen atoms. Complex 2 reacts with 2,6-dimethylphenyl isocyanide (CNXylyl) to yield the corresponding iminoacyl derivative, Cp2Zr(η2-MeCNXylyl)(SR) (4). The molecular structure of 4 shows that the thiolate group is η1-bonded while the iminoacyl group behaves as a bidentate ligand. Reaction of compound 2 with different acidic reagents gives formation of methane and different zirconium complexes. Reaction with HSR renders Cp2Zr(SR)2 (3) and with (NHEt3)(BPh4) the cationic complex [Cp2Zr(SR)][BPh4] (5). An hydride thiolate complex, Cp*2ZrH(SR) (Cp* = η5-C5Me5) (6) can also be prepared by reaction of “Cp*2Zr” with HSR by an oxidative a...

The reactions of [Cp*TiMe{(OCH2)2py}] (1) and [Cp*TiMe{(OOC)2py}] (2) with triflic acid (HOTf) in the presence of a series of Lewis bases, such as water, pyridine, and tert-butylpyridine, give rise to the corresponding cationic species, namely [Cp*TiL{(OCH2)2py}]+OTf- (3−5) and [Cp*TiL{(OOC)2py}]+OTf- (6, 7). Similar processes with 1 and HOTf in the presence of 2,6-pyridinedimethanol and 2-pyridinemethanol lead to the binuclear complexes [{Cp*Ti((OCH2)2py)}2{μ-(HOCH2)2py}]OTf2 (8) and [Cp*Ti{(OCH2)2py}{(HOCH2)py}]OTf (9), respectively. In an unusual process, the reaction of 3 with NaBPh4 or 1 with B(C6F5)3 yields hydroxo-containing binuclear species, namely [{Cp*Ti((OCH2)2py)}2(μ-OH)][BPh4] (10) and [Cp*Ti(μ-OH){(OCH2)2py}][BMe(C6F5)3] (12), respectively. The X-ray molecular structures of 10 and 12 have been established. Finally, the titanium−aluminum heterometallic complex [Cp*Ti{(OCH2)2py}(μ-O-AlMeOTf)] (16) has been prepared by reaction of 3 with AlMe3., We gratefully acknowledge financial support from the Ministerio de Educación y Ciencia of Spain (Grant Nos. MAT2003-05345 and CTQ 2005-07918-CO2-01/BQU) and Junta de Comunidades de Castilla-La Mancha (Grant Nos. PBI05-023 and GC-02-010).

Titanium complexes with chelating alkoxide ligands [TiCp*(O(2)Bz)(OBzOH)] (1) and [TiCp*(Me)((OCH(2))(2)Py)] (2) were synthesised by reaction of [TiCp*Me(3)] (Cp*=eta(5)-C(5)Me(5)) with 2-hydroxybenzyl alcohol ((HO)(2)Bz) and 2,6-pyridinedimethanol ((HOCH(2))(2)Py), respectively. Complex 1 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) to yield the early-late heterobimetallic complexes [TiCp*(O(2)Bz)(2)M(cod)] [M=Rh (3), Ir (4)]. Carbon monoxide readily replaces the COD ligand in 3 to give the rhodium dicarbonyl derivative [TiCp*(O(2)Bz)(2)Rh(CO)(2)] (5). Compound 2 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) with protonolysis of a Tibond;Me bond to give [TiCp*((OCH(2))(2)Py)(mu-O)M(cod)] [M=Rh (6), Ir (7)]. The molecular structures of complexes 3, 5 and 7 were established by single-crystal X-ray diffraction studies.

The diamagnetic complex [Ru(SR)2(PPh3)2] and the paramagnetic compounds [Ru(SR)3(PR′3)2] (R = C6F5, C6F4H, C6FH4, or C6H5; PR′3 = PPh3, PMe2Ph or PEt2Ph) have been prepared by treatment of [RuCl2(PPh3)3] or [RuCl3(PR′3)3]. respectively, with [Pb(SR)2] in acetone or tetrahydrofuran. An X-ray diFfraction study on [Ru(SC6F5)2PC6H4(H-2)(C6H5)22] has revealed a pseudo-octahedral structure, apparently with two CHRu interactions. The complexes [Ru(SR)3(PR′3)2] have μeff in the range 1.8–1.9 BM and EPR spectra are reported. An X-ray study of [RuSC6F4(F-2)(SC6F5)2(PMe2Ph)2] has shown that it has essentially octahedral geometry, involving a CFRu interaction.

The catalytic performance for the hydroformylation reaction of hept-1-ene at 343 K and 30 atm total pressure has been studied over some rhodium-(I) complexes anchored to 2% DVB crosslinked phosphinated polystyrene. The catalysts were prepared from the common [RhCl(COD)] 2 precursor and characterized by FTIR and photoelectron (XPS) spectroscopy techniques. The activity profiles and the number of cycles operative in the reactor were found to depend markedly on the Rh:P ratio. A joint discussion involving the data obtained from the homogeneous process is also presented.

Treatment of [{Ir(COD)(μ-Cl)}2] with excess of the electron-rich olefin [ CN(Ar)(CH 2 ) 2 N Ar]2 (abbreviated as (LAr)2, Ar = C6H4Me-p or C6H4OMe-p) affords the ortho-metallated tricycle [ Ir(L A r )3], which for Ar = C6H4Me-p (Ia) with HCL yields [ Ir(L A r )2(LAr)]Cl (IV); X-ray data show that in IV there is an unexpectedly close Ir⋯C(o-aryl) contact (2;52(1) A) involving the “free” LAr which compares with an IrC(o-aryl) distance of 2.09(3) A in Ia or 2.07(3) A in the ortho-metallated LAr ligand of complex IV.

The complex [Ru(SC 6 F 5 ) 2 (PPh 3 ) 2 ] has been prepared from [RuCl 2 (PPh 3 ) 3 ] and [Pb(SC 6 F 5 ) 2 ] and shown by X-rays to have a pseudo-octahedral structure apparently with two RuHC interactions. It reacts with CO to give [Ru(SC 6 F 5 ) 2 -(CO) 2 (PPh 3 ) 2 ].