Titanium(IV) terminal hydroxo complexes containing chelating bis(phosphine oxide) ligands

Yi, Xiao‐Yi; Williams, Ian D.; Leung, Wa‐Hung

doi:10.1016/j.jorganchem.2005.12.007

Cited by 8 publications

(4 citation statements)

References 22 publications

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“…27 The phenolate groups are in the trans configuration as in 2 defining a dihedral angle of 154.3(2)°between the planes containing the phenolate rings. There are few examples of crystallographically characterized titanium complexes with terminal hydroxido groups restricted mostly to those supported by cyclopentadienyl ligands, 36 an example with a chelating bis( phosphine oxide) ligand 37 and an example with a tripodal amine tris ( phenolate) ligand. 38 The Ti1-O4 bond length of the hydroxido ligand [1.819(3) Å] compares well with the value reported for the tripodal amine tris( phenolate) complex.…”

Section: Hydrolysis Studiesmentioning

confidence: 99%

Synthesis, cytotoxic and hydrolytic studies of titanium complexes anchored by a tripodal diamine bis(phenolate) ligand

Barroso¹,

Gómez‐Ruiz²,

Žižak³

et al. 2014

Dalton Trans.

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The reactivity, cytotoxic studies and hydrolytic behaviour of diamine bis(phenolate) titanium complexes are reported. The reactions of [Ti((tBu2)O2NN')Cl]2(μ-O) (1) with LiO(I)Pr or HO(I)Pr in the presence of NEt3, aiming at the synthesis of the alkoxido derivative of 1 led to no reaction or to the synthesis of the monomeric complex [Ti((tBu2)O2NN')(O(i)Pr)2] (3), respectively. A small amount of the alkoxidotitanium dimer [Ti((tBu2)O2NN')(O(i)Pr)]2(μ-O) (2) crystallized out of a solution of 3 and DFT calculations showed that the transformation of 1 into 3 is a thermodynamically favorable process in the presence of a base (NEt3) (ΔG = -14.7 kcal mol(-1)). 2 was quantitatively obtained through the direct reaction of the ligand precursor H2((tBu2)O2NN') with titanium tetra(isopropoxido). Further reaction of 2 with an excess of TMSCl was revealed to be the most suitable method for the preparation of [Ti((tBu2)O2NN')Cl2] (4). 1 and 3 disclosed cytotoxic activity towards HeLa, Fem-x, MDA-MB-361 and K562 cells and 1 exhibited moderate binding affinity to FS-DNA. (1)H NMR hydrolysis studies attested the fast decomposition of 4 in the presence of D2O. The hydrolysis of 3 is slower and proceeds through the formation of [Ti((tBu2)O2NN')(OH)]2(μ-O) (5) that was crystallographically characterized. Upon D2O addition 1 immediately forms complex new species, stable in solution for long periods (weeks).

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Section: Hydrolysis Studiesmentioning

confidence: 99%

Synthesis, cytotoxic and hydrolytic studies of titanium complexes anchored by a tripodal diamine bis(phenolate) ligand

Barroso¹,

Gómez‐Ruiz²,

Žižak³

et al. 2014

Dalton Trans.

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“…However, reaction of a concentrated solution of 3 with MeOTf in C 6 H 6 gave a precipitate of pure 7-OTf (albeit in low yield) which could be successfully characterized. Although the 19 F NMR spectrum of 7-OTf does not unambiguously eliminate OTf − anion coordination (free and coordinated OTf − have verysimilar 19 F shifts , ), its infrared spectrum is consistent with a free OTf − anion as indicated by strong, broad bands between 1260 and 1295 cm −1 . Attempts to observe 7 + by electrospray mass spectrometry were unsuccessful.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Structures and Reactivity of Group 4 Hydrazido Complexes Supported by Calix[4]arene Ligands

et al. 2008

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Reaction of TiCl(2)(Me(2)Calix) with 2 equiv of LiNHNRR' afforded the corresponding terminal hydrazido(2-) complexes Ti(NNRR')(Me(2)Calix) (R = Ph, R' = Ph (1) or Me; R = R' = Me (3)) which were all structurally characterized. The X-ray structure of Ph(2)NNH(2) is reported for comparison. Compound 1 was also prepared from Na(2)[Me(2)Calix] and Ti(NNPh(2))Cl(2)(py)(3). Reaction of ZrCl(2)(Me(2)Calix) with 2 equiv of LiNHNR(2) afforded only the bis(hydrazido(1-)) complexes Zr(NHNR(2))(2)(Me(2)Calix) (R = Ph or Me). Treatment of Ti(NNMe(2))(Me(2)Calix) (3) with MeI gave the zwitterionic hydrazidium species Ti(NNMe(3))(MeCalix) (6) via a net isomerization reaction which was found to be catalytic in MeI. The corresponding reaction of 3 with CD(3)I gave Ti(NNMe(2)CD(3))(MeCalix) (6-d(3)) with concomitant elimination of MeI. Reaction of 3 with 1 equiv of MeOTf gave [Ti(NNMe(3))(Me(2)Calix)][OTf] (7-OTf) which in turn reacted with (n)Bu(4)NI to form 6 and MeI. Addition of PhCHO to 3 gave the mu-oxo dimer [Ti(mu-O)(Me(2)Calix)](2) and benzaldehyde-dimethylhydrazone. Reaction of either 3 or 6 with (t)BuNCO gave the zwitterionic species Ti{(t)BuNC(NNMe(3))O}(MeCalix) (10) which has been crystallographically characterized. Compound 10 is the formal product of insertion of an isocyanate into the Ti=N(alpha) bond of a titanium hydrazide or hydrazidium species (Me(2)Calix or MeCalix = dianion or trianion of the di- or monomethyl ether of p-tert-butyl calix[4]arene, respectively).

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“…This type of reactivity, namely protonolysis of the M−C bond, has been well documented, and in several cases the appropriate cationic species with the triflate counterion has been isolated. It is well-known, however, that under certain conditions the classic ‘noncoordinating” anion SO 3 CF 3 - (OTf - ) coordinates to the metal center, making possible the isolation of neutral species …”

Section: Resultsmentioning

confidence: 99%

Cationic Titanium Complexes Containing Alkoxide and Carboxylate Pincer Ligands; Noninnocent Role of the Anionic Moieties in Their Reactivity

et al. 2007

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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.

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Titanium(IV) terminal hydroxo complexes containing chelating bis(phosphine oxide) ligands

Cited by 8 publications

References 22 publications

Synthesis, cytotoxic and hydrolytic studies of titanium complexes anchored by a tripodal diamine bis(phenolate) ligand

Synthesis, cytotoxic and hydrolytic studies of titanium complexes anchored by a tripodal diamine bis(phenolate) ligand

Synthesis, Structures and Reactivity of Group 4 Hydrazido Complexes Supported by Calix[4]arene Ligands

Cationic Titanium Complexes Containing Alkoxide and Carboxylate Pincer Ligands; Noninnocent Role of the Anionic Moieties in Their Reactivity

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