Transition metal complexes bearing a 2,2-bis(3,5-dimethylpyrazol-1-yl)propionate ligand: one methyl more matters

Türkoglu, Gazi; Heinemann, Frank W.; Burzlaff, Nicolai

doi:10.1039/c1dt00022e

Cited by 19 publications

(11 citation statements)

References 42 publications

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“…Alternatively, rigid ligand systems such as the anionic Tp (hydridotris(pyrazol-1-yl)borate), Cp (cyclopentadienyl) , and bdmpza (bis(3,5-dimethylpyrazol-1-yl)acetato) or neutral PNP (N( n Pr)-(CH 2 CH 2 PPh 2 ) 2 ) and dppe (1,2-bis(diphenylphosphino)ethane) ,, are more commonly employed for the formation of allenylidene complexes. In particular, the precursor [Ru(bdmpza)Cl(PPh 3 ) 2 ] has shown interesting organometallic chemistry, often similar to the chemistry reported for analogous Cp and Tp complexes. The main difference is the formation of structural isomers, which occur due to the reduced symmetry of the N , N , O -coordination motif in comparison to the ligands that show rotational symmetry.…”

Section: Introductionmentioning

confidence: 67%

Carbon-Rich Ruthenium Allenylidene Complexes Bearing Heteroscorpionate Ligands

et al. 2014

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A series of ruthenium allenylidene complexes bearing polyaromatic substituents have been prepared starting from [Ru(bdmpza)Cl(PPh 3 ) 2 ] (1) (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetato). Reacting 1 with 1,1-bis(3,5-ditert-butylphenyl)-1-methoxy-2-propyne results in the formation of two structural isomers of an allenylidene complex [Ru(bdmpza)Cl(CCC(Ph t Bu 2 ) 2 )(PPh 3 )] (5A/5B), as well as the related carbonyl complex [Ru(bdmpza)Cl(CO)-(PPh 3 )] (4A/4B). Conversion of 9-ethynyl-9-fluorenol leads to the corresponding allenylidene complex [Ru(bdmpza)Cl(CC(FN))(PPh 3 )] (7A/7B) (FN = fluorenyl). Based on anthraquinone, a new synthetic route toward 10-ethynyl-10-hydroxyanthracen-9-one via the trimethylsilyl-protected propargyl alcohol is described, and subsequent conversion of this compound to the allenylidene complex ([Ru(bdmpza)Cl(C C(AO))(PPh 3 )] (12A/12B) (AO = anthrone) is reported. The synthetic route from 7H-benzo[no]tetraphen-7-one to the propargyl alcohol 7-ethynyl-7H-benzo[no]tetraphen-7-ol is described, which is followed by the transformation into the allenylidene complex [Ru(bdmpza)Cl(CC(BT))(PPh 3 )] (17A/17B) (BT = benzotetraphene). The molecular structures of 4B, 7A, 7B, 12A, 12B, 13A, and 17A have been characterized by single-crystal X-ray crystallography, and these analyses suggest that 17A might function as a "metal-tuned organic field effect transistor". The electrochemical properties of the allenylidene complexes have been studied via cyclic voltammetry, and time-dependent DFT calculations have been conducted to assign weak absorptions in the NIR region to forbidden MLCT transitions. ■ INTRODUCTIONOrganometallic complexes containing allenylidene moieties are of considerable interest due to their characteristic chemical and physical properties. 1 The synthesis of cumulene based complexes has benefited immensely from the methodology published by Selegue. 2 The reaction of substituted propargyl alcohols with a variety of ruthenium based metal complexes allows for the direct formation of ionic and neutral complexes, and this has dramatically simplified the synthetic demand for such work. π-Conjugated systems based on ruthenium are important in systems that allow exchange of electrons via the cumulenylidene unit between remote terminal groups, 3 thus leading to interesting properties and potential applications in molecular-scale electronic, magnetic, and optical devices. 4 Special attention has been put on dinuclear compounds that can communicate along the allenylidene unit. The linking between the two metal centers can be achieved either via functionalization of the allenylidene with nitrogen based donor substituents, as in the bis(pyridyl)allenylidene−ruthenium(II) complex trans-[Cl(16-TMC)RuCCC(2-py) 2 ] + 5,9,5,9, py = pyridyl), 5 or via all carbon linked systems such as trans-[Cl(dppe) 2 Ru−CC−C(CH 3 )C(H)−C(CH 3 )CC Ru(dppe) 2 Cl]BF 4 , which results from the coupling of the diynyl and allenylidene moieties. 6 Nevertheless, classical mononuclear ruthenium allenylide...

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Section: Introductionmentioning

confidence: 67%

Carbon-Rich Ruthenium Allenylidene Complexes Bearing Heteroscorpionate Ligands

et al. 2014

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“…Very recently we reported on ruthenium complexes derived from 2,2-bis(3,5-dimethylpyrazol-1-yl)propionic acid (2,2-Hbdmpzp) (2) with increased steric hindrance by the bdmpzp ligand and therefore improved reactivity. 16 Thus, we also focused on the synthesis of the mononuclear dicarbonyl complex [Ru(2,2-bdmpzp)Cl(CO) 2 ] (4). Following the procedure described above, the synthesis of 4 was achieved by deprotonation of 2,2-Hbdmpzp with KO t Bu and a subsequent reaction with [RuCl 2 (CO) 2 ] n (Scheme 1).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Actually, the catalytic activity of complex 4 bearing the methyl-substituted N,N,O ligand 2 was expected to be higher than that of complex 3. In a recent report we were able to show that changing steric properties caused by the methyl group introduced in ligand 2 can facilitate the dissociation of coligands, 16 resulting in coordinatively unsaturated species that might serve as key intermediates in catalytic cycles.…”

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confidence: 98%

Ruthenium Carbonyl Complexes Bearing Bis(pyrazol-1-yl)carboxylato Ligands

et al. 2012

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The syntheses of the two dicarbonyl complexes [Ru(bdmpza)Cl(CO)2] (3) and [Ru(2,2-bdmpzp)Cl(CO)2] (4), bearing a bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) or a 2,2-bis(3,5-dimethylpyrazol-1-yl)propionato (2,2-bdmpzp) scorpionate ligand, are described. Both complexes are obtained by reacting the polymer [RuCl2(CO)2] n with either K[bdmpza] or K[2,2-bdmpzp]. Reaction of the acid Hbdmpza with [Ru3(CO)12] results in the formation of two structural isomers of a hydrido complex, [Ru(bdmpza)H(CO)2] (5a,b). Under aerobic conditions conversion of [Ru(bdmpza)H(CO)2] (5a,b) to form the Ru(I) dimer [Ru(bdmpza)(CO)(μ-CO)]2 (6) seems to be hindered in comparison to the case for the η5-C5H5 (Cp) analogues. Dimer 6 is obtained via a reaction of Hbdmpza with catena-[Ru(OAc)(CO)2] n instead. The molecular structures of 3, 4, and 6 have been obtained by single-crystal X-ray structure determinations. The precatalytic properties of the two dicarbonyl complexes 3 and 4 toward the catalytic oxidation of cyclohexene with different oxidizing agents are discussed as well.

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“…These intriguing heteroscorpionate ligands can contain different functional groups, such as carboxylate, dithiocarboxylate, alkoxide, thiolate, aryloxide, sulfonate, cyclopentadienyl, acetamidate, thioacetamidate, amidate, amide and organometallic groups, 10 a situation that has broadened the scope of application of these novel ligands. Complexes that contain these ligands are of considerable interest owing to their important uses as biological enzyme models 11 and as catalysts for different catalytic processes. 12 Acetamidate or thioacetamidate heteroscorpionate ligands are highly versatile in terms of coordination modes due to the existence of three possible tautomers.…”

Section: Introductionmentioning

confidence: 99%

Heteroscorpionate aluminium complexes as chiral building blocks to engineer helical architectures

et al. 2013

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Treatment of heteroscorpionate ligand precursors pbptamH, pbpamH, sbpamH and (S)-mbpamH with 2 equivalents of AlR3 (R = Et, Me) yielded the corresponding binuclear organoaluminium complexes [Al2R4(μ-pbptam)] (R = Me 1, Et 2), [Al2R4(μ-pbpam)] (R = Me 3, Et 4), [Al2R4(μ-sbpam)] (R = Me 5, Et 6) and [Al2R4{μ-(S)-mbpam}] (R = Me 7, Et 8). These complexes have helical chirality due to the demands of the fixed pyrazole rings. The stereoisomerism and the self-assembly processes of these helicates have been studied in some detail in solution by NMR and in the solid state by X-ray diffraction. Mixtures of M- and P-handed enantiomers and mixtures of M- and P-handed diastereoisomers were obtained when achiral (1–4) and chiral (5–8) heteroscorpionate ligands were used as scaffolds, respectively. Re-crystallization from hexane allowed us to obtain M-homochiral architectures in the solid state for the helical complexes [Al2Et4(μ-sbpam)] (6) and [Al2Et4{μ-(S)-mbpam}] (8). The reaction of heteroscorpionate ligands with 3 equivalents of AlR3 (R = Me, Et) led to the corresponding trinuclear organoaluminium complexes [Al3R7(μ3-pbptam)] (R = Me 9, Et 10), [Al3R7(μ3-pbpam)] (R = Me 11, Et 12), [Al3R7(μ3-sbpam)] (R = Me 13, Et 14) and [Al3R7{μ3-(S)-mbpam}] (R = Me 15, Et 16). The extra AlR3 molecule contributes to the formation of a diastereomeric excess of the PS helicate for complexes 15 and 16. X-ray determination of some of the helical complexes allowed us to witness a versatile and efficient self-assembly process of the building blocks (heteroscorpionate aluminium complexes) directed by noncovalent intermolecular CH–π interactions. The structures of these complexes have been determined by spectroscopic methods and the X-ray crystal structures of 2, 6, 8, and 16 have also been established. Concentration-dependent 1H pulsed field-gradient spin echo (PFGSE) NMR experiments provided evidence for the self-assembly of the single molecular species of complex 2 in solution. The degree of aggregation was calculated for complex 2, with the average number of units constituting the aggregate (N) estimated to be a maximum of 4 molecules in solution before reaching the solid state.

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Transition metal complexes bearing a 2,2-bis(3,5-dimethylpyrazol-1-yl)propionate ligand: one methyl more matters

Cited by 19 publications

References 42 publications

Carbon-Rich Ruthenium Allenylidene Complexes Bearing Heteroscorpionate Ligands

Carbon-Rich Ruthenium Allenylidene Complexes Bearing Heteroscorpionate Ligands

Ruthenium Carbonyl Complexes Bearing Bis(pyrazol-1-yl)carboxylato Ligands

Heteroscorpionate aluminium complexes as chiral building blocks to engineer helical architectures

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