Rinaldo Poli | Institut National Polytechnique de Toulouse (original) (raw)
Papers by Rinaldo Poli
Polyhedron
The W TM carbonyl compounds [(Ring)WX3(CO)2](Ring = C5H5, C5H4Me, C5Me5; X = C1, Br, I) have been... more The W TM carbonyl compounds [(Ring)WX3(CO)2](Ring = C5H5, C5H4Me, C5Me5; X = C1, Br, I) have been prepared by a one-step oxidation of the corresponding [(Ring)W(CO)3]2 with PhICI2, Br2 and I2, respectively, in high yields. The structure of Cp*WBr3(CO)2 has been elucidated by X-ray methods. It exhibits a distorted, pseudo
Coordination Chemistry Reviews, 2008
The chemistry of organomolybdenum and -tungsten compounds in high oxidation states (mostly V and ... more The chemistry of organomolybdenum and -tungsten compounds in high oxidation states (mostly V and VI) is reviewed, with special attention on the behaviour in protic media and with respect to protic reagents. The high metal-carbon bond covalency imparts a great degree of inertness to these bonds relative to protonolysis. Hence, extensive chemistry in a wide variety of media and with protic reagents is possible without affecting the metal-(hydrocarbyl ligand) interactions. This article does not cover metallocene [i.e. bis(cyclopentadienyl)], alkylidene and alkylidyne derivatives, that have been extensively covered in other recent reviews.
Organometallics, 1987
... NC5H4-and N,N'-Di-p -tolylformamidinato-Bridged Complexes of Diiridium( II) F. Albert Co... more ... NC5H4-and N,N'-Di-p -tolylformamidinato-Bridged Complexes of Diiridium( II) F. Albert Cotton” and Rinaldo Poli Department of Chemistry and Laboratory for Molecular Structure and Bonding, Texas A&M University, College Station, Texas 77843 Received January 29, 1987 ...
J Am Chem Soc, 1992
Homoleptic (L = L') and heteroleptic (L # L') edgesharing bicctahedral Mo(II1) complexes of formu... more Homoleptic (L = L') and heteroleptic (L # L') edgesharing bicctahedral Mo(II1) complexes of formula MqC&L+&', (n = 0-2; L, L' = PMe,Et,; x = 0-3) have been generated in solution and investigated by paramagnetic 'H N M R spectroscopy.
![Research paper thumbnail of Metal-metal bonding in pentamethylcyclopentadienylmolybdenum(IV) dinuclear compounds: chloride abstraction from non-bonded Cp ∗ 2Mo 2Cl 6 to afford bonded [Cp ∗ 2Mo 2Cl 5] +](https://attachments.academia-assets.com/52079994/thumbnails/1.jpg)
](Inorg Chim Acta, 1995
Chloride abstraction from Cp*2M02Cl 6 (Cp*= ~75-C5Me5) is accomplished by interaction with the Le... more Chloride abstraction from Cp*2M02Cl 6 (Cp*= ~75-C5Me5) is accomplished by interaction with the Lewis acid AICl 3 to afford the structurally characterized salt [Cp*2Mo2CIs]+[AICIa] -. Crystal data: triclinic, space group Pi, a =8.3903(13), b= 15.797(3), c =24.036(2) /~, ct =86.766(11), /3 = 80.916(10), -y= 81.616(14) °, 1-'=3110.5(8) ~3, Dc = 1.726 Mg m -3, /z(Mo Ka)= 1.618 mm -x, R=0.0637. The structure exhibits two four-legged piano stools joined by three bridging Cl atoms. The Mo-Mo distance of 2.866(2) ~ is significantly longer than all other reported bonded Mo(IV)-Mo(IV) distances and longer than the single bond (o'2~'262) distance in the related Mo(III) complexes [(ring)MoCl2]2 (ring= substitute cyclopentadienyl ring). The reasons for this lengthening are analyzed and discussed on the basis of structural data and Fenske-Hall MO calculations.
Organometallics, 1992
... SOC. 1986,108,1537. (d) Nolan, SP; Hoff, CD; Stoutland, P. 0.; Newman, LJ; Buchanan, J. M.; B... more ... SOC. 1986,108,1537. (d) Nolan, SP; Hoff, CD; Stoutland, P. 0.; Newman, LJ; Buchanan, J. M.; Bergman, RG; Yang, GK; Peters, KS J. Am. Chem. ... 2. Reactions of (q5-C,R,)MoCI(PMe,), (R = H, Me) with Neutral Donors Fatima Abugldeiri, Malcolm A. Kelland, and Rinaldo Poll" ...
Polyhedron, 1997
The hydrotris(3,5-dimethylpyrazolyl)borate complexes are rare examples of 16-electron carbonyl de... more The hydrotris(3,5-dimethylpyrazolyl)borate complexes are rare examples of 16-electron carbonyl derivatives with a spin triplet ground state, which exhibit relatively sharp contactshifted 1H NMR spectra. Oxidation of Tp∗MoI(CO)2 led to the isolation and crystallographic characterization of Tp∗MoOI2.
Organometallics, 1997
With the aim of generating stable 17-electron polyhydride species for further activation and reac... more With the aim of generating stable 17-electron polyhydride species for further activation and reactivity studies, the authors have synthesized new compounds of the general class (ηâµ-ring) MHâLâ (ring = cyclopentadienyl ligand, M = group 6 metal, L = tertiary phosphine). Oxidation studies of these derivatives had not previously been reported, while protonation studies were limited to (ηâµ-CâHâPr{sup i})MoHâ(PMeâ)â with HCl
![Research paper thumbnail of Reactivity of molecules containing element-element bonds. 2. Transition elements [Erratum to document cited in CA114(15):143614m]](https://attachments.academia-assets.com/52079989/thumbnails/1.jpg)
](Inorg Chem, 1992
was done by extraction with THF (20 mL) followed by vacuum drying, dissolution in water (10 mL) a... more was done by extraction with THF (20 mL) followed by vacuum drying, dissolution in water (10 mL) and addition of NaCl (20% w/v, 7.5 mL), and, after overnight standing, filtration of a small precipitated impurity, followed by cautiously layering on the clear solution of CsCl (3% w/v, 20 mL). After complete diffusion (several weeks), the precipitated pure C S~[ P~~R~~~( C O ) ~~] was filtered and washed with CsCl (3% w/v, 10 mL). The clear mother liquor and collected washings were treated with CH3COOH (4 mL) to give after about 3 h a fine crystalline precipitate. After the mixture was allowed to stand overnight, C S~[ P~~R~~~( C O )~~] was separated from the mother liquor by decantation and vacuum dried. Yields: 100-150 mg (3-4%). The product gave no hydrido signals in 'H NMR. (b) Synthesis as a Byproduct of the Synthesis of [F'tzRh~(CO)zz]3-. [PPN][PtRh5(CO)15] (1.143 g, 0.685 "01)
Tetrahedron Asymmetry, 2004
The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bon... more The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge in a 3:1 ratio via reaction of an α-metallated P-chirogenic phosphine borane with a benzaldimine is described. The diastereoselectivity is attributed to a transition state where the lithium cation chelates the phosphine borane carbanion and the nitrogen of the imine and the attack of the CN occurs on the face opposite to the P–B bond, due to its interaction with the antibonding P–B bond. The major diastereoisomeric β-aminophosphine borane was then separated and decomplexed into the corresponding β-aminophosphine under neutral conditions and without epimerization by heating at reflux in EtOH. This synthesis offers a short hemisynthetic route to the P-chirogenic β-P,N-ligands, by bridge formation starting from methylphosphine boranes.The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge is described in three steps, via a key reaction of the α-metallated P-chirogenic phosphine borane with a benzaldimine.(1S,2R)-2-N-phenylamino-2-phenyl-1-(o-anisylphenylphosphinoborane)ethaneC27H29NOBP[α]D=−76 (c 0.5, CHCl3)(1S,2R)-2-N-phenylamino-2-phenyl-1-(o-anisylphenylphosphino)ethaneC27H26NOP[α]D=−10 (c 1, CHCl3)
New Journal of Chemistry, 2006
ABSTRACT A detailed electrochemical study of the oxidative decomposition of the trihydride comple... more ABSTRACT A detailed electrochemical study of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile is presented. For the Mo complex, the decomposition occurs by four different pathways involving classical and non-classical tautomers, whereas only the classical form is accessible for the W derivative. Each of the decomposition pathways has been quantitatively assessed by analyses of the linear sweep voltammograms. In addition to the previously established (B. Pleune, D. Morales, R. Meunier-Prest, P. Richard, E. Collange, J. C. Fettinger and R. Poli, J. Am. Chem. Soc., 1999, 121, 2209–2225) deprotonation, disproportionation, and H2 reductive elimination occurring via the non-classical tautomer of the 17-electron complex [Cp*Mo(dppe)H3]+ (obtained by oxidation at E1/2 = −0.33 V vs. Ag/AgCl), a new decomposition pathway from the more stable classical tautomer has been identified following a second oxidation process. In addition, the oxidatively induced H2 reductive elimination, previously evidenced only in THF or CH2Cl2, has been quantitatively assessed in MeCN. This process occurs preferentially by an associative mechanism (k = 0.020(4) M−1s−1) via the 19-electron [Cp*Mo(dppe)H(H2)(MeCN)]+ intermediate and is therefore in direct competition with the disproportionation mechanism. The resulting 17-electron [Cp*Mo(dppe)H(MeCN)]+ product is further oxidized at ca. 0.2 V. The oxidation of [Cp*Mo(dppe)H3]+ occurs at ca. 1.0 V and the resulting 16-electron [Cp*Mo(dppe)H3]2+ complex immediately delivers a proton to the starting material, giving [Cp*Mo(dppe)H4]+ and [Cp*Mo(dppe)H2]+. The latter coordinates MeCN in a rate determining step to afford [Cp*Mo(dppe)H2(MeCN)]+. The mechanistic details are consistent with studies at different scan rates and different MeCN concentrations, and are backed up by DFT calculations.
Acta Crystallogr C Cryst Str, 2008
A second polymorphic form (form I) of the previously reported compound {2-[(2-hydroxyethyl)iminio... more A second polymorphic form (form I) of the previously reported compound {2-[(2-hydroxyethyl)iminiomethyl]phenolato-kappaO}dioxido{2-[(2-oxidoethyl)iminomethyl]phenolato-kappa(3)O,N,O'}molybdenum(VI) (form II), [Mo(C(9)H(9)NO(2))O(2)(C(9)H(11)NO(2))], is presented. The title structure differs from the previously reported polymorph [Głowiak, Jerzykiewicz, Sobczak & Ziółkowski (2003). Inorg. Chim. Acta, 356, 387-392] by the fact that the asymmetric unit contains three molecules linked by O-H...O hydrogen bonds. These trimeric units are further linked through O-H...O hydrogen bonds to form a chain parallel to the [111] direction. As in the previous polymorph, each molecule is built up from an MoO(2)(2+) cation surrounded by an O,N,O'-tridentate ligand (O(-)C(6)H(4)CH=NCH(2)CH(2)O(-)) and weakly coordinated by a second zwitterionic ligand (O(-)C(6)H(4)CH=N(+)HC(2)H(4)OH). All complexes are chiral with the absolute configuration at Mo being C or A. The main difference between the two polymorphs results from the alternation of the chirality at Mo within the chain.
Organometallics, Oct 11, 2002
DFT calculations have been carried out on the compounds Ln[CH(SiR 2 R′)(SiR 3 )] 3 for Ln ) La, S... more DFT calculations have been carried out on the compounds Ln[CH(SiR 2 R′)(SiR 3 )] 3 for Ln ) La, Sm and (i) R ) R′ ) Me, (ii) R ) H, R′ ) Me, and (iii) R ) R′ ) H. The results are compared with the X-ray structures that are available from the literature for both metals and R ) R′ ) Me. The calculations correctly reproduce the experimental structural features in these complexes exhibiting the peculiar pyramidal coordination geometry. The results show significant increases in the Si-C bond lengths associated with -Si-C agostic interactions, whereas little structural changes are found for γ-C-H agostic interactions. The latter are in fact repulsive. The simplified model system with R ) H and R′ ) Me that retains one agostic methyl interaction in each alkyl ligand also correctly reproduces the essential geometrical features. The simplest model with only SiH 3 groups, while also adopting a pyramidal coordination geometry, no longer accurately describes the real molecule, since the -Si-C agostic interactions are replaced by -Si-H interactions. A Mulliken analysis of the electronic structure shows a relatively covalent Ln-C interaction with significant 5d orbital participation in the bonding. A number of calculations with different basis sets on the model system Sm[CH(SiH 2 Me)(SiH 3 )] 3 shows that the addition of polarization functions (d functions on Si and C, p functions on H, or f functions on Sm) has little or no beneficial effect on the quality of the results.
![Research paper thumbnail of Synthesis, solid-state and solution structure, and physicochemical properties of the iodide-bridged face-sharing bioctahedral molybdenum(III) dimers [Cat]+[Mo2I7(PMe3)2]-(Cat = PHMe3, NMe4 AsPh4)](https://attachments.academia-assets.com/52079988/thumbnails/1.jpg)
](Inorg Chem, 1987
forbidden transitions (4A2, -+ 2E,) of d3 configuration in an effective octahedral field. A speci... more forbidden transitions (4A2, -+ 2E,) of d3 configuration in an effective octahedral field. A special feature of the Cr(II1)-Mn(I1) spectrum is a very sharp band at 420 nm (e -123 M-' cm-'), which is assigned to the single excitation (6A1 -4E4Al) at the Mn(I1) center.
Cheminform, Dec 17, 1991
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance th... more AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Inorg Chem, 2003
ABSTRACT The diastereoselective addition of Ph2PH to the chiral ortho-substituted η6-benzaldimine... more ABSTRACT The diastereoselective addition of Ph2PH to the chiral ortho-substituted η6-benzaldimine complexes (η6-o-X - C6H4CH=NAr)Cr(CO)3 (1, X = MeO, Ar = p-C6H4OMe; 2, X = Cl, Ar = Ph) leads to the formation of the corresponding chiral aminophosphines (α-P,N) Ph2P-CH(Ar1)-NHAr2 (3, Ar1 = o-C6H4(OCH3)[Cr(CO)3], Ar2 = p-C6H4OCH3; 4, Ar1 = o-C6H4Cl[Cr(CO)3], Ar2 = Ph) in equilibrium with the starting materials. The uncomplexed benzaldimine (o-ClC6H4CH=NPh), 2′, analogously produces an equilibrium amount of the corresponding aminophosphine Ph2PCH(Ar1)-NHAr2 (4′, Ar1 = o-C6H4Cl, Ar2 = Ph). Depending on the equilibrium constant, the subsequent addition of 1/2 equiv of [RhCl(COD)]2 (COD = 1,5-cyclooctadiene) leads to either Ph2PH oxidative addition in the case of 3 or to the corresponding [RhCl(COD)(α-P,N)] complexes [RhCl(COD)(Ph2P-CH{o-C6H4Cl[Cr(CO)3]}-NHPh)] (5) and [RhCl(COD)(Ph2P-CH(o-C6H4Cl)-NHPh)] (5′) in the cases of the aminophosphines 4 and 4′. The addition of the latter ligands, as racemic mixtures, to 1/4 equiv of [Rh(CO)2Cl]2 leads to the [RhCl(CO)(α-P,N)2] complexes [RhCO(Ph2P-CH{o-C6H4Cl[Cr (CO)3]}-NHPh)2Cl] (7) or [RhCO(Ph2P-CH(o-C6H4Cl)-NHPh)2Cl] (7′) as mixtures of (Rc,Sc)/(Sc,Rc) and (Rc,Rc)/(Sc,Sc) diastereomers. The rhodium complexes 5 and 7′ have been fully characterized by IR and 31P NMR spectroscopies and X-ray crystallography. These compounds exhibit intramolecular Rh-Cl⋯ H-N interactions in the solid state and in solution. The stability of the new rhodium complexes has been studied under different CO pressures. Under 1 atm of CO, 5 is converted to an unstable complex [RhCl(CO)2(α-P,N)], 6, which undergoes ligand redistribution leading to 7 plus an unidentified complex. This reaction is inhibited under higher CO or syngas pressure, as confirmed by the observation of the same catalytic activity in hydroformylation when styrene was added to a catalytic mixture that was either freshly prepared or left standing for 20 h under high CO pressure.
Organometallics, 1998
... Experimental and Theoretical Studies of Nonclassical d 0 Cyclopentadienyl Polyhydride Complex... more ... Experimental and Theoretical Studies of Nonclassical d 0 Cyclopentadienyl Polyhydride Complexes of Molybdenum and Tungsten. ...
Organometallics, 1998
The interaction of CpMoH(CO)â(PMeâ), 1, with AgBFâ in acetonitrile establishes an equilibrium (K ... more The interaction of CpMoH(CO)â(PMeâ), 1, with AgBFâ in acetonitrile establishes an equilibrium (K = 9 {+-} 1) with the hydride-bridged adduct [Cp(CO)â(PMeâ)Mo(μ-H)Ag(MeCN)â]BFâ, 4, which is in a fast chemical exchange on the NMR time scale with compound 1. The interaction of 1 and AgBFâ in THF leads to the formation of the trinuclear complex {l_brace}[CpMoH-(CO)â(PMeâ)]âAg{r_brace}BFâ, 5, as an insoluble white solid in 73% yield when the Mo/Ag ratio is 2:1. The nature of the precipitate does not depend on the relative stoichiometry of the two reagents. When redissolved in acetonitrile, compound 5 dissociates, generating a mixture of 1 and 4. Compound 4 slowly evolves to the solvent adduct, [CpMo(CO)â(PMeâ)(MeCN)]BFâ, 3, with elimination of hydrogen gas and metallic silver. The decomposition of 4 could be interpreted as either an inner-sphere electron transfer or a substitution of unstable AgH.
Polyhedron
The W TM carbonyl compounds [(Ring)WX3(CO)2](Ring = C5H5, C5H4Me, C5Me5; X = C1, Br, I) have been... more The W TM carbonyl compounds [(Ring)WX3(CO)2](Ring = C5H5, C5H4Me, C5Me5; X = C1, Br, I) have been prepared by a one-step oxidation of the corresponding [(Ring)W(CO)3]2 with PhICI2, Br2 and I2, respectively, in high yields. The structure of Cp*WBr3(CO)2 has been elucidated by X-ray methods. It exhibits a distorted, pseudo
Coordination Chemistry Reviews, 2008
The chemistry of organomolybdenum and -tungsten compounds in high oxidation states (mostly V and ... more The chemistry of organomolybdenum and -tungsten compounds in high oxidation states (mostly V and VI) is reviewed, with special attention on the behaviour in protic media and with respect to protic reagents. The high metal-carbon bond covalency imparts a great degree of inertness to these bonds relative to protonolysis. Hence, extensive chemistry in a wide variety of media and with protic reagents is possible without affecting the metal-(hydrocarbyl ligand) interactions. This article does not cover metallocene [i.e. bis(cyclopentadienyl)], alkylidene and alkylidyne derivatives, that have been extensively covered in other recent reviews.
Organometallics, 1987
... NC5H4-and N,N'-Di-p -tolylformamidinato-Bridged Complexes of Diiridium( II) F. Albert Co... more ... NC5H4-and N,N'-Di-p -tolylformamidinato-Bridged Complexes of Diiridium( II) F. Albert Cotton” and Rinaldo Poli Department of Chemistry and Laboratory for Molecular Structure and Bonding, Texas A&M University, College Station, Texas 77843 Received January 29, 1987 ...
J Am Chem Soc, 1992
Homoleptic (L = L') and heteroleptic (L # L') edgesharing bicctahedral Mo(II1) complexes of formu... more Homoleptic (L = L') and heteroleptic (L # L') edgesharing bicctahedral Mo(II1) complexes of formula MqC&L+&', (n = 0-2; L, L' = PMe,Et,; x = 0-3) have been generated in solution and investigated by paramagnetic 'H N M R spectroscopy.
Inorg Chim Acta, 1995
Chloride abstraction from Cp*2M02Cl 6 (Cp*= ~75-C5Me5) is accomplished by interaction with the Le... more Chloride abstraction from Cp*2M02Cl 6 (Cp*= ~75-C5Me5) is accomplished by interaction with the Lewis acid AICl 3 to afford the structurally characterized salt [Cp*2Mo2CIs]+[AICIa] -. Crystal data: triclinic, space group Pi, a =8.3903(13), b= 15.797(3), c =24.036(2) /~, ct =86.766(11), /3 = 80.916(10), -y= 81.616(14) °, 1-'=3110.5(8) ~3, Dc = 1.726 Mg m -3, /z(Mo Ka)= 1.618 mm -x, R=0.0637. The structure exhibits two four-legged piano stools joined by three bridging Cl atoms. The Mo-Mo distance of 2.866(2) ~ is significantly longer than all other reported bonded Mo(IV)-Mo(IV) distances and longer than the single bond (o'2~'262) distance in the related Mo(III) complexes [(ring)MoCl2]2 (ring= substitute cyclopentadienyl ring). The reasons for this lengthening are analyzed and discussed on the basis of structural data and Fenske-Hall MO calculations.
Organometallics, 1992
... SOC. 1986,108,1537. (d) Nolan, SP; Hoff, CD; Stoutland, P. 0.; Newman, LJ; Buchanan, J. M.; B... more ... SOC. 1986,108,1537. (d) Nolan, SP; Hoff, CD; Stoutland, P. 0.; Newman, LJ; Buchanan, J. M.; Bergman, RG; Yang, GK; Peters, KS J. Am. Chem. ... 2. Reactions of (q5-C,R,)MoCI(PMe,), (R = H, Me) with Neutral Donors Fatima Abugldeiri, Malcolm A. Kelland, and Rinaldo Poll" ...
Polyhedron, 1997
The hydrotris(3,5-dimethylpyrazolyl)borate complexes are rare examples of 16-electron carbonyl de... more The hydrotris(3,5-dimethylpyrazolyl)borate complexes are rare examples of 16-electron carbonyl derivatives with a spin triplet ground state, which exhibit relatively sharp contactshifted 1H NMR spectra. Oxidation of Tp∗MoI(CO)2 led to the isolation and crystallographic characterization of Tp∗MoOI2.
Organometallics, 1997
With the aim of generating stable 17-electron polyhydride species for further activation and reac... more With the aim of generating stable 17-electron polyhydride species for further activation and reactivity studies, the authors have synthesized new compounds of the general class (ηâµ-ring) MHâLâ (ring = cyclopentadienyl ligand, M = group 6 metal, L = tertiary phosphine). Oxidation studies of these derivatives had not previously been reported, while protonation studies were limited to (ηâµ-CâHâPr{sup i})MoHâ(PMeâ)â with HCl
Inorg Chem, 1992
was done by extraction with THF (20 mL) followed by vacuum drying, dissolution in water (10 mL) a... more was done by extraction with THF (20 mL) followed by vacuum drying, dissolution in water (10 mL) and addition of NaCl (20% w/v, 7.5 mL), and, after overnight standing, filtration of a small precipitated impurity, followed by cautiously layering on the clear solution of CsCl (3% w/v, 20 mL). After complete diffusion (several weeks), the precipitated pure C S~[ P~~R~~~( C O ) ~~] was filtered and washed with CsCl (3% w/v, 10 mL). The clear mother liquor and collected washings were treated with CH3COOH (4 mL) to give after about 3 h a fine crystalline precipitate. After the mixture was allowed to stand overnight, C S~[ P~~R~~~( C O )~~] was separated from the mother liquor by decantation and vacuum dried. Yields: 100-150 mg (3-4%). The product gave no hydrido signals in 'H NMR. (b) Synthesis as a Byproduct of the Synthesis of [F'tzRh~(CO)zz]3-. [PPN][PtRh5(CO)15] (1.143 g, 0.685 "01)
Tetrahedron Asymmetry, 2004
The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bon... more The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge in a 3:1 ratio via reaction of an α-metallated P-chirogenic phosphine borane with a benzaldimine is described. The diastereoselectivity is attributed to a transition state where the lithium cation chelates the phosphine borane carbanion and the nitrogen of the imine and the attack of the CN occurs on the face opposite to the P–B bond, due to its interaction with the antibonding P–B bond. The major diastereoisomeric β-aminophosphine borane was then separated and decomplexed into the corresponding β-aminophosphine under neutral conditions and without epimerization by heating at reflux in EtOH. This synthesis offers a short hemisynthetic route to the P-chirogenic β-P,N-ligands, by bridge formation starting from methylphosphine boranes.The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge is described in three steps, via a key reaction of the α-metallated P-chirogenic phosphine borane with a benzaldimine.(1S,2R)-2-N-phenylamino-2-phenyl-1-(o-anisylphenylphosphinoborane)ethaneC27H29NOBP[α]D=−76 (c 0.5, CHCl3)(1S,2R)-2-N-phenylamino-2-phenyl-1-(o-anisylphenylphosphino)ethaneC27H26NOP[α]D=−10 (c 1, CHCl3)
New Journal of Chemistry, 2006
ABSTRACT A detailed electrochemical study of the oxidative decomposition of the trihydride comple... more ABSTRACT A detailed electrochemical study of the oxidative decomposition of the trihydride complexes Cp*M(dppe)H3 (M = Mo, W) in acetonitrile is presented. For the Mo complex, the decomposition occurs by four different pathways involving classical and non-classical tautomers, whereas only the classical form is accessible for the W derivative. Each of the decomposition pathways has been quantitatively assessed by analyses of the linear sweep voltammograms. In addition to the previously established (B. Pleune, D. Morales, R. Meunier-Prest, P. Richard, E. Collange, J. C. Fettinger and R. Poli, J. Am. Chem. Soc., 1999, 121, 2209–2225) deprotonation, disproportionation, and H2 reductive elimination occurring via the non-classical tautomer of the 17-electron complex [Cp*Mo(dppe)H3]+ (obtained by oxidation at E1/2 = −0.33 V vs. Ag/AgCl), a new decomposition pathway from the more stable classical tautomer has been identified following a second oxidation process. In addition, the oxidatively induced H2 reductive elimination, previously evidenced only in THF or CH2Cl2, has been quantitatively assessed in MeCN. This process occurs preferentially by an associative mechanism (k = 0.020(4) M−1s−1) via the 19-electron [Cp*Mo(dppe)H(H2)(MeCN)]+ intermediate and is therefore in direct competition with the disproportionation mechanism. The resulting 17-electron [Cp*Mo(dppe)H(MeCN)]+ product is further oxidized at ca. 0.2 V. The oxidation of [Cp*Mo(dppe)H3]+ occurs at ca. 1.0 V and the resulting 16-electron [Cp*Mo(dppe)H3]2+ complex immediately delivers a proton to the starting material, giving [Cp*Mo(dppe)H4]+ and [Cp*Mo(dppe)H2]+. The latter coordinates MeCN in a rate determining step to afford [Cp*Mo(dppe)H2(MeCN)]+. The mechanistic details are consistent with studies at different scan rates and different MeCN concentrations, and are backed up by DFT calculations.
Acta Crystallogr C Cryst Str, 2008
A second polymorphic form (form I) of the previously reported compound {2-[(2-hydroxyethyl)iminio... more A second polymorphic form (form I) of the previously reported compound {2-[(2-hydroxyethyl)iminiomethyl]phenolato-kappaO}dioxido{2-[(2-oxidoethyl)iminomethyl]phenolato-kappa(3)O,N,O'}molybdenum(VI) (form II), [Mo(C(9)H(9)NO(2))O(2)(C(9)H(11)NO(2))], is presented. The title structure differs from the previously reported polymorph [Głowiak, Jerzykiewicz, Sobczak & Ziółkowski (2003). Inorg. Chim. Acta, 356, 387-392] by the fact that the asymmetric unit contains three molecules linked by O-H...O hydrogen bonds. These trimeric units are further linked through O-H...O hydrogen bonds to form a chain parallel to the [111] direction. As in the previous polymorph, each molecule is built up from an MoO(2)(2+) cation surrounded by an O,N,O'-tridentate ligand (O(-)C(6)H(4)CH=NCH(2)CH(2)O(-)) and weakly coordinated by a second zwitterionic ligand (O(-)C(6)H(4)CH=N(+)HC(2)H(4)OH). All complexes are chiral with the absolute configuration at Mo being C or A. The main difference between the two polymorphs results from the alternation of the chirality at Mo within the chain.
Organometallics, Oct 11, 2002
DFT calculations have been carried out on the compounds Ln[CH(SiR 2 R′)(SiR 3 )] 3 for Ln ) La, S... more DFT calculations have been carried out on the compounds Ln[CH(SiR 2 R′)(SiR 3 )] 3 for Ln ) La, Sm and (i) R ) R′ ) Me, (ii) R ) H, R′ ) Me, and (iii) R ) R′ ) H. The results are compared with the X-ray structures that are available from the literature for both metals and R ) R′ ) Me. The calculations correctly reproduce the experimental structural features in these complexes exhibiting the peculiar pyramidal coordination geometry. The results show significant increases in the Si-C bond lengths associated with -Si-C agostic interactions, whereas little structural changes are found for γ-C-H agostic interactions. The latter are in fact repulsive. The simplified model system with R ) H and R′ ) Me that retains one agostic methyl interaction in each alkyl ligand also correctly reproduces the essential geometrical features. The simplest model with only SiH 3 groups, while also adopting a pyramidal coordination geometry, no longer accurately describes the real molecule, since the -Si-C agostic interactions are replaced by -Si-H interactions. A Mulliken analysis of the electronic structure shows a relatively covalent Ln-C interaction with significant 5d orbital participation in the bonding. A number of calculations with different basis sets on the model system Sm[CH(SiH 2 Me)(SiH 3 )] 3 shows that the addition of polarization functions (d functions on Si and C, p functions on H, or f functions on Sm) has little or no beneficial effect on the quality of the results.
Inorg Chem, 1987
forbidden transitions (4A2, -+ 2E,) of d3 configuration in an effective octahedral field. A speci... more forbidden transitions (4A2, -+ 2E,) of d3 configuration in an effective octahedral field. A special feature of the Cr(II1)-Mn(I1) spectrum is a very sharp band at 420 nm (e -123 M-' cm-'), which is assigned to the single excitation (6A1 -4E4Al) at the Mn(I1) center.
Cheminform, Dec 17, 1991
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance th... more AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Inorg Chem, 2003
ABSTRACT The diastereoselective addition of Ph2PH to the chiral ortho-substituted η6-benzaldimine... more ABSTRACT The diastereoselective addition of Ph2PH to the chiral ortho-substituted η6-benzaldimine complexes (η6-o-X - C6H4CH=NAr)Cr(CO)3 (1, X = MeO, Ar = p-C6H4OMe; 2, X = Cl, Ar = Ph) leads to the formation of the corresponding chiral aminophosphines (α-P,N) Ph2P-CH(Ar1)-NHAr2 (3, Ar1 = o-C6H4(OCH3)[Cr(CO)3], Ar2 = p-C6H4OCH3; 4, Ar1 = o-C6H4Cl[Cr(CO)3], Ar2 = Ph) in equilibrium with the starting materials. The uncomplexed benzaldimine (o-ClC6H4CH=NPh), 2′, analogously produces an equilibrium amount of the corresponding aminophosphine Ph2PCH(Ar1)-NHAr2 (4′, Ar1 = o-C6H4Cl, Ar2 = Ph). Depending on the equilibrium constant, the subsequent addition of 1/2 equiv of [RhCl(COD)]2 (COD = 1,5-cyclooctadiene) leads to either Ph2PH oxidative addition in the case of 3 or to the corresponding [RhCl(COD)(α-P,N)] complexes [RhCl(COD)(Ph2P-CH{o-C6H4Cl[Cr(CO)3]}-NHPh)] (5) and [RhCl(COD)(Ph2P-CH(o-C6H4Cl)-NHPh)] (5′) in the cases of the aminophosphines 4 and 4′. The addition of the latter ligands, as racemic mixtures, to 1/4 equiv of [Rh(CO)2Cl]2 leads to the [RhCl(CO)(α-P,N)2] complexes [RhCO(Ph2P-CH{o-C6H4Cl[Cr (CO)3]}-NHPh)2Cl] (7) or [RhCO(Ph2P-CH(o-C6H4Cl)-NHPh)2Cl] (7′) as mixtures of (Rc,Sc)/(Sc,Rc) and (Rc,Rc)/(Sc,Sc) diastereomers. The rhodium complexes 5 and 7′ have been fully characterized by IR and 31P NMR spectroscopies and X-ray crystallography. These compounds exhibit intramolecular Rh-Cl⋯ H-N interactions in the solid state and in solution. The stability of the new rhodium complexes has been studied under different CO pressures. Under 1 atm of CO, 5 is converted to an unstable complex [RhCl(CO)2(α-P,N)], 6, which undergoes ligand redistribution leading to 7 plus an unidentified complex. This reaction is inhibited under higher CO or syngas pressure, as confirmed by the observation of the same catalytic activity in hydroformylation when styrene was added to a catalytic mixture that was either freshly prepared or left standing for 20 h under high CO pressure.
Organometallics, 1998
... Experimental and Theoretical Studies of Nonclassical d 0 Cyclopentadienyl Polyhydride Complex... more ... Experimental and Theoretical Studies of Nonclassical d 0 Cyclopentadienyl Polyhydride Complexes of Molybdenum and Tungsten. ...
Organometallics, 1998
The interaction of CpMoH(CO)â(PMeâ), 1, with AgBFâ in acetonitrile establishes an equilibrium (K ... more The interaction of CpMoH(CO)â(PMeâ), 1, with AgBFâ in acetonitrile establishes an equilibrium (K = 9 {+-} 1) with the hydride-bridged adduct [Cp(CO)â(PMeâ)Mo(μ-H)Ag(MeCN)â]BFâ, 4, which is in a fast chemical exchange on the NMR time scale with compound 1. The interaction of 1 and AgBFâ in THF leads to the formation of the trinuclear complex {l_brace}[CpMoH-(CO)â(PMeâ)]âAg{r_brace}BFâ, 5, as an insoluble white solid in 73% yield when the Mo/Ag ratio is 2:1. The nature of the precipitate does not depend on the relative stoichiometry of the two reagents. When redissolved in acetonitrile, compound 5 dissociates, generating a mixture of 1 and 4. Compound 4 slowly evolves to the solvent adduct, [CpMo(CO)â(PMeâ)(MeCN)]BFâ, 3, with elimination of hydrogen gas and metallic silver. The decomposition of 4 could be interpreted as either an inner-sphere electron transfer or a substitution of unstable AgH.