Insertion Reaction of Phenyl Isocyanate into the Ln−C σ-Bond of Organolanthanide Complexes: Synthesis, Characterization, and Crystal Structures of {(C5H4CH3)2Ln[μ-η1:η3-OC(R)NPh]}2 (Ln = Sm, Dy, Er, Ho; R = n-butyl, α-naphthyl)

Aluminium-catalysed isocyanate trimerization, enhanced by exploiting a dynamic coordination sphere

Main-group metals are inherently labile, hindering their use in catalysis. We exploit this lability in the synthesis of isocyanurates. For the first time we report a highly active catalyst that trimerizes alkyl, allyl and aryl isocyanates, and di-isocyanates, with low catalyst loadings under mild conditions, using a hemi-labile aluminium-pyridyl-bis(iminophenolate) complex.

Synthesis, characterization, and reactivity of dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands: substituent effects on coordination and reactivity

Two series of new dinuclear organo-rare-earth-metal alkyl complexes supported by 2-amidate-functionalized indolyl ligands with different haptic modes were synthesized and characterized. The treatment of [RE(CH2SiMe3)3(THF)2] with 1 equiv. of 2-(2,6-iPr2C6H3NHC[double bond, length as m-dash]O)C8H5NH (H2L1) and 2-(2-tBuC6H4NHC[double bond, length as m-dash]O)C8H5NH (H2L2) in toluene yielded the dinuclear organo-rare-earth-metal alkyl complexes {[η1:(μ2-η1:η1)-L1]RE(CH2SiMe3)(THF)2}2 [RE = Gd (1a), Dy (1b), Y (1c), Er (1d), and Yb (1e)] and {[η1:(μ2-η1:η1):η1-L2]RE(CH2SiMe3)(THF)2}2 [RE = Gd (2a), Dy (2b), Y (2c), Er (2d), and Yb (2e)] in good yields. When [RE(CH2SiMe3)3(THF)2] were treated with 2 equiv. of H2L1 or H2L2 in THF, the dinuclear organo-rare-earth-metal complexes {(η1:η1-HL)[η1:(μ2-η1:η1):η1-L]RE(THF)}2 (1ca: RE = Y, L = L1; 2ea: RE = Yb, L = L2) were obtained. The complexes could react with small organic molecules such as N,N'-diisopropylcarbodiimide (DIC), phenyl isocyanate, N-methylallylamine, phenylacetylene, pyridine, N-phenylimidazole, or 4-dimethylaminopyridine (DMAP) to yield a series of new complexes with different reactivity patterns along with the reported rare-earth-metal alkyl complexes. In the presence of cocatalysts, these dinuclear organo-rare-earth-metal alkyl complexes could initiate isoprene polymerization with high activity (100% conversion of 2000 equiv. of isoprene in 12 h), yielding polymers with high regioselectivity (1,4 polymers up to 96.1%).

Yttrium dialkyl supported by a silaamidinate ligand: synthesis, structure and catalysis on cyclotrimerization of isocyanates

A four-coordinate yttrium dialkyl complex with a sterically demanding silaamidinate ligand exhibited high activity and excellent functional group tolerance for the catalysis of isocyanate cyclotrimerization.

Improved reactivity of a cyclic 13/15 compound by increased steric demand

The reactivity of a masked flp was investigated for the sterically overloaded group 13/15 ring compound [tBu₂GaP(H)tBu₂Ph]₂, as can be seen from its reaction with phenyl-isocyanate.

Isocyanate deinsertion from κ1-O amidates: facile access to perfluoroaryl rhodium(i) complexes

Perfluorophenyl-subsituted amidates undergo unprecedented C₆F₅ migration to Rh(i) on heating, providing a new route to Rh-C₆F₅ organometallic fragments.

Isocyanate diinsertion into the N-H bond of the 2-pyridylamino ligand of organolanthanides

[Cp2LnNHPy]2 (Py = 2-pyridyl) (1a-e) react with phenyl isocyanate to form the N-H diinsertion products Cp2Ln[eta2:eta1-PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c), Dy (3d), Gd (3e)). It has been proven that nPr2NH can abstract one PhNCO unit from 3c to form Cp2Y[eta3-OC(NHPh)NPy] (2c) and nPr2NHCONHPh (4), representing a rare example of selective release of a functional group of ligands in organolanthanide chemistry. Hydrolysis of 2c gives the organic nitrogen-containing product PyNHCONHPh (5). Moreover, 3c can also be obtained by the reaction of 2c with PhNCO. These results demonstrate that the diinsertion of PhN=C=O into the N-H bond of coordinated amino ligands might proceed in a stepwise manner. All the compounds were characterized by elemental analysis and spectroscopic properties. The structures of compounds 3a-e and 4 are also determined through X-ray single-crystal diffraction analysis.

Precursor approach to lanthanide dioxo monocarbodiimides Ln2O2CN2 (Ln=Y, Ho, Er, Yb) by insertion of CO2 into organometallic Ln-N compounds

We present two organometallic precursor approaches leading to the hitherto-unknown dioxo monocarbodiimides (Ln(2)O(2)CN(2)) of the late lanthanides Ho, Er, and Yb as well as yttrium. One involves insertion of CO(2), and the other one is a straightforward route using a molecular single-source precursor. To this end the reactivity of the activated amido lanthanide compound [(Cp(2)ErNH(2))(2)] towards carbon dioxide absorption under supercritical conditions was studied. Selective insertion of CO(2) into the amido complex yielded the single-source precursor [Er(2)(O(2)CN(2)H(4))Cp(4)], which was characterized by vibrational spectroscopy and thermal and elemental analyses. Ammonolysis of this amorphous compound at 700 degrees C affords Er(2)O(2)CN(2). To gain deeper insight into the structural characteristics of the amorphous precursor, a similar molecular carbamato complex was synthesized and fully characterized. X-ray structure analysis of the dimeric complex [Cp(4)Ho(2){mu-eta(1):eta(2)-OC(OtBu)NH}] shows an unusual bonding mode of the tert-butylcarbamate ligand, which acts as both a bridging and side-on chelating group. Ammonolysis of this compound also yielded dioxo monocarbodiimides, and therefore the crystalline carbamato complex turned out to be an alternative precursor for the straightforward synthesis of Ln(2)O(2)CN(2). Analogously, the dioxo monocarbodiimides of Y, Ho, Er, and Yb were synthesized by this route. The crystal structures were determined from X-ray powder diffraction data and refined by the Rietveld method (Ln=Ho, Er). Further spectroscopic characterization and elemental analysis evidenced the existence of phase-pure products. The dioxo monocarbodiimides of holmium and erbium crystallize in the trigonal space group P[over]3m1. According to X-ray powder diffraction, they adopt the Ln(2)O(2)CN(2) (Ln=Ce-Gd) structure type.

Synthesis and structural characterization of lanthanide complexes with the di- or tri-anionic diguanidinate ligand: new insight into the flexibility and distinct reactivity of the linked diguanidinate ligand

Unprecedented disproportionation and deprotonation of the linked diguanidinate ligand have been established, demonstrating, for the first time, that the number and distribution of negative charges on the diguanidinate ligand are tunable, and representing a new and efficient method for synthesis of linked diguanidinate di- and tri-anion complexes.

Reactivity of Lanthanocene Amide Complexes toward Ketenes: Unprecedented Organolanthanide-Induced Conjugate Electrophilic Addition of Ketenes to Arenes

This paper presents some unusual types of reactions of lanthanocene amide complexes with ketenes, and demonstrates that these reactions are dependent on the nature of amide ligands and ketenes as well as the stoichiometric ratio under the conditions involved. The reaction of [{Cp(2)LnNiPr(2)}(2)] with four equivalents of Ph(2)CCO in toluene affords the unexpected enolization dearomatization products [Cp(2)Ln(OC{2,5-C(6)H(5)(==CPhCONiPr(2)-4)}==CPh(2))] (Ln = Yb (1 a), Er (1 b)) in good yields, representing an unprecedented conjugate electrophilic addition to a non-coordinated benzenoid nucleus. Treatment of [{Cp(2)LnNiPr(2)}(2)] with four equivalents of PhEtCCO under the same conditions gives the unexpected enolization dearomatization/rearomatization products [{Cp(2)Ln(OC{C(6)H(4)(p-CHEtCONiPr(2))}==CEtPh)}(2)] (Ln = Yb (2 a), Er (2 b), Dy (2 c)). However, reaction of [{Cp(2)YbNiPr(2)}(2)] with PhEtCCO in THF forms only the mono-insertion product [Cp(2)Yb{OC(NiPr(2))==CEtPh}](THF) (3). Hydrolysis of 2 afforded aryl ketone PhEtCHCOC(6)H(4)(p-CHEtCONiPr(2)) (4) and the overall formation of aryl ketone 4 provides an alternative route to the acylation of aromatic compounds. Moreover, reaction of [{Cp(2)LnNHPh}(2)] with excess of PhEtCCO or Ph(2)CCO in toluene affords only the products from a formal insertion of the C==C bond of the ketene into the N--H bond, [(Cp(2)Ln{OC(CHEtPh)NPh})(2)] (Ln = Yb (5 a), Y (5 b)) or [(Cp(2)Er{OC(CHPh(2))NPh})(2)] (6), respectively, indicating that an isomerization involving a 1,3-hydrogen shift occurs more easily than the conjugate electrophilic addition reaction, along with the initial amide attack on the ketene carbonyl carbon. [{Cp(2)ErNHEt}(2)] reacts with an excess of PhEtCCO to give [(Cp(2)Er{PhEtCHCON(Et)COCEtPh})(2)] (7), revealing another unique pattern of double-insertion of ketenes into the metal-ligand bond without bond formation between two ketene molecules. All complexes were characterized by elemental analysis and by their spectroscopic properties. The structures of complexes 1 b, 2 a, 2 b, 5 a, 5 b, 6, and 7 were also determined through X-ray single-crystal diffraction analysis.

Unusual modification methods for the ureido ligand of lanthanocene derivatives

(C5H5)2Ln[OC(PzMe2)=NPh](THF) (Ln = Dy (1a), Er (1b), Yb (1c), Y (1d)) were prepared in good yields by the PhNCO insertion into the Ln-N bond of (C(5)H(5))(2)Ln(PzMe(2))(THF) (PzMe(2) = 3,5-dimethylpyrazolate) in THF at room temperature. Treatment of with p-aminothiophenol in THF at room temperature gives unusual ligand-based substitution derivatives {(C5H5)2Ln[mu-eta1:eta3-OC(p-H2NC6H4S)NPh]}2.2THF (Ln = Dy (2a), Er (2b), Yb (2c), Y (2d)), while reaction of 1c with o-aminothiophenol instead of p-aminothiophenol allows the occurrence of a tandem substitution/cyclization/elimination to form unexpected benzothiazole-2-oxide complex [(C5H5)2Yb(mu-eta1:eta3-OSNC7H4)]2 (3c), representing a novel modification method for non-cyclopentadienyl ligands of lanthanocene derivatives. However, complex does not react with benzyl thiol, indicating that the nature of thiols has a profound influence on the substitution reaction. All complexes were characterized by elemental analysis and spectroscopic properties. The X-ray diffraction analysis reveals that and are solvated monomeric structures, while and are centrosymmetric dimeric ones with an unusual intermolecular hydrogen bond interaction involving THF.