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A series of bis(tetramethylaluminate) lanthanide complexes {2-[Ph2P═X]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(AlMe4)2 (X = O, Ln = La (1); X = O, Ln = Nd (2); X = O, Ln = Sm (3); X = S, Ln = La (4); X = S, Ln...

The isolable bis(tetramethylaluminate) lanthanide complexes [2-R2,6-XC6H4NC(tBu)(2,6-R12C6H3)]Ln(AlMe4)2 (R1 = R2 = X = Me, Ln = La (1); R1 = R2 = X = Me, Ln = Nd (2); R1 = iPr, R2 = H, X = OMe, Ln...

In the search for new f–d luminescent complexes of Eu(II) and Yb(II) the metathesis reactions of diiodides of these metals with perfluorinated 2-mercaptobenzothiazolates of alkali metals were studi...

A series of new isolable and thermally stable half-sandwich Ln(II) benzhydryl complexes coordinated by the sterically demanding ligands tert-butylcarbazol-9-yl [tBu4Carb]Ln[(p-tBu-C6H4)2CH](L) (Ln = Sm, L = DME (4); Ln = Yb, L = DME (5); Ln = Yb, L = TMEDA (6)) and 2,7-di-tert-butyl-fluoren-9-trimethylsilylyl [2,7-tBu2-9-Me3Si-C13H6]Yb[(p-tBu-C6H4)2CH](DME) (7) were synthesized by the alkane elimination reaction of [(p-tBu-C6H4)2CH]2Ln(Ln) (Ln = Sm, Yb) with tBu4CarbH and 2,7-tBu2-9-Me3Si-C13H7. X-ray analysis revealed that in 4, 5, and 7 the benzhydryl ligand is coordinated to the metal ion in an η3 coordination mode, while in 6 it is η1-bound. The type of coordination of the benzhydryl ligands in diamagnetic 5–7 is retained in their C6D6 solutions. Complexes 4–7 demonstrated unprecedented thermal stability and do not undergo decomposition after heating their solutions in C6D6 or toluene at 100 °C for 72 h. The reactions of [tBu4Carb]Ln[(p-tBu-C6H4)2CH](DME) (Ln = Sm (4), Ln = Yb (5)) with an excess of D...

A series of alkali-metal alkyl complexes containing a tridentate benzhydryl ligand, [2,2′-(4-MeC6H4NMe2)2CH]Li(TMEDA) (1TMEDA), [2,2′-(4-MeC6H4NMe2)2CH]Na(THF)3 (2THF), {[2,2′-(4-MeC6H4NMe2)2CH]K(THF}2 (3THF), and [2,2′-(4-MeC6H4NMe2)2C(SiMe3)]K (5), were synthesized and structurally characterized. Smaller Li and Na ions form the monomeric complexes 1TMEDA and 2THF featuring η4-CCCN coordination of the [2,2′-(4-MeC6H4NMe2)2CH]− ligand, while the larger K affords the dimeric complex 3THF, in which two different types of metal–ligand bonding, μ-η5-pentadienyl-κ2-NN and μ-κ3-CNN:η6-arene are realized. Application of the Me3Si-substituited analogue [2,2′-(4-MeC6H4NMe2)2C(SiMe3)]− leads to the formation of the 1D coordination polymer {[2,2′-(4-MeC6H4NMe2)2C(SiMe3)]K}∞ (5) with μ-η3:η6 bridging coordination of the ligands to potassium ions.

Two synthetic approaches to the new three-decker Yb(II) complex [CpBn5Yb(DME)]2[μ-C10H8] (1) were successfully employed: the reaction of [CpBn5Yb(DME)(μ-I)]2 (2) with 2 molar equiv of [C10H8]−·K in DME and the reaction of [YbI(DME)2]2[μ-C10H8] (3) with CpBn5K in a 1:2 molar ratio in DME. Complex 1 was proved to be a Yb(II) binuclear triple-decker complex containing a dianionic naphthalene ligand bridging two CpBn5Yb(DME) fragments in a μ-η4:η4 fashion. An oxidative substitution of (C10H8)2– by trans-(1E,3E)-1,4-diphenylbuta-1,3-diene afforded the three-decker Yb(II) complex [CpBn5Yb(DME)]2(μ-η4:η4 -PhCHCHCHCHPh) (4) with a dianionic μ-η4:η4-bridging diphenylbutadiene ligand and naphthalene. The reaction of 1 with excess P4 also occurs with oxidation of (C10H8)2–, whereas Yb remains divalent. The reaction results in the formation of the trinuclear Yb(II) complex with a μ-bridging P73– ligand [CpBn5Yb(DME)]3(P7) (5). Protonation of the Yb–C10H8 bond in 1 with PhPH2 (1:2 molar ratio) afforded the dimeric pho...

The reactions of bis(pyrazolyl)methanes CH2(C3HN2R2-3,5)2 (R = Me, tBu) with Y(CH2SiMe3)3(THF)2 and LY(CH2SiMe3)2(THF)n (L = amidopyridinate (Ap′), amidinate (Amd), tridentate amidinate bearing 2-methoxyphenyl pendant in a side arm (AmdOMe) and pentamethylcyclopentadienyl (Cp*); n = 0, 1) were investigated. CH2(C3HN2tBu2-3,5)2 turned out to be inert in these reactions, while less bulky CH2(C3HN2Me2-3,5)2 easily undergoes metalation by yttrium alkyls. The reaction of Y(CH2SiMe3)3(THF)2 with CH2(C3HN2Me2-3,5)2 regardless of the molar ratio of the reagents affords a homoleptic tris(alkyl) species, Y[CH(C3HN2Me2-3,5)2]3 (1). However, the reactions of equimolar amounts of LY(CH2SiMe3)2(THF)n and CH2(C3HN2Me2-3,5)2 occur selectively with replacement of a sole CH2SiMe3 fragment and afford the related heteroalkyl complexes LY(CH2SiMe3)[CH(C3HN2Me2-3,5)2](THF)n (L = Ap′, n = 1 (6); Amd, n = 0 (7); AmdOMe, n = 1 (8); Cp*, n = 1 (9)) in good yields. The second equivalent of CH2(C3HN2Me2-3,5)2 does not react with het...

Metalation of CpBn5H with PhCH2K (1:1 molar ratio) and subsequent reactions with 0.5 equiv of LnI2(THF)n (Ln = Yb, Sm, Eu, n = 2, 3) (THF, 30 °C, 1 h) afforded new lanthanoidocenes (CpBn5)2Ln (Ln = Yb (1), Sm (2), Eu (3)), which were isolated in reasonable yields. The X-ray diffraction studies revealed that the obtained complexes adopt the structures of bent sandwiches (CpCentr–Ln–CpCentr = 141.8–142.9°). Complexes 1–3 do not contain coordinated Lewis base molecules directly after recrystallization from toluene at ambient temperature; however they feature short contacts between Ln(II) ions and o-carbon atoms of two pendant Ph groups. The reaction of equimolar amounts of YbI2(THF)2 and CpBn5K in DME afforded monocyclopentadienyl Yb(II) complex [CpBn5Yb(DME)(μ-I)]2 (4). Complex 4 proved to be a centrosymmetric iodo-bridged dimer with trans-disposed cyclopentadienyl ligands, and no interactions of the Yb(II) ion with pendant Ph groups were detected. Complexes 1–3 were inert toward Lewis bases (THF, DME, PMe3...

Introduction of four tBu groups into a carbazol-yl framework leads to switching of the metal–ligand bonding in the Ln(II) and Ca complexes from σ to π. Complexes [(tBu4Carb)2Ln] (Ln = Sm, Eu, Yb, Ca) are amido analogues of metallocenes, which adopt the sandwich structures with parallel disposition of the aromatic ligands and strong contribution of η3-mode into η5 metal–ligand bonding. The DFT calculations demonstrated that the geometry is due to steric effects (presence of the bulky tBu groups) as well as the maximization of the overlap between the Sm 4f orbital and the π-type nitrogen lone pair of the carbazol-yl ligand. Coordination of DME to the metal centers in [(tBu4Carb)2M] (M = Sm, Yb) results in the heterolytic dissociation of the metal–ligand π-bond and the formation of ionic complexes [tBu4Carb–]2[Ln2+(DME)n].

Neutral bis(alkyl)-organolanthanide complexes supported by tridentate (N-,N,N) monoanionic 5-methylthiazole- or benzothiazole-amidopyridinate ligands have been prepared and completely characterized: (LThiaMe2)Ln(CH2SiMe3)2 [Ln = Lu3+ (3), Er3+ (7), Yb3+ (8)] and (LBnThMe2)Lu(CH2SiMe3)2 (5). Similarly to related Y3+ systems, the nature of the thiazole unit controls the ultimate catalyst stability in solution. In the diamagnetic Lu3+ complex 5, a progressive and complete rearrangement of its metal coordination sphere takes place through a metal-to-ligand alkyl migration with subsequent benzothiazole ring-opening and generation of the Lu3+ mono(alkyl)-arylthiolate species stabilized by a tetradentate (N-,N,N,S)- dianionic ligand. On the other hand, the 5-methylthiazole containing complexes 3, 7 and 8 showed no evidence of any ligand rearrangement. Complexes 3-8 have been tested as homogeneous catalysts in the isoprene (IP) polymerization, after activation with selected organoborates. Binary systems 3/TB and 7/TB [TB = tritylium tetrakis(pentafluorophenyl)borate] show the highest activity and living character toward the IP polymerization affording polymers with relatively high trans-1,4-selectivity (up to 76.4 %), moderate molecular weights (Mn up to 146 000 g/mol) and narrow polydispersities (Mw/Mn). Depending on the rare-earth ion of choice, a prevalent trans-1,4 (Lu3+, Er3+, Yb3+; up to 76.4 %) or a dominant 3,4 (Y3+; 92.7 %) polymer structure is observed. The influence of the ligand type, metal ion and activator(s) on the ultimate catalyst activity and selectivity are discussed.

The reactions of 2,6-diisopropylaniline with equimolar amounts of alkyl-heteroaryl yttrium complexes containing Y-C(sp3, alkyl) along with Y-C(sp2, heteroaryl) bonds resulting from intramolecular C-H bond activation of the amido-pyridinate ligands [NNOBzFur]YCH2SiMe3(THF)2, [NNSBzTh]YCH2SiMe3(THF)2, and [NNSEtTh]YCH2SiMe3(THF)2 have been scrutinized with the aim of synthesizing yttrium terminal imido species. These reactions occur at ambient temperature with the protonolysis of the Y-C(sp3,alkyl) bond, thus affording anilido-heteroaryl species and maintaining the residual Y-C(sp2, heteroaryl) bond untouched. However, the subsequent transformation of the as-synthesized anilido-heteroaryl complexes depends on the nature of the substituent on the 6-position of the pyridyl ring. In the case of the benzofuryl yttrium derivative [NNOBzFur]YNH-2,6-iPr2C6H3(THF)2 (4), heating to 50 °C results in benzofuran ring opening with the formation of an anilido species supported by a dianionic amido-yne-phenolate ligand framework, [NNC=CO]YNH-2,6-iPr2C6H3(THF) (6). In contrast, a complex containing a benzothiophenyl moiety, [NNSBzTh]YNH-2,6-iPr2C6H3(THF)2 (7), slowly undergoes protonation of the Y-C(sp2, heteroaryl) bond and a ligand redistribution reaction takes place, affording an yttrium bis(anilido) species supported by a monoanionic amido-pyridinate ligand featuring intramolecular Y-S heteroaryl coordination, [NNSBzTh]Y[NH-2,6-iPr2C6H3]2 (9). It is worth noting that an yttrium complex containing ?-thiophenyl fragment, [NNSEtTh]YNH-2,6-iPr2C6H3(THF)2 (10), turned out to be extraordinarily robust and no transformation was ever detected even upon heating the complex at 100 °C for prolonged times.

Oxidation reactions of the Yb(II) hydride [{tBuC(NC6H3-2,6-iPr2)2}Yb(μ-H)]2 (1) with CuCl (1:2 molar ratio) and (PhCH2S)2 (1:1 molar ratio) revealed that the hydrido anion in 1 is a stronger reductant than the Yb(II) cation. Both reactions occur with evolution of H2 and afford the dimeric Yb(II) species [{tBuC(NC6H3-2,6-iPr2)2}Yb(μ-X)]2 (X = Cl (2), SCH2Ph (3)) in which a κ1-amido,η6-arene type of coordination of amidinate ligand is retained. Reaction of 1 with 2 equiv of (PhCH2S)2 results in oxidation of both Yb(II) and hydrido centers and leads to the formation of the Yb(III) complex [{tBuC(NC6H3-2,6-iPr2)2}Yb(μ-SCH2Ph)2]2 (4). Complex 4 can be also synthesized by oxidation of 3 with an equimolar amount of (PhCH2S)2. It was demonstrated that oxidation of the ytterbium center to the trivalent state leads to switching of the coordination mode of amidinate ligand from κ1-amido, η6-arene to “classical” κ1,κ1-N,N-chelating. Unlike Yb(III) bis(alkyl) species supported by bulky amidopyridinate ligands, the rea...

The reactions of bis(trimethylsilylmethyl)yttrium complexes supported by bulky amidopyridinate (Ap) and amidinate (Amd) ligands (LY(CH2SiMe3)2(THF)n: L = Ap, n = 1 (1); L = Amd, n = 1 (2)) with 2,6-diisopropylaniline and phenylacetylene were performed. The reaction of 1 with an equimolar amount of 2,6-diisopropylaniline occurs with TMS elimination and affords an yttrium alkyl anilido species which was isolated as a DME adduct, ApY(CH2SiMe3)(NH-2,6-iPr2C6H3)(DME) (3). The protonolysis of 3 with phenylacetylene results in the alkynyl anilido derivative ApY(C≡CPh)(NH-2,6-iPr2C6H3)(DME) (6). The treatment of complexes 3 and 6 with 2,2′-bipy leads to the formation of the bis(anilido) derivative ApY(NH-2,6-iPr2C6H3)2(bipy) (5). The formation of a dimeric complex containing two ApY fragments linked by two μ2-alkynyl groups and a μ-η2:η2-butatrienediyl fragment, [{AmdY(μ2-C≡CPh)}2(μ2-η2:η2-PhCCCCPh)] (7), was observed in the reaction of 2 with 2 equiv of phenylacetylene.

ansa-Bis(amidinate) ligands with a rigid o-phenylene linker, C6H4-1,2-{NC(tBu)N(2,6-R2C6H3)H}2 (R = Me (1), iPr (2)), were successfully employed for the synthesis of rare-earth chloro and alkyl species. The reaction of dilithium derivatives of 1 and 2 with LnCl3 (Ln = Y, Lu) afforded the monomeric bis(amidinate) chloro lanthanide complexes [C6H4-1,2-{NC(tBu)N(2,6-R2C6H3)}2]Y(THF)(μ-Cl)2Li(THF)2 (R = Me (3), iPr (5)) and [C6H4-1,2-{NC(tBu)N(2,6-Me2C6H3)}2]LuCl(THF)2 (4). Bis(amidinate) ligands in complexes 3 and 4 are coordinated to the metal atoms in a tetradentate fashion, while the bulkier ligand in 5 is tridentate. The alkane elimination reactions of 1 and 2 with equimolar amounts of (Me3SiCH2)3Ln(THF)2 (Ln = Y, Lu) allowed us to obtain the monoalkyl complexes [C6H4-1,2-{NC(tBu)N(2,6-R2C6H3)}2]Ln(CH2SiMe3)(THF)n (Ln = Y, R = Me, n = 1 (6); Ln = Lu, R = Me, n = 1 (7); Ln = Y, R = iPr, n = 2 (8)). The kinetics of thermal decomposition of complexes 6–8 were measured, and for 6 the activation energy was ob...

The reaction of Cp*2Yb(THF)2 with an equimolar amount of 7,7,8,8-tetracyanoquinodimethane (TCNQ) affords the Yb(III) complex [Cp*2Yb(CH3CN){(μ-CN)2C(C6H4)C(CN)2(C5Me5)}]2, containing a monoanionic polycyano ligand arising from one-electron reduction of TCNQ and the coupling of its methylidene carbon with the allylic carbon atom of a Cp* fragment. Reaction of Cp*2Yb(THF)2 with 1,2,4,5-tetracyanobenzene (TCNB) in a 1:1 molar ratio results in oxidation of the ytterbium atom and the formation of the Yb(III) complex [Cp*2Yb{(μ-CN)2(C6H4)(CN)2}]2—the first example of the dianionic π-dimer [TCNB2]2− participating in μ:η4 bonding with two metal centers.

Unprecedented NC bond insertion into the η5 Yb−C9H7 bond occurs in the reaction of 2-(((2,6-diisopropylphenyl)imino)methyl)pyridine with (C9H7)2Yb(THF)2 and affords the Yb(III) derivative [Yb(η5-C9H7){N(2,6-i-Pr2C6H3)CH(C9H7)(C5H4N)}{2,6-i-Pr2C6H3NCH(C5H4N)•-}]. For the complexes Cp2Yb(THF)2 (Cp = C13H9, Cp*) coordinated by bulkier η5 ligands the same reaction results in an oxidative cleavage of the η5 Yb−Cp (Cp = C13H9, Cp*) bond and formation of [Yb{(2,6-i-Pr2C6H5NCH(C5H4N)•-}3] and [Yb(C5Me5){(2,6-i-Pr2C6H3NCH(C5H4N)•-}2], respectively.

The reaction of anhydrous YCl3 with an equimolar amount of lithium N,N‘-dicyclohexyl-N‘ ‘-bis(trimethylsilyl)guanidinate, Li[(Me3Si)2NC(NCy)2], in THF afforded the monoguanidinate dichloro complex [{(Me3Si)2NC(NCy)2}Y{(μ-Cl)2Li(THF)2}(μ-Cl)]2 (1). X-ray diffraction study showed that complex 1 has a bimetallic tetranuclear dimeric core with six μ2-bridging chloro ligands. Treatment of complex 1 with 4 molar equiv of LiCH2SiMe3 in hexane at 0 °C yielded the monomeric salt-free dialkyl complex {(Me3Si)2NC(NCy)2}Y(CH2SiMe3)2(THF)2 (2). The monoguanidinate tetramethyl ate-complex {(Me3Si)2NC(NCy)2}Y[(μ-Me)2Li(TMEDA)]2 (3) was prepared by the reaction of complex 1 with 8 equiv of MeLi in the presence of excess TMEDA in toluene at 20 °C. The complexes 2 and 3 were structurally characterized. Alkylation of complex 1 with t-BuLi (1:4 molar ratio) in hexane resulted in the formation of the bis(guanidinate) alkyl yttrium complex {(Me3Si)2NC(NCy)2}2Y(t-Bu) (4) in 42% yield. The guanidinate ligand redistribution was a...

The (Phenylethynyl)cuprate europium complex {[(PhC⋮C)3Cu][Eu(Py)(THF)2]}2 (1) was synthesized by reaction of Eu with PhC⋮CCu in pyridine. The cuprate ytterbium complex {[(PhC⋮C)3Cu][Yb(THF)2]}2 (2) was synthesized by reaction of Yb with PhC⋮CCu in THF in the presence of a catalytic amount of ytterbium diiodide and also by the reaction of (PhC⋮C)2Yb with PhC⋮CCu.