Postmetallocene Lanthanide–Hydrido Chemistry: A New Family of Complexes [{Ln{(Me3Si)2NC(NiPr)2}2(μ‐H)}2] (Ln=Y, Nd, Sm, Gd, Yb) Supported by Guanidinate Ligands—Synthesis, Structure, and Catalytic Activity in Olefin Polymerization

Trifonov, Alexander A.; Скворцов, Г. Г.; Lyubov, Dmitry M.; Skorodumova, N. A.; Fukin, Georgy K.; Баранов, Е. В.; Glushakova, V. N.

doi:10.1002/chem.200600058

Cited by 104 publications

(48 citation statements)

References 53 publications

(49 reference statements)

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“…21, 22 The guanidinate ligands are observed as the following set of signals: a singlet at δ H 1.42 corresponding to the protons of the Me group of the N(SiMe 3 ) 2 fragment and a doublet (J H-H = 6.4 Hz) at δ H 0.29 corresponding to the Me protons of the isopropyl groups. The signal for the methine protons of the isopropyl groups (δ H = 3.22) partially overlaps with the signal for the β methylene pro tons of the THF molecule (δ H = 3.32).…”

Section: Methodsmentioning

confidence: 99%

Synthesis, molecular structure, and catalytic activity of borohydride complexes [(Me3Si)2NC(NPri)2]2Nd(BH4)2Li(thf)2 and [(Me3Si)2NC(NPri)2]2Sm(BH4)2Li(thf)2

et al. 2007

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The reactions of lanthanide tris(borohydrides) Ln(BH 4 ) 3 (thf) 3 (Ln = Sm or Nd) with 2 equiv. of lithium N,N´ diisopropyl N´ bis(trimethylsilyl)guanidinate in toluene produced the [(Me 3 Si) 2 NC(NPr i ) 2 ]Ln(BH 4 ) 2 Li(thf) 2 complexes (Ln = Sm or Nd), which were isolated in 57 and 42% yields, respectively, by recrystallization from hexane. X ray diffraction experi ments and NMR and IR spectroscopic studies demonstrated that the reactions afford mono meric ate complexes, in which the lanthanide and lithium atoms are linked to each other by two bridging borohydride groups. The complexes exhibit catalytic activity in polymerization of methyl methacrylate.Lanthanide borohydride complexes of the metallocene series have been known for more than three decades. 1 Nevertheless, this class of compounds continues to at tract considerable interest because of the structural diver sity and high catalytic activity. 2 The borohydride groups can serve as both bridging and terminal ligands having different dentation. 3,4 Depending on the ionic radius of the central atom and its coordination environment, boro hydride groups can serve as bi , 1,3-8 tri , 1,9 or tetradentate ligands. 3,4 A renewed interest in lanthanide borohydride complexes has been stimulated by reports on their high catalytic activity in polymerization of lactones, 10,11 me thyl methacrylate, 12 and isoprene. 13 The reactivity of or ganic derivatives of lanthanides depends primarily on the high polarity of the metal-ligand bond and large ionic radii of Ln. Due to this, combined with a large positive charge on the metal center, these compounds are very sensitive to the degree of steric saturation of their coordi nation sphere. Hence, a search for new types of the coor dination environment, which can stabilize lanthanide complexes and modify their reactivity and catalytic activ ity, is an important problem. Until recently, the range of known rare earth metal borohydride complexes has been limited primarily to derivatives of the metallocene se ries. 2 The yttrium bis(amidinate) borohydride complex [PhC(NSiMe 3 ) 2 ] 2 YBH 4 (thf) 14 and lanthanide derivatives containing the polydentate diphenoxide O,O,N,N li gands 11,12 are the only exception. In the synthesis of new lanthanide borohydride complexes, we used tetrasub stituted guanidinate ligands, whose steric and electronic properties can easily be modified by varying substituents at the N atoms. The aim of the present study was to synthesize lanthanide bis(guanidinate) borohydride de rivatives {(Me 3 Si) 2 NC(NPr i ) 2 } 2 Ln(BH 4 ) 2 Li(thf) 2 (Ln = Sm (1) or Nd(2)) and investigate their structures and catalytic activity. Results and DiscussionInitially, we intended to prepare borohydride complexes by the reactions of NaBH 4 with the cor responding bis(guanidinate) chloride derivatives [{(Me 3 Si) 2 NC(NPr i ) 2 } 2 LnCl] 2 (Ln = Nd or Sm). 15,16 The latter are easily produced in the reaction of anhydrous halides LnCl 3 with 2 equiv. of {(Me 3 Si) 2 NC(NPr i ) 2 }Li, which is generated in situ from [(Me 3 Si...

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Section: Methodsmentioning

confidence: 99%

Synthesis, molecular structure, and catalytic activity of borohydride complexes [(Me3Si)2NC(NPri)2]2Nd(BH4)2Li(thf)2 and [(Me3Si)2NC(NPri)2]2Sm(BH4)2Li(thf)2

et al. 2007

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“…The gado linium atom in compound 1 is coordinated by two ni trogen atoms of the chelate guanidinate ligand, two oxy gen atoms of the DME molecule, and two borohydride groups BH 4 (9) plexes, it was noted 18 that the treatment of the products, which were obtained in the reaction of Ln(BH 4 ) 3 (THF) 2 with (Me 3 Si) 2 NC(NR 2 )M (R = Pr i or Cy; M = Li or Na) in a molar ratio of 1 : 2, with 1,2 dimethoxyethane af forded monoguanidinate bis(borohydride) derivatives. We hypothesized that the ligand redistribution occurs dur ing the treatment of the complexes with dimethoxyethane and is provoked by the replacement of monodentate THF in the coordination sphere of the lanthanide atom by bidentate DME.…”

Section: Methodsmentioning

confidence: 99%

“…1 Recently, guanidinate ligands have been successfully used in the chemistry of rare earth metals for the synthesis of highly reactive alkyl and hydride derivatives. [2][3][4][5][6][7][8][9] Lanthanide borohydride complexes are of great interest because of their structural diversity 10 and high catalytic activity in polymerization of lac tones, 11,12 methyl methacrylate, 13 and isoprene. 14 Re cently, we have synthesized and characterized a series of lanthanide bis(guanidinate) borohydride complexes.…”

mentioning

confidence: 99%

Guanidinate borohydride derivatives of lanthanides: synthesis and molecular structures of the [(Me3Si)2NC(NCy)2]Gd(BH4)2DME and [{(Me3Si)2NC(NPri)2}2Sm(BH4)2]−[Li(DME)3]+ complexes. Catalytic activity of the [(Me3Si)2NC(NCy)2]2Ln(BH4)2Li(THF)2 complexes (Ln = Nd, Sm, or Yb) in methyl methacrylate polymerization

et al. 2007

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The reaction of Gd(BH 4 ) 3 (THF) 2 with two equivalents of sodium N,N´ dicyclohexyl N″ bis(trimethylsilyl)guanidinate in THF followed by the treatment of the reaction prod uct with 1,2 dimethoxyethane produced the monoguanidinate bis(borohydride) complex [(Me 3 Si) 2 NC(NCy) 2 ]Gd(BH 4 ) 2 DME (1) (Cy is cyclohexyl). The treatment of the hetero bimetallic samarium complex {(Me 3 Si) 2 NC(NPr i ) 2 } 2 Sm(BH 4 ) 2 Li(THF) 2 , in which the lan thanide and lithium atoms are linked by two bridging borohydride groups, with 1,2 dimethoxy ethane afforded the ionic complex [{(Me 3 Si) 2 NC(NPr i ) 2 } 2 Sm(BH 4 ) 2 ] -[Li(DME) 3 ] + (2). The structures of complexes 1 and 2 were established by X ray diffraction. The [(Me 3 Si) 2 NC(NCy) 2 ] 2 Ln(BH 4 ) 2 Li(THF) 2 complexes (Ln = Nd (3), Sm (4), or Yb (5)) were found to catalyze methyl methacrylate polymerization.Chelate guanidinate ligands have found wide appli cation in coordination and organometallic chemistry as stabilizing groups and were used in the synthesis of a wide range of d transition and main group metal derivatives. 1 Recently, guanidinate ligands have been successfully used in the chemistry of rare earth metals for the synthesis of highly reactive alkyl and hydride derivatives. 2-9 Lanthanide borohydride complexes are of great interest because of their structural diversity 10 and high catalytic activity in polymerization of lac tones, 11,12 methyl methacrylate, 13 and isoprene. 14 Re cently, we have synthesized and characterized a series of lanthanide bis(guanidinate) borohydride complexes. The use of these complexes as initiators for the poly merization of lactides allows the reactions to be per formed at high rate at room temperature under con trolled conditions resulting in the formation of high molecular weight polymers with very low polydisper sity (1.09). 15 Metallocene type borohydride complexes are gener ally synthesized by the reactions of the corresponding chloride derivatives with NaBH 4 or LiBH 4 in tetrahydro furan or diethyl ether. 10 A convenient procedure for the synthesis of both bis(borohydride) and monoborohydride complexes is based on the reactions of lanthanide tris(borohydrides) Ln(BH 4 ) 3 (THF) n with alkali metal salts LM (M = Na or K) of the corresponding ligands. 11,14,16,17 The reactions are completed in 8 h and produce the boro hydride complexes in high yields. As a rule, the alkali metal borohydrides MBH 4 , which are also formed in the reactions, do not complicate the isolation of the target products.Recently, 18 we have found that the reac tions of the bis(guanidinate) chloride derivatives [{(Me 3 Si) 2 NC(NPr i ) 2 } 2 LnCl] 2 (Ln = Nd or Sm) with NaBH 4 are more complex than those of the cyclopenta dienyl derivatives. In some cases, the redistribution of the ligands was observed, producing monoguanidinate bis(borohydride) derivatives instead of the expected bis(guanidinate) borohydride complexes regardless of the ratio of the starting reagents.In the present study, we synthesized new guanidinate borohydride derivatives of ...

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“…178,185,186] , 这些配合物在室温下不稳定, 但可以用于原位制备氢化物 [185] . 在 TMEDA 的存在下, 胍基稀土氯化物与 MeLi 在己烷中反应生成热稳定性较好的盐型配合物 [175,177,187] .…”

Section: β-二亚胺稀土金属有机配合物 β-二亚胺是最为重要的双齿配体unclassified

“…图 31 二胍基稀土烷基配合物的合成 Figure 31 Synthesis of bis(guanidinato) rare-earth metal alkyl complexes [185,186] . 钇的氢化物和含 C-C 多重键的底物不发生加成反应.…”

Section: β-二亚胺稀土金属有机配合物 β-二亚胺是最为重要的双齿配体unclassified

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

Changtao¹,

Wang²,

Chen³

2014

Acta Chim. Sinica

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Rare-earth elements include scandium, yttrium and fifteen lanthanides. Since Wilkinson and Birmingham reported the fist example of rare-earth organometallic complex, the chemistry of rare-earth organometallic complexes has had a great advance during the past sixty years. A variety of Cp containing rare-earth metal complexes, including mono-Cp, bis-Cp, and tri-Cp complexes, have been synthesized. Variation of the size of substituent on Cp ring, introducing the nitrogen or oxygen containing pendant arm to Cp ring or using ansa bis-Cp ligands make the synthesis and stabilization of these three types of rare-earth metal Cp complexes available. The Cp related ligands, such as indenyl and fluorenyl, also have been applied for the rare-earth organometallic complexes. From 1990's, there was a tendency to explore the rare-earth organometallic complexes with ancillary ligands beyond Cp and its derivatives in order to search for more efficient rare-earth metal catalysts. Non-Cp ligands, such as biphenolates, β-diketiminates, amidinates, guanidinates, etc. have been introduced into the chemistry of rare-earth organometallic complexes, and a larger number of non-Cp rare-earth organometallic complexes have been synthesized and characterized. The application of non-cyclopentadienyl ligands not only resulted in the rare-earth organometallic complexes with new structural features, but also the catalysts with high activity and high selectivity for the polymer synthesis and organic synthesis. The rare-earth organometallic complexes catalyze homo-and co-polymerization of olefins as well as specific polymerization of dienes and polar monomers. The discovery of the catalytic system composed of the neutral rare-earth metal dialkyls/borate enables to synthesize some interesting polymers which are difficult to be prepared by using other catalytic system. The rare-earth organometallic complexes are also able to catalyze some important organic reactions, such as hydroamination, hydrophosphinylation, and hydroalkoxylation, etc. Different from the late-translation metal catalyzed organic reactions, most of the rare-earth metal catalyzed ones do not involve oxidative addition and reductive elimination steps. The review describes some important developments of the chemistry of rare-earth organometallic complexes in the past sixty years.

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Postmetallocene Lanthanide–Hydrido Chemistry: A New Family of Complexes [{Ln{(Me₃Si)₂NC(NiPr)₂}₂(μ‐H)}₂] (Ln=Y, Nd, Sm, Gd, Yb) Supported by Guanidinate Ligands—Synthesis, Structure, and Catalytic Activity in Olefin Polymerization

Cited by 104 publications

References 53 publications

Synthesis, molecular structure, and catalytic activity of borohydride complexes [(Me3Si)2NC(NPri)2]2Nd(BH4)2Li(thf)2 and [(Me3Si)2NC(NPri)2]2Sm(BH4)2Li(thf)2

Synthesis, molecular structure, and catalytic activity of borohydride complexes [(Me3Si)2NC(NPri)2]2Nd(BH4)2Li(thf)2 and [(Me3Si)2NC(NPri)2]2Sm(BH4)2Li(thf)2

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

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