Steric control of the reduction of carbodiimides by samarium(ii) and the synthesis of very crowded samarium(iii) complexes

Cole, Marcus L.; Deacon, Glen B.; Forsyth, Craig M.; Junk, Peter Courtney; Polo-Cerón, Dorian; Wang, Jun

doi:10.1039/b922031c

Cited by 32 publications

(27 citation statements)

References 26 publications

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“…or Tianjiao (Baotou, People's Republic of China) as ingots, powders, or rods and stored under nitrogen in a glovebox. [Sm(DippForm) 2 (thf) 2 ] (1), 9 [La(DippForm) 2 F(thf)], 7 tetraphenylcyclopentadiene, 26 [Li(DippForm)(thf) 3 ], 27 Dipp-FormH, 28 and Hg(2-BrC 6 F 4 ) 2 29 were prepared by literature methods. Synthesis of [Sm(DippForm) 2 Cl(thf)] (2).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Bulky Formamidinate-Supported Lanthanoid Halides and Alkyls, Including a Rare Terminal La–Me Species

et al. 2012

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The oxidation of [Sm(DippForm) 2 (thf) 2 ] (1; DippFormH = N,N′bis(2,6-diisopropylphenyl)formamidine) by tert-butyl chloride, 1,2-dibromoethane, and iodine, respectively, at ambient temperature led to the isolation of the light yellow crystalline samarium(III) halide complexes [Sm(DippForm) 2 X(thf)] (2, X = Cl; 3, X = Br; 4, X = I) in good yield. The subsequent metathesis reaction of [Ln(DippForm) 2 X(thf)] (2, Ln = Sm, X = Cl; Ln = La, X = F) with LiMe and LiCH 2 SiMe 3 generated the samarium alkyl complexes [Sm(DippForm) 2 R(thf)] (5, R = Me; 6, R = CH 2 SiMe 3 ) and the rare terminal La−Me complex [La-(DippForm) 2 Me(thf)] ( 7). The attempted ligand exchange reaction of 7 with 1,2,3,4-tetraphenylcyclopentadiene gave, unexpectedly, the homoleptic tris-(formamidinato)lanthanum complex [La(DippForm) 3 ] (8) in very low yield. The redox transmetalation/protolysis (RTP) reaction from samarium metal with bis(2bromo-3,4,5,6-tetrafluorophenyl)mercury and DippFormH in thf yielded the mono(formamidinato)samarium(III) complex [Sm(DippForm)Br 2 (thf) 3 ] (9) as a coproduct with the bis(formamidinate) 3. Redox reaction of the divalent samarium complex [Sm(DippForm) 2 (thf) 2 ] (1) with diphenylmercury resulted in the ethenolate complex [Sm(DippForm) 2 (OCHCH 2 )(thf)] (10) instead of the target Sm−Ph complex, the product resulting from the decomposition of Lewis base thf molecules.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Bulky Formamidinate-Supported Lanthanoid Halides and Alkyls, Including a Rare Terminal La–Me Species

et al. 2012

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“…12 Oxidation studies of rare‐earth metal formamidinate complexes have so far only involved reactions of divalent Yb11c and Sm complexes 12. 13 Currently there is only one example of a cerium formamidinate complex, namely the trivalent [Ce(DippForm) 2 F(thf)] (DippForm= N , N ′‐bis(2,6‐diisopropylphenyl)formamidinate), and its possible oxidation was not examined 11b. Thus, trivalent and tetravalent cerium formamidinate chemistry is still an unexplored area.…”

Section: Introductionmentioning

confidence: 99%

Cerium(III/IV) Formamidinate Chemistry, and a Stable Cerium(IV) Diolate

Werner

Deacon

Junk

et al. 2014

Chemistry A European J

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Four new cerium(III) formamidinate complexes comprising [Ce(p-TolForm)3 ], [Ce(DFForm)3 (thf)2 ], [Ce(DFForm)3 ], and [Ce(EtForm)3 ] were synthesized by protonolysis reactions using [Ce{N(SiMe3 )2 }3 ] and formamidines of varying functionality, namely N,N'-bis(4-methylphenyl)formamidine (p-TolFormH), N,N'-bis(2,6-difluorophenyl)formamidine (DFFormH), and the sterically more demanding N,N'-bis(2,6-diethylphenyl)formamidine (EtFormH). The bimetallic cerium lithium complex [LiCe(DFForm)4 ] was synthesized by treating a mixture of [Ce{N(SiHMe2 )2 }3 (thf)2 ] and [Li{N(SiHMe2 )2 }] with four equivalents of DFFormH in toluene. Oxidation of the trivalent cerium(III) formamidinate complexes by trityl chloride (Ph3 CCl) caused dramatic color changes, although the cerium(IV) species appeared transient and reformed cerium(III) complexes and N'-trityl-N,N'-diarylformamidines shortly after oxidation. The first structurally characterized homoleptic cerium(IV) formamidinate complex [Ce(p-TolForm)4 ] was obtained through a protonolysis reaction between [Ce{N(SiHMe2 )2 }4 ] and four equivalents of p-TolFormH. [Ce{N(SiHMe2 )2 }4 ] was also treated with DFFormH and EtFormH, but the resulting cerium(IV) complexes decomposed before isolation was possible. The new cerium(IV) silylamide complex [Ce{N(SiMe3 )2 }3 (bda)0.5 ]2 (bda=1,4-benzenediolato) was synthesized by treatment of [Ce{N(SiMe3 )2 }3 ] with half an equivalent of 1,4-benzoquinone, and showed remarkable resistance towards protonolysis or reduction.

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“…In a related study, Hill et al have recently shown that the Mg-mediated reaction between alkynes and isocyanates forms bis(imidazolidine-2,4-diones). 5 Carbodiimide insertion into M−C bonds of terminal acetylides to afford the corresponding propargylamidinate has been documented for Li, 6 K, 7 Ca, 8 Y, 9 Sm, 10 Yb, 9a Lu, 9a and U. 11 Several compounds produce the C−C coupled product catalytically, 6a,8,9c,12 with the most extensively studied system promoted by {Me 2 Si(C 5 Me 4 )(NPh)}Y(CH 2 SiMe 3 )(THF).…”

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“…Carbodiimide insertion into M–C bonds of terminal acetylides to afford the corresponding propargylamidinate has been documented for Li, K, Ca, Y, Sm, Yb, Lu, and U . Several compounds produce the C–C coupled product catalytically, ,,, with the most extensively studied system promoted by {Me 2 Si(C 5 Me 4 )(NPh)}Y(CH 2 SiMe 3 )(THF) .…”

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Catalytic C–C Bond Formation Promoted by Organo- and Amidomagnesium(II) Compounds

Schwamm

Coles

2013

Organometallics

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Steric control of the reduction of carbodiimides by samarium(ii) and the synthesis of very crowded samarium(iii) complexes

Cited by 32 publications

References 26 publications

Bulky Formamidinate-Supported Lanthanoid Halides and Alkyls, Including a Rare Terminal La–Me Species

Bulky Formamidinate-Supported Lanthanoid Halides and Alkyls, Including a Rare Terminal La–Me Species

Cerium(III/IV) Formamidinate Chemistry, and a Stable Cerium(IV) Diolate

Catalytic C–C Bond Formation Promoted by Organo- and Amidomagnesium(II) Compounds

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