2162-74-5Relevant academic research and scientific papers
Copper(I) Complexes of Zwitterionic Imidazolium-2-Amidinates, a Promising Class of Electroneutral, Amidinate-Type Ligands
Márquez, Astrid,ávila, Elena,Urbaneja, Carmen,álvarez, Eleuterio,Palma, Pilar,Cámpora, Juan
, p. 11007 - 11017 (2015)
The first complexes containing imidazolium-2-amidinates as ligands (betaine-type adducts of imidazolium-based carbenes and carbodiimides, NHC-CDI) are reported. Interaction of the sterically hindered betaines ICyCDIDiPP and IMeCDIDiPP [both bearing 2,6-diisopropylphenyl (DiPP) substituents on the terminal N atoms] with Cu(I) acetate affords mononuclear, electroneutral complexes 1a and 1b, which contain NHC-CDI and acetate ligands terminally bound to linear Cu(I) centers. In contrast, the less encumbered ligand ICyCDIp-Tol, with p-tolyl substituents on the nitrogen donor atoms, affords a dicationic trigonal paddlewheel complex, [Cu2(μ-ICyCDIp-Tol)3]2+[OAc-]2 (2-OAc). The nuclear magnetic resonance (NMR) resonances of this compound are broad and indicate that in solution the acetate anion and the betaine ligands compete for binding the Cu atom. Replacing the external acetate with the less coordinating tetraphenylborate anion provides the corresponding derivative 2-BPh4 that, in contrast with 2-OAc, gives rise to sharp and well-defined NMR spectra. The short Cu-Cu distance in the binuclear dication [Cu2(μ-ICyCDIp-Tol)3]2+ observed in the X-ray structures of 2-BPh4 and 2-OAc, ca. 2.42 ?, points to a relatively strong "cuprophilic" interaction. Attempts to force the bridging coordination mode of IMeCDIDiPP displacing the acetate anion with BPh4- led to the isolation of the cationic mononuclear derivative [Cu(IMeCDIDiPP)2]+[BPh4]- (3b) that contains two terminally bound betaine ligands. Compound 3b readily decomposes upon being heated, cleanly affording the bis-carbene complex [Cu(IMe)2]+[BPh4-] (4) and releasing the corresponding carbodiimide (C(=N-DiPP)2).
Synthesis and structure of two new (guanidinate)boron dichlorides and their attempted conversion to boron(i) derivatives
Findlater, Michael,Hill, Nicholas J.,Cowley, Alan H.
, p. 4419 - 4423 (2008)
To test the feasibility of the guanidinate architecture for the support of boron(i) carbene analogues the energy gap between the singlet and triplet states of the model compound, [Me2NC{N(Ph)}2B:] (7), has been probed by both DFT and second order Moller-Plesset (MP2) methods. The singlet state is calculated to be more stable than the triplet state by between 6.0 and 10.1 kcal mol-1. The new (guanidinate)boron dichlorides [Ph2NC{N(Mes)2]BCl2 (14) and [Ph 2NC{N(Dipp)2]BCl2 (15) have been prepared and characterized by single-crystal X-ray diffraction. Attempts to reduce 14 and 15 to the corresponding boron(i) species were not successful.
METHOD FOR PRODUCING CARBODIIMIDES
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Paragraph 0053, (2020/10/31)
The invention relates to a novel method for preparing carbodiimides.
Synthesis of 1,2,4-oxadiazolidines via [3+2] cycloaddition of nitrones with carbodiimides
Chen, Yuan,Fuyue, Liuting,Wang, Gangqiang,Wang, Hang,Lu, Chun,Guo, Haibing,St. Amant, Chiara,Sun, Shaofa,Xing, Yalan
supporting information, p. 4329 - 4332 (2019/03/19)
An efficient [3+2] cycloaddition of nitrones and carbodiimides has been developed. This 1,3-dipolar cycloaddition features high regioselectivity, mild and metal-free conditions, excellent functional group compatibility, and a broad substrate scope. The X-ray structures of two regio-isomers confirmed the regioselectivity of this transformation.
Synthesis, Structure, and Reactivity of Low-Spin Cobalt(II) Imido Complexes [(Me3P)3Co(NAr)]
Liu, Yang,Du, Jingzhen,Deng, Liang
, p. 8278 - 8286 (2017/07/22)
The reactions of [Co(PMe3)4] with the bulky organic azides, DippN3 and DmpN3 [Dipp, 2,6-diisopropylphenyl; Dmp, 2,6-di(2′,4′,6′-trimethylphenyl)phenyl], afforded the cobalt(II) terminal imido complexes [(Me3P)3Co(NAr)] (Ar = Dipp, 1; Dmp, 2). The cobalt imido complexes in their solid states show trigonal pyramidal coordination geometry and long Co-N(imido) separations (ca. 1.71 ?). Spectroscopic characterization and theoretical studies indicated their low-spin cobalt(II) nature. Reactivity studies on 1 revealed its nitrene-transfer reactions with PMe3 and CO, the imido/oxo and imido/sulfido exchange reactions with PhCHO and CS2, and the single-electron oxidation reaction by ferrocenium cation to form cobalt(III) imide.
Metal-free access of bulky: N, N ′-diarylcarbodiimides and their reduction: Bulky N, N ′-diarylformamidines
Peddarao, Thota,Baishya, Ashim,Barman, Milan Kr.,Kumar, Ajay,Nembenna, Sharanappa
, p. 7627 - 7636 (2016/09/12)
A metal-free synthesis of symmetrical and unsymmetrical bulky N,N′-diaryl carbodiimides from the dehydrosulfurisation of their corresponding N,N′-diarylthiourea with 4-dimethylaminopyridine (DMAP) and iodine under mild reaction conditions with moderate to excellent yields has been established. In the literature, the classical method of dehydrosulfurisation of bulky N,N′-diarylthiourea to N,N′-diarylcarbodiimide has been reported using toxic metal oxide (HgO) and magnesium sulphate (MgSO4) under harsh reaction conditions. Furthermore, easy access to 1,3-disubstituted symmetric and unsymmetrical N,N′-diaryl formamidines involving the reaction of symmetrical and unsymmetrical N,N′-diaryl carbodiimides with sodium borohydride is described. The widely used method for the preparation of bulky N,N′-diaryl formamidines is the treatment of primary amines with triethylorthoformate in the presence of acid under high temperature reaction conditions.
Synthesis, characterisation and structural studies of amidinate and guanidinate alkaline earth–transition metal bonded complexes
Green, Ross,Walker, Alicia C.,Blake, Matthew P.,Mountford, Philip
, p. 64 - 75 (2016/08/23)
Reaction of magnesium amidinate complexes of the form [{MesC(NR)2}MgBr(OEt2)]2(R?=?iPr, Dipp, Mes) with the potassium salts of transition metal anions K[CpFe(CO)2] (K[Fp]) and K[Co(CO)3(PCy3)](THF)2gave the complexes {MesC(NR)2}MgFp(THF) and {MesC(NR)2}Mg{Co(CO)3(PCy3)}(THF). Single crystal X-ray diffraction studies of {MesC(NR)2}Mg{Co(CO)3(PCy3)}(THF) for R?=?iPr and Dipp confirm these to have Mg–Co bonds in the solid state. Reaction of the structurally similar magnesium guanidinate complex {Me2NC(NDipp)2}MgI(OEt2) with the aforementioned transition metal anions or K[Co(CO)3(PPh3)](THF) gave the series of complexes [{Me2NC(NDipp)2}MgFp]2, {Me2NC(NDipp)2}Mg{Co(CO)3(PCy3)}(OEt2) and {Me2NC(NDipp)2}Mg{Co(CO)3(PPh3)}(OEt2). Structural authentication by X-ray crystallography showed [{Me2NC(NDipp)2}MgFp]2to be a very rare example of a base-free alkaline earth–transition bonded complex, having two Mg–Fe bonds. IR and diffusion NMR spectroscopy was carried out to gain further insight into the solid state and solution phase structures.
Efficient synthesis of aluminium-terminated polyethylene by means of irreversible coordinative chain-transfer polymerisation using a guanidinatotitanium catalyst
Obenauf, Johannes,Kretschmer, Winfried P.,Kempe, Rhett
, p. 1446 - 1453 (2014/04/03)
A series of guanidinato-ligand-stabilised titanium complexes has been synthesised and characterised. These compounds can be prepared by carbodiimide insertion into titanium-amide bonds. Reaction of carbodiimides N,N′-bis(2,6-diisopropylphenyl)carbodiimide, N,N′-bis(2,6- dimethylphenyl)carbodiimide and N-tert-butyl-N′-(2,6-diisopropylphenyl) carbodiimide (2a-2c, respectively) with [(Et2N)TiCl3] led to mono(guanidinato)trichloridotitanium(IV) complexes (3a-3c). Subsequent conversion with methylmagnesium chloride gave the corresponding trimethyl complexes (4a and 4b). Single-crystal X-ray diffraction analyses were carried out for all complexes. Compound 4a showed very high activities in the polymerisation of ethylene in the presence of very high amounts of triethylaluminium and undergoes polymeryl chain transfer to aluminium. Irreversible coordinative chain-transfer polymerisation and a unique combination of catalyst economy and high activity were observed. In the presence of 1000 equivalents of aluminium, a chain elongation of 83.3 % could be achieved with an activity of 9900 kgPE molcat-1 h-1 bar-1. The influence of the steric demand of the ligand on the polymerisation capability is significant and was investigated too. A series of novel mono(guanidinato)titanium(IV) complexes has been synthesised and characterised. Single-crystal analyses were performed for all complexes. Compound 4a showed very high activities in the polymerisation of ethylene in the presence of very high amounts of aluminium after activation with fluorinated borates. Irreversible coordinative chain transfer to aluminium was observed. Copyright
Efficient synthesis of aluminium-terminated polyethylene by means of irreversible coordinative chain-transfer polymerisation using a guanidinatotitanium catalyst
Obenauf, Johannes,Kretschmer, Winfried P.,Kempe, Rhett
, p. 1446 - 1453 (2015/04/27)
A series of guanidinato-ligand-stabilised titanium complexes has been synthesised and characterised. These compounds can be prepared by carbodiimide insertion into titanium-amide bonds. Reaction of carbodiimides N,N′-bis(2,6-diisopropylphenyl)carbodiimide, N,N′-bis(2,6-dimethylphenyl)carbodiimide and N-tert-butyl-N′-(2,6-diisopropylphenyl)carbodiimide (2a-2c, respectively) with [(Et2N)TiCl3] led to mono(guanidinato)trichloridotitanium(IV) complexes (3a-3c). Subsequent conversion with methylmagnesium chloride gave the corresponding trimethyl complexes (4a and 4b). Single-crystal X-ray diffraction analyses were carried out for all complexes. Compound 4a showed very high activities in the polymerisation of ethylene in the presence of very high amounts of triethylaluminium and undergoes polymeryl chain transfer to aluminium. Irreversible coordinative chain-transfer polymerisation and a unique combination of catalyst economy and high activity were observed. In the presence of 1000 equivalents of aluminium, a chain elongation of 83.3 % could be achieved with an activity of 9900 kgPE molcat-1 h-1 bar-1. The influence of the steric demand of the ligand on the polymerisation capability is significant and was investigated too. A series of novel mono(guanidinato)titanium(IV) complexes has been synthesised and characterised. Single-crystal analyses were performed for all complexes. Compound 4a showed very high activities in the polymerisation of ethylene in the presence of very high amounts of aluminium after activation with fluorinated borates. Irreversible coordinative chain transfer to aluminium was observed.
Novel synthesis of 2,4-dihydro-5-amino[1,2,4]triazol-3-ones from 1,3-disubstituted thioureas
Jin, Can,Liu, Chuangwei,Su, Weike
body text, p. 607 - 610 (2009/07/01)
A facile two-step synthesis of 2,4-dihydro-5-amino-[1,2,4]triazol-3-ones is described. Firstly, 1,3-disubstituted thioureas reacted with bis(trichloromethyl) carbonate (BTC) in the presence of a base such as NaHCO3 to form the intermediate 4-(a
