Conversion of alkanenitriles to amidines and carboxylic acids mediated by a cobalt(II)–ketoxime system

Kopylovich, Maximilian N.; Kukushkin, Vadim Yu.; Silva, M. Fátima C. Guedes da; Haukka, Matti; Silva, João J. R. Fraústo da; Pombeiro, Armando J. L.

doi:10.1039/b101337h

Cited by 60 publications

(56 citation statements)

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“…8b), phthalocyanines, 8c,17 diacylamides, 18 N-acylamidines, 19 imidic anhydrides, 3 and amidines. 16,20 Our current experiments and the previous data 8a, [17][18][19][20] suggest that the mechanism of the reaction shown in Scheme 3 is not simple and perhaps involves internal generation of ammonia at a nickel(II) center as one of the fast reaction steps.…”

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confidence: 55%

“…Previously, one of us reported the relevant (Co II / oxime)-mediated conversion of nitriles NCR (R = alkyl, aryl) leading to amidines RC(NH 2 )vNH. 16 In the latter transformation, again, the addition of external ammonia does not affect the yield of the formed amidines. Furthermore, the generation of coupling products with in situ generated ammonia was observed upon metal-mediated syntheses of 1,3,5-triazapentadienes (for a review on triazapentadiene complexes see ref.…”

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confidence: 95%

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Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

et al. 2017

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The nitrosoguanidinate complexes [Ni{NH[double bond, length as m-dash]C(NR)NN(O)}] (R = Me1, (CH)O 2, (CH)3, (CH)4, (Me)Ph 5, Ph6, (p-MeCH)7) were obtained in low-to-moderate (12-26%) yields but reproducible yields in an unexpected metal-mediated reaction in MeOH between the nickel salt NiCl·2HO, N,N-disubstituted cyanamides NCNR, and the amidoxime MeC([double bond, length as m-dash]NOH)NH. These complexes were formed along with a spectrum of cyanamide-oxime coupling products. The IR and X-ray data indicate the delocalization within the NNO and NCN systems of the nitrosoguanidinate ligand. This delocalization was additionally confirmed by inspection of Wiberg bond indices for the selected bonds. In the X-ray structure of 5, the rare metallophilic contacts NiNi between stacks of the square-planar complexes were detected and these non-covalent interactions were studied by non-relativistic and relativistic DFT calculations and topological analysis of the electron density distribution within the framework of Bader's theory (QTAIM method). The estimated strength of the NiNi interactions is 1.3-1.9 kcal mol and they are mostly determined by crystal packing effects and weak attractive interactions between adjacent metal centers due to the overlapping of their d and p orbitals.

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confidence: 95%

Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

et al. 2017

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“…The iminoacylation of oximes that is mediated by the inert centers proceeds through intermolecular nucleophilic addition of an oxime to a nitrile ligand, whereas the reaction at the labile centers typically occurs through ligation of an oxime to a metal atom followed by intramolecular nucleophilic attack of the oxime HO group on the CN moiety. It is noteworthy that metal‐mediated reactions between ketoximes and nitriles also occur at Co II[9] and Zn II[10] metal centers, but these lead to amidines,9 carboxamides,10d and 1,2,4‐oxadiazoles,10a,10c,11 with no iminoacylated oximes being detected. However, iminoacylated oximes were postulated as plausible reaction intermediates 8a,10d,11…”

Section: Introductionmentioning

confidence: 99%

Highly Reactive Ni^II‐Bound Nitrile–Oxime Coupling Intermediates Stabilized by Substituting Conventional Nitriles with a Dialkylcyanamide

et al. 2015

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Nickel(II)‐mediated coupling between the cyanamide Me2NCN and the ketoximes Me(R)C=NOH (R = Me, Ph) gives chelates of the general formula [NiClx(H2O)y{HN=C(NMe2)(ON=C(R)Me)}2]n+ ([1]+: R = Me; x = 1, y = 0; salts with both Cl– and [NiCl4]2– were isolated; [2]2+: R = Me; x = 0, y = 2; salt with Cl– was isolated; [3]+: R = Ph; x = 1, y = 1; salt with Cl– was isolated) and the iminium salts [H2N=C(NMe2)ON=C(R)Me]+ ([4]+: R = Me; salt with [NiCl4]2– was isolated; [5]+: R = Ph; salt with Cl– was isolated). This reaction demonstrates the difference in the reactivity between conventional nitriles and dialkylcyanamides: whereas nitriles RCN (R = Alk, Ar) react with NiII/ketoxime systems to afford (1,3,5‐triazapentadiene)NiII species, formed by postulated nitrile–oxime coupling intermediates, cyanamides under the same conditions give either stable cyanamide–oxime coupling products or the Busch‐type complex [Ni{HN=C(Me)CH2C(Me2)NH2}2]Cl2 ([6]Cl2). The reason for the different stability of the coupling products was interpreted theoretically on the basis of quantum chemical calculations (M06‐L/6‐31G* level of theory). The NMe2 moiety in the chelate ligands leads to an increase in electron‐density delocalization and also stabilizes the systems in terms of electrostatic factors.

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“…Similar [Co(MeCN) 4 (X) 2 ] n+ (where X are additional acetonitrile ligands or an oxygen donor ligand) complexes have been characterized in solution [39] using XAS or the solid state [40,41]. In the latter instance, the complex [Co(MeCN) 4 (H 2 O) 2 ] 2+ was crystallized as an inclusion complex, with Co-N bond lengths of 2.124 and 2.101 Å that match well with those observed in 1·Co-ACN (Co-N bond lengths 2.071(8) and 2.115(2) Å).…”

Section: Non-framework-bound Complexes Within Mofmentioning

confidence: 99%

X-ray crystallographic insights into post-synthetic metalation products in a metal–organic framework

Huxley

Coghlan

Bloch

et al. 2017

Phil. Trans. R. Soc. A.

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ResearchCite this article: Huxley MT, Coghlan CJ, Bloch WM, Burgun A, Doonan CJ, Sumby CJ. 2017 X-ray crystallographic insights into post-synthetic metalation products in a metal-organic framework. Post-synthetic modification of metal-organic frameworks (MOFs) facilitates a strategic transformation of potentially inert frameworks into functionalized materials, tailoring them for specific applications. In particular, the postsynthetic incorporation of transition-metal complexes within MOFs, a process known as 'metalation', is a particularly promising avenue towards functionalizing MOFs. Herein, we describe the post-synthetic metalation of a microporous MOF with various transition-metal nitrates. The parent framework, 1, contains free-nitrogen donor chelation sites, which readily coordinate metal complexes in a single-crystal to single-crystal transformation which, remarkably, can be readily monitored by X-ray crystallography. The presence of an open void surrounding the chelation site in 1 prompted us to investigate the effect of the MOF pore environment on included metal complexes, particularly examining whether void space would induce changes in the coordination sphere of chelated complexes reminiscent of those found in the solution state. To test this hypothesis, we systematically metalated 1 with first-row transition-metal nitrates and elucidated the coordination environment of the respective transition-metal complexes using X-ray

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Conversion of alkanenitriles to amidines and carboxylic acids mediated by a cobalt(II)–ketoxime system

Cited by 60 publications

References 32 publications

Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

Highly Reactive Ni^II‐Bound Nitrile–Oxime Coupling Intermediates Stabilized by Substituting Conventional Nitriles with a Dialkylcyanamide

X-ray crystallographic insights into post-synthetic metalation products in a metal–organic framework

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Conversion of alkanenitriles to amidines and carboxylic acids mediated by a cobalt(II)–ketoxime system

Cited by 60 publications

References 32 publications

Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

Metal-mediated reactions between dialkylcyanamides and acetamidoxime generate unusual (nitrosoguanidinate)nickel(ii) complexes

Highly Reactive NiII‐Bound Nitrile–Oxime Coupling Intermediates Stabilized by Substituting Conventional Nitriles with a Dialkylcyanamide

X-ray crystallographic insights into post-synthetic metalation products in a metal–organic framework

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Highly Reactive Ni^II‐Bound Nitrile–Oxime Coupling Intermediates Stabilized by Substituting Conventional Nitriles with a Dialkylcyanamide