Komplexbildung und selektive Cyclisierung substituierter Oxalamidine

Döring, Manfred; Fehling, Peer; Görls, Helmar; Imhof, Wolfgang; Beckert, Rainer; Lindauer, Dirk

doi:10.1002/(sici)1521-3897(199911)341:8<748::aid-prac748>3.3.co;2-a

Cited by 5 publications

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“…In addition to the resonances of the coordinated THF (at δ ) 1.17 and 3.53 ppm), only one signal for the methyl groups bound to the metal center was observed, which gives rise to a singlet at δ ) -0.80 ppm in the 1 H NMR spectrum and to a signal at δ ) -5.3 ppm in the 13 C NMR spectrum. Since also only one signal at δ ) 2.17 ppm was observed in the 7 Li NMR spectrum of 5 in benzene-d 6 , we can assume that the THF ligands coordinated to two of the four Li atoms undergo a rapid exchange at room temperature.…”

Section: Resultsmentioning

confidence: 96%

“…3 Recently, complexes of the type Cp 2 Ti(oxam)-Mo(CO) 4 have been synthesized and structurally characterized by Do ¨ring and Beckert. 4 Moreover, coordination compounds containing oxam ligands are also relatively rare [5][6][7][8] since the ligands tend to form illdefined coordination polymers. 9 In this article we describe the synthesis and structures of the first dinuclear organometallic compounds in which an oxam ligand acts as bridge between two organometallic R-Ni(II) fragments (R ) Me, Ph, HCtC, PhCtC) (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

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Dinuclear [RNi(oxam)NiR] Complexes (oxam = N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]₂Li₂Ni₂Me₈ and [Li(THF)]₄Ni₂Me₈

2001

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The reaction between 1 equiv of [{(acac)Ni} 2 (A)] and 2 equiv of LiR in THF afforded the binuclear organometallic complexes [(RNi) 2 (A)] (A: N 1 ,N 2 -bis(2-pyridylmethyl)-N 3 ,N 4 -bis-(2,4,6-trimethylphenyl)oxalamidinate; 1: R ) Me; 2: R ) Ph). Analogously, 3b (R ) CtC-H was formed from [{(acac)Ni} 2 (A)] and sodium acetylide. The reaction of 1 with phenylacetylene resulted in the formation of complex 3a (R ) CtC-Ph), accompanied by the evolution of methane. Compounds 1-3 were characterized by 1 H and 13 C NMR spectroscopy, elemental analysis, and mass spectroscopy. In addition, the molecular structures of 1 and 3b were determined by X-ray crystallography. The NMR spectra of the complexes showed very simple patterns, thus indicating that only one isomer is present in solution containing a highly symmetrical structure with planar Ni(II) centers. X-ray studies confirmed that two Ni(II) centers are connected via the oxalamidinato bridge A, which coordinates in a tridentate fashion at each Ni atom. The fourth position at the metal center is occupied by the organic groups R. Compound 1 reacts with an excess of LiMe in THF, yielding [Li(THF)] 2 Li 2 Ni 2 Me 8 (5). Upon recrystallization, the THF-enriched complex [Li(THF)] 4 Ni 2 Me 8 (6) was isolated. Both complexes were characterized by X-ray crystallography and 1 H/ 13 C NMR spectroscopy. Both 5 and 6 are highly symmetrical compounds in which each planar Ni(II) center is surrounded by four methyl groups. The Ni‚‚‚Ni separations are relatively long (3.167(1) and 3.142(1) Å, respectively), reflecting the absence of a metal-metal bond between those two metal centers. Furthermore, agostic Li-H interactions stabilize the structure in a way similar to that in the corresponding Cr(II) compound [Li 4 (THF) 4 Cr 2 Me 8 ], in which very short contacts have been found (Cr‚‚‚Cr distance 1.968(2) Å).

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Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Dinuclear [RNi(oxam)NiR] Complexes (oxam = N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]₂Li₂Ni₂Me₈ and [Li(THF)]₄Ni₂Me₈

2001

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“…Yield: 1.75 g (79%). 13 The red-orange complex 1b was prepared by reaction of 1a in THF with equimolar amounts of NaBF 4 Single crystals of these complexes, suitable for an X-ray diffraction analysis, were obtained from THF or toluene.…”

Section: Methodsmentioning

confidence: 99%

Simultaneous Cation/Anion Coordination by Bifunctional 1,2-Diimine/1,2-Diamine Type Ligands: Synthesis, Structures, and Properties of Tight Ion Pair Complexes of Ruthenium and Iron

Rau

Böttcher

Schebesta

et al. 2002

Eur. J. Inorg. Chem.

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The reaction between [(η 6 -p-cymene)RuCl 2 ] 2 and tetra-p-tolyloxalic amidine (oxam1) results in a coupled cation/anion coordination forming the ion-paired complex [(η 6 -p-cymene)RuCl(oxam1)Cl] (1a). According to an X-ray single crystal diffraction analysis the Ru moiety is coordinated at the 1,2-diimine part yielding a five-membered chelate ring. Furthermore, the 1,2-diamine group on the opposite side binds to a chloride anion via two N−H groups. Exchange of the chloride anion by trifluoractetate yields [(η 6 -p-cymene)RuCl(oxam1)CF 3 CO 2 ] (1c) in which the C=O group is bonded to the diamine part. Similarly, bis(mesityl)bis(pyridylmethyl)oxalic amidine (oxam2) reacts with FeX 2 to yield the ion-paired complexes 3a (X: Cl), and 3b (X: Br). X-ray diffraction studies of both compounds reveal that the oxalic amidine ligand acts as a four-dentate chelating ligand. One halide is fixed in the same way as in 1a. The complex 1a

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“…To date, a few of oxalamidino complexes of transition and main metals have been developed. [2][3][4][5][6][7] Most of these published complexes were synthesized by the deprotonation reaction of oxalic amidines with corresponding metal complexes [2][3][4][5][6][7] or by transmetallation reaction. 6 Only one example in the literature has been synthesized through reductive coupling of carbodiimine by dicarbonylbis-(cyclopentadienyl)titanium(II).…”

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A first oxalamidino complex of samarium via reduction-coupling of carbodiimine: synthesis and molecular structure of [η⁴-C₂(NR)₄][(MeC₅H₄)₂Sm(HMPA)]₂·2THF (R = Prⁱ, Cy)

et al. 2004

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Komplexbildung und selektive Cyclisierung substituierter Oxalamidine

Cited by 5 publications

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Dinuclear [RNi(oxam)NiR] Complexes (oxam = N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]₂Li₂Ni₂Me₈ and [Li(THF)]₄Ni₂Me₈

Dinuclear [RNi(oxam)NiR] Complexes (oxam = N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]₂Li₂Ni₂Me₈ and [Li(THF)]₄Ni₂Me₈

Simultaneous Cation/Anion Coordination by Bifunctional 1,2-Diimine/1,2-Diamine Type Ligands: Synthesis, Structures, and Properties of Tight Ion Pair Complexes of Ruthenium and Iron

A first oxalamidino complex of samarium via reduction-coupling of carbodiimine: synthesis and molecular structure of [η⁴-C₂(NR)₄][(MeC₅H₄)₂Sm(HMPA)]₂·2THF (R = Prⁱ, Cy)

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Komplexbildung und selektive Cyclisierung substituierter Oxalamidine

Cited by 5 publications

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Dinuclear [RNi(oxam)NiR] Complexes (oxam = N1,N2-bis(2-pyridylmethyl)-N3,N4-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]2Li2Ni2Me8 and [Li(THF)]4Ni2Me8

Dinuclear [RNi(oxam)NiR] Complexes (oxam = N1,N2-bis(2-pyridylmethyl)-N3,N4-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]2Li2Ni2Me8 and [Li(THF)]4Ni2Me8

Simultaneous Cation/Anion Coordination by Bifunctional 1,2-Diimine/1,2-Diamine Type Ligands: Synthesis, Structures, and Properties of Tight Ion Pair Complexes of Ruthenium and Iron

A first oxalamidino complex of samarium via reduction-coupling of carbodiimine: synthesis and molecular structure of [η4-C2(NR)4][(MeC5H4)2Sm(HMPA)]2·2THF (R = Pri, Cy)

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Dinuclear [RNi(oxam)NiR] Complexes (oxam = N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]₂Li₂Ni₂Me₈ and [Li(THF)]₄Ni₂Me₈

Dinuclear [RNi(oxam)NiR] Complexes (oxam = N¹,N²-bis(2-pyridylmethyl)-N³,N⁴-bis(2,4,6-trimethylphenyl)oxalamidinate; R = Me, Ph, C⋮CH, C⋮CPh): Reactions of the Methyl Complex and Formation of [Li(THF)]₂Li₂Ni₂Me₈ and [Li(THF)]₄Ni₂Me₈

A first oxalamidino complex of samarium via reduction-coupling of carbodiimine: synthesis and molecular structure of [η⁴-C₂(NR)₄][(MeC₅H₄)₂Sm(HMPA)]₂·2THF (R = Prⁱ, Cy)