Synthesis and characterization of a 2-chloro-1,3,2-diaza-phospholidine-4,5-diimine

Mourgas, Georgios; Benkő, Zoltán; Förster, Daniela; Nieger, Martin; Gudat, Dietrich

doi:10.3998/ark.5550190.0013.206

Cited by 3 publications

(5 citation statements)

References 15 publications

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“…A closer look reveals, however, that N- and P-bound ligands differ not only in the cisoid rather than transoid arrangement of the “flaps” of the two envelope shaped six-membered rings but show also some significant deviations in bond distances. The carbon–nitrogen distances in the amidine units of P-bound ligands are similar as in diazaphospholidine–4,5-diimines 2a , b , and fall into two clearly separated ranges, thus allowing to localize “amine” bonds with prevalent single bond character (C–N 1.36–1.42 Å), and “imine” bonds with prevalent double bond character (CN 1.24–1.30 Å). Comparable values were also observed for the N,N′-bound ligands in transition metal complexes of 2a , b , whereas complexes [( 2b )SnCl 4 ] and 9 reveal some equalization of amine (1.328–1.350 Å) and imine bonds (1.287–1.298 Å), and both types of bonds become finally indistinguishable within experimental error in 10·AsCl 3 (1.303 and 1.308 for amine vs 1.313 and 1.320 Å for imine bonds).…”

Section: Resultsmentioning

confidence: 93%

“…The reaction with PCl 3 produced according to a 31 P NMR spectroscopic assay a mixture of two phosphorus-containing products neither of which could be separated or isolated in pure form. One product was readily identified as the known Me 2 NPCl 2 (δ 31 P = 164) whereas the second species displays a similar 31 P chemical shift (δ 31 P = 130) as 2a (δ 31 P = 134.6 8 ) and was on this basis formulated as P-chloro phosphine 4b (Scheme 1). Formation of both products is consistently explained as resulting from a similar ring metathesis reaction as had previously been observed in the reaction of 2b with PBr 3 .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…By analogy to the synthesis of 2 , , tricyclic target compounds 4 , 5 should in principle be accessible starting from appropriate cyclic oxalamidines like octahydro-bipyrimidine ( 6 ; see Scheme ) or 2,2′-bi-imidazoline, respectively. Anticipating that a ring system of three anellated five-membered rings exhibits substantial geometrical constraints which might limit the metal coordination ability of the diimine unit, we chose conformationally more flexible 6 for our further studies.…”

Section: Resultsmentioning

confidence: 99%

“…31 P{ 1 H} NMR (CDCl 3 ): δ = 103.9 (s, 1 J PW = 333 Hz). 1 13 C NMR (CDCl 3 ) δ = 19.9 (d, 3 J PC = 5.0 Hz, C-5/5′), 36.2 (d, 2 J PC = 7.6 Hz, NCH 3 ), 38.6 (d, 2 J PC = 8.4 Hz, C-6/6′), 44.2 (d, 4 J PC = 0.7 Hz, C-4/4′), 144.9 (d, 2 9-Dimethylamino-4,4′,8a,8a′-tetraaza-9-phospha-2,3,6,7,8,8a,9,9a-octahydro-1H-fluorene-cyclopentadienylcobalt carbonyl (8). CpCo(CO) 2 (903 mg, 5.0 mmol) was added via syringe to a solution of 4a (1.00 g, 4.2 mmol) in toluene (50 mL).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The ligands used to date lack any functional modification of their heterocyclic rings, making thus the phosphorus atom the only metal binding site. We have recently introduced 1,3,2-diazaphospholidine-4,5-diimines 2 , which combine the P -donor function with two imine moieties that are part of an oxalamidine unit. Oxalamidines, like diimines in general, form stable chelate complexes with various transition metals, − and the heterocycles 2 are thus potentially ditopic ligands which exhibit two metal binding sites with different characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Conformationally Constrained N-Heterocyclic Phosphine–Diimine with Dual Functionality

et al. 2013

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Condensation of octahydro-2,2'-bipyrimidine with P(NMe2)3 gave a 1,3,2-diazaphospholidine-4,5-diimine 4a in which the "open" (exo/exo) conformation of the diimine unit was enforced by incorporation into a tricyclic molecular backbone. The coordination behavior of this potentially ambident ligand was sampled in reactions with ([(nbd)W(CO)4] and [CpCo(CO)2]) and pnictogen halides ECl3 (E = P, As, Sb). While PCl3 reacted under ring metathesis, all other reactions gave isolable complexes of composition (4a)MLn (MLn = W(CO)5, CpCo(CO), AsCl3, SbCl3); attempted recrystallization of the As-adduct yielded a complex (4a)(AsCl3)2 which was also accessible from reaction of 4a with 2 equiv of AsCl3. Single-crystal X-ray diffraction studies revealed that the ligand in [(4a)W(CO)5] and [(4a)CpCo(CO)] binds through its phosphorus lone-pair; [(4a)SbCl3] and [(4a)(AsCl3)2] contain a T-shaped ECl3 unit which binds to the chelating diimine moiety, and associate further via chloride bridges to give centrosymmetric dimers. Reactions of 4a with excess metal substrates gave no evidence that formation of bimetallic complexes with μ-bridging 1κ(2)(N,N')-2κP-coordination is feasible; the extra AsCl3 moiety in [(4a)(AsCl3)2] avoids this coordination mode by interacting with the peripheral chlorides of the central core. The observed selectivity suggests that ligand 4a specifically addresses transition metal centers with low positive charge and some back-bonding capacity through the phosphorus lone-pair, and electrophiles that behave essentially as "pure" Lewis acids through the diimine unit. This assumption was confirmed by DFT studies which disclosed further that binding of the first metal center deactivates the opposite binding site and thus strongly inhibits the formation of dinuclear complexes.

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Section: Resultsmentioning

confidence: 93%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Conformationally Constrained N-Heterocyclic Phosphine–Diimine with Dual Functionality

et al. 2013

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On the Synthesis and Coordination Properties of N‐Aryl‐substituted 1, 3, 2‐Diazaphospholidine‐4, 5‐diimines

Mourgas

Tiritiris

Nieger

et al. 2013

Zeitschrift anorg allge chemie

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New 1, 3, 2‐diazaphospholidine‐4, 5‐diimines were synthesized by condensation of lithiated oxalamidines with PCl3 or PhPCl2, and characterized by spectral and analytic data. The products react selectively with [(nbd)W(CO)4], [Mo(CO)6], or [(PhCN)2PdCl2] to give stable complexes, in which the heterocycle binds as chelating, bidentate ligand through the nitrogen atoms of the diimine unit. Formation of P‐bound or dinuclear complexes was not observed. Reaction with PCl3 or AsCl3 in the presence of SnCl2 as reducing agent was unspecific. Evidence for the formation of bicyclic products arising from formal [4+1] cycloaddition between the diimine unit and a transient pnictogen(I) species was not obtained, and only a diimine complex of SnCl4 was isolated in moderate yield. Single‐crystal X‐ray diffraction studies reveal that coordination of the diimine unit induces a substantial structural distortion of the ligand framework, which allows to explain the occurrence of substantial 31P coordination shifts despite the absence of a direct metal‐phosphorus bond.

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PCl bond length depression upon coordination of a diazaphosphasiletidine to a group 13 element Lewis acid or a transition metal carbonyl fragment – Synthesis and structural characterization of diazaphosphasiletidine adducts withP-coordination

Gün

Casel

Frank

2017

Zeitschrift Für Naturforschung B

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Three P-chloro-substituted diazaphosphasiletidines, Me2Si(NtBu)2PCl (1) and Me2Si(NtBu)2P(E)Cl (E=BCl3 (2); W(CO)5 (3)), are presented for comparison. 1 was first prepared more than 30 years ago and studied by means of spectroscopic methods, however, no crystal structure has been reported until now. In the presence of the comparatively weak Lewis acid BCl3 and the labile metal carbonyl complex [W(CO)5(THF)], 1 can be easily converted into its corresponding adducts 2 and 3. All products were characterized by single-crystal X-ray diffraction studies. The structures of the new compounds 2 and 3 reveal a remarkable P–Cl bond contraction caused by the coordination of 1 to the Lewis acid or the Lewis acidic W(CO)5 fragment. Although the coordination number of the P atom is increased in 2 and 3, the P–Cl bond length is reduced dramatically, some kind of bond length paradoxon. A computational study suggests that these P–Cl bond shortenings result from a less effective donation of electron density from the lone pairs at the nitrogen atoms to the antibonding σ*(P–Cl) orbital in 2 and 3 as compared to 1.

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Synthesis and characterization of a 2-chloro-1,3,2-diaza-phospholidine-4,5-diimine

Cited by 3 publications

References 15 publications

Conformationally Constrained N-Heterocyclic Phosphine–Diimine with Dual Functionality

Conformationally Constrained N-Heterocyclic Phosphine–Diimine with Dual Functionality

On the Synthesis and Coordination Properties of N‐Aryl‐substituted 1, 3, 2‐Diazaphospholidine‐4, 5‐diimines

PCl bond length depression upon coordination of a diazaphosphasiletidine to a group 13 element Lewis acid or a transition metal carbonyl fragment – Synthesis and structural characterization of diazaphosphasiletidine adducts withP-coordination

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