Titanium ferrocenyl-phosphinimide complexes

Ramos, Alberto; Stephan, Douglas W.

doi:10.1039/b918919j

Cited by 16 publications

(10 citation statements)

References 63 publications

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“…We reasoned that terminal PN coordination to kinetically labile, late first row transition metals would be enforced via the incorporation of such ligands into a rigid, multidentate framework. To date, however, very few multidentate PN scaffolds have been prepared, and these suffer from pronounced flexibility and concomitant ambiguity in their metal coordination chemistry. − Hence, a tris-PN pro-ligand (H 3 R L) based on a rigid triarylbenzene backbone was designed (Scheme A). Using a similar backbone, tris-alkoxide, -siloxide, and -carboxylate variants have been described, − and tris-phosphine precursors (Int1) bearing phenyl- or adamantyl substituents are readily prepared (Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

et al. 2021

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Terminal, π-basic moieties occupy a prominent position in the stabilization of unusual or reactive inorganic species. The electron-releasing, π-basic properties of phosphinimides (PN) have been employed to stabilize electron-deficient early transition metals and lanthanides. In principle, a ligand field comprised of terminal PN groups should enable access to high-valent states of late first row transition metals. Herein, we report a new class of multidentate phosphinimide ligands to logically explore this hypothesis. Access to such ligands is made possible by a new procedure for the electrophilic amination of rigid, sterically encumbering, multidentate phosphines. Such frameworks facilitate terminal PN coordination to cobalt as demonstrated by the synthesis of a trinuclear CoII 3 complex and a homoleptic, three-coordinate CoIII complex. Interestingly, the CoIII complex exhibits an exceedingly rare S = 2 ground state. Combined XRD, magnetic susceptibility, and DFT studies highlight that terminally bound PNs engage in strong dπ–pπ interactions that present a weak ligand field appropriate to stabilize high-spin states of late transition metals.

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Section: Resultsmentioning

confidence: 99%

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

et al. 2021

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“…Reactions of [Ti(η 5 -C 5 Me 4 SiMe 2 Cl)Cl 3 ] (1) with Diamines NHR(CH 2 ) n NR 0 R 00 (n g 3). Treatment of 1 with an equimolar amount of diamine NH 2 (CH 2 ) n NH 2 (n = 3, 4), in aromatic solvents and in the presence of 2 equiv of NEt 3 , resulted in the formation of the tethered dimetallic cyclopentadienyl-silyl-amido complexes [Ti{η 5 -C 5 Me 4 SiMe 2 -κ-N(CH 2 ) n/2 -}Cl 2 ] 2 (n = 3, 2a; 4, 2b) along with a small amount (in a molar ratio < 10%, as revealed by NMR) of the corresponding mononuclear cyclopentadienyl-silyl-amido derivatives [Ti{η 5 -C 5 Me 4 SiMe 2κ-N(CH 2 ) n NH 2 }Cl 2 ] (n = 3, 3a; 4, 3b) with a pendant amino functionality (Scheme 1). This result is in sharp contrast to that achieved using different shorter carbon chain ethylenediamines, H 2 N(CH 2 ) 2 NRR 0 , where the corresponding mononuclear constrained-geometry complexes are regioselectively formed.…”

Section: ' Resultsmentioning

confidence: 99%

“…5 -C 5 Me 4 SiMe 2 -K-N(CH 2 ) 3 NMe 2 }Cl 2 ] (8). the procedure for the synthesis of 7, using NH 2 (CH 2 ) 3 NMe 2 (0.34 mL, 2.72 mmol), compound 8 was obtained in 78% yield.Anal.…”

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confidence: 99%

Reactions of [Ti(η⁵-C₅Me₄SiMe₂Cl)Cl₃] with Diamines, a Suitable Approach to Prepare Mono- and Dinuclear Cyclopentadienyl-silyl-amido Titanium Complexes with Constrained and Unstrained Structures

et al. 2011

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Complex [Ti(η5-C5Me4SiMe2Cl)Cl3] (1) reacts with NH2(CH2) n NH2 (n = 3, 4), under appropriate reaction conditions, to yield the corresponding di- and mononuclear constrained-geometry cyclopentadienyl-silyl-amido complexes [Ti{η5-C5Me4SiMe2-κ-N(CH2) n/2}Cl2-]2 (n = 3, 2a; 4, 2b) and [Ti{η5-C5Me4SiMe2-κ-N(CH2) n NH2}Cl2] (n = 3, 3a; 4, 3b). Complexes 2a and 2b are obtained as pure compounds when the reaction is carried out in a 1(Ti):1.5(diamine) molar ratio, while the derivatives 3 cannot be selectively prepared. Treatment of 1 with NH2(CH2)5NH2 gives the dinuclear derivative [Ti{η5-C5Me4SiMe2-κ-N(CH2)2.5-}Cl2]2 (2c) as a single complex, regardless of the reaction stoichiometry. On monitoring these reactions by NMR spectroscopy, the formation of the transient asymmetrical dinuclear complexes [TiCl2{η5-C5Me4SiMe2-κ-N(CH2) n NH-η5-C5Me4SiMe2}TiCl3] (n = 3, 4a; 4, 4b; 5, 4c) is observed. The analogue dinuclear complex [TiCl2{η5-C5Me4SiMe2-κ-N(CH2)3NMe-η5-C5Me4SiMe2}TiCl3] (6) is synthesized, on a preparative scale, by treatment of 1 with an equimolar amount of N-methylpropylenediamine, which is transformed into the mononuclear derivative [Ti{η5-C5Me4SiMe2-κ-N(CH2)3NHMe}Cl2] (7) upon addition of a further equivalent of the diamine. However, treatment of 1 with 1 equiv of N-methylpropylenediamine proceeds with the formation of the mononuclear constrained-geometry compound [Ti{η5-C5Me4SiMe2-κ-N(CH2)3NHMe·HCl}Cl2] (5). The reaction of 1 with 2 equiv of NH2(CH2)3NMe2 or NHMe(CH2)3NMe2 specifically affords, respectively, a mononuclear cyclopentadienyl-silyl-amido derivative with constrained geometry, [Ti{η5-C5Me4SiMe2-κ-N(CH2)3NMe2}Cl2] (8), or unconstrained geometry, [Ti{η5-C5Me4SiMe2NMe(CH2)3-κ-NMe}Cl2] (9). When the reaction with NHMe(CH2)3NHMe is monitored by NMR spectroscopy, the mononuclear intermediate [Ti{η5-C5Me4SiMe2NMe(CH2)3NHMe}Cl3] (11) and the dinuclear complex [Ti{η5-C5Me4SiMe2NMe(CH2)1.5-}Cl3]2 (12) are observed. The dinuclear complex [Ti{η5-C5Me4SiMe2NMe(CH2)3-}Cl3]2 (13) is synthesized by treatment of 1 with 1 equiv of NHMe(CH2)6NHMe. All the reported compounds were characterized by the usual analytical and spectroscopic methods, and the crystal structure of 9 has been determined by X-ray diffraction methods.

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“…Bidentate phosphinimine ligands, which have seen substantially increased use in recent years, were utilized to support a wide range of metals,1 including early2 and late transition metals,3 rare‐earth metals,4 main group elements,5 and a variety of zinc complexes 6. The diverse applications found for these species include olefin polymerization,2a ring‐opening polymerization of lactones,4a,4b,6e and hydroamination 4d. We have been studying chemically robust, formally neutral phosphinimine ligand architectures for stabilizing cationic divalent metal atoms 7.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structural Diversity of ZnCl₂ and Zn(C₆F₅)₂ Complexes of a Phosphinimine Ligand

Wheaton

Ireland

Hayes

2011

Zeitschrift anorg allge chemie

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Zinc complexes of the potentially bidentate neutral monophosphinimine ligand 4‐(ArN=PPh2)dibenzofuran were prepared. Two derivatives of this framework were studied, which differ in the steric demand of the N‐aryl group (Ar = Dipp, Mes). The ligand interacts with diethylzinc in solution but does not form a tightly bound complex, whereby the degree of association is found to be dependent on temperature. However, isolable complexes are formed upon reaction with the more Lewis acidic precursors ZnCl2 and Zn(C6F5)2. In this way, the ZnCl2 complexes 1 and 2 and Zn(C6F5)2 complexes 3 and 4 were prepared and structurally characterized. The nuclearity of 1 and 2 was shown to depend on the bulk of the ligand. Furthermore, the strength of the bonding interaction between the zinc atoms and the dibenzofuran oxygen atoms in 3 and 4 also depends on the choice of ancillary ligand. Attempts to further derivatize these complexes were unsuccessful, and thus, functionalization of the complex LZnEt(OTf) was undertaken instead, resulting in formation of the novel linear trinuclear complex 5.

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Titanium ferrocenyl-phosphinimide complexes

Cited by 16 publications

References 63 publications

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

Reactions of [Ti(η⁵-C₅Me₄SiMe₂Cl)Cl₃] with Diamines, a Suitable Approach to Prepare Mono- and Dinuclear Cyclopentadienyl-silyl-amido Titanium Complexes with Constrained and Unstrained Structures

Synthesis and Structural Diversity of ZnCl₂ and Zn(C₆F₅)₂ Complexes of a Phosphinimine Ligand

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Titanium ferrocenyl-phosphinimide complexes

Cited by 16 publications

References 63 publications

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

High Spin Cobalt Complexes Supported by a Trigonal Tris(Phosphinimide) Ligand

Reactions of [Ti(η5-C5Me4SiMe2Cl)Cl3] with Diamines, a Suitable Approach to Prepare Mono- and Dinuclear Cyclopentadienyl-silyl-amido Titanium Complexes with Constrained and Unstrained Structures

Synthesis and Structural Diversity of ZnCl2 and Zn(C6F5)2 Complexes of a Phosphinimine Ligand

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Reactions of [Ti(η⁵-C₅Me₄SiMe₂Cl)Cl₃] with Diamines, a Suitable Approach to Prepare Mono- and Dinuclear Cyclopentadienyl-silyl-amido Titanium Complexes with Constrained and Unstrained Structures

Synthesis and Structural Diversity of ZnCl₂ and Zn(C₆F₅)₂ Complexes of a Phosphinimine Ligand