Zirconium complexes containing a diarylamido diphosphine ligand: Structural preferences controlled by ligand electronics and sterics

Liang, Lan‐Chang; Chien, Pin‐Shu; Hsiao, Yi-Chen; Li, Chunwei; Chang, Chih‐Hsiang

doi:10.1016/j.jorganchem.2011.07.045

Cited by 16 publications

(12 citation statements)

References 50 publications

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“…We prepared [( Et DIP)ZrCl 4 ] ( 1a ) and its Hf analog 1b (Scheme ); a single‐crystal X‐ray structure determination of 1a (Figure ) confirms its PBP geometry. The metal coordination environment is roughly similar to that found in [{(PNP)ZrCl 2 } 2 (µ‐Cl) 2 ] where PNP is an anionic tridentate amido/phosphine ligand; it seems likely that the small bite angles enforced by the tridentate DIP and PNP ligands favour formation of such PBP structures. The C=N and C im –C py distances within the DIP ligand of 1a clearly indicate the presence of a neutral, innocent ligand as expected.…”

Section: Resultssupporting

confidence: 64%

Formation and Rearrangement of Reduced Diiminepyridine Complexes of Zr and Hf

2018

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Reduction of seven‐coordinate [(EtDIP)MCl4] {EtDIP = 2,6‐(2,6‐Et2–C6H3N=CMe)2C5H3N; M = Zr or Hf} produces formally divalent complexes [(EtDIP)MCl2] containing in reality a doubly reduced DIP ligand. The Hf complex is five‐coordinate, but the Zr analog crystallizes as a chloride‐bridged dimer with an unusual coordination geometry; the monomer‐dimer equilibrium is fast at room temperature. Reaction of [(EtDIP)HfCl2] with MeMgBr or LiCH2SiMe3 produced the corresponding dialkyls [(EtDIP)HfR2]. An unexpected ligand isomerization to an amido/enamido form was observed for [(EtDIP)ZrCl2], [(EtDIP)HfMe2] and [(EtDIP)TiMe2], and a mechanism is proposed based on DFT calculations.

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Section: Resultssupporting

confidence: 64%

Formation and Rearrangement of Reduced Diiminepyridine Complexes of Zr and Hf

2018

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“…As illustrated, 2a is a η 4 ‐COD complex whereas 2b is a η 2 ‐COD derivative. The coordination geometry of 2a is best described as trigonal bipyramidal where the 1a ligand is bound to iridium in a facial coordination mode, contrasting with what has been usually found for PNP as a pincer ligand . The dihedral angle between two N‐Ir‐P planes is 120.21°.…”

Section: Resultsmentioning

confidence: 89%

Amido PNP complexes of iridium: Synthesis and catalytic olefin and alkyne hydrogenation

Huang

Zou

Liang

2019

J Chinese Chemical Soc

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In situ lithiation of HN(o‐C6H4PPh2)2 (H[1a]) or HN(o‐C6H4PiPr2)2 (H[1b]) with nBuLi in THF at −35°C followed by addition of [Ir(μ‐Cl)(COD)]2 (COD = 1,5‐cyclooctadiene) in toluene at −35°C generates 5‐coordinate [1a]Ir(η4‐COD) (2a) or 4‐coordinate [1b]Ir(η2‐COD) (2b), respectively. Oxidative addition of N‐H in H[1b] to [Ir(μ‐Cl)(COD)]2 affords square pyramidal [1b]Ir(H)(Cl) (3b). Metathetical reaction of 3b with LiBHEt3 in the presence of 1 atm of H2 in toluene produces [1b]Ir(H)2 (4b). Both 2a and 4b are active for catalytic hydrogenation of olefins and alkynes under extremely mild conditions.

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“…In the 1 H NMR spectrum, distinct resonances at 3.69 (overlapping resonances), 6.51, and 6.58 ppm were observed as doublets of doublets consistent with the CH 2 hydrogens being diastereotopic. The 31 P{ 1 H} NMR spectrum displays four singlets at −2.62, −2.01, 30.46, and 30.73 ppm, and the high-field-shifted 31 P resonances indicate the presence of weakly bound phosphines to the metal center from each PNP ligand . These significantly different features in NMR spectra reveal a C 1 -symmetrical dinuclear system being retained in solution where the P arms couple weakly, if at all.…”

Section: Resultsmentioning

confidence: 99%

Reactivity Studies of a Zirconium Methylidene Complex: Group Transfer and Methylenation Reactions

et al. 2016

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The zirconium methylidene complex (PNP)-ZrCH 2 (OAr) (1; PNP = N[2-P i Pr 2 -4-methylphenyl] 2 − , Ar = 2,6-i Pr 2 C 6 H 3 ), prepared from photolysis of (PNP)Zr-(CH 3 ) 2 (OAr), can engage in incomplete and complete methylidene group transfer reactions with CO, CDCl 3 , cyclododecanone, and benzophenone. When CO was treated with 1, methylenation occurred via the putative metalloketene adduct [(PNP)Zr(OCCH 2 )(OAr)], which ultimately afforded t h e C − C c o u p l e d e n o l a t e d i m e r [ ( P N P ) Z r -(OAr)] 2 (OCH 2 CCCH 2 O) (2). Addition of CDCl 3 to 1 rapidly resulted in formation of (PNP)ZrCl 2 (OAr) (3) along with liberation of d 1 -vinyl chloride, H 2 CCDCl. Complex 3 could be readily prepared independently from (PNP)ZrCl 3 and 1 equiv of NaOAr. Wittig reactivity was observed between 1 and cyclododecanone to afford methylenecyclododecane. Similarly, treating 1 with the ketone OCPh 2 resulted in methylenation of the ortho position followed by tautomerization to produce the chelated alkyloxide complex (PNP)Zr(OAr)[OCHPh(C 6 H 4 )-CH 2 ] (4). In addition to the isolation of 4, complex 1 also engages in a cross-metathesis reaction involving the methylidene and ketone oxygen of benzophenone, as well as in olefin metathesis involving the formed olefin H 2 CCPh 2 . Complexes 2−4 have been fully characterized, including solid-state structural analysis, and proposed mechanisms for the formation of species such as 2−4 are presented and discussed.

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Zirconium complexes containing a diarylamido diphosphine ligand: Structural preferences controlled by ligand electronics and sterics

Cited by 16 publications

References 50 publications

Formation and Rearrangement of Reduced Diiminepyridine Complexes of Zr and Hf

Formation and Rearrangement of Reduced Diiminepyridine Complexes of Zr and Hf

Amido PNP complexes of iridium: Synthesis and catalytic olefin and alkyne hydrogenation

Reactivity Studies of a Zirconium Methylidene Complex: Group Transfer and Methylenation Reactions

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