An electron spin resonance study of some cyclopentadienyl–organophosphi de complexes of titanium(<scp>III</scp>) and zirconium(<scp>III</scp>)

Kenworthy, J. G.; Myatt, J.; Todd, P. F.

doi:10.1039/c29690000263

Cited by 13 publications

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“…The 'H NMR spectrum of this product at ambient ' temperature was consistent with the presence of cyclopentadienyl groups and resonances attributable to the ethyl moieties. Although the broadness of the observed resonances suggested the presence of paramagnetic centers, 1 was EPR silent at 298 K. In previous reports in which CpzTiClz had been reduced in the presence of phosphide, the product was formulated as a diamagnetic dimer, [Cp2Ti(p-PR2)I2 (14)(15)(16). Combustion analyses were consistent with the empirical formula CpzTiPEt2 for 1.…”

Section: Resultsmentioning

confidence: 54%

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Structure and magnetic properties of [Cp₂M(μ-PEt₂)]₂ (M = Ti, Zr)

Dick¹,

Stephan²

1991

Can. J. Chem.

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. Can. J. Chem. 69, 1 146 (1991). The complex ]2 (1) crystallizes in the monoclinic space group P2'/n with a = 16.591(3) A, b = 8.662 (2) A, c = 37.407(2) 1, P = 102.40(1)", Z = 8, and V = 5250(2) A'. The Ti2P2 core of the dimeric complex is planar and the angles at Ti and P are close to 90". The Ti.. .Ti separations were found to be 3.732(1) and 3.706(1) A in the two independent molecules in the unit cell. Bulk magnetic susceptibility measurements on solid 1 show that the species is diamagnetic over the range 5-340 K. The coupling constant for the antiferromagnetic interaction between the Ti centers of 1 is found to be at least -300 cm-'. Extended Hiickel Molecular Orbital calculations suggest that mixing of the frontier l a l orbitals of the Cp2Ti fragments with the p orbitals of the phosphide fragments affords a mechanism for super-exchange through the ligands. In THF solution, variable temperature 'H, and 3 '~{ '~) NMR and EPR spectra for 1 are consistent with the generation of the paramagnetic monomeric species Cp2TiPEt2, 3. As well, the data suggest thermal populations of the paramagnetic triplet state of the dimer may occur to a small extent at 340 K. In contrast, the analogous Zr dimer 2 shows no evidence of dissociation or of thermal population of the triplet state at temperatures to 340 K.Key words: titanium phosphides, structures, magnetic properties. IntroductionAs part of a continuing interest in early-late heterobimetallic (ELHB) complexes (1-1 1) we and others have recently described a route to monophosphido-bridged, ELHB species employing the Ti(II1) or Zr(II1) phosphido species [Cp2M(p-PR2:)I2 as precursors. While the chemistry of the derived ELHB complexes is a subject of ongoing investigations, further development in synthetic strategies to such complexes hinges on a thorough understanding of early metal phosphides.The preparation of the first zironocene(1V) diphosphide species (a) was first reported by Ellerman and Poersch in 1967 (12). However, it was not until the report of Baker et al. in 1983 (13), that a complete spectroscopic and structural study of metallocene(1V) diphosphides of the form (b), was presented.The related Ti(II1) and Zr(II1) phosphide species were first synthesized in 1966 by Issleib and Hackert (14). Subsequent spectroscopic studies suggested several species were formed in the reactions of phosphides with metallocene dihalides (16, 17).The nature of these ill-characterized species was dependent on the mode of preparation, nature of the phosphide substituents, and temperature of reaction. Furthermore, variations in the magnetic properties of the resultant metallocene-phosphide species appear to depend on how the low-valent precursor was generated. This confusion spurred recent structural studies of the complexes [Cp2M(p-PMe2)I2 (M = Ti ( 17), Zr ( 18)) in which the dimeric structure originally proposed by Issleib and Hackert was confirmed. In this report, we describe the structure and magnetic properties of the dimeric species [Cp2M(pPEt2)12 (M = Ti, 1; Zr, 2). The mag...

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Section: Resultsmentioning

confidence: 54%

“…Subsequent spectroscopic studies suggested several species were formed in the reactions of phosphides with metallocene dihalides (16,17).…”

Section: Introductionmentioning

confidence: 99%

Structure and magnetic properties of [Cp₂M(μ-PEt₂)]₂ (M = Ti, Zr)

Dick¹,

Stephan²

1991

Can. J. Chem.

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“…Coordination mode of ligand 1 in solution cannot be unambiguously determined by EPR method. It should note however, that similar phosphorous isotropic hyperfine coupling constant (10.8 G) was observed in Cp 2 TiPMe 2 , containing direct phosphorus-metal r-bond [6]. High value of hyperfine coupling constant for 2 may be attributed to the p-conjugation in this system and electron-acceptor properties of the ligand.…”

Section: Resultsmentioning

confidence: 47%

Binuclear titanium(III) complex derived from diphenylphosphanylmalononitrile, [μ2(N,N′)-Ph2PC(CN)2TiCp2]2: Synthesis, structure and properties

Min’ko

Belina

Sushev

et al. 2007

Journal of Organometallic Chemistry

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“…Furthermore, the diamagnetism of the resultant species appears to depend on how the low-valent precursors are generated. 8 These reasons prompted us to reinvestigate the chemistry of the phosphido-bridged dimeric Zr(III) and Hf(III) species with the dual purpose of clarifying their structure and magnetic behavior, thereby gaining insight into the nature of the metal-metal interaction and providing Zr(III) compounds in large scale for further reactivity studies.…”

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confidence: 99%

Dinuclear and diamagnetic zirconium(III) derivatives without Zr-Zr bond. Synthesis and x-ray structure of {Cp2Zr[.mu.-P(CH3)2]}2 and (Cp2Zr)2(.mu.-Cl)[.mu.-P(CH3)2]

Chiang¹,

Gambarotta²,

Vanbolhuis³

1988

Organometallics

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An electron spin resonance study of some cyclopentadienyl–organophosphi de complexes of titanium(III) and zirconium(III)

Cited by 13 publications

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Structure and magnetic properties of [Cp₂M(μ-PEt₂)]₂ (M = Ti, Zr)

Structure and magnetic properties of [Cp₂M(μ-PEt₂)]₂ (M = Ti, Zr)

Binuclear titanium(III) complex derived from diphenylphosphanylmalononitrile, [μ2(N,N′)-Ph2PC(CN)2TiCp2]2: Synthesis, structure and properties

Dinuclear and diamagnetic zirconium(III) derivatives without Zr-Zr bond. Synthesis and x-ray structure of {Cp2Zr[.mu.-P(CH3)2]}2 and (Cp2Zr)2(.mu.-Cl)[.mu.-P(CH3)2]

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An electron spin resonance study of some cyclopentadienyl–organophosphi de complexes of titanium(III) and zirconium(III)

Cited by 13 publications

References 0 publications

Structure and magnetic properties of [Cp2M(μ-PEt2)]2 (M = Ti, Zr)

Structure and magnetic properties of [Cp2M(μ-PEt2)]2 (M = Ti, Zr)

Binuclear titanium(III) complex derived from diphenylphosphanylmalononitrile, [μ2(N,N′)-Ph2PC(CN)2TiCp2]2: Synthesis, structure and properties

Dinuclear and diamagnetic zirconium(III) derivatives without Zr-Zr bond. Synthesis and x-ray structure of {Cp2Zr[.mu.-P(CH3)2]}2 and (Cp2Zr)2(.mu.-Cl)[.mu.-P(CH3)2]

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Structure and magnetic properties of [Cp₂M(μ-PEt₂)]₂ (M = Ti, Zr)

Structure and magnetic properties of [Cp₂M(μ-PEt₂)]₂ (M = Ti, Zr)