A ligand-imposed cradle geometry for a dicobalt tetracarbonyl tetratertiary phosphine complex

Laneman, Scott A.; Fronczek, Frank R.; Stanley, George G.

doi:10.1021/ic00306a003

Cited by 23 publications

(50 citation statements)

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“…As in the iron DPPEPM complex, the internal Ru-P distances that are trans to chloride are shorter than the external ones. In contrast to 2, however, the solid-state geometry of 3 is consistent with the solution-state structure suggested by 31 …”

Section: Synthesis Of Fe[(dppepm)cl 2 (Co)] (6) Fe(dppepm)clsupporting

confidence: 75%

“…Attempts to obtain an X-ray quality single crystal of 1 were not successful. 31,35,41 The signal at -9.2 ppm is close to that for the PPh 2 groups in the free ligand 31 (-11.9 ppm, see Table 1) and is assigned to an uncoordinated external PPh 2 group in the complex. The resonances at 8.9 and 16.0 ppm correspond to the internal PPh groups and that at 53.4 ppm to a coordinated external PPh 2 .…”

Section: Synthesis Of Fe[(dppepm)cl 2 (Co)] (6) Fe(dppepm)clmentioning

confidence: 70%

“…Spectra obtained with the more standard relaxation delay of one second appeared to be identical but required much longer acquisition times for the same S/N ratio. The signals in the 1 H NMR spectrum of 5 were broad, but a reasonably sharp 31 …”

Section: P{mentioning

confidence: 96%

“…31 The meso and rac diastereomers were separated by fractional crystallization from ether. The meso form precipitated first as a white powder and was separated by filtration.…”

Section: ' Experimental Sectionmentioning

confidence: 99%

“…One approach involves replacing the central ethylene unit in DPPEPE with a methylene to shorten the ligand backbone and provide the ligand Ph 2 PCH 2 CH 2 PPhCH 2 PPhCH 2 -CH 2 PPh 2 (DPPEPM, Chart 1). 31 Monometallic rhodium(III) compounds of the related tetraphosphine-containing diethylphosphino groups, Et 2 Our interest in phosphine complexes of group 8 metals arises from their potential in nitrogen activation and reduction. 22,24,36 In a recent example, an iron complex containing two bidentate phosphine ligands has been shown to react with molecular hydrogen and nitrogen through a series of intermediates to generate measurable amounts of ammonia and hydrazine.…”

Section: ' Introductionmentioning

confidence: 99%

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Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines

Jana¹,

Ellern²,

Pestovsky³

et al. 2011

Inorg. Chem.

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rac-Bis [{(diphenylphosphino)ethyl}-phenylphosphino]methane (DPPEPM) reacts with iron(II) and ruthenium(II) halides to generate complexes with folded DPPEPM coordination. The paramagnetic, fivecoordinate Fe(DPPEPM)Cl2 (1) in CD2Cl2 features a tridentate binding mode as established by 31P{1H} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br2 (2) revealed a pseudo-octahedral, cis-α geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD2Cl2solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru(κ4-DPPEPM)Cl2 Multidentate ligands are often used to provide stabilized coordination complexes through the chelate effect. At the same time, the structure of a polydentate ligand provides means to control the bite angle, chelate ring size, and stereochemistry. The resulting electronic and steric effects can be used to enhance the reactivity of a metal center. In well-studied organometallic examples, ansa-metallocenes 1-3 and constrained-geometry compounds 4-9 provide enhanced reactivity in olefin polymerization and bond activation, while inhibiting disproportionation reactions. Similarly, bidentate phosphines enforce cis coordination geometries, even though trans configurations might be sterically or electronically preferred, and tridentate phosphines such as MeSi (CH 2 24 and FeCl 2 (DHPePE) 2 (DHPePE = 1,2-bis(bis(hydroxypropyl)phosphino)ethane). 25 The trans geometry in these compounds may limit their reactivity by suppressing processes that require cis-disposed valencies, although cis-iron(II) complexes of bidentate and meso isomers of linear tetradentate phosphines are also formed on occasion. 23,[25][26][27][28][29][30] Ligand modifications can introduce strain, as well as control the geometry and configuration of late metal polyphosphine complexes. One approach involves replacing the central ethylene unit in DPPEPE with a methylene to shorten the ligand backbone and provide the ligand

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Section: Synthesis Of Fe[(dppepm)cl 2 (Co)] (6) Fe(dppepm)clsupporting

confidence: 75%

Section: Synthesis Of Fe[(dppepm)cl 2 (Co)] (6) Fe(dppepm)clmentioning

confidence: 70%

Section: P{mentioning

confidence: 96%

“…31 The meso and rac diastereomers were separated by fractional crystallization from ether. The meso form precipitated first as a white powder and was separated by filtration.…”

Section: ' Experimental Sectionmentioning

confidence: 99%

Section: ' Introductionmentioning

confidence: 99%

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Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines

Jana¹,

Ellern²,

Pestovsky³

et al. 2011

Inorg. Chem.

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The [M2(CO)8] Complexes of the Cobalt Group

Aullón

Álvarez

2001

Eur. J. Inorg. Chem.

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A theoretical study of the carbonyl complexes [M 2 (CO) 8 ] of the group 9 metals (M = Co, Rh, Ir) is presented. Three isomers were found for each metal, with the relative stabilities and energies differing from one metal to another, and two transition states corresponding to their interconversion processes were identified. The minima in the potential energy surface have been fully characterized through a vibrational

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