Synthese von [(η5-C5H5)2Ti(Cl)(CCSiMe3)]Ni(CO) und dessen Reaktionsverhalten gegenüber Phosphiten: die Festkörperstruktur von (CO)2Ni[P(OC6H4CH3-2)3]2

Meichel, Eduard; Stein, Thomas M.; Kralik, Joachim; Rheinwald, Gerd; Lang, Heinrich

doi:10.1016/s0022-328x(02)01117-8

Cited by 5 publications

(2 citation statements)

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“…We concretely evaluated two possible mechanisms (Scheme ). Mechanism i involves coordination of the phosphite to nickel(II), forming a five-coordinate intermediate that reductively eliminates to produce a Ni(0) phosphite complex, − which then decomposes into zerovalent (metallic) fcc Ni particles (Scheme i). This inner sphere reaction and its required intermediates are well-known, having ample precedent in the organometallic literature. , Alternatively, mechanism ii involves direct reduction of nickel(II) to Ni(0) by the free, uncoordinated phosphite (Scheme ii).…”

Section: Resultsmentioning

confidence: 99%

Phase-Programmed Nanofabrication: Effect of Organophosphite Precursor Reactivity on the Evolution of Nickel and Nickel Phosphide Nanocrystals

et al. 2015

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A better understanding of the chemistry of molecular precursors is useful in achieving more predictable and reproducible nanocrystal preparations. Recently, an efficient approach was introduced that consists of finetuning the chemical reactivity of the synthetic molecular precursors used, while keeping all other reaction conditions constant. Using nickel phosphides as a research platform, we have studied how the chemical structure and reactivity of a family of commercially available organophosphite precursors (P(OR)3, R = alkyl or aryl) alter the preparation of metallic and metal phosphide nanocrystals. Organophosphites are a versatile addition to the pnictide synthetic toolbox, nicely complementing other available precursors such as elemental phosphorus or trioctylphosphine (TOP). Experimental and computational data show that different organophosphite precursors selectively yield Ni, Ni12P5, and Ni2P and that these phases evolve over time through separate mechanistic pathways. Based on our observations, we propose that nickel phosphide formation requires organophosphite coordination to a nickel precursor, followed by intramolecular rearrangement. We also propose that metallic nickel formation involves outer sphere reduction by uncoordinated organophosphite. These two independent pathways are supported by the fact that preformed Ni nanocrystals do not react with some of the most reactive phosphide-forming organophosphites, failing to evolve into nickel phosphide nanocrystals. Overall, the rate at which organophosphites react with nickel(II) chloride or acetate to form nickel phosphides increases in the order P(OMe)3 < P(OEt)3 < P(OnBu)3 < P(OCH2tBu)3 < P(OiPr)3 < P(OPh)3. Some organophosphites, such as P(OMe)3 or P(OiPr)3, transiently form zerovalent, metallic nickel, while this is the only persistent product observed with the bulky organophosphite P(O-2,4-tBu2C6H4)3. We expect that these results will alleviate the need for timeconsuming testing and random optimization of several different reaction conditions, thus enabling a faster development of these and similar pnictide nanomaterials for practical applications. Disciplines Chemistry CommentsReprinted (adapted) with permission from Chemistry of Materials 27 (2015) ABSTRACT: A better understanding of the chemistry of molecular precursors is useful in achieving more predictable and reproducible nanocrystal preparations. Recently, an efficient approach was introduced that consists of fine-tuning the chemical reactivity of the synthetic molecular precursors used, while keeping all other reaction conditions constant. Using nickel phosphides as a research platform, we have studied how the chemical structure and reactivity of a family of commercially available organophosphite precursors (P(OR) 3 , R = alkyl or aryl) alter the preparation of metallic and metal phosphide nanocrystals. Organophosphites are a versatile addition to the pnictide synthetic toolbox, nicely complementing other available precursors such as elemental phosphorus or trioctylphosphine (TO...

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Section: Resultsmentioning

confidence: 99%

Phase-Programmed Nanofabrication: Effect of Organophosphite Precursor Reactivity on the Evolution of Nickel and Nickel Phosphide Nanocrystals

et al. 2015

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“…The results show that the coordination around the Ni 0 atom, which lies on a twofold rotation axis, is distorted tetrahedral, composed of two triphenylphosphine P atoms [NiÐP1 = 2.2167 (1) A Ê ] and two carbonyl C atoms [NiÐC19 = 1.7808 (4) A Ê ]. The Ni 0 atom assumes a distorted tetrahedral con®guration as in a series of other complexes: [Ni(R 3 P) 2 (CO) 2 ], where R 3 P is tricyclohexylphosphine (Del Pra et al, 1981), diphenyl(2-pyridinyl)phosphine (Wang et al, 1989), tris(o-tolyloxy)phosphine (Meichel et al, 2002), (4-hydroxybutyl)diphenylphosphine (Reinhard et al, 2003) and 1,3,5-triaza-7-phosphaadamantane (Darensbourg et al, 1999). The geometric parameters of the present structure agree well with those previously reported by Kru È ger & Tsay (1974), but with signi®cantly improved precision.…”

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confidence: 99%