The coordination chemistry of the amidine ligand

Barker, James; Kilner, M.

doi:10.1016/0010-8545(94)80059-6

Cited by 674 publications

(376 citation statements)

References 239 publications

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“…We proposed that redistribution of substituents about boron is caused by an initial dissociation of the weak TMU-BF, donor-acceptor bond, followed by rapid fluorine exchange between the freed BF, with the four-coordinate boron species, giving a generalized redistribution reaction including donor-for-halogen as well as halogen-for-halogen exchange, generating the mixed chlorofluoroborate anions as well as (TMU),BF,+, a typical reaction being eq. [7], in which the chlorine bridge in the transition state or reactive intermediate is similar to the fluorine bridge of the B,F,-ion (41). Mechanisms of this type have been dealt with in detail by JanZen and co-workers (42).…”

Section: Mechanistic Implicationsmentioning

confidence: 99%

“…We now report the extension of our hindrance tertiary amines selectively displace heavy halide ion carbon atom and the amino nitrogen (6). Amidines with their strong basicity have interesting coordination chemistry (7). Monomeric, dimeric, and cluster metal amidine complexes have been studied.…”

Section: Introductionmentioning

confidence: 99%

“…Monomeric, dimeric, and cluster metal amidine complexes have been studied. N-H containing acyclic amidines can lose a proton to form [R1-N=CR-N-R"]-species, which can act as bridging ligands (7,8). To avoid problems of N-H proton transfer, we have limited our work to N,N,N1-trialkyl-substituted amidines.…”

Section: Introductionmentioning

confidence: 99%

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Bis- and tris(amidine)fluoroboron cations and mixed tetrahaloborate anions: NMR studies of mixed boron trihalide adduct redistribution reactions involving amidines as strong nitrogen bases

Hartman¹,

Yuan²,

Fox³

et al. 1996

Can. J. Chem.

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Section: Mechanistic Implicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bis- and tris(amidine)fluoroboron cations and mixed tetrahaloborate anions: NMR studies of mixed boron trihalide adduct redistribution reactions involving amidines as strong nitrogen bases

Hartman¹,

Yuan²,

Fox³

et al. 1996

Can. J. Chem.

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“…Early uses of metal amidinates have been reported in catalysis, to promote polymerizations and other related reactions. [1][2][3] More recently, metal amidinates have been developed as promising precursors for the deposition of solid thin films. [4][5][6][7][8] They have proven particularly useful in atomic layer deposition (ALD) processes, where the surface chemistry of film growth is split into two self-limiting and complementary half-reactions in order to control the deposition at a monolayer level.…”

Section: Introductionmentioning

confidence: 99%

Surface Chemistry of Copper(I) Acetamidinates in Connection with Atomic Layer Deposition (ALD) Processes

et al. 2011

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The thermal chemistry of copper(I)-N,N 0 -di-secbutylacetamidinate on Ni(110) single-crystal and cobalt polycrystalline surfaces was characterized under ultrahigh vacuum (UHV) conditions by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD). A complex network of reactions were identified, starting with the dissociative adsorption of the precursor, from its dimeric form in its free state to a monomer once bonded to the nickel surface. The dissociation of a CÀN bond in the acetamidinate ligand at ∼200 K leads to the formation of adsorbed 2-butene and N-secbutylacetamidinate. Some of the latter intermediates hydrogenate around 300 K to release N-sec-butylacetamidine into the gas phase, while the remaining adsorbed species dissociate further around 400 K, as the copper atoms become reduced to a metallic state, possibly to form acetonitrile and a sec-butylamido surface species that reacts further at 485 K to release 2-butene. By 800 K, only copper and a small amount of carbon can be seen on the surface by XPS. The implications of this chemistry to the growth of metal films by atomic layer deposition (ALD) are discussed.

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“…8 Amidinate ligands are also known to enhance the thermodynamic stability of their complexes due to the chelating effect of the bidentate ligands. 9,10 Some transition metals, such as Cu, Co, Fe, Ru, Mn, and Ni, as well as their nitrides and oxides and rare earth oxides have been successfully grown by ALD from the corresponding amidinate precursors. 7,[11][12][13][14][15][16] However, the surface chemistry of these relatively new precursors has not yet been investigated in situ, because most studies to-date have focused on ex situ film characterization by electrical, physical, or chemical measurements.…”

Section: Introductionmentioning

confidence: 99%

In Situ Infrared Characterization during Atomic Layer Deposition of Lanthanum Oxide

et al. 2008

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Mechanisms of atomic layer deposition (ALD) growth of lanthanum oxide on H-terminated Si(111) using lanthanum tris(N,N′-diisopropylacetamidinate) (La( i Pr-MeAMD) 3 ) are investigated using infrared (IR) absorption spectroscopy. The reactivity of this amidinate precursor is high, with almost all surface Si-H bonds consumed after 5 ALD cycles at 300°C. Gas phase IR spectra show that, although most of the precursor (La( i Pr-MeAMD) 3 ) remains intact, a strong feature at 1665 cm -1 , characteristic of a hydrogenated and dissociated free ligand with localized electrons in the N-CdN bonds, is present. Such partial precursor dissociation in the gas phase is due to hydrolysis by traces of water vapor remaining in the reactor, even after purging. As a result, some Si-O-La bonds are formed upon reaction with the surface during the first La( i PrMeAMD) 3 pulse, prior to any water pulse. During film growth, acetate/carbonate and hydroxyl impurities are incorporated into the film. Annealing to 500°C in dry N 2 removes these impurities but fosters the growth of interfacial SiO 2 . Deposition at 300°C leads to decomposition of adsorbed ligands, as evidenced by the formation of cyanamide or carbodiimide vibrational bands (or both) at 1990 and 2110 cm -1 , respectively. Despite this decomposition, ideal self-limited ALD growth is maintained because the decomposed ligands are removed by the subsequent water pulse. Growth of pure lanthanum oxide films is often characterized by nonuniform film thickness if purging is not complete because of reversible absorption of water by the La 2 O 3 film. Uniform ALD growth can be maintained without a rigorous dry purge by introducing alternating trimethylaluminum (TMA)/D 2 O ALD cycles between La/D 2 O cycles.

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The coordination chemistry of the amidine ligand

Cited by 674 publications

References 239 publications

Bis- and tris(amidine)fluoroboron cations and mixed tetrahaloborate anions: NMR studies of mixed boron trihalide adduct redistribution reactions involving amidines as strong nitrogen bases

Bis- and tris(amidine)fluoroboron cations and mixed tetrahaloborate anions: NMR studies of mixed boron trihalide adduct redistribution reactions involving amidines as strong nitrogen bases

Surface Chemistry of Copper(I) Acetamidinates in Connection with Atomic Layer Deposition (ALD) Processes

In Situ Infrared Characterization during Atomic Layer Deposition of Lanthanum Oxide

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