Synthesis of Bis(η<sup>6</sup>-alkylbenzene)molybdenum by Arene Metathesis

and, Victor S. Asirvatham; Ashby, Michael T.

doi:10.1021/om001010b

Cited by 10 publications

(4 citation statements)

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“…The conversion of 1 to 2 involves the displacement of bound naphthalene by anthracene, which is an unprecedented reaction for a homoleptic system. Exchange of both naphthalenes in bis(naphthalene)chromium(0) by 1,4-dimethylnaphthalene under comparatively forcing conditions (120 °C, 25 h) to yield bis(1,4-dimethylnaphthalene)chromium(0) appears to be the only known related reaction involving multiple polyarene substitutions on one metal center …”

mentioning

confidence: 63%

Tris(η4-naphthalene)- and Tris(1-4-η4-anthracene)tantalate(1−): First Homoleptic Arene Complexes of Anionic Tantalum

et al. 2002

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Reduction of tantalum pentachloride by 6 equiv of sodium naphthalene in 1,2-dimethoxyethane provided, after recrystallization from tetrahydrofuran, 50-55% yields of yellow, pyrophoric [Na(THF)][Ta(C10H8)3]. The product was shown by 1H and 13C NMR spectra and an X-ray study (on the corresponding [Na(crypt 2.2.2)]salt) to be tris(eta4-naphthalene)tantalate(1-), 1, the first homoleptic naphthalene complex of a third row (5d) transition metal. Salts of 1 react under mild conditions with excess CO (1 atm pressure, -60 degrees to +20 degrees C) and 3 equiv of anthracene, C14H10 (20 degrees C), to give 99 and 52% yields of yellow [Ta(CO)6]- and orange [Ta(C14H10)3]-, (2), respectively. The latter is the first homoleptic anthracene complex of a group 5 element and only the third one known, the others being Cr(eta6-C14H10)2 and [Co(eta4-C14H10)2]-. NMR spectra and X-ray structural characterization, as the [Na(crypt 2.2.2)] salt, established 2 to be [Ta(1-4-eta4-C14H10)3]- and is very similar to 1 in solution and in the solid state. Salts of 2 also undergo facile ligand substitution reactions. For example, it reacts with 1,3,5,7-cyclooctatetraene, COT, at 20 degrees in THF to give high yields of the previously known [Ta(COT)3]-, which was structurally characterized as the Na(crypt 2.2.2)salt. One particularly important feature concerning 1 and 2 is that they are the first available synthons for "naked" atomic Ta- and promise to be useful reagents for the general exploration of low-valent tantalum chemistry. Also, 1 and 2 represent the first homoleptic arene tantalum complexes to have been prepared by conventional syntheses. The only previously known substance of this class is the neutral bis(benzene)tantalum(0), which was accessed by the co-condensation of atomic tantalum and benzene vapor in a sophisticated (electron-gun furnace equipped) metal atom reactor.

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confidence: 63%

Tris(η4-naphthalene)- and Tris(1-4-η4-anthracene)tantalate(1−): First Homoleptic Arene Complexes of Anionic Tantalum

et al. 2002

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“…For PEt 3 and COD, the 1 H NMR spectra revealed the formation of byproducts, which we could not identify so far. For [Mo(C 6 H 6 ) 2 ] it is known that the benzene ligands are relatively labile and that is what makes the compound a common starting material for half-sandwich complexes. , However, the substitution of benzene in [Mo(C 6 H 6 ) 2 ] by other arenes requires forcing thermal conditions (160 °C; 48 h) . The respective ligand substitution in the galla[1]molybdarenophane 2b which yields 3b is catalyzed by the donor species, and it seems that the reaction occurs at relatively mild conditions because of the high strain of 2b .…”

Section: Resultsmentioning

confidence: 99%

[1]Molybdarenophanes: Strained Metallarenophanes with Aluminum, Gallium, and Silicon in Bridging Positions

et al. 2007

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The first [1]molybdarenophanes were synthesized and structurally characterized. The aluminum and gallium compounds [(Me2Ntsi)Al(eta6-C6H5)2Mo] (2a) and [(Me2Ntsi)Ga(eta6-C6H5)2Mo] (2b) [Me2Ntsi = C(SiMe3)2(SiMe2NMe2)] were obtained from [Mo(LiC6H5)2].TMEDA and (Me2Ntsi)ECl2 [E = Al, Ga] in analytical pure form with isolated yields of 74% (2a) and 52% (2b). The silicon-bridged species [Ph2Si(eta6-C6H5)2Mo] (2c) was synthesized from [Mo(LiC6H5)2].TMEDA and Ph2SiCl2. Compound 2c was isolated as a crystalline material in an approximately 90% overall purity, from which a single crystal was used for X-ray analysis. The molecular structures of all three [1]molybdarenophanes 2a-c were determined by single-crystal X-ray analysis. The ring-tilt angle alpha was found to be 18.28(17), 21.24(10), and 20.23(29) degrees for 2a, 2b, and 2c, respectively. Variable temperature NMR measurements of 2a and 2b (-80 to 80 degrees C; 500 MHz) showed a dynamic behavior of the gallium species 2b but not of compound 2a. The dynamic behavior of 2b was rationalized by assuming that the Ga-N donor bond breaks, inversion at the nitrogen atom occurs, and a rotation of the Me2Ntsi ligand takes place followed by a re-formation of the Ga-N bond on the other side of the gallium atom. The analysis of the signals of meta and ortho protons of 2b gave approximate values of DeltaG not equal of 59.6 and 59.1 kJ mol-1, respectively. Compound 2b reacted with [Pt(PEt3)3] to give the ring-open product [(eta6-C6H6)Mo{eta6-C6H5[GaPh(Me2Ntsi)]}] (3b). The molecular structure of 3b was deduced from a single-crystal X-ray determination. The formation of the unexpected platinum-free product 3b can be rationalized by assuming that benzene reacted with 2b in a 1:1 ratio. Through a series of 1H NMR experiments with 2b it was shown that small amounts of donor molecules (e.g., THF) in benzene are needed to form 3b; in the absence of a donor molecule, 2b is thermally stable.

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“…123 It has been found that bis(η 6 -arene)molybdenum complexes with alkyl substituents are readily synthesized by metathesis of the arene ligands of bis(η 6 -benzene)molybdenum, avoiding Fischer-Hafner synthesis conditions. 124 New di-imido derivatives of the form [MCp 2 (NR) 2 ] have been isolated and structurally characterised. 125 Aqueous [MoCp 2 Cl 2 ] forms a crystalline 1 : 1 inclusion complex with β-cyclodextrin in which the Mo-Cl bond remains intact, 126 whereas both the neutral complex [MoCp(η 3 -C 6 H 7 )(CO) 2 ] and its tetrafluoroborate salt [MoCp(η 4 -C 6 H 8 )(CO) 2 ][BF 4 ] form 2 : 1 host-guest, crystalline, channel-type inclusion compounds.…”

Section: Chromium Molybdenum and Tungstenmentioning

confidence: 99%

20 Organometallic chemistry of monometallic species

Arnold

2002

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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Synthesis of Bis(η⁶-alkylbenzene)molybdenum by Arene Metathesis

Cited by 10 publications

References 11 publications

Tris(η4-naphthalene)- and Tris(1-4-η4-anthracene)tantalate(1−): First Homoleptic Arene Complexes of Anionic Tantalum

Tris(η4-naphthalene)- and Tris(1-4-η4-anthracene)tantalate(1−): First Homoleptic Arene Complexes of Anionic Tantalum

[1]Molybdarenophanes: Strained Metallarenophanes with Aluminum, Gallium, and Silicon in Bridging Positions

20 Organometallic chemistry of monometallic species

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Synthesis of Bis(η6-alkylbenzene)molybdenum by Arene Metathesis

Cited by 10 publications

References 11 publications

Tris(η4-naphthalene)- and Tris(1-4-η4-anthracene)tantalate(1−): First Homoleptic Arene Complexes of Anionic Tantalum

Tris(η4-naphthalene)- and Tris(1-4-η4-anthracene)tantalate(1−): First Homoleptic Arene Complexes of Anionic Tantalum

[1]Molybdarenophanes: Strained Metallarenophanes with Aluminum, Gallium, and Silicon in Bridging Positions

20 Organometallic chemistry of monometallic species

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Synthesis of Bis(η⁶-alkylbenzene)molybdenum by Arene Metathesis