Synthesis of a thiocarbamoyl alkylidyne complex and caveats associated with the use of [Mo(≡CLi)(CO)2(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate)

Annie L. Colebatch; Anthony F. Hill; Rong Shang; Anthony C. Willis

doi:10.1021/om1008296

Synthesis of a thiocarbamoyl alkylidyne complex and caveats associated with the use of [Mo(≡CLi)(CO)₂(Tp)] (Tp = hydrotris(3,5-dimethylpyrazol-1-yl)borate)

Annie L. Colebatch, Anthony F. Hill, Rong Shang, Anthony C. Willis

Research output: Contribution to journal › Article › peer-review

45 Citations (Scopus)

Abstract

The successive reactions of [Mo(≡CBr)(CO)₂(Tp*)] (1; Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with ⁿBuLi and N,N′-dimethylthiocarbamoyl chloride provides as intended, via formation of [Mo(≡CLi)(CO)₂(Tp*)] (2a), the thiocarbamoyl alkylidyne complex [Mo{≡CC(=S)NMe₂}(CO)₂(Tp*) ] (3). Although the yields are poor, analysis of the side products obtained provides insights into caveats to be considered when employing the lithium/halogen exchange protocol in these systems: the 1-pentylidyne [Mo(≡CⁿBu)(CO)₂{HB(pzMe₂)₃}] (4) would appear to arise from competition between ⁿBuBr and the electrophile of choice, and Templeton's nonclassical vinylidene [Mo ₂(μ-CCH₂)(CO)₄(Tp*)₂] (5a) most likely arises under strictly anhydrous conditions from ⁿBuBr acting as a proton donor (i.e., E₂) rather than electrophile (S _N2). The formation of the ethanediylidyne [Tp*(CO) ₂Mo≡CC≡Mo(CO)₂(Tp*)] (6) may be accounted for by single-electron-transfer (outer-sphere) oxidation of 2 to provide the radical carbido complex [Mo(≡C•)(CO) ₂{HB(pzMe₂)₃}] (7), which dimerizes to provide 6. The dimer 6 is also formed alongside 5a in the reaction of 2 with [Fe(η-C₅H₅)₂]PF₆, supporting the intermediacy of 7 in the formation of 6.

Original language	English
Pages (from-to)	6482-6487
Number of pages	6
Journal	Organometallics
Volume	29
Issue number	23
DOIs	https://doi.org/10.1021/om1008296
Publication status	Published - 13 Dec 2010

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title = "Synthesis of a thiocarbamoyl alkylidyne complex and caveats associated with the use of [Mo(≡CLi)(CO)2(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate)",

abstract = "The successive reactions of [Mo(≡CBr)(CO)2(Tp*)] (1; Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with nBuLi and N,N′-dimethylthiocarbamoyl chloride provides as intended, via formation of [Mo(≡CLi)(CO)2(Tp*)] (2a), the thiocarbamoyl alkylidyne complex [Mo{≡CC(=S)NMe2}(CO)2(Tp*) ] (3). Although the yields are poor, analysis of the side products obtained provides insights into caveats to be considered when employing the lithium/halogen exchange protocol in these systems: the 1-pentylidyne [Mo(≡CnBu)(CO)2{HB(pzMe2)3}] (4) would appear to arise from competition between nBuBr and the electrophile of choice, and Templeton's nonclassical vinylidene [Mo 2(μ-CCH2)(CO)4(Tp*)2] (5a) most likely arises under strictly anhydrous conditions from nBuBr acting as a proton donor (i.e., E2) rather than electrophile (S N2). The formation of the ethanediylidyne [Tp*(CO) 2Mo≡CC≡Mo(CO)2(Tp*)] (6) may be accounted for by single-electron-transfer (outer-sphere) oxidation of 2 to provide the radical carbido complex [Mo(≡C•)(CO) 2{HB(pzMe2)3}] (7), which dimerizes to provide 6. The dimer 6 is also formed alongside 5a in the reaction of 2 with [Fe(η-C5H5)2]PF6, supporting the intermediacy of 7 in the formation of 6.",

author = "Colebatch, {Annie L.} and Hill, {Anthony F.} and Rong Shang and Willis, {Anthony C.}",

year = "2010",

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doi = "10.1021/om1008296",

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T1 - Synthesis of a thiocarbamoyl alkylidyne complex and caveats associated with the use of [Mo(≡CLi)(CO)2(Tp*)] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate)

AU - Colebatch, Annie L.

AU - Hill, Anthony F.

AU - Shang, Rong

AU - Willis, Anthony C.

PY - 2010/12/13

Y1 - 2010/12/13

N2 - The successive reactions of [Mo(≡CBr)(CO)2(Tp*)] (1; Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with nBuLi and N,N′-dimethylthiocarbamoyl chloride provides as intended, via formation of [Mo(≡CLi)(CO)2(Tp*)] (2a), the thiocarbamoyl alkylidyne complex [Mo{≡CC(=S)NMe2}(CO)2(Tp*) ] (3). Although the yields are poor, analysis of the side products obtained provides insights into caveats to be considered when employing the lithium/halogen exchange protocol in these systems: the 1-pentylidyne [Mo(≡CnBu)(CO)2{HB(pzMe2)3}] (4) would appear to arise from competition between nBuBr and the electrophile of choice, and Templeton's nonclassical vinylidene [Mo 2(μ-CCH2)(CO)4(Tp*)2] (5a) most likely arises under strictly anhydrous conditions from nBuBr acting as a proton donor (i.e., E2) rather than electrophile (S N2). The formation of the ethanediylidyne [Tp*(CO) 2Mo≡CC≡Mo(CO)2(Tp*)] (6) may be accounted for by single-electron-transfer (outer-sphere) oxidation of 2 to provide the radical carbido complex [Mo(≡C•)(CO) 2{HB(pzMe2)3}] (7), which dimerizes to provide 6. The dimer 6 is also formed alongside 5a in the reaction of 2 with [Fe(η-C5H5)2]PF6, supporting the intermediacy of 7 in the formation of 6.

AB - The successive reactions of [Mo(≡CBr)(CO)2(Tp*)] (1; Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) with nBuLi and N,N′-dimethylthiocarbamoyl chloride provides as intended, via formation of [Mo(≡CLi)(CO)2(Tp*)] (2a), the thiocarbamoyl alkylidyne complex [Mo{≡CC(=S)NMe2}(CO)2(Tp*) ] (3). Although the yields are poor, analysis of the side products obtained provides insights into caveats to be considered when employing the lithium/halogen exchange protocol in these systems: the 1-pentylidyne [Mo(≡CnBu)(CO)2{HB(pzMe2)3}] (4) would appear to arise from competition between nBuBr and the electrophile of choice, and Templeton's nonclassical vinylidene [Mo 2(μ-CCH2)(CO)4(Tp*)2] (5a) most likely arises under strictly anhydrous conditions from nBuBr acting as a proton donor (i.e., E2) rather than electrophile (S N2). The formation of the ethanediylidyne [Tp*(CO) 2Mo≡CC≡Mo(CO)2(Tp*)] (6) may be accounted for by single-electron-transfer (outer-sphere) oxidation of 2 to provide the radical carbido complex [Mo(≡C•)(CO) 2{HB(pzMe2)3}] (7), which dimerizes to provide 6. The dimer 6 is also formed alongside 5a in the reaction of 2 with [Fe(η-C5H5)2]PF6, supporting the intermediacy of 7 in the formation of 6.

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U2 - 10.1021/om1008296

DO - 10.1021/om1008296

M3 - Article

SN - 0276-7333

VL - 29

SP - 6482

EP - 6487

JO - Organometallics

JF - Organometallics

IS - 23

ER -

Synthesis of a thiocarbamoyl alkylidyne complex and caveats associated with the use of [Mo(≡CLi)(CO)₂(Tp)] (Tp = hydrotris(3,5-dimethylpyrazol-1-yl)borate)

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