Structures of Dineopentylbis(triethylphosphine)platinum(II) and Bis(triethylphosphine)-3,3-dimethylplatinacyclobutane: Reactant and Product in a Thermal Cyclometalation Reaction

James A. Ibers*, Robert DiCosimo, George M. Whitesides

*Corresponding author for this work

Research output: Contribution to journalArticle

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Abstract

Thermal decomposition of dineopentylbis(triethylphosphine)platinum(II), 1, Pt(CH2C(CH3)3)2(P(C2H5)3)2, yields neopentane and bis(triethylphosphine)-3,3-dimethylplatinacyclobutane, 5, [formula omitted]. Compound 1 crystallizes with four molecules in space group (C2h6−C2/c of the monoclinic system in a cell at −158 °C of dimensions a = 8.776 (2) Å, b = 17.761 (3) Å, c = 17.669 (3) Å, and β = 109.62 (1)∘. The structure has been refined to an R index on F2 of 0.035 for 6877 observations and 115 variables. Compound 1 has crystallographically imposed C2 symmetry. Compound 5 crystallizes with four molecules in space group C2v9−Pn21a of the orthorhombic system in a cell at −158 °C of dimensions a = 15.947 (3) Å, b = 14.301 (2) Å, and c = 9.383 (2) Å. The structure has been refined to a R index on F2 of 0.032 for 3255 observations and 181 variables. Some average metrical parameters for 1 and 5 respectively are as follows: Pt-P, 2.322 (1), 2.285 (2) Å; Pt-C, 2.118 (2), 2.083 (3) Å; P-C, 1.839 (2), 1.827 (2) Å; C-C (ethyl), 1.525 (3), 1.521 (4) Å; P-Pt-P, 94.09 (3), 103.01 (9)∘; C-Pt-C, 85.5 (1), 67.3 (3)∘. In 1 the neopentyl group is of normal geometry with a C-C(terminal) distance of 1.529 (3) Å; in 5 the C-C distances of the metallacycle average 1.535 (6) Å and the β-C atom is 0.38 Å out of the plane through PPPtCC. A comparison of structures of 1 and 5 indicates that 1 is significantly sterically congested and suggests that relief of this congestion may be an important component of the thermodynamic driving force for the conversion of 1 to 5.

Original languageEnglish (US)
Pages (from-to)13-20
Number of pages8
JournalOrganometallics
Volume1
Issue number1
DOIs
StatePublished - Jan 1 1982

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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