Please use this identifier to cite or link to this item: https://doi.org/10.1021/ic991416k
Title: Structural, dynamic, and theoretical studies of [Au(n)Pt2(PPh3)4(μ-S)(2-n)(μ3-S)(n)L][PF6](n) [n = 1, L = PPh3; n = 2, L = Ph2PCH2PPh2, (C5H4PPh2)2Fe]
Authors: Li, Z.
Loh, Z.-H.
Mok, K.F. 
Hor, T.S.A. 
Issue Date: 13-Nov-2000
Citation: Li, Z., Loh, Z.-H., Mok, K.F., Hor, T.S.A. (2000-11-13). Structural, dynamic, and theoretical studies of [Au(n)Pt2(PPh3)4(μ-S)(2-n)(μ3-S)(n)L][PF6](n) [n = 1, L = PPh3; n = 2, L = Ph2PCH2PPh2, (C5H4PPh2)2Fe]. Inorganic Chemistry 39 (23) : 5299-5305. ScholarBank@NUS Repository. https://doi.org/10.1021/ic991416k
Abstract: Three heterometallic Au-Pt complexes [Pt2(PPh3)4(μ-S)(μ3-S)Au(PPh3)][PF6] (2), [Pt2(PPh3)4(μ3-S)2Au2(μ-dppm)]-[PF6]2 (3), and [pt2(Pph3)4(μ3-S)2(μ-dppf)][PF6]2 (4) have been synthesized from Pt2(PPh3)4(μ-S)2 (1) [dppm = Ph2PCH2PPh2; dppf = (C5H4PPh2)2Fe] and characterized by single-crystal X-ray crystallography. In 2, the Au(I) atom is anchored on only one of the sulfur centers. In 3 and 4, both sulfur atoms are aurated, showing the ability of 1 to support an overhead bridge structure, viz. [Au2(P-P)], with or without the presence of Au-Au bond. The change of dppf to dppm facilitates such active interactions. Two stereoisomers of complex 3 (3a,b) have been obtained and characterized by single-crystal X-ray crystallography. NLDFT calculations on 2 show that the linear coordination mode is stabilized with respect to the trigonal planar mode by 14.0 kJ/mol. All complexes (2-4) are fluxional in solution with different mechanisms. In 2, the [Au(PPh3)] fragment switches rapidly between the two sulfur sites. Our hybrid MM-NLDFT calculations found a transition state in which the Au(I) bears an irregular trigonal planar geometry (ΔG(+) = 19.9 kJ/mol), as well as an intermediate in which Au(I) adopts a regular trigonal planar geometry. Complexes 3a,b are roughly diastereoisomeric and related by σ (mirror plane) conversion. This symmetry operation can be broken down to two mutually dependent fluxional processes: (i) rapid flipping of the dppm methylene group across the molecular plane defined by the overhead bridge; (ii) rocking motion of the two Au atoms across the S ···S axis of the {Pt2S2} core. Modeling of the former by molecular mechanics yields a steric barrier of 29.0 kJ/mol, close to that obtained from variable-temperature 31P{1H} NMR study (33.7 kJ/mol). In 4, the twisting of the ferrocenyl moiety across the S ··· S axis is in concert with a rocking motion of the two gold atoms. The movement of dppf is sterically most demanding, and hence, 4 is the only complex that shows a static structure at lower temperatures. Pertinent crystallographic data: (2) space group P1, a = 15.0340(5) Å, b = 15.5009(5) Å, c = 21.9604(7) Å, α = 74.805(1) Å, β = 85.3733(1)°, γ = 78-553(1)°, R = 0.0500; (3a) space group Pna21, a = 32.0538(4) Å, b = 16.0822(3) Å, c = 18.9388(3) Å, R = 0.0347; (3b) space group Pna21, a = 31.950(2) Å, b = 16.0157(8) Å, c = 18.8460(9) Å, R = 0.0478; (4) space group P21/c, a = 13.8668(2) Å, b = 51.7754(4) Å, c = 15.9660(2) Å, β = 113.786(1)°, R = 0.0649.
Source Title: Inorganic Chemistry
URI: http://scholarbank.nus.edu.sg/handle/10635/94911
ISSN: 00201669
DOI: 10.1021/ic991416k
Appears in Collections:Staff Publications

Show full item record
Files in This Item:
There are no files associated with this item.

SCOPUSTM   
Citations

34
checked on Sep 24, 2018

WEB OF SCIENCETM
Citations

28
checked on Sep 24, 2018

Page view(s)

19
checked on Aug 17, 2018

Google ScholarTM

Check

Altmetric


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.