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A Significant but Constrained Geometry Pt→Al Interaction: Fixation of CO2 and CS2, Activation of H2 and PhCONH2.

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Title: A Significant but Constrained Geometry Pt→Al Interaction: Fixation of CO2 and CS2, Activation of H2 and PhCONH2.
Authors: Devillard, Marc1,2, Declercq, Richard1,2, Nicolas, Emmanuel3, Ehlers, Andreas W.3, Backs, Jana4, Saffon-Merceron, Nathalie5, Bouhadir, Ghenwa1,2 bouhadir@chimie.ups-tlse.fr, Slootweg, J. Chris3 j.c.slootweg@vu.nl, Uhl, Werner4 uhlw@uni-muenster.de, Bourissou, Didier1,2 dbouriss@chimie.ups-tlse.fr
Source: Journal of the American Chemical Society. 4/13/2016, Vol. 138 Issue 14, p4917-4926. 10p.
Subjects: Chemical reactions, Ligands (Chemistry), Cyclic compounds, X-ray diffraction, Chemical structure
Abstract: Reaction of the geminal PAl ligand [Mes2PC(=CHPh)AltBu2] (1) with [Pt(PPh3)2(ethylene)] affords the T-shape Pt complex [(1)Pt(PPh3)] (2). X-ray diffraction analysis and DFT calculations reveal the presence of a significant Pt→Al interaction in 2, despite the strain associated with the four-membered cyclic structure. The Pt⋯Al distance is short [2.561(1) Å], the Al center is in a pyramidal environment [Σ(C-Al-C) = 346.6°], and the PCAl framework is strongly bent (98.3°). Release of the ring strain and formation of X→Al interactions (X = O, S, H) impart rich reactivity. Complex 2 reacts with CO2 to give the T-shape adduct 3 stabilized by an O→Al interaction, which is a rare example of a CO2 adduct of a group 10 metal and actually the first with η¹-CO2 coordination. Reaction of 2 with CS2 affords the crystalline complex 4, in which the PPtP framework is bent, the CS2 molecule is η²-coordinated to Pt, and one S atom interacts with Al. The Pt complex 2 also smoothly reacts with H2 and benzamide PhCONH2 via oxidative addition of H-H and H-N bonds, respectively. The ensuing complexes 5 and 7 are stabilized by Pt-H→Al and Pt-NH-C(Ph) = O→Al bridging interactions, resulting in 5- and 7-membered metallacycles, respectively. DFT calculations have been performed in parallel with the experimental work. In particular, the mechanism of reaction of 2 with H2 has been thoroughly analyzed, and the role of the Lewis acid moiety has been delineated. These results generalize the concept of constrained geometry TM→LA interactions and demonstrate the ability of Al-based ambiphilic ligands to participate in TM/LA cooperative reactivity. They extend the scope of small molecule substrates prone to such cooperative activation and contribute to improve our knowledge of the underlying factors. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Reaction of the geminal PAl ligand [Mes2PC(=CHPh)AltBu2] (1) with [Pt(PPh3)2(ethylene)] affords the T-shape Pt complex [(1)Pt(PPh3)] (2). X-ray diffraction analysis and DFT calculations reveal the presence of a significant Pt→Al interaction in 2, despite the strain associated with the four-membered cyclic structure. The Pt⋯Al distance is short [2.561(1) Å], the Al center is in a pyramidal environment [Σ(C-Al-C) = 346.6°], and the PCAl framework is strongly bent (98.3°). Release of the ring strain and formation of X→Al interactions (X = O, S, H) impart rich reactivity. Complex 2 reacts with CO2 to give the T-shape adduct 3 stabilized by an O→Al interaction, which is a rare example of a CO2 adduct of a group 10 metal and actually the first with η¹-CO2 coordination. Reaction of 2 with CS2 affords the crystalline complex 4, in which the PPtP framework is bent, the CS2 molecule is η²-coordinated to Pt, and one S atom interacts with Al. The Pt complex 2 also smoothly reacts with H2 and benzamide PhCONH2 via oxidative addition of H-H and H-N bonds, respectively. The ensuing complexes 5 and 7 are stabilized by Pt-H→Al and Pt-NH-C(Ph) = O→Al bridging interactions, resulting in 5- and 7-membered metallacycles, respectively. DFT calculations have been performed in parallel with the experimental work. In particular, the mechanism of reaction of 2 with H2 has been thoroughly analyzed, and the role of the Lewis acid moiety has been delineated. These results generalize the concept of constrained geometry TM→LA interactions and demonstrate the ability of Al-based ambiphilic ligands to participate in TM/LA cooperative reactivity. They extend the scope of small molecule substrates prone to such cooperative activation and contribute to improve our knowledge of the underlying factors. [ABSTRACT FROM AUTHOR]
ISSN:00027863
DOI:10.1021/jacs.6b01320