title: A Significant but Constrained Geometry Pt→Al Interaction: Fixation of CO2 and CS2, Activation of H2 and PhCONH2.
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 η(1)-CO2 coordination. Reaction of 2 with CS2 affords the crystalline complex 4, in which the PPtP framework is bent, the CS2 molecule is η(2)-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.
authors.affiliation: Université de Toulouse, UPS, LHFA, 118 route de Narbonne, 31062 Toulouse, France.|CNRS, LHFA, UMR 5069, 31062 Toulouse, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Devillard
authors.affiliation: Université de Toulouse, UPS, LHFA, 118 route de Narbonne, 31062 Toulouse, France.|CNRS, LHFA, UMR 5069, 31062 Toulouse, France.
authors.forename: Richard
authors.initials: R
authors.lastname: Declercq
authors.affiliation: Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Nicolas
authors.affiliation: Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Ehlers
authors.affiliation: Institut für Anorganische und Analytische Chemie der Westfälischen, Wilhelms-Universität Münster , Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Backs
authors.affiliation: Université Paul Sabatier , Institut de Chimie de Toulouse (FR 2599), 118 route de Narbonne, 31062 Toulouse cedex 9, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Saffon-Merceron
authors.affiliation: Université de Toulouse, UPS, LHFA, 118 route de Narbonne, 31062 Toulouse, France.|CNRS, LHFA, UMR 5069, 31062 Toulouse, France.
authors.forename: Ghenwa
authors.initials: G
authors.lastname: Bouhadir
authors.affiliation: Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam , De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: J Chris
authors.initials: JC
authors.lastname: Slootweg
authors.affiliation: Institut für Anorganische und Analytische Chemie der Westfälischen, Wilhelms-Universität Münster , Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Uhl
authors.affiliation: Université de Toulouse, UPS, LHFA, 118 route de Narbonne, 31062 Toulouse, France.|CNRS, LHFA, UMR 5069, 31062 Toulouse, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Bourissou