Diacetylplatinum(II) and ‐platinum(IV) Complexes Bearing κ2‐ and κ3‐Coordinated Tris(pyrazolyl)methane Ligands: Investigations on the Synthesis, Fluxionality, and Reactivity in Relation to the Substitution Pattern of the Ligands. Issue 13 (8th March 2013)

• Record Type: Journal Article
• Authors: Bette, Martin; Schmidt, Jürgen; Steinborn, Dirk
• Is Part Of: European journal of inorganic chemistry. Issue 13(2013)
• Page Start: 2395
• Page End: 2410
• Publication Date: 2013-03-08
• Subjects: Platinum -- Tridentate ligands -- Hydrogen bonds -- Fluxionality -- Ab initio calculations; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201201468
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: Reactions of the dinuclear platina‐β‐diketone [Pt2 {(COMe)2 H}2 (μ‐Cl)2 ] (1 ) with HC(pz)3 and HC(3, 5‐Me2 pz)3 (pz = pyrazol‐1‐yl; 3, 5‐Me2 pz = 3, 5‐dimethylpyrazol‐1‐yl) afforded cationic, thermally labile diacetyl(hydrido)platinum(IV) complexes [Pt(COMe)2 H{(pz)3 CH}]Cl (3a ) and [Pt(COMe)2 H{(3, 5‐Me2 pz)3 CH}]Cl (3b ) with κ 3 ‐coordinated tris(pyrazolyl)methane ligands, which were found to react with NaOH or NEt3 to yield neutral diacetylplatinum(II) complexes with κ 2 ‐coordinated tris(pyrazolyl)methane ligands {[Pt(COMe)2 {(pz)3 CH}] (4a ); [Pt(COMe)2 {(3, 5‐Me2 pz)3 CH}] (4b )}. In4a /b, a molecular rearrangement (decoordination of a pyrazolyl ring and coordination of the originally pendant one) has been found that has been investigated by variable‐temperature 1 H NMR spectroscopic measurements (coalescence method) as well as by DFT calculations. Diacetylplatinum(II) complexes4 were found to react in oxidative addition reactions with ROTf (R = H, Me; OTf = trifluoromethanesulfonate) and methyl iodide to yield cationic diacetylplatinum(IV) complexes of the type [Pt(COMe)2 R{(pz)3 CH}]X (R/X = H/OTf, 5a ; Me/OTf, 6a ; Me/I, 7a ) and [Pt(COMe)2 R{(3, 5‐Me2 pz)3 CH}]X [R/X = H/OTf (5b ), Me/OTf (6b ), Me/I (7b )] with κ 3 ‐bonded tris(pyrazolyl)methane ligands. Treatment of4b with alkynyliodine(III) reagents of the type [IPh(C≡CR)]X (R/X = SiMe3 /OTf, Ph/OTf, t Bu/OTos, i Pr/OTos; OTos = p ‐toluenesulfonate) led to the formation of cationic diacetyl(alkynyl)platinum(IV) complexes [Pt(COMe)2 (C≡CR){(3, 5‐Me2 pz)3 CH}]X [R/X = SiMe3 /OTf (8a ), Ph/OTf (8b ), t Bu/OTos (8c ), i Pr/OTos (8d )]. The identities of all platinum complexes were unambiguously proven by high‐resolution mass spectrometric investigations, by NMR ( 1 H, 13 C, 195 Pt) and IR spectroscopy, as well as by single‐crystal X‐ray diffraction analyses (4a, 4b, 7a, 8a /d ). The constitution of the thermally labile complexes3a /b has been confirmed by low‐temperature (–80 °C) NMR ( 1 H, 13 C) spectroscopic measurements. The electronic and steric influence of the additional methyl groups in HC(3, 5‐Me2 pz)3 on reactivity, stability, and properties of the investigated compounds will be discussed. Abstract : The influence of the substitution pattern of tris(pyrazolyl)methane ligands (pz versus 3, 5‐Me2 pz) on the reactivity and fluxionality of diacetylplatinum(II) complexes as well as the synthesis of diacetyl(alkynyl)platinum(IV) complexes by means of oxidative addition reactions using alkynyliodine(III) reagents is described.