Rollover-assisted C(sp2)-C(sp3) bond formation.

Rollover cyclometalation involves bidentate heterocyclic donors, unusually acting as cyclometalated ligands. The resulting products, possessing a free donor atom, react differently from the classical cyclometalated complexes. Taking advantage of a "rollover"/"retro-rollover" reaction sequence, a succession of oxidative addition and reductive elimination in a series of platinum(II) complexes [Pt(N,C)(Me)(PR3)] resulted in a rare C(sp(2))-C(sp(3)) bond formation to give the bidentate nitrogen ligands 3-methyl-2,2'-bipyridine, 3,6-dimethyl-2,2'-bipyridine, and 3-methyl-2-(2'-pyridyl)-quinoline, which were isolated and characterized. The nature of the phosphane PR3 is essential to the outcome of the reaction. This route constitutes a new method for the activation and functionalization of C-H bond in the C(3) position of bidentate heterocyclic compounds, a position usually difficult to functionalize.

[1]  W. Thiel,et al.  C–H Activation at a Ruthenium(II) Complex – The Key Step for a Base‐Free Catalytic Transfer Hydrogenation? , 2013 .

[2]  M. Crespo,et al.  Regioselective C–H Activation Preceded by Csp2–Csp3 Reductive Elimination from Cyclometalated Platinum(IV) Complexes , 2013 .

[3]  S. Galli,et al.  Rollover cyclometalation with 2-(2'-pyridyl)quinoline. , 2013, Inorganic chemistry.

[4]  G. Clarkson,et al.  Oxidative Addition of MeI to a Rollover Complex of Platinum(II): Isolation of the Kinetic Product , 2013 .

[5]  M. Cinellu,et al.  Mesoionic Complexes of Platinum(II) Derived from “Rollover” Cyclometalation: A Delicate Balance between Pt–C(sp3) and Pt–C(sp2) Bond Cleavage as a Result of Different Reaction Conditions , 2013 .

[6]  Yousung Jung,et al.  Rollover cyclometalation pathway in rhodium catalysis: dramatic NHC effects in the C-H bond functionalization. , 2012, Journal of the American Chemical Society.

[7]  G. Clarkson,et al.  Relieving steric strain at octahedral platinum(IV) : isomerization and reductive coupling of alkyl and aryl chlorides , 2012 .

[8]  T. Otani,et al.  Rh(III)-catalyzed C-H bond activation along with "rollover" for the synthesis of 4-azafluorenes. , 2012, Organic letters.

[9]  M. Crespo,et al.  Reductive Elimination from Cyclometalated Platinum(IV) Complexes To Form Csp2–Csp3 Bonds and Subsequent Competition between Csp2–H and Csp3–H Bond Activation , 2012 .

[10]  G. Clarkson,et al.  Concerted reductive coupling of an alkyl chloride at Pt(IV). , 2012, Chemical communications.

[11]  G. Clarkson,et al.  Heterobimetallic Rollover Derivatives , 2012 .

[12]  H. R. Shahsavari,et al.  Oxidative addition of MeI to some cyclometalated organoplatinum(II) complexes: Kinetics and mechanism , 2012 .

[13]  H. Schwarz,et al.  “Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects , 2012 .

[14]  J. Love,et al.  Exploration of the Mechanism of Platinum(II)-Catalyzed C–F Activation: Characterization and Reactivity of Platinum(IV) Fluoroaryl Complexes Relevant to Catalysis , 2012 .

[15]  H. Schwarz,et al.  On the Activation of Chloromethanes by Cyclometalated [Pt(bipy – H)]+ in the Gas Phase: A Mechanistic Study , 2011 .

[16]  G. Clarkson,et al.  Reactions of a Platinum(II) Agostic Complex: Decyclometalation, Dicyclometalation, and Solvent-Switchable Formation of a Rollover Complex , 2011 .

[17]  M. Manassero,et al.  Platinum(II)-Cyclometalated “Roll-over” Complexes with a Chiral Pinene-Derived 2,2′-Bipyridine , 2011 .

[18]  H. Schwarz,et al.  Mechanistic Study on the Gas-Phase Generation of “Rollover”-Cyclometalated [M(bipy − H)]+ (M = Ni, Pd, Pt)† , 2010 .

[19]  I. Goldberg,et al.  Aryl-bromide reductive elimination from an isolated Pt(IV) complex. , 2010, Chemical communications.

[20]  M. Albrecht.  Cyclometalation using d-block transition metals: fundamental aspects and recent trends. , 2010, Chemical reviews.

[21]  H. Buckley,et al.  User-Friendly Precatalyst for the Methylation of Polyfluoroaryl Imines , 2009 .

[22]  H. Schwarz,et al.  Platinum(II)-mediated dehydrosulfurization and oxidative carbon–carbon coupling in the gas-phase decomposition of thioethers , 2009 .

[23]  M. Manassero,et al.  Cyclometalation of 2,2′-Bipyridine. Mono- and Dinuclear C,N Platinum(II) Derivatives , 2009 .

[24]  H. Schwarz,et al.  "Roll-over" cyclometalation of 2,2'-bipyridine platinum(II) complexes in the gas phase: a combined experimental and computational study. , 2008, Chemistry.

[25]  J. Love,et al.  Insight into the Mechanism of Platinum-Catalyzed Cross-Coupling of Polyfluoroaryl Imines , 2008 .

[26]  I. Goldberg,et al.  Competitive aryl-iodide vs aryl-aryl reductive elimination reactions in Pt(IV) complexes: experimental and theoretical studies. , 2008, Journal of the American Chemical Society.

[27]  G. Sheldrick.  A short history of SHELX. , 2008, Acta crystallographica. Section A, Foundations of crystallography.

[28]  J. Love,et al.  Platinum(II)-catalyzed cross-coupling of polyfluoroaryl imines. , 2007, Organic letters.

[29]  K. I. Goldberg,et al.  Reductive elimination of ethane from five-coordinate platinum(IV) alkyl complexes. , 2007, Inorganic chemistry.

[30]  Summer B. Thyme,et al.  Mechanistic study of competitive sp(3)-sp(3) and sp(2)-sp(3) carbon-carbon reductive elimination from a platinum (IV) center and the isolation of a C-C agostic complex. , 2007, Journal of the American Chemical Society.

[31]  M. Manassero,et al.  Dinuclear platinum(II) complexes with bridging twofold deprotonated 2,2′:6′,2″-terpyridine. New molecules with a 3,5-diplatinated-pyridyl inner core: [Pt2(terpy-2H)(Me)2(L)2], [Pt2(terpy-2H)(X)2(L)2] and [Pt2(terpy-2H)(H)2(L)2] (L = neutral ligand; X = halide) – Crystal and molecular structure of [P , 2006 .

[32]  I. Goldberg,et al.  Aryl-halide versus aryl-aryl reductive elimination in Pt(IV)-phosphine complexes. , 2006, Journal of the American Chemical Society.

[33]  R. Crabtree.  The Organometallic Chemistry of the Transition Metals: Crabtree/The Organometallic Chemistry , 2005 .

[34]  M. Crespo,et al.  Oxidative addition of methyl iodide to dimethylplatinum (II) compounds containing bulky and/or chiral ligands. Crystal structure of compound [PtMe3I{1-(Me2NCH2 CH2NCH)C10H7}] , 2003 .

[35]  M. Jennings,et al.  The mechanism of protonolysis of phenylplatinum(II) bonds in complexes with phenyl trans to nitrogen or carbon donors , 2003 .

[36]  M. Cinellu,et al.  Activation of a C−H Bond in a Pyridine Ring. Reaction of 6-Substituted 2,2‘-Bipyridines with Methyl and Phenyl Platinum(II) Derivatives: N‘,C(3)-“Rollover” Cyclometalation , 2003 .

[37]  M. Crespo,et al.  Reactions of [C,N,N′]-cyclometallated platinum compounds with phosphines: transphobia and effect of the chloro substituents: Crystal structure of [PtCl(3,5-C6H2Cl2CHNCH2CH2NMe2)(PPh3)2] , 2003 .

[38]  M. Crespo,et al.  Stereoselective oxidative addition of methyl iodide to chiral cyclometallated platinum(II) compounds derived from (R)-(+)-1-(1-naphthylethylamine). Crystal structure of [PtMe{3-(R)-(C10H7)CHMeNCHC4H2S}PPh3] , 2001 .

[39]  A. Spek,et al.  C(arenium)-C(alkyl) bond making and breaking: key process in the platinum-mediated C(aryl)-C(alkyl) bond formation. Analogies to organic electrophilic aromatic substitution. , 2001, Journal of the American Chemical Society.

[40]  R. Seeber,et al.  Platinum complexes with NNC ligands. Syntheses, electrochemical and spectroscopic characterisations of platinum(II) and relevant electroreduced species , 2000 .

[41]  G. Koten,et al.  Metal-Mediated C-C Bond Making and Breaking : First Direct Evidence for a Reversible Migration of a Benzyl Group Along a Metal-Carbon Bond , 1999 .

[42]  J. Vicente,et al.  Synthesis and Reactivity of 2‐Aminophenylpalladium(II) Complexes: Insertion Reactions of Oxygen and Carbon Monoxide into Carbon−Palladium Bonds—New Examples of “Transphobia” , 1999 .

[43]  D. Milstein,et al.  Metallinsertion in C-C-Bindungen in Lösung , 1999 .

[44]  D. Milstein,et al.  Metal Insertion into C-C Bonds in Solution. , 1999, Angewandte Chemie.

[45]  V. Catalano,et al.  (2,2′: 6′,2″‐Terpyridine)Methylplatinum(II) Chloride and (1,10‐Phenanthroline)‐Methylchloroplatinum(II) , 2007 .

[46]  R. Puddephatt,et al.  Oxidative Addition Reactions of Organoplatinum(II) Complexes with Nitrogen-Donor Ligands. , 1997, Chemical reviews.

[47]  J. Vicente,et al.  The Difficulty of Coordinating Mutually trans Phosphine and Aryl Ligands in Palladium Complexes and Its Relation to Important Coupling Processes. Syntheses and Crystal Structures of a Family of Palladium Phosphino, Triflato, Perchlorato, and Aquo-2-(arylazo)aryl Complexes , 1997 .

[48]  Jim Patel,et al.  WATER AND PROTIC ACIDS AS OXIDANTS FOR PLATINUM(II) : DIORGANO(HYDRIDO)PLATINUM(IV) AND DIORGANO(HYDROXO)PLATINUM(IV) CHEMISTRY, INCLUDING STRUCTURAL STUDIES OF POLY(PYRAZOL-1-YL)BORATE COMPLEXES PT(OH)R2(PZ)3BH (R = METHYL, P-TOLYL) AND PT(OH)ME2(PZ)4B.H2O , 1997 .

[49]  G. B. Young,et al.  ‘Roll-over’ 3-metallation of co-ordinated 2,2′-bipyridyl in the thermal rearrangement of diary(bipyridyl)platinum(II) complexes: molecular structure of (µ-bidyl)[PtPh(Butpy)]2 , 1985 .

[50]  R. Hoffmann,et al.  Reductive Elimination of d8-Organotransition Metal Complexes , 1981 .

[51]  C. Eaborn,et al.  Synthesis of platinum(II) alkyl and aryl complexes from K2[PtCl4] and tetraorganotin compounds in dimethyl sulphoxide , 1981 .

[52]  H. Bönnemann.  Cobalt-katalysierte Pyridin-Synthesen aus Alkinen und Nitrilen , 1978 .

[53]  J. Hoste.  On a new copper specific group , 1950 .