Cis-(hydrido)hydrocarbylplatinum(IV) complexes as intermediates in the PtIIC bond breaking

[2.1.1]-(2,6)-Pyridinophane(L)-controlled alkane C–H bond cleavage: (L)PtMe2H+ as a precursor to the geometrically “tense” transient (L)PtMe+Electronic supplementary information (ESI) available: complete experimental and characterization data. See http://www.rsc.org/suppdata/nj/b3/b302055j/.

“…16 Particular examples include platinum(IV) alkyl hydrido species, 17 which are supposed to be responsible for so-called Shilov-type chemistry, 18 and recently for methane transformation into methylhydrosulfate 19 and some other reactions involving hydrocarbon CH bond cleavage. 17 Both moderately persistant 20,21 and even quite persistant ('' stable '') platinum(IV) alkyl hydrides [22][23][24] permit testing the intermediacy of platinum(IV) alkyl hydrides in alkane functionalization and to reveal some factors controlling their reactivity. 17 Moreover, alkane oxidative addition to the presumably 14-electron platinum(II) transient species Tp*PtMe 8 has proven this is a feasible process.…”

“…The new cationic hydridodimethyl platinum(IV) complex [PtMe 2 H(L)] + can be obtained by protonation of the corresponding [PtMe 2 (Z 2 -L)] 27,31 with a suitable Brønsted acid according to the known method. [20][21][22][23] To preserve the reactivity of the platinum(II) species I, we have used the anion tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, BAr FÀ 4 and a solvent of low donicity, dichloromethane. This is accomplished by onepot protonation of the corresponding dimethylplatinum(II) y Electronic supplementary information (ESI) available: complete experimental and characterization data.…”

Mechanism of the Platinum(II)-Catalyzed Hydroamination of 4-Pentenylamines

“…In the case of 6b ·R 3 NHCl, the platinum-bound chloride would have to compete with exogenous Cl – , which is typically a stronger hydrogen bond acceptor than is a M–Cl bond. , However, the presence of a strong σ-donor alkyl ligand trans to the chloride ligand in 6 , which is reflected in the long Pt–Cl bond (2.41 Å), may enhance the hydrogen bond acceptor ability of the chloride ligand to the extent that it competes effectively with exogenous Cl – . Because of the preferred 90° angle of the Pt–Cl···H hydrogen bond, association of the ammonium ion via hydrogen bonding would properly orient the proton for transfer to Pt to generate a reactive Pt­(IV) hydride species which is a potential intermediate in the protodemetallation event (see below) …”

“…The facile and exergonic conversion of both 8 to 5 and 5 to 6 likely renders C–N bond formation irreversible under reaction conditions. The azaplatinacyclobutane–ammonium adduct 6· R 3 NHCl represents the catalyst resting state and is consumed via turnover-limiting intramolecular protonolysis (Δ G ⧧ 393 K = 27 kcal/mol), presumably through an unobserved Pt­(IV) hydride intermediate followed by reductive elimination, to form the unobserved platinum pyrrolidine complex II . Associative ligand exchange of 1 with II would release 2 and regenerate the nitrogen-bound platinum 4-pentenylamine complex 4 (Scheme ).…”

Hydrocarbon C—H Bond Activation with Tp'Pt Complexes

“…Diimine (26,27), diamine (28), and trialkylphosphine (21) alkyl(hydrido)platinum(IV) complexes readily reductively eliminate alkane at or below room temperature. Alkane elimination in such systems has been proposed to occur through a five-coordinate intermediate generated by loss of a labile ligand.…”