Platinum–Carbon σ-Bonded Complexes

Pt(PEt3)(κ2-P,C-PEt2CHMe)(C6Cl5): An Unexpected Intermediate in the Synthesis ofcis-Pt(PEt3)2(Cl)(C6Cl5)

“…, 680 (39), 683 (22), 682 (17), 678 (27), 677 (28), 684 (11), 685 (12), 686 (4), 687 (3); [M -C 6 Cl 5 ] þ 429 (40), 430 (39), 431 (29), 433 (10), 432 (7), 434 (2), 427 (22). 1 H NMR (CDCl 3 , 500 MHz): 2.10-1.87 (overlapping m's, 5H, PEt(CH 2 Me)CHMe and PEt 2 CHCH 3 ), 1.68 (br m, 6H, P(CH 2 Me) 3 ), 1.28 (overlapping dq, J HH = 7, J PH = 9, 2H, PEt(CH 2 Me) 0 CHMe), 1.23 (dt overlapping with 1.28 signal, J HH = 8, J PH = 18, 3H, PEt(CH 2 CH 3 )CHMe)), 1.06 (dt, 3H, J HH = 7, J PH = 19, PEt(CH 2 CH 3 ) 0 CHMe)), 0.99 (overlapping dt, 9H, P(CH 2 CH 3 ) 3 ). The COSY spectrum indicates that the PEt 2 CHMe resonance is buried under the signals around δ 1.1 and adds 1H to the integration in this region.…”

“…A common method for the synthesis of Pt(II) alkyl and aryl complexes involves addition of an organolithium or organomagnesium reagent to a Pt(II) halide followed by an aqueous, often acidic workup to remove excess reagent and coproduct salts. , It is usually assumed that the Pt alkyl or aryl complex is formed directly in the reaction and is present before and after the workup. Herein, we report an example where this is not the case, and the final Pt(II) aryl complex is obtained only after acidic treatment of an initially formed phosphine ligand metalation product …”

Platinum(IV) Complexes: C−H Activation at Low Temperatures

“…In an attempt to identify any intermediates in the oxidation of 1, we performed the reactions in an NMR tube inside the NMR spectrometer, monitoring both 1 H and 19 F resonances. In chloroform, at -40 °C both reactants are cleanly consumed, with no visible byproducts, giving 3 and iodobenzene cleanly.…”

“…To date, the vast majority of cycloplatination reactions have involved starting with, and ending up, with platinum(II) species, although some examples have platinum(IV) species being synthesized via oxidative addition to platinum(II) complexes. − However, even though the reductive elimination of hydrocarbons from platinum(IV), which can be seen as analogous to the reverse of a C−H activation, has been widely studied, − there have been few reports of C−H activation by a platinum(IV) center to date. ,− …”

“…15,16 To date, the vast majority of cycloplatination reactions have involved starting with, and ending up, with platinum(II) species, although some examples have platinum(IV) species being synthesized via oxidative addition to platinum(II) complexes. [17][18][19][20] However, even though the reductive elimination of hydrocarbons from platinum(IV), which can be seen as analogous to the reverse of a C-H activation, has been widely studied, [21][22][23][24][25][26] there have been few reports of C-H activation by a platinum(IV) center to date. 1,[27][28][29][30] The work we report here builds on our previous work on C-H activation with platinum(II) species, work that leads to the only high-yielding route to CNC triply coordinating complexes 31,32 and to the unusual C-H activation that gave a carbene species, rather than a cyclometalated species.…”