Rearrangement or C−H Activation Processes Promoted by Reaction with the Solvate [cis-Pt(C₆F₅)₂(thf)₂]

Abstract

A new series of functionalized (μ-hydride)(μ-acetylide) isomeric derivatives [trans-(PPh3)(C6F5)Pt(μ-H)(μ-1κC α:η2-C⋮CR)Pt(C6F5)(PPh3)] (3) and [cis,cis-(PPh3)2Pt(μ-H)(μ-1κCα:η2-C⋮CR)Pt(C6F5)2] (4) (R = (4-CH3)C6H4, a; (4-CN)C6H4, b; CMeCH2, c; C(OH)Me2, d; C(OH)EtMe, e; C(OH)Ph2, f) have been prepared by reaction in mild conditions of the disolvated [cis-Pt(C6F5)2(thf)2] with the corresponding Pt(II) [trans-PtH(C⋮CR)(PPh3)2] (1) or Pt(0) [Pt(η2-HC⋮CR)(PPh3)2] (2) isomers. The course of these reactions seems to be rather general, but in the case of the diphenylhydroxy precursors is strongly influenced by an easy gem (4f) to trans (3f) isomerization and the presence of water, which leads to the formation of the unexpected (μ-hydroxy)(μ-vinyl) complex [cis,cis-(PPh3)2Pt{μ-1κC α:η2-CHCHC(OH)Ph2}(μ-OH)Pt(C6F5)2] (5f). Control of the latter reaction has allowed us to detect the mixed-valence intermediate [cis,cis-(PPh3)2Pt{μ-η2:η2-HC⋮C(OH)Ph2}Pt(C6F5)2(thf)] (6f). Starting from [Pt(η2-HC⋮C5H4N-4)(PPh3)2] (2g) and [cis-Pt(C6F5)2(thf)2] only the trinuclear mixed-valence adduct [{(PPh3)2Pt(μ-η2:2κN-HC⋮C5H4N-4)}2{cis-Pt(C6F5)2}] (7g) is obtained.

Platinum Complexes of a Borane‐Appended Analogue of 1,1′‐Bis(diphenylphosphino)ferrocene: Flexible Borane Coordination Modes and in situ Vinylborane Formation

“…An 11 B NMR chemical shift of 11 ppm indicates that the hydride ligand in 5 resides in a bridging position between platinum and boron, as was observed in 4 . The CC stretch for 5 was located at 2126 cm −1 in the IR spectrum,39 which is very similar to that observed for trans ‐[PtH(C 2 C 6 H 4 Me‐ p )(PPh 3 ) 2 ] (ν(CC)=2111 cm −1 ) 40. Similar oxidative addition reactivity with HC 2 Ph was reported recently for [Fe(N 2 )( i Pr TPB)], but in this case the resulting hydride is completely abstracted by the borane to afford zwitterionic [Fe (C 2 Ph)( i Pr TPB‐H)] (ν(CC)=2040 cm −1 ; ν(BH)=2490 cm −1 ) 12…”

“…The CC stretch for 5 was located at 2126 cm À1 in the IR spectrum, [39] which is very similar to that observed for trans-[PtH(C 2 C 6 H 4 Me-p)(PPh 3 ) 2 ] (n(CC) = 2111 cm À1 ). [40] Similar oxidative addition reactivity with HC 2 Ph was reported recently for [Fe(N 2 )( iPr TPB)], but in this case the resulting hydride is completely abstracted by the borane to afford zwitterionic [Fe (C 2 Ph)( iPr TPB-H)] (n(CC) = 2040 cm À1 ; n(BÀH) = 2490 cm À1 ). [12] Complex 6 A is a vinylborane analogue of arylborane complex 1, and both complexes feature an h 3 BCC-coordination mode, almost identical 31 P NMR chemical shifts (50.3 and 27.6 for 6 A, 50.8 and 28.5 ppm for 1) and similar 11 B NMR chemical shifts (24 and 21 ppm for 6 A and 1, respectively).…”

A Hydrido η1-Alkynyl Diplatinum Complex Obtained from a Phosphinito Phosphanido Complex and Trimethylsilylacetylene

“…As is shown in Figure 4b, each water molecule is simultaneously hydrogen bonded to two phosphinite ligands of two neighboring diplatinum complexes, giving rise to a dimer generated at equivalent positions (−x, −y, −z). A similar feature has been observed in the mononuclear phosphinito complex [22,[28][29][30][31] for which the existence of a through-ring Pt-Pt bonding interaction has been suggested on the basis of theoretical calculations [32]. The Pt-C(1) (2.036(4) Å) and Pt-P distances (2.2409(10)-2.3255(10) Å) and structural details of the terminal C≡CSiMe3 (C≡C 1.192(6) Å; Pt(1)-C(1)-C(2) 177.1(4)º; C(1)-C(2)-Si(1) 177.2(4)º) are unexceptional for these ligands.…”

C–H and P–C(Ph) activation competitive processes caused by interaction with the solvate [cis-Pt(C6F5)2(thf)2]

“…[7][8][9][10][11][12][13][14][15][16] In this field, our group has recently reported an easy C-H bond activation of a terminal alkyne at platinum(0) derivatives [Pt(g 2 -HC≡CR)(PPh 3 ) 2 ], (R = Ph, (4-CH 3 )C 6 H 4 , (4-CN)C 6 H 4 , CMe=CH 2 , C(OH)Me 2 and C(OH)-EtMe), in very mild conditions, by reaction with the platinum(II) species [cis-Pt(C 6 F 5 ) 2 (thf) 2 ], to yield the (l-hydride)(l-acetylide) diplatinum complexes [cis,cis-(PPh 3 ) 2 Pt(l-H)(l-1jC a :g 2 -C≡CR)-Pt(C 6 F 5 ) 2 ] (Chart 1, i). 17, 18 Interestingly, the reaction, in very mild conditions, of the same solvate [cis-Pt(C 6 F 5 ) 2 (thf) 2 ] with the isomeric Pt(II) substrates [trans-PtH(C≡CR)(PPh 3 ) 2 ], leads to the corresponding (l-hydride)(l-acetylide) diplatinum isomers [trans-(PPh 3 )(C 6 F 5 )Pt(l-H)(l-1jC a :g 2 -C≡CR)Pt(C 6 F 5 )(PPh 3 )] (Chart 1, ii). 17, 18 However, in spite of the notable group functionalization tolerance of these reactions, we have also found some differences in behavior depending on the substituent of the alkynyl fragments.…”