Electrochemical generation and reactivity of bis(tertiary phosphine)platinum(0) complexes: a comparison of the reactivity of [Pt(PPh3)2] and [Pt(PEt3)2] equivalents

Abstract

Electrochemical reduction of cis-[PtCl2(PR3)2] (R = Ph, Et) in CH3CN/C6H6 containing NBu4C104 at a Hg pool electrode generates [Pt(PR3)2] equivalents in solution. Where R = Ph, the [Pt(PR3)2] equivalent may be trapped by 02, 02/C02, HC1, Mel, C6H6C0C1, and RC=CR (R = Ph, COOMe) but not by the less -reactive substrate PhCl. Where R = Et, the [Pt(PR3)2] equivalent reacts with the NBu4+ cation to ultimately generate trans-[PtH(Cl)(PEt3)2]. Prolonged electrolyses cause reduction of trans-[PtH(Cl) (PEt3)2] leading to hydride attack on the CH3CN solvent and ultimately forming trons-[PtH(CH2CN) (PEt3)2]. In the presence of bases such as NBu3, trans-[PtH(CH2CN) (PEt3)2] is isomerized in CH3CN solution producing iruns-[PtCN(CH3) (PEt3)2]. The use of electroinactive trapping agents such as PhCl or PhCN as cosolvents for the reduction of cis-[PtCl2(PEt3)2] allows trapping of the [Pt(PEt3)2] equivalents as irons-[PtPh-(X)(PEt3)2] (X = Cl, CN).

Synthesis and electrochemistry of 1,1′-bis(phosphino)cobaltocenium compounds

“…An irreversible two electron reduction of the Pd in [PdCl 2 (dppf)] has been observed at À1.59 V vs. FcH 0/þ [50]. The bisphosphine complexes [PtCl 2 (PPh 3 ) 2 ] and [PtCl 2 (PEt 3 ) 2 ] also undergo irreversible two electron reductions of the Pt metal at À2.10 V and À2.56 V vs. FcH 0/þ , respectively [51]. a The structure has two crystallographically independent molecules in the unit cell.…”

Dendrimer−Phosphine Complexes with Platinum(0) at the Core

“…So, the reactions of Pt(PPh 3 ) 3 ( 10c ) and 10a,b were studied (Table ). The reaction of CH 3 I with 10c , 29a,c 10a and 10b was too fast and completed within 2 min (before the 31 P NMR measurement) to afford trans adducts 14c ( 31 P resonance at 27.7 ppm with 1 J P-Pt = 3063 Hz: lit 29c. 26.8 ppm, 1 J P - Pt = 3064 Hz), 14a (26.4 ppm with 1 J P - Pt = 3050 Hz), and 14b (26.3 ppm with 1 J P - Pt = 3039 Hz), respectively, in quantitative yields (entries 1−3).…”

“…Plots of ln[PtL 3 ] vs time showed a straight line ( R 2 = 0.97−0.99) up to 80% conversion. In both benzene and 1,2-dichloroethane as a solvent, 10c afforded trans adduct 14d ( 31 P resonance at 22.9 ppm with 1 J P - Pt = 3086 Hz: lit 29b. 21.2 ppm with 1 J P - Pt = 3097 Hz) quantitatively (entries 4 and 5), while 10b reacted two times slower to afford trans adduct 14e ( 31 P resonance at 20.8 ppm with 1 J P - Pt = 3050 Hz) (entries 6 and 7).…”

“…For all the oxidative addition studies, H 3 PO 4 in D 2 O in a small sealed capillary was used as an internal standard for integrating the 31 P resonance. 31 P resonances of 14a − e were as follows: 14a , 26.4 ppm ( 1 J P - Pt = 3050 Hz); 14b , 26.3 ppm ( 1 J P - Pt = 3039 Hz); 14c ,29c 27.7 ppm ( 1 J P - Pt = 3063 Hz); 14d ,29b 20.8 ppm ( 1 J P - Pt = 3050 Hz); 14e , 22.9 ppm ( 1 J P - Pt = 3086 Hz).…”

Synthesis and characterization of monomeric and polymeric Pd(II) and Pt(II) complexes of 3,4-ethylenedioxythiophene-functionalized phosphine ligands

“…There have been several studies of the irreversible redox behavior of cis-and trans-[PtCl 2 (PR 3 ) 2 ], although most of the attention has focussed on reduction to Pt(0). [40][41][42][43][44][45][46] Similarly, because of the importance of [Pd(PR 3 ) 2 ] and related species as intermediates in Pd-catalyzed coupling cycles, there has been intensive electrochemical study of Pd(0)/Pd(II) interconversion involving phosphine ligands. [47][48][49][50] In contrast, however, few studies have appeared on M(II)/M(IV) couples.…”