Acceptor Pincer Coordination Chemistry of Platinum: Reactivity Properties of (^CF₃PCP)Pt(L)⁺ (L = NC₅F₅, C₂H₄)

Abstract

1)/n Unit cell dimensions a = 16.4459(2) Å α= 90°. b = 20.6746(3) Å β= 90.6980(10)°. c = 22.0032(3) Å γ = 90°. Volume 7480.81(17) Å 3 Z 8 Density (calculated) 2.390 Mg/m 3 Absorption coefficient 7.857 mm -1 F(000) 5016 Crystal size 0.32 x 0.32 x 0.27 mm 3 Theta range for data collection 1.83 to 35.63°. Index ranges -26<=h<=26, -33<=k<=33, -36<=l<=36 Reflections collected 187817 Independent reflections 34495 [R(int) = 0.0407] Completeness to theta = 35.63° 100.0 % Absorption correction Numerical Max. and min. transmission 0.2255 and 0.1877 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 34495 / 0 / 1045 Goodness-of-fit on F 2 1.014 Final R indices [I>2sigma(I)] R1 = 0.0306, wR2 = 0.0611 R indices (all data) R1 = 0.0535, wR2 = 0.0689 Largest diff. peak and hole 4.356 and -3.920 e.Å -3

A Cationic Unsaturated Platinum(II) Complex that Promotes the Tautomerization of Acetylene to Vinylidene

“…[2c] Liberation of CH 4 occurred instead, with formation of complexes [PtMe(S)(PMe 2 Ar Dipp 2 )] + (2·S; Scheme 1), which feature rather large 1 J PPt and 3 J PtH (Pt-Me) couplings of about 4800 and 77 Hz, respectively.T hese complexes exhibited dynamic behavior at 25 8 8C, [21] although below À10 8 8C, the molecular structure became rigid on the NMR time scale.Below 25 8 8C, the Dipp rings give rise to two septets (2.38 and 2.28 ppm in C 2 D 2 Cl 4 )a nd four doublets (between 1.52 and 1.06 ppm) for the i Pr substituents.A t higher temperatures ( Figure S12 in the Supporting Information) the two rings become equivalent (above 110 8 8C; DG°= 19 AE 2kcal mol À1 at the coalescence temperature of 100 8 8C). Figure 1) and forms aPt ÀObond with anormal [22] length of 2.143(4) .O ther metric parameters have the expected values,although the Pt···C arene interaction (Pt1 À C22 in Figure 1) of 2.348(5) is significantly longer than normal olefinic Pt II À Cb onds (ca. 2.11-2.…”

“…[24,27] These compounds are related to the catalyst resting state involved in Pd-and Ni-catalyzed olefin polymerization [1a] and in the Pt-catalyzed dimerization of ethylene. [22,28,29] Addition of C 2 H 4 to CH 2 Cl 2 solutions of complex 2·S led to the adduct [PtMe(h 2 -C 2 H 4 )(PMe 2 Ar Dipp 2 )] + (4), which once again exhibits chelating k 2 -P,C phosphine ligation. TheP t À C 2 H 4 linkage undergoes fast C 2 H 4 rotation at 20 8 8C, with ab arrier of DG°= 11 AE 1kcal mol À1 at the coalescence temperature of 25 8 8C( Figure S13).…”

“…At room temperature, it gives rise to abroad 13 C{ 1 H} NMR resonance at 102.2 ppm, with as hift of the olefin coordination to lower frequencies relative to C 2 H 4 .F or comparison, in dicationic [Pt(PNP)(C 2 H 4 )] 2+ , Dd = À45 ppm. [7c,30] This observation is indicative of asignificantly decreased contribution of p backdonation in complex 4, [31] which is in agreement with the high p-acidity of the Pt II center in 2·S.C omplex 4 is nonetheless stable at 20 8 8Ctowards C 2 H 4 migratory insertion into the PtÀ Me bond, although under excess C 2 H 4 (2 bar), 4 becomes acatalyst precursor for C 2 H 4 dimerization [22,28,29] above 55 8 8C (see the Supporting Information). Related diimine Pt catalysts required heating for 2days at 100 8 8C.…”

A Cationic Unsaturated Platinum(II) Complex that Promotes the Tautomerization of Acetylene to Vinylidene

“…Adventitious H 2 O originated crystals of the aquo complex [PtMe(H 2 O)(PMe 2 Ar )]BAr F ( 2⋅H 2 O ) in preference to those of 2⋅Et 2 O or 2⋅CH 2 Cl 2 . The H 2 O ligand is trans to P (Figure ) and forms a Pt−O bond with a normal length of 2.143(4) Å. Other metric parameters have the expected values, although the Pt⋅⋅⋅C arene interaction (Pt1−C22 in Figure ) of 2.348(5) Å is significantly longer than normal olefinic Pt II −C bonds (ca.…”

“…Complex 2⋅S also offered the possibility of accommodating Pt–alkene or Pt–alkyne functions cis to the Pt−Me bond, thus making it amenable to experience insertion reactions . These compounds are related to the catalyst resting state involved in Pd‐ and Ni‐catalyzed olefin polymerization and in the Pt‐catalyzed dimerization of ethylene …”