Reactivity of the phosphinito bridged Pt(i) complex [(PHCy₂)Pt(μ-PCy₂){κ²P,O-μ-P(O)Cy₂}Pt(PHCy₂)](Pt–Pt) towards Au(i) and Ag(i) electrophiles

Abstract

The reactivity of the phosphinito bridged Pt(I) complex [(PHCy(2))Pt(1)(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(2)(PHCy(2))](Pt-Pt) (1) towards Au(I) and Ag(I) electrophiles was explored. Treatment of 1 with AuCl yielded the dichloro Pt(II) complex [(Cl)(PHCy(2))Pt(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(Cl)(PHCy(2))] (4), while [Au(PPh(3))Cl] in thf (or toluene) caused ligand exchange resulting in the formation of [(PPh(3))Pt(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(PHCy(2))](Pt-Pt) (7) and [(PPh(3))Pt(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(PPh(3))](Pt-Pt) (8). With [Au(PPh(3))OTf] (independently from the solvent) or with [Au(PPh(3))Cl] (only in dichloromethane), reaction with 1 gave [(PHCy(2))Pt(1)(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(2){μ-Au(PPh(3))}(PHCy(2))]X(Pt-Pt) ([6]X, X = OTf, Cl) clusters in which the [Au(PPh(3))] moiety bridges the μP-Pt(2) bond. The [Ag(PPh(3))](+) electrophile attacks complex 1 selectively at the Pt(2)-μP bond to afford, at low T, the cationic cluster [(PHCy(2))Pt(1)(μ-PCy(2)){κ(2)P,O-μ-P(O)Cy(2)}Pt(2){μ-Ag(PPh(3))}(PHCy(2))](+)(Pt-Pt) (10(+)) in which the [Ag(PPh(3))](+) moiety bridges the μP-Pt(2) bond. Clusters analogous to 10(+), but without PPh(3) bonded to Ag, are obtained from reactions of 1 with AgOTf, AgBF(4), AgClO(4) and AgCl.

Addition of Nucleophiles to Phosphanido Derivatives of Pt(III): Formation of P–C, P–N, and P–O Bonds

“…The addition of OH – can take place with formation of a coordinated PPh 2 OH (PPh 2 /OH coupling) which affords the P , O -bridging phosphinito complex 3 upon deprotonation by a second hydroxide (Scheme ). Some phosphinito bridged complexes showing the Pt–P–O–Pt sequence have been structurally characterized, − and examples with both μ-phosphanido and μ-phosphinito Pt(I) derivatives have been synthesized and studied. − On the other hand, we have recently reported the synthesis of [(PPh 2 R F )(R F )Pt II (μ-OH)(μ-PPh 2 )­Pt II (dppe)][ClO 4 ] which seems to be formed from an undetected Pt(III),Pt(III) cationic intermediate [(R F ) 2 Pt III (μ-PPh 2 ) 2 Pt III (dppe)][ClO 4 ] 2 through a PPh 2 /C 6 F 5 coupling and the coordination of a bridging OH, but we did not observe the PPh 2 /OH coupling as in 3 . If the proposed azide or cyanate Pt(II),Pt(IV) intermediates evolve according to pathway a, a P–N bond can be formed by reductive coupling between phosphanido and azide (or cyanate) giving a coordinate PPh 2 N 3 (or PPh 2 NCO) which eliminates and easily decomposes. , Finally, the coordination environment of the metal centers can be completed with a μ 1,1 -N 3 ligand (or NCO), and 4a (or 5a ) could be formed.…”

Multinuclear Solid-State NMR and DFT Studies on Phosphanido-Bridged Diplatinum Complexes

“…Platinum diorganophosphanido complexes have been the object of intense study in the last years due to the rich chemistry they exhibit. − NMR spectroscopy is a powerful technique for investigating the structure and dynamics in solution of such complexes, owing to the presence of several different spin 1/2 nuclei in these molecules ( 1 H, 31 P, 195 Pt, 13 C, and in several cases 19 F). Although NMR studies on this kind of complexes have been performed for several decades, some issues about 195 Pt NMR and 31 P NMR remain unclear.…”

Uncovering Intramolecular π‐Type Hydrogen Bonds in Solution by NMR Spectroscopy and DFT Calculations

“…The existence of a π‐type hydrogen bond between the PO−H and the C≡C triple bond in solution is also suggested by the sharpness of the 31 P NMR signal of the P 4 HCy 2 ligand. In fact, for systems analogous to 2 , the 31 P NMR signal of the P 4 HCy 2 ligand is expected to be quite broad when the P(OH)Cy 2 in the cis position can freely rotate about the Pt−P bond, and relatively sharp when the rotation of the P(OH)Cy 2 ligand is hindered due to the formation of the PO⋅⋅⋅H⋅⋅⋅X bridge (X=Lewis base) …”

“…The existence of a p-type hydrogen bond between the POÀ Ha nd the CCt riple bond in solution is also suggestedb yt he sharpnesso ft he 31 PNMR signalo ft he P 4 HCy 2 ligand.I nf act, for systems analogoust o2,t he 31 PNMR signal of the P 4 HCy 2 ligand is expected to be quite broad when the P(OH)Cy 2 in the cis positionc an freely rotate about the PtÀPb ond, [21] and rela-tively sharpw hen the rotationo ft he P(OH)Cy 2 ligand is hindered due to the formationo ft he PO···H···X bridge (X = Lewis base). [22][23][24][25][26] Another clue to the presence of the p-type hydrogen bond derives from the analysis of the 1 H-195 Pt HMQC spectrum of 2 ( Figure 1) displaying, besides the correlation between the Cy 2 PH protons and the 195 Pt atoms to which the phosphanes are bonded, intense cross peaks between the POH protona nd Pt 1 (but not Pt 2 ).…”