Bi- and tridentate stannylphosphines and their coordination to low-valent platinum. Issue 42 (25th September 2019)

• Record Type: Journal Article
• Authors: Salazar-Díaz, J. Jacobo; Muñoz-Hernández, Miguel A.; Rufino-Felipe, Ernesto; Flores-Alamo, Marcos; Ramírez-Solís, Alejandro; Montiel-Palma, Virginia
• Is Part Of: Dalton transactions. Volume 48:Issue 42(2019)
• Page Start: 15896
• Page End: 15905
• Publication Date: 2019-09-25
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c9dt03317c
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Preferential cleavage of Sn–C sp 3 versus Sn–C sp 2 bonds and establishment of trans influence trend SnMe3 > SnPh2 (CH2 R) > SnPh3 in platinum stannylphosphines. Abstract : Semirigid bifunctional tin-substituted o -tolylphosphines of general formulae [Ph2 P( o -C6 H4 CH2 )SnR3 ] (R = Ph, 1 ; R = Me, 2 ) and [{Ph2 P( o -C6 H4 CH2 )}2 SnPh2 ] (3 ) were synthesized and isolated in good yields. The new compounds were fully characterized by single-crystal X-ray diffraction and multinuclear solution NMR spectroscopic techniques. The observed J ( 119 Sn, 31 P) values in solution NMR spectroscopy as well as the P⋯Sn distances in the solid state and DFT calculations (B3LYP) on compounds 1 and 3 do not support the existence of intramolecular P → Sn bond interactions in either of the three compounds. 1 and 2 reacted with stoichiometric amounts of tristriphenylphosphine platinum(0) [Pt(PPh3 )3 ] under toluene refluxing conditions leading to formation of Pt(ii ) distorted square-planar complexes [Ph2 P( o -C6 H4 CH2 )Pt(SnR3 )(PPh3 )], (R = Ph, 4 ; R = Me, 5 ), each bearing a five-membered carbometallated ring resulting from Pt coordination to P and the benzylic C sp 3 atom of the ligand architecture rather than from activation of the terminal Sn–C carbon bonds of the phenyl or methyl substituents which would have rendered six-membered rings. Additionally, the fragment SnR3 also binds to the metal centre disposing cis to the cyclometalated carbon atom and to the single remaining PPh3 . This carbometallation takes place affecting the integrity of the ligand skeleton. NBO calculations show the Sn fragment coordinates to the metal as X-type stannyl, SnR3 . The analogous reaction of [Pt(PPh3 )3 ] towards the stannyldiphosphine 3 leads to the quantitative formation of complex [(Ph2 P- o -C6 H4 CH2 )Pt(Ph2 P- o -C6 H4 CH2 SnPh3 )], 6, which exhibits five- and six-membered metallacycles at the expense of the ligand frame. All compounds were characterized exhaustively by solution spectroscopic measurements and by single crystal X-ray diffraction analysis. DFT computations corroborate the higher stability of the observed products over those resulting from preservation of the ligand backbone.