From Neutral to Ionic Species: Syntheses and X‐ray Crystallographic and Multinuclear NMR Spectroscopic Studies of Li···P(SiMe₃)–PtBu₂ and Its Solvent Complexes

Abstract

Li(THF) 3 P(SiMe 3 )-PtBu 2 (1) prepared by the reaction of (Me 3 Si) 2 P-PtBu 2 with n-butyllithium in THF has been isolated in good yields. or 12-crown-4, respectively, in solution. The molecular structures of 1-5 were established by single crystal X-ray diffraction. Compound 3 forms a cyclic tetramer with a flat butterfly geometry. Extensive solution NMR spectroscopic investigations have shown that all species except of 3 exist in the same form in solution as in the solid state. Moreover, multinuclear variable-temperature NMR studies showed that 2 is involved in a rapid conversion between conformers at 298 K, which can be slowed down on the NMR time scale at 183 K.

First Copper(I) and Silver(I) Complexes Containing Phosphanylphosphido Ligands

“…It should be also mentioned, that in these complexes the phosphanylphosphido ligands exhibit the monodentate (terminal) and bidentate (side‐on) coordination to the central metal atom, but never bridging coordination. The bridging coordination of RR ′P‐P(SiMe 3 ) ligands are only known for dimeric and tetrameric forms observed in the derivatives of lithium salts: [Li(THF)(Me 3 Si)P‐P t Bu 2 ] 2 and [Li(THF)(Me 3 Si)P‐P t Bu 2 ] 4 . The solvent used to crystallization process of these compounds is significant.…”

“…The solvent used to crystallization process of these compounds is significant. The applying of THF solution promotes the formation of cyclical forms, while the chelating solutions (TMEDA, 12‐Crown‐4) lead to the monomeric, ionic forms: [Li(TMEDA) 2 ] + [(Me 3 Si)P–P t Bu 2 ] – and [Li(12‐Crown‐4) 2 ] + [(Me 3 Si)P–P t Bu 2 ] – . Surprisingly, up to now the complexes of late transition metal with phosphanylphosphido ligands have never been synthesized and described.…”

Investigations of LiP(SiMe2CH2SiMe3)–PtBu2, the Surprising Byproduct in the Metalation of (Me3Si)2P–PtBu2

“…(Me 3 Si) 2 P–P t Bu 2 can effortlessly be metalated with n ‐butyllithium in thf, resulting in the formation of Li(thf) n P(SiMe 3 )–P t Bu 2 ( n = 1–3; 1 ), which can be isolated as the main product by crystallization from a mixture of thf/hexane . Although the first crystal fraction contained only compound 1 , a second, more soluble compound accumulated in subsequent fractions.…”

“…[Li(thf)P(SiMe 2 CH 2 SiMe 3 )–P t Bu 2 ] 2 ( 2a ; Figure ) crystallizes in the monoclinic crystal system with space group C 2/ c ; the asymmetric unit contains half of a molecule. Compound 2a exhibits a similar geometry to the dimer of 1 , that is, [Li(thf)P(SiMe 3 )–P t Bu 2 ] 2 ( 1a ) . The molecule contains a planar P 2 Li 2 ring with tetrahedrally coordinated phosphorus atoms.…”

“…Recently, we reported on the behavior of both the solvent‐free and solvated complexes of LiP(SiMe 3 )–P t Bu 2 . Li(thf) 3 P(SiMe 3 )–P t Bu 2 , prepared from the reaction of (Me 3 Si) 2 P–P t Bu 2 with n ‐butyllithium in thf, exists as a monomer and eliminates thf upon drying in vacuo to yield the dimeric [Li(thf)P(SiMe 3 )–P t Bu 2 ] 2 with a [( µ ‐P) 2 Li 2 ] core.…”