Synthesis of zwitterionic phosphapalladacycles: unusual reactivity pattern of six-membered P,N-chelates

Abstract

A cyclometalation motif has been discovered in the unprecedented reaction of Pd­(II) precursors with simple pentane-2,4-diyl based aminoalkyl-phosphines. The unique six-membered zwitterionic palladacycles can easily be synthesized in the presence of 1 molar equiv of oxidant in high yields in a pure form. A comparison between the analogous ligands of different tether lengths revealed that the formation of the zwitterionic palladacycles is the exclusive privilege of the six-membered rings.

Probing Charge‐Transfer Processes in a Covalently Linked [Ge9]‐Cluster Imine Dyad

“…This bond elongation correlates with a shorter Ge1−C1 distance in 1‐H (Table 1), which, however, is in range of various reported Ge−C single bonds [33–36] . Slightly elongated C=N bonds have previously been reported for molecules comprising cationic iminium moieties [37] . The C=N double bond character in 1‐K and 1‐H is confirmed by the planar coordination of C1 by Ge1, N1 and C2, showing for both compounds the sum of bond angles around C1 of perfect 360.0° and featuring also dihedral angles ω C2−C1−Ge1−N1 of approximately 180° (Table 1).…”

“…[33][34][35][36] Slightly elongated C=N bonds have previously been reported for molecules comprising cationic iminium moieties. [37] The C=N double bond character in 1-K and 1-H is confirmed by the planar coordination of C1 by Ge1, N1 and C2, showing for both compounds the sum of bond angles around C1 of perfect 360.0°and featuring also dihedral angles ω C2À C1À Ge1À N1 of approximately 180°(Table 1). 1-H is also the first transition metal-free, charge neutral [Ge 9 ] cluster bearing only three substituents.…”

Untersuchung von Ladungstransferprozessen in einer kovalent verknüpften [Ge9]‐Cluster‐Imin Dyade

“…[33][34][35][36] Zuvor wurden für Moleküle mit kationischen Iminiumeinheiten leicht verlängerte C=N-Bindungen beschrieben. [37] Der C=N-Doppelbindungscharakter in 1-K und 1-H wird durch die planare Koordination von C1 durch Ge1, B1 und C2 bestätigt, mit Winkelsummen für beide Verbindungen von…”

“…Diese Bindungsaufweitung in 1‐H korreliert mit einem kürzeren Ge1‐C1‐Abstand (Tabelle 1), welcher jedoch im Bereich verschiedener bekannter Ge<C‐Einfachbindungen liegt [33–36] . Zuvor wurden für Moleküle mit kationischen Iminiumeinheiten leicht verlängerte C=N‐Bindungen beschrieben [37] . Der C=N‐Doppelbindungscharakter in 1‐K und 1‐H wird durch die planare Koordination von C1 durch Ge1, B1 und C2 bestätigt, mit Winkelsummen für beide Verbindungen von fast perfekten 360° und Diederwinkeln ω C2−C1−Ge1−N1 von ungefähr 180 0 (Tabelle 1).…”