Dichloro(pentamethylcyclopentadienyl)ruthenium ‐ neuartige Dichotomie einer Molekülstruktur

Abstract

Norhcv-t KIUfl. Lnrs Wiwr?iutin. Ulli Englut und GcvAurd E. Hcrherich Die Titelverbindung [(Cp*RuCI, ),I, (Cp* = $-C,Me,) I I t . ' I, 1st ein vielverwendetes Reagens fur die Herstellung von Cp*Ru-Sandwich-und insbesondere Halbsandwich-Verbindunger~[~-'I. Obgleich die Loslichkeit des Komplexes in halogenierten Kohlenwasserstoffen und die osmometrische Molmassenbestimmung in Chloroform[hh1 gegen das Vorliegen eines Polymers sprechen. wird die Verbindung durchgehend als solches angesehen[81. Wir berichten iiber Strukturuntersuchungen an 1Iy] sowie am analog aufgebauten Komplex [ (Cp'RuCI) 2 ] 2['01 (Cp' = C,Me,Et) und dem Bromderivat ((Cp*RuBr2 ),I 3Ihh1. Bei der Herstellung aus RuCl,~nH,O und Cp*H in Methanol"] oder Ethanol['] fYlt 1 als rotbraunes. mikrokristallines Pulver aus. welches allen Kristallisationsversuchen widerstand. Wird dieses jedoch durch Chromatographie an silyliertem Kieselgel[l (Laufmittel Ether/Methylenchlorid) gereinigt. so konnen fur die Rontgenstrukturanalyse geeignete Kristallell durch Diffusion von Ether in eine konzentrierte Methylenchloridlosung von 1 erhalten werden. 2 und 3 kristallisier,:n ohne vorherige chromatographische Reinigung.C1 CI Br Ahb 1 Schakal D d r s t e h n g der Struktur des Isomers 1 b im Kristall Die Strukt urbestimmung" ' -51 ergab. wie zu erwarten, fur alle drei Verbindungen jeweils Dimere. Als Besonderheit treten in den Kristallen von 1 zu gleichen Teilen die Formen 1 a und 1 b (Abb. 1) mit stark unterschiedlichen Ru-CI-Abstanden und Ru-CI-Ru-Winkeln sowie Ru-Ru-Abstanden von 2.93 bzw. 3.75 8, (Abb. 2) auf, welche die Lagen 000 und 0;;(1 a) bzu. ii; und to0 (1 b) der monoklinen Elementarzelle besetzen. Die zentralen Bindungsparameter von 1 a und I b sind so unterschiedlich, dafl es berechtigt erscheint, von zwei ,,Deformationsisomeren" zu sprechen. Die Molekiilgeometrien der Verbindungen 2 und 3. deren Kristalle aus nur einer Form zusammengesetzt sind, entsprechen der des Isomers 1 a (Tabelle 1).Die unterschiedlichen Ru-Ru-Abstande in den Isomeren legen eine starke Austauschwechselwirkung der beiden unge-

Crystallographic Snapshots of the Bond‐Breaking Isomerization Reactions Involving Nickel(II) Complexes with Hemilabile Ligands

“…Based on the characterization of three distinct isomers in the solid state, we decided to determine if the three structures exist in solution as well. [30] All data are consistent with the solution and solid-state structures being very similar. Since substitution of the methyl group on the thioether with a phenyl ring reduces the electron richness of the thioether, [6] this ligand should favor an "open" monodentate coordination mode.…”

“…[30] All data are consistent with the solution and solid-state structures being very similar. [30] The solid-state structure of 4 b showed a square-planar nickel center, much like 4 a, with two equivalents of N-bound SCN À ligands and two equivalents of the non-chelating phosphine each arranged in a trans configuration. Importantly, the room temperature 31 P{ 1 H} NMR spectrum of 4 a in CD 2 Cl 2 exhibits a broad resonance at d = 10.9 ppm, which sharpens with decreasing temperature (Supporting Information, Figure S1 B), consistent with a monodentate coordination mode for the phosphine ligand.…”

Crystallographic Snapshots of the Bond‐Breaking Isomerization Reactions Involving Nickel(II) Complexes with Hemilabile Ligands

“…Indeed, complex 4 a was synthesized from a complex (3 a) prepared from NiCl 2 ·6 H 2 O and two equivalents of Ph 2 PCH 2 CH 2 SPh under similar conditions to those used to prepare 2 a-c (see the Supporting Information). As well as being characterized in the solid state by a single-crystal X-ray diffraction study (Figure 2 a) [30] All data are consistent with the solution and solid-state structures being very similar. [28,29] The solid-state structure of 4 a consists of a square-planar nickel center with two equivalents of N-bound SCN À ligands and two equivalents of P-bound monodentate P,S À Ph ligands arranged in trans configurations.…”

“…As in the case of 4 a, a single-crystal X-ray diffraction study of 4 b and 31 P{ 1 H}, 1 H, and 13 C{ 1 H} NMR spectroscopy indicated similar structures in solution and the solid state (Figure 2 b). [30] The solid-state structure of 4 b showed a square-planar nickel center, much like 4 a, with two equivalents of N-bound SCN À ligands and two equivalents of the non-chelating phosphine each arranged in a trans configuration. Significantly, room-temperature 31 P{ 1 H} NMR spectroscopy of 4 b in CD 2 Cl 2 showed a single sharp resonance at d = 16.7 ppm that remains unchanged with decreasing temperature.…”

“…Single-crystal X-ray diffraction studies of the purple, orange, and red crystals showed that they were 2 a, 2 b, and 2 c, respectively ( Figure 1). [30] The structure of 2 a consists of a nickel(II) center in an octahedral geometry, defined by two chelating P,S À Me ligands coordinated in a trans configuration to form the equatorial plane. Furthermore, it has two apical nitrogen-bound SCN À ligands, which are bent relative to the equatorial plane (150-1608; Figure 1 a and Supporting Information, Table S1).…”