Komplexe des Typs [MCl₄(SEt₂)₂] mit M = Mo und W. Kristallstrukturen, NMR-Spektren und magnetisches Verhalten/[MCl₄(SEt₂)₂] Complexes with M = Mo and W. Crystal Structures, NMR Spectra, and Magnetic Behaviour

Abstract

The crystal structures of the thioether complexes [MCl4(SEt2)2] with M = Mo and W have been solved by X-ray methods. Both compounds crystallize isotypically in the triclinic space group P1̄ with two formula units per cell unit. The metal atoms are octahedrally coordinated by four chlorine atoms and by the two sulfur atoms of the thioether molecules in transposition (symmetry Ci) with bond lengths (average): Mo-Cl 233.1, Mo-S 253.4, W-Cl 233.1, and W-S 251.7 pm. Both complexes were also characterized by 1H and 13C NMR spectroscopy as well as by measurement of the magnetic susceptibilities in the temperature range from 1.8 to 350 K.

Improved Preparations of Molybdenum Coordination Compounds from Tetrachlorobis(diethyl ether)molybdenum(IV)

“…[13] Besides elemental analysis and IR, no additional characterization was shown in the previous reports. In this respect, it resembles its sulfur congener [MoCl 4 (SEt 2 ) 2 ].…”

“…[13] As for the bis-Et 2 O analogue, we were unable to grow single crystals of this compound. This route appears to give a cleaner [MoCl 4 (THF) 2 ] product relative to the previously described synthesis from [MoCl 4 (MeCN) 2 ].…”

“…In this respect, it resembles its sulfur congener [MoCl 4 (SEt 2 ) 2 ]. the highly shifted resonances of the bis-THF adduct, vide infra, or those of the sulfur congener [MoCl 4 (SEt 2 ) 2 ] [13] ). The magnetic moment (µ eff ϭ 2.33 µ B ) is significantly lower than the spinonly value for two unpaired electrons because of the expected spin-orbit coupling for the triplet ground state derived from the pseudo-t 2g 2 configuration.…”

“…), namely 2.2Ϫ2.5 µ B . [13] [MoCl 4 (CH 3 OCH 2 CH 2-OCH 3 )] has a cis arrangement enforced by the chelating dimethoxyethane ligand. These resonances are broad as may be expected for a paramagnetic complex.…”

Kristallstruktur und Bindungsverhältnisse von [W(O-t-Bu)4(THF)]

“…Im Rahmen unserer Untersuchungen u È ber Alkin-Komplexe von Ûbergangsmetallen in hohen Oxidationsstufen hatten wir in der oxidativen Addition von Alkinen an [WCl 4 (SEt 2 ) 2 ] [1], in dem nach einer Kristallstrukturanalyse die SEt 2 -Gruppen trans-sta Èndig sind [2], einen sehr schonenden Syntheseweg zur Herstellung von Verbindungen des Typs [(Et 2 S)WCl 4( R±C≡C±R)] gefunden, der sich vor allem bei Anwendung funktionalisierter Alkine bewa È hrt hat [3±5]. Da sich Versuche, die Chloroliganden dieser Komplexe durch Reaktion mit Alkalimetall-Alkoxylaten zu substituieren, als ungeeignet erwiesen, haben wir zuna È chst Wolframtetrachlorid mit LiO-t-Bu umgesetzt, um das gebildete W(O-t-Bu) 4 anschlieûend der oxidativen Addition mit Alkinen zu unterziehen.…”