Übergangsmetallkomplexe mit Schwefelliganden. LIX. Reversible μ‐Oxo‐Verknüpfung von [Mo(NO)(′S₄′)]‐Fragmenten: Hydrolyse von [Mo(X)(NO)(′S₄′)] (X = Cl, Br, NMe₂, NPMe₃) zu [μ‐O {Mo(NO)(′S₄′)}₂] (′S₄′²⁻ = 2,3,8,9‐Dibenzo‐1,4,7,10‐tetrathiadecan(2−))

Abstract

Zur Untersuchung der spezifischen Eigenschaften von Übergangsmetall‐Schwefelkomplexen mit dem vierzähnigen Liganden ′S4′2− = 2,3,8,9‐Dibenzo‐1,4,7,10‐tetrathiadecan(2−) wurde [μ‐O{Mo(NO)(′S4′)}2], 1, synthetisiert. Es entsteht bei der Hydrolyse von [Mo(X)(NO)(S4′)] (X = Cl, Br, NMe2, NPMe3). 1, kristallisiert als 1. THF in der triklinen Raum‐gruppe P1 mit Z = 2, a = 1066,7(6), b = 1442,4(4) c = 1547,0(5) pm, α = 65,01(2), β = 87,79(4), γ = 70,48(3)°, R = 0,065, Rw = 0,053. Die Röntgenstrukturanalyse zeigt, daß beide Mo‐Zentren pseudooktaedrisch von zwei Thiolat‐S‐, zwei Thioether‐S‐, einem Nitrosyl‐N‐Atom und dem verbrückenden O‐Atom umgeben sind. Der μ‐Oxo‐Ligand fungiert als σ‐π‐Donor, so daß das Mo‐Zentrum eine formale 18e‐Konfiguration erhält. Die Mo(μ‐O)‐Bindungen (MoO: 186,6(6), 189,1(6) pm) weisen Doppelbindungscharakter auf. Die Röntgenstrukturanalyse beweist das Vorliegen eines RR/SS‐Enantiomerenpaares im festen Zustand, wohingegen 13C‐NMR‐spektroskopische Ergebnisse die Existenz von zwei unterschiedlichen Isomeren in Lösung aufzeigen. Aus Umsetzung von 1 mit gasförmigem HCl resultiert in einer reversiblen Reaktion, unter Erhalt der stabilen [Mo(NO)(′S4′)]‐Fragmente, der einkernige Komplex [Mo(Cl)(NO)(′S4′)], 2.

Coordination and Organometallic Chemistry of Metal−NO Complexes

“…Numerous nitrosyl complexes of the group 6 metals with sulfur-dominated coordination spheres have been synthesized and characterized by Sellmann and co-workers, often in the quest for complexes modeling functional characteristics of metal sulfur oxidoreductases. Examples of such complexes include Cr(NO) x (‘S 4 ') y ( x = 2, y = 1; x =1, y = 2), [W(NO) 2 (‘S 2 ') 2 ] 2- , W(L)(NO)(‘S 4 ') (L = NO, NPMe 3 , NPEt 3 ), (μ-O)[W(NO)(‘S 4 ')] 2 , and MX(NO)(‘S 4 ') (M = Mo, W; X = Cl, SR, NHNR 2 ) in which ‘S 2 ' 2- = 1,2-benzenedithiolate(2−) and ‘S 4 ' 2- = 1,2-bis(2-mercaptophenylthio)ethane(2−). − Hydrolysis of MoX(NO)(‘S 4 ') complexes (X = Cl, Br, NMe 2 , NPMe 3 ) affords (μ-O)[Mo(NO)(‘S 4 ')] 2 in which the μ-oxo ligand acts as a σ,π donor to each metal center . Redox-substitution reactions of Mo III (SPh)(NO)(‘S 4 ') with phosphines yield the 17e complexes, Mo II (PR 3 )(NO)(‘S 4 '), which can be oxidized or reduced electrochemically .…”

“…139 It has also been reported that treatment of cis-(Ald)Mo(CO) 4 (Ald ) aldimines) with NO affords mixtures of unusual (NO)(Ald)Mo(CO) 2 (NO 2 ) and (NO) 2 (Ald)Mo(NO 2 ) 2 complexes, whereas ClNO yields only (Ald)Mo(CO) 2 (NO)Cl. 140 Numerous nitrosyl complexes of the group 6 metals with sulfur-dominated coordination spheres have 144 Redox-substitution reactions of Mo III (SPh)(NO)('S 4 ') with phosphines yield the 17e complexes, Mo II (PR 3 )(NO)('S 4 '), which can be oxidized or reduced electrochemically. 145 Alkylation of Mo(NO)(Cl)('S 4 ') by [R 3 O] + (R ) Me, Et) yields the monoalkyl derivatives, [Mo(NO)(Cl)(R-'S 4 ')] + , and the chloro ligand in the neutral complex may be metathesized by thiolates.…”

Synthesis of Bridged Oxo-Tungsten Complexes

“…Transition metal complexes with terminal hydroxo and oxo ligands attract considerable interest due to their involvement in industrially relevant processes and enzyme-catalyzed reactions . A variety of methods for the synthesis of early as well as late transition metal hydoxo and μ-oxo complexes are available, such as oxidation of metal−metal bonds by exposure to molecular oxygen or hydrolysis of metal−halogen bonds. − Intending to prepare the tungsten complex A , containing a terminal hydoxo group and a phosphane ligand, we investigated the hydrolysis of chlorophosphinovinyl complexes 3a − c . Generally it is expected that phosphane groups stabilize the hydroxo complexes, but the dehydratization to the μ-oxo complexes is a thermodynamically favored process and the hydroxo ligands have a strong propensity to bridge between two metal centers .…”