Ernst Guggolz

Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen: VII. Oxidative decarbonylierungsprozessein der photochemie von tricarbonyl(η5-pentamethylcyclopentadienyl)rhenium: Neue oxo—rhenium-komplexe

Short-wavelength photolysis of tricarbonyl(η5-pentamethylcyclopentadienyl)rhenium (1) (λ < 300 nm, quartz-glass) in tetrahydrofuran yields under partial or complete decarbonylation three novel organorhenium compounds, with the relative yields depending upon the irradiation time. Formed by exhaustive oxidative decarbonylation, the complex trioxo(η5-pentamethylcyclopentadienyl)rhenium(VII) (5) represents the first example of the new class of oxo half-sandwich complexes. The derivatives (μ-O)[(η5-C5Me5)Re(CO)2]2 (2; Me = CH3) and (η5-C5Me5)2Re2(CO)2O2 (3; Me = CH3) containing both oxo and carbonyl ligands are formed from 1 at shorter irradiation times. Both compounds are isolable intermediates along the mechanistically not yet fully established sequence 1 → → 5 as they are degraded to 5 under CO2 elimination in the presence of air and/or light. The mixed oxo carbonyl complex 2 has been characterized by means of single-crystal X-ray diffraction techniques (triclinic, space group P1-Ci1; a 907.4(2), b 1040.2(3), c 1414.3(4) pm; α 79.99(2), β 88.42(2), γ 66.18(2)°; Riso = 0.068, Raniso = 0.037, Rw = 0.031). The molecular structure centres around an isosceles Re2O triangle whose metal centres exhibit a strongly distorted square-pyramidal geometry; the metal-metal distance recorded at 281.7(1) pm is in agreement with a single bond by the EAN rule. The centrically coordinated, planar five-membered ring ligands are parallel to each other (interplanar angle 2°) and occupy trans-positions with respect to the central Re2O geometry.

Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen. XV: Reduktive Aggregation des Halbsandwich-Komplexes Trioxo(η5-pentamethylcyclopentadienyl)rhenium

Abstract The trioxo complex (η 5 -C 5 Me 5 )ReO 3 ( 1 ) undergoes partial deoxygenation in the presence of the Lewis base triphenylphosphane. When this reaction is conducted in tetrahydrofuran solution with rigorous exclusion of air, the dinuclear, very oxygen-sensitive d 2 -Re V derivative 2 of composition (η 5 -C 5 Me 5 ) 2 Re 2 O 4 is cleanly formed. In the presence of trace amounts of oxygen, however, a second reaction pathway is opened up, which leads to the tetranuclear Re V /Re VII complex 3 in 30–60% yield. This compound is structurally derived from the dinuclear species 2 , in that one of the two terminal oxo groups is replaced by two O -coordinated perrhenate ligands; in keeping with the requirements of the EAN rule and supported by the bond length of 265.1(1) pm, the doubly oxygen-bridged Re V -Re V interaction is best interpreted in terms of a metal—metal double bond (single-crystal X-ray diffraction study). Finally, upon treatment of 1 with triphenylphosphane in air-saturated solutions of tetrahydrofuran, the ionic cluster compound 4 of net composition (C 5 Me 5 ) 3 Re 5 O 14 is surprisingly formed in 70–90% yield. This latter complex exhibits the C 3 -symmetrical cation [(η 5 -C 5 Me 5 ) 3 Re 3 (μ-O) 6 ] 2+ , with the two counter-ions being isolated perrhenate groups. The metal—metal distances within the cyclic cation are crystallographically identical and amount to 274.7(2) pm (single-crystal X-ray diffraction study).

Untersuchungen zur Reaktivität der MetallMetall-Dreifachbindungen in den Spezies (C5R5)2M2(CO)4 (R = H, Me; M = Cr, Mo, W) gegenüber kondensierten Dämpfen von Schwefel, Selen und Tellur

Abstract Condensation of chalcogenide vapours (S, Se, Te) onto a THF matrix containing the species (C 5 R 5 ) 2 M 2 (CO) 4 (MM) (R = H, CH 3 ; M = Cr, Mo, W) in a metal vapour apparatus (temperature of liquid nitrogen, 10 −4 bar) upon warming (S 10, Se 15, Te 5 (CH 3 ) 5 W 2 (CO) 4 E 3 (E = S ( 2 ), Se ( 13 )) and (C 5 (CH 3 ) 5 ) 2 W 2 (CO) 4 E 2 (Se, ( 13a ), Te ( 17 )). The species, which are primary adducts of the chalcogenides to the WW bond, could not be synthesized by the “thermic” reactions reported in the literature. The species 2 and 13 are readily converted into the chalcogenide complexes such as (C 5 (CH 3 ) 5 ) 2 Mo 2 O 2 Se ( 16 ) liberating CO. 17 was protonated to give the complex salt [(C 5 (CH 3 ) 5 ) 2 W 2 (CO) 4 (Te 2 H 2 )] 2+ [BF 4 ] 2 − ( 18 ) by HBF 4 . The compounds were characterized by elemental analysis and their spectroscopic data, X-ray diffraction studies of 13a, 16 and 18 are described.

Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen: XVI. Doppelte oxidative addition von monosilan an das koordinativ ungesättigte organometall-fragment (η5-C5Me5)Mn(CO)2: Darstellung und molekülstruktur von μ-silylen-bis[dicarbonyl(hydrido)(η5-pentamethylcyclopentadienyl)mangan]☆

Abstract Upon treatment of the labile ether complex (η 5 -C 5 Me 5 )Mn(CO) 2 (THF) ( 1 ) with monosilane the novel dinuclear complex of composition (μ-SiH 2 )[(η 5 -C 5 Me 5 )Mn(CO) 2 H] 2 ( 2 ) is formed in 15% isolated yield via double oxidative addition of the binary hydride precursor. According to a single-crystal X-ray diffraction study, the molecule exhibits a bent MnSiMn′ framework (≮Mn, Si, Mn′ 124.4(3)°), with the manganese—silicon bond lengths representing single bonds (243.4(3) pm). The resulting distance of 430.6 pm between the manganese atoms precludes any metal—metal bonding so that the complex fragments (η 5 -C 5 Me 5 )Mn(CO) 2 H are exclusively connected to each other via the bridging silylene ligand. The hydrogen ligands attached to the manganese atoms could not be located by X-ray diffraction methods but were detected by NMR spectroscopy (δ(SiH) 4.59, δ(MnH) −11.55; CDCl 3 ). Although thermolysis of 2 yields elemental hydrogen, the expected and hitherto unknown complex (μ-Si)[(η 5 -C 5 Me 5 )Mn(CO) 2 ] 2 is not observed.

Darstellung und molekülstruktur einer neuartigen σ-alkyl/π-Oxoallyl-tantal-verbindung

Abstract the novel tantalum compound (η 5 -C 5 H 5 )T [O⋯C(CH 3 )⋯CH C(CH 3 ) 2 ]Cl 2 has been synthesized by reductive high-pressure carbonylation of (η 5 -C 5 H 5 )TaCl 4 and subsequent treatment of the reactive intermediate with mesityl oxide. The σ-alkyl/π-oxoallyl coordination of the oxo ligand has been established by measn of X-ray diffraction methods.

Photochemische Reaktionen von Re2(CO)10 in Gegenwart von Cyclooctatetraen und 1.3-Butadien / Photochemical Reactions of Re2(CO)10 in the Presence of Cyclooctatriene and 1,3-Butadiene

Abstract Rhenium Carbonyl Olefin Complexes Re2(CO)io has been photolyzed in the presence of cyclooctatetraene, 1,3-butadiene and 1,4-pentadiene, respectively. In pentane solutions the species (CO)4Re-μ-(η3 :η1-C4H6)Re(CO)5, (CO)4Re-μ-(η2:η2-C4H6]Re(CO)4 (11) and HRe3(CO)14 could be isolated with 1,3-butadiene. C8H8 yielded several compounds of which the following could be unequivocally characterized (CO)4Re-μ-(η3:η1-C8H8)Re(CO)5 (14), (η2-C8H8)Re(CO)4-μ-(1,2,8-η3:5-η1-C8H8)-Re(CO)4 and (CO)3Re-μ-(η4:η4-C8H8)Re(CO)3.11 and 14 have been characterized by X-ray structure analysis.

Über die Reaktivität von [(CH3)2N]6W2 (W≡W) gegenüber CS2/S8 und CS2/Se8. Röntgenstrukturanalyse von [(CH3)2NCS2]2W(S)(S2) / Reactivity of [(CH3)2N]6W2 (W≡W) Towards CS2/S8 and CS2/Se8. X-Ray Structure Analysis of [(CH3)2NCS2]2W(S)(S2)

Abstract In this paper we report two improved preparation methods for [(CH3)2N]6W2 (W≡W) (1), one starting from WCl4 (yield 51%), and a second one starting from W2C16(THF)4 (ca. 60% yield). We have studied the reactions of 1 with different nucleophiles, among them triphenylalkylidenphosphoranes (like Ph3P=CH2 and Ph3P=CHPh·LiCl; Ph = phenyl), sulfur and CS2 . 1 reacts with S8 and CS2 in hexane to yield the two new compounds (Me2NCS2)2WS(S2) (4) and W(CS2H)(Me2NCS2)2 (5), both containing dithiocarbamato ligands formed by insertion of CS2 into the W-N bond. The two mononuclear compounds were characterized spectroscopically, in the case of 4 an X-ray diffraction structure analysis was performed. The reaction of 1 with Se and CS2 , leads to the compounds 4, (Me2NCS2)2W2S4 (6) and [(Me2N)2C]CS2 (7), which were also characterized spectroscopically. No Se-containing compounds could be isolated. 4 crystallizes monoclinically, C52h-P21/n, with a = 648.6(3), b = 1346.7(6) and c = 1745.9(7) pm, β = 91.85(3)°, V = 1524x106 pm3 , Z = 4. The structure of the seven-coordinate tungsten compound is discussed and compared to complexes with similar ligands and geometry.

Tetrahydrothiophen als Komplexligand; Darstellung und Charakterisierung von Spezies der Zusammensetzung M2(CO)9(C4H8S) (M = Mn, Re) und Mn2(CO)8(C4H8S). Röntgenstrukturanalysen von Mn2(CO)9(C4H8S) und Mn2(CO)8(C4H8S) / Tetrahydrothiophene as a Complex Ligand; Synthesis and Characterization of Species of Composition M2(CO)9(C4H8S) (M = Mn, Re) and Mn2(CO)8(C4H8S). X-Ray Structures of Mn2(CO)9(C4H8S) and Mn2(CO)8(C4H8S)

Heating of the decacarbonyls M2(CO)10 (M = Mn, Re) in tetrahydrothiophene under reflux gave the substitution products M2(CO)9(C4H8S) (M = Mn, Re) and Mn2(CO)8(C4H8S), respectively. In the former an equatorial CO group has been substituted, while in the latter the tetra- hydrothiophene ligand bridges symmetrically two Mn-Mn bonded Mn(CO)4 units. The manganese compounds (monoclinic, P21/c) were characterized by means of X-Ray structure analysis