The tungsten-tungsten triple bond. 1. Preparation, properties, and structural characterization of hexakis(dimethylamido)ditungsten(III) and some homologs

Abstract

Metathetic reactions involving a variety of tungsten halides and LiNMe2 lead to W2(NMea)6, W(NMe2)e, and mixtures of these dimethylamides depending on the tungsten halides used. Pure W2(NMe2)é, free from W(NMe2)e, is prepared from the reaction of WCU with LiNMe2 (4 equiv). The related compounds W2(NMeEt)é and W2(NEt2)e are prepared by similar reactions. These tungsten(III) dialkylamides are pale-yellow, diamagnetic crystalline solids and have been characterized by a number of physical techniques including variable temperature NMR spectroscopy, infrared and Raman spectroscopy, and mass spectroscopy. Two compounds have been studied crystallographically. A substance consisting of W2(NMe2)s molecules and W(NMe2)é molecules in a 2:1 ratio crystallizes in the space group Pi, with unit cell dimensions: a = b = 13.556(2),_c = 9.420 (2) Á; V = 1499.6 (5) Á3. The W(NMe2)e molecule occupies the crystallographic position 0, 0, V2 with symmetry 3. The dimensions agree well with those previously determined for the pure W(NMe2)é phase. The W2(NMe2)6 molecules occupy the V3, %, z and %, V3, z positions with crystallographic symmetry 3. The W-W distance is 2.294 (1) Á; the mean W-N distance and mean W-W-N angles are, respectively, 1.98 Á and 103.8°. The structure was refined to R1 = 0.047 and T?2 = 0.061 using 4531 reflections having 7 > 3 ( ). Crystals consisting entirely of W2(NMe2)ó molecules belong to space group P2\/c (isomorphous with the corresponding Mo compound) with unit cell dimensions of a = 11.465 (3) Á, b = 11.948 (3) Á, c = 15.409 (3) Á, ß = 101.84 (2)°, and V = 2065.9 (8) Á3. There are two crystallographically independent molecules, each having crystallographic symmetry I but virtual symmetry which deviates only slightly from 3m (Du) and even less from 3 (Se). In these molecules the W-W distances are 2.290 (2) and 2.294 (2) Á. The mean values of the W-N distance and the W-W-N angles in both molecules are, respectively, 1.97 Á and 103.3°. This structure was refined to R¡ = 0.055 and T?2 = 0.067 using 1521 reflections having 7 > 3 (7).

Detailed electronic description of triple bonds between transition metal atoms and verification by photoelectron spectroscopy

“…Using the SCF-Xa-SW method the ground state electronic structures of (HO)3Mo==Mo(0H)3, (H2N) (7,8) and W2X6 (9-11) compounds. In these compounds there is a 3-fold axis of symmetry which makes it easy to formulate a qualitative, approximate description of the bonding.…”

The tetradecaisopropoxydihydridotetratungsten story

“…The tungsten hydride resonance at 6 = 7.87 ppm shows satellites due to coupling to 18 Addition of 1-butene showed no reaction at room temperature over 2 days, but at +60 0 C isomerization to cis-2-butene occurred without any significant loss of the hydride resonance. …”

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)(SZiegler1, Blechschmitt2, Böck3 et al. 1988Zeitschrift Für Naturforschung B7010View full textAdd to dashboardCite

“…2h -P2Jn, with a = 648.6(3), b = 1346.7 (6) and c = 1745.9(7) pm, ß = 91.85(3)°, V = 1524xl0 6 pm 3 , Z = 4. The structure of the seven-coordinate tungsten compound is discussed and compared to complexes with similar ligands and geometry.…”

“…Für die M 2 L 6 -Spezies kennt man heute Substitutionsreaktionen, wie beim Umsatz von M 2 (NMe 2 ) 6 (Me = CH 3 ) mit Alkoholen zu M 2 (OR) 6 [1], reversible Addukt-Bildung mit Lewis-Basen [2], Insertionsreaktionen z.B. von C0 2 in die M-L-Bindung (L = * Sonderdruckanforderungen an Prof. Dr. L. Ziegler.…”

“…In der vorliegenden Arbeit berichten wir über Umsetzungen von W 2 (NMe 2 ) 6 Es treten also keine selenhaltigen Produkte auf, wohl aber Verbindungen mit Schwefel-Liganden, wobei der Schwefel aus dem eingesetzten CS 2 stammen muß [12]. Der Reaktionsverlauf ist also eindeutig anders als bei der Umsetzung von 1 mit S 8 2 , wobei (B -B) den monoanionischen Liganden Dimethyldithiocarbamat (dmtc) darstellt.…”