Tris(N,N'-dimethylethylenediamido)dimolybdenum (M.tplbond.M). A metallopropellane with a near-eclipsed central molybdenum nitride (Mo2N6) moiety

Blatchford, Timothy P.; Chisholm, Malcolm H.; Folting, Kirsten; Huffman, John C.

doi:10.1021/ic50212a069

Cited by 13 publications

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“…11 Chisholm and coworkers have reported a number of nearly eclipsed compounds possessing ligands that bridge a Mo 2 6+ or W 2 6+ core to form six-membered chelate rings. [12][13][14][15] For example, Mo 2 (MeNCH 2 CH 2 NMe) 3 exhibits N-Mo-Mo-N torsion angles which average to 12°. 13 Generally, it has been found that the M 2 X 6 conformation has little influence on distances and angles in the complexes, or on their electronic properties.…”

Section: Resultsmentioning

confidence: 99%

“…The structure of 1 is interesting in light of long-standing discussions concerning the most stable conformations for X 3 M⋮MX 3 compounds. − In 1978, Albright and Hoffmann suggested that triply bonded d 3 −d 3 dimers of this type should have an electronic preference for an eclipsed geometry. The preponderance of staggered geometries observed for such dimers was attributed to a purely steric factor .…”

Section: Resultsmentioning

confidence: 99%

“…The preponderance of staggered geometries observed for such dimers was attributed to a purely steric factor . Chisholm and co-workers have reported a number of nearly eclipsed compounds possessing ligands that bridge a Mo 2 6+ or W 2 6+ core to form six-membered chelate rings. − For example, Mo 2 (MeNCH 2 CH 2 NMe) 3 exhibits N−Mo−Mo−N torsion angles which average to 12° …”

Section: Resultsmentioning

confidence: 99%

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Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo₂[O₂Si(O^tBu)₂]₃ and W₂(NHMe₂)₂[O₂Si(O^tBu)₂]₂[OSi(OH)(O^tBu)₂]₂

Tilley

1997

Chem. Mater.

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Reaction of Mo 2 (NMe 2 ) 6 with 3 equiv of ( t BuO) 2 Si(OH) 2 afforded a new siloxide complex, Mo 2 [O 2 Si(O t Bu) 2 ] 3 (1), as the only metal-containing product. An X-ray crystal structure determination reveals that 1 adopts an eclipsed structure with three di-tert-butoxysilanediolato ligands bridging the molybdenum centers in a symmetrical fashion. Lewis acidic complex 1 forms an isolable adduct with pyridine. Reaction of W 2 (NMe 2 ) 6 with 3 equiv of ( t BuO) 2 Si(OH 3), which was isolated as air-sensitive orange crystals. In this molecule, two O 2 Si(O t Bu) 2 ligands bridge the WtW bond in an η 1 ,η 1 fashion, and OSi(OH)(O t Bu) 2 ligands are coordinated to each W atom. This molecule adopts a highly eclipsed conformation and has a 2-fold axis of symmetry which perpendicularly bisects the tungsten-tungsten bond. Complex 1 undergoes a twostep weight loss (by TGA), which corresponds to the initial loss of isobutene and water (at ca. 200 °C), followed by the loss of molybdenum by evaporation of MoO 3 at 700-1050 °C. The pyrolysis of 1 at 550 °C for 2 h under argon gave a ceramic material with the approximate formula Mo 2 Si 3 O 10 . When the sample was heated at 1200 °C for 1 h, evaporation of MoO 3 occurred and the final ceramic material had a composition of Mo 0.5 Si 3 O 6.5 . Very low carbon contents for these materials are consistent with a clean elimination process during the pyrolysis. The material heated to 550 °C is amorphous, while the material taken to 1200 °C contains MoO 2 as the only crystalline phase. Pyrolysis of 1 in air at 1200 °C resulted in the extensive loss of molybdenum (2.14% Mo; no crystalline phases by XRD). Interestingly, pyrolysis of small crystals of 1 occurs with retention of the crystals' shape and size, despite a great loss in weight (75%). Pyrolysis of 3 at 550 and 1200 °C under argon produced ceramic materials consistent with the formulas W 2.2 Si 4 O 17.4 and W 2.2 Si 4 O 13 , respectively. While the 550 °C ceramic is amorphous, the 1200 °C material contains crystalline W and WO 2 (by XRD analysis).

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo₂[O₂Si(O^tBu)₂]₃ and W₂(NHMe₂)₂[O₂Si(O^tBu)₂]₂[OSi(OH)(O^tBu)₂]₂

Tilley

1997

Chem. Mater.

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“…The preference for an eclipsed configuration vanishes when configuration interaction is included in higher order calculations. − Nevertheless, steric factors enforce a staggered conformation in M 2 X 6 complexes with monodentate ligands . An eclipsed geometry is only approached when bidentate ligands span the metal−metal bond. − Chisholm and Armstrong have synthesized several d 3 −d 3 bimetallic compounds bridged by four-atom dianionic ligands; these compounds deviate from an eclipsed geometry by 10.7−13.9°. − In one case, a triple metal−metal bond species has been prepared with a bidentate ligand possessing a three-atom bridge; this disiloxide-ligated complex exhibits a variance of only 3° from an eclipsed conformation.…”

Section: Introductionmentioning

confidence: 99%

Eclipsed M₂X₆ Compounds Exhibiting Very Short Metal−Metal Triple Bonds

2004

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The preparation, characterization, and electronic structure of homoleptic complexes of molybdenum and tungsten bridged by bis(alkylamido)phenylboranes, M(2)[RN-B(Ph)-NR](3) (M = Mo, R = Et (1), (i)Pr (2); M = W, R = Et (3), (i)Pr (4)), are described. These triple metal-metal bond species (i) exhibit a nearly eclipsed ligand geometry and (ii) possess the shortest metal-metal bonds of neutral dimolybdenum and ditungsten M(2)X(6) complexes observed to date (d(Mo-Mo) = 2.1612(6) A (1); d(W-W) = 2.2351(7) A (4)).

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“…There are many factors that may come into play to affect metal–metal distances. For example, in the triply bonded M 2 X 6 complexes, although the coordination geometry with the ligands assuming an ethane‐like staggered, D 3d , conformation predominates, shorter metal–metal distances are theoretically predicted and experimentally observed in an eclipsed ligand geometry . In the quadruple bonding, it is much more complicated.…”

Section: Introductionmentioning

confidence: 99%

Chromium to chromium quintuple bonds in a trigonal lantern configuration

Yen

Lin

Hsueh

et al. 2019

J Chinese Chemical Soc

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A new family of the quintuply bonded dichromium complexes [Cr2{μ‐κ2‐HC(N‐2,6‐R2C6H3)2}2(μ‐κ2‐HC[NAr]2)] (R = iPr, Ar = 4‐MeC6H4 (5), Ar = 3,5‐Me2C6H3 (6), and Ar = 2,6‐Me2C6H3 (7); R = Et, Ar = 4‐MeC6H4 (8), Ar = 3,5‐Me2C6H3 [9], and Ar = 2,6‐Et2C6H3 (10)) with a heteroleptic lantern configuration was obtained upon the addition of one equivalent of amidinate to the quintuply bonded dichromium amidinates [Cr{μ‐κ2‐HC(N‐2,6‐R2C6H3)2}]2 (R = iPr, Et). Additionally, the same approach was applied to the preparation of the acetate derivative [Cr2{μ‐κ2‐HC(N‐2,6‐ iPr2C6H3)2}2(μ‐κ2‐CH3CO2)] (11), which represents the first example that the quintuply bonded dinuclear complex contains an oxygen‐containing ligand. Of particular interest is that the Cr‐Cr bond lengths in these new trigonal paddlewheel quintuple Cr‐Cr bond species are comparable with those in their precursor compounds. They show ultrashort Cr‐Cr bond lengths in a narrow range of 1.740–1.755 å on the basis of single‐crystal X‐ray crystallography. The small Mayer bond orders of the long Cr‐N bonds as well as divergent, C2v and D3h, structural conformations in 5–11 suggest that the metal–ligand interactions possess minor covalent character and the electrostatic interactions play a dominant role. As a result, these extremely short Cr‐Cr quintuple bonds are caused by the overlap between five pairs of d orbitals that do not involve much in metal–ligand bonding. Additionally, anionic lantern dichromium trisamidinates 5–10 can be chemically oxidized by one electron, supported by electrochemistry, and their ease to undergo oxidation is presumably associated with their neutral lantern dichromium trisamindinate products, whose structures inherently display a Jahn‐Teller distortion, exemplified by the structure of the homoleptic dichromium complex [Cr2{μ‐κ2‐HC(N‐2,6‐Et2C6H3)2}3] [12] determined by X‐ray crystallography. These results unambiguously support the Cr‐Cr quintuple bonding in these novel anionic lantern dichromium complexes.

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Tris(N,N'-dimethylethylenediamido)dimolybdenum (M.tplbond.M). A metallopropellane with a near-eclipsed central molybdenum nitride (Mo2N6) moiety

Cited by 13 publications

References 1 publication

Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo₂[O₂Si(O^tBu)₂]₃ and W₂(NHMe₂)₂[O₂Si(O^tBu)₂]₂[OSi(OH)(O^tBu)₂]₂

Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo₂[O₂Si(O^tBu)₂]₃ and W₂(NHMe₂)₂[O₂Si(O^tBu)₂]₂[OSi(OH)(O^tBu)₂]₂

Eclipsed M₂X₆ Compounds Exhibiting Very Short Metal−Metal Triple Bonds

Chromium to chromium quintuple bonds in a trigonal lantern configuration

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Tris(N,N'-dimethylethylenediamido)dimolybdenum (M.tplbond.M). A metallopropellane with a near-eclipsed central molybdenum nitride (Mo2N6) moiety

Cited by 13 publications

References 1 publication

Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo2[O2Si(OtBu)2]3 and W2(NHMe2)2[O2Si(OtBu)2]2[OSi(OH)(OtBu)2]2

Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo2[O2Si(OtBu)2]3 and W2(NHMe2)2[O2Si(OtBu)2]2[OSi(OH)(OtBu)2]2

Eclipsed M2X6 Compounds Exhibiting Very Short Metal−Metal Triple Bonds

Chromium to chromium quintuple bonds in a trigonal lantern configuration

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Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo₂[O₂Si(O^tBu)₂]₃ and W₂(NHMe₂)₂[O₂Si(O^tBu)₂]₂[OSi(OH)(O^tBu)₂]₂

Molecular Routes to Metal Oxides and Metal Silicates. Synthesis and Thermal Decomposition Studies of Eclipsed Mo₂[O₂Si(O^tBu)₂]₃ and W₂(NHMe₂)₂[O₂Si(O^tBu)₂]₂[OSi(OH)(O^tBu)₂]₂

Eclipsed M₂X₆ Compounds Exhibiting Very Short Metal−Metal Triple Bonds