Tris(N,N'-dimethylethylenediaminato)dimolybdenum and tris(N,N'-dimethylethylenediaminato)ditungsten. A comparison of eclipsed and staggered triple bonds, .sigma.2.pi.4, between molybdenum and tungsten atoms in X3M.ident.MX3 compounds

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

doi:10.1021/ic00259a022

Cited by 17 publications

(18 citation statements)

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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%

“…Infrared spectra were obtained on a Mattson Galaxy Series Fourier transform spectrophotometer. 1 H (400.1 MHz) and 13 C (100.6 MHz) NMR spectra were obtained on a Bruker AMX 400 spectrometer equipped with the appropriate decoupling accessories. X-ray powder diffraction (XRD) spectra were recorded on a Sintag XDS 2000 X-ray diffractometer using Cu KR radiation.…”

Section: Methodsmentioning

confidence: 99%

“…1 H NMR (benzene-d6, containing HNMe2 from the reaction mixture, 400.1 MHz) δ 1.54 (s, 54 H, OCMe3). 13 C{ 1 H} NMR (benzene-d6, containing HNMe2 from the reaction mixture, 100.6 MHz) δ 31.2 (OCMe3), 73.4 (OCMe3). IR (Nujol, NaCl, cm -1 ) 2996 vs, 2930 s, 2848 s, 1463 s, 1389 s, 1258 m, 1217 m, 1200 m, 1085 m, 880 m, 839 m, 807 m, 733 w, 676 w, 659 w, 585 m, 520 w.…”

Section: Methodsmentioning

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: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

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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“…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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“…Similarly, the usually staggered ethane-like d 3 −d 3 dinuclear complexes of type X 3 M⋮MX 3 (X = alkyl, NMe 2 , OR, SR, SeR, etc. ) may be constrained to an eclipsed geometry through the use of chelating amide and pinacolate ligands as was shown for M 2 (MeNCH 2 CH 2 NMe) 3 and M 2 (OCMe 2 CMe 2 O) 3 …”

Section: Introductionmentioning

confidence: 99%

Dinuclear (d³−d³) Diolate Complexes of Molybdenum and Tungsten. 2.¹Derivatives of 2,2‘-Methylenebis(6-tert-butyl-4-methylphenoxide). Direct Observation of the Conversion of Bridged to Chelate Isomers (M = Mo) and Reversible Carbon−Hydrogen Bond Oxidative Addition (M = W)

et al. 1997

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Hydrocarbon solutions of Mo(2)(NMe(2))(6) and 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (>/=2 equiv), HO&ndblwave;CH(2)&ndblwave;OH, yield Mo(2)(NMe(2))(2)(O&ndblwave;CH(2)&ndblwave;O)(2), I, which exists in bridged Ib and chelated Ic isomers. These are formed under kinetic control, and recrystallization allows the separation of Ib (orange cubes) from Ic (yellow cubes) both of which have been crystallographically characterized. In each there is an ethane-like O(2)NMo&tbd1;MoO(2)N core with Mo-Mo = 2.2 Å (average). In Ib the two O&ndblwave;CH(2)&ndblwave;O ligands span the Mo&tbd1;Mo bond yielding a molecule of C(2) symmetry. In Ic the molecule has near-C(2) symmetry in the solid state, but in solution there is either rapid rotation about the M&tbd1;M bond or the anti-rotamer is preferred. In benzene-d(6), Ib and Ic do not interconvert at 110 degrees C over a period of days. However, the addition of pyridine or acetonitrile causes the isomerization of Ib to Ic, thereby establishing that Ic is the thermodynamic isomer. The rate of conversion of Ib to Ic has been shown to be dependent on the square of the concentration of added pyridine: k(obs) = k[py](2). From the temperature dependence of k(obs), we determine DeltaH() = 19 (+/-1) kcal/mol and DeltaS() = -25 (+/-3) eu for the pyridine-promoted isomerization of Ib to Ic. The related reaction involving W(2)(NMe(2))(6) and HO&ndblwave;CH(2)&ndblwave;OH (>/=2 equiv) in hydrocarbon solvents at room temperature and below yields a dark brown crystalline compound, wherein C-H activation has occurred at one of the O&ndblwave;CH(2)&ndblwave;O diolate ligands, W(2)(&mgr;-H)(&mgr;-NMe(2))(NMe(2))(eta(2)-O&ndblwave;CH(2)&ndblwave;O)(eta(3)-O&ndblwave;CH&ndblwave;O)(HNMe(2)), 2. The W-W distance in 2 is 2.495(1) Å, consistent with a (W=W)(8+) core. Heating 2 in the solid-state under a dynamic vacuum leads to the elimination of HNMe(2) and the formation of 3, W(2)(NMe(2))(2)(eta(2)-O&ndblwave;CH(2)&ndblwave;O)(2), an analog of Ic. In benzene-d(6) the equilibrium involving 2 and 3 + HNMe(2) has been observed by (1)H NMR spectroscopy. The addition of pyridine to hydrocarbon solutions of 3 yields W(2)(&mgr;-H)(&mgr;-NMe(2))(eta(2)-O&ndblwave;CH(2)&ndblwave;O)(&mgr;(3)-O&ndblwave;CH&ndblwave;O)(NMe(2))(py), 4, which has been shown by single-crystal X-ray crystallography to be an analogue of 2. Studies of the addition of PMe(3) to toluene-d(8) solutions of 3 at low temperatures reveal that adduct formation occurs prior to C-H oxidative addition. For the equilibrium involving 4 and 3 + py in benzene-d(6), DeltaH degrees = 14 (+/-1) kcal/mol and DeltaS degrees = 22 (+/-3) eu.

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Tris(N,N'-dimethylethylenediaminato)dimolybdenum and tris(N,N'-dimethylethylenediaminato)ditungsten. A comparison of eclipsed and staggered triple bonds, .sigma.2.pi.4, between molybdenum and tungsten atoms in X3M.ident.MX3 compounds

Cited by 17 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

Chromium to chromium quintuple bonds in a trigonal lantern configuration

Dinuclear (d³−d³) Diolate Complexes of Molybdenum and Tungsten. 2.¹Derivatives of 2,2‘-Methylenebis(6-tert-butyl-4-methylphenoxide). Direct Observation of the Conversion of Bridged to Chelate Isomers (M = Mo) and Reversible Carbon−Hydrogen Bond Oxidative Addition (M = W)

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Tris(N,N'-dimethylethylenediaminato)dimolybdenum and tris(N,N'-dimethylethylenediaminato)ditungsten. A comparison of eclipsed and staggered triple bonds, .sigma.2.pi.4, between molybdenum and tungsten atoms in X3M.ident.MX3 compounds

Cited by 17 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

Chromium to chromium quintuple bonds in a trigonal lantern configuration

Dinuclear (d3−d3) Diolate Complexes of Molybdenum and Tungsten. 2.1Derivatives of 2,2‘-Methylenebis(6-tert-butyl-4-methylphenoxide). Direct Observation of the Conversion of Bridged to Chelate Isomers (M = Mo) and Reversible Carbon−Hydrogen Bond Oxidative Addition (M = W)

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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

Dinuclear (d³−d³) Diolate Complexes of Molybdenum and Tungsten. 2.¹Derivatives of 2,2‘-Methylenebis(6-tert-butyl-4-methylphenoxide). Direct Observation of the Conversion of Bridged to Chelate Isomers (M = Mo) and Reversible Carbon−Hydrogen Bond Oxidative Addition (M = W)