Synthesis and Reactivity of Calix[4]arene‐Supported Group 4 Imido Complexes

Dubberley, Stuart R.; Friedrich, Andreas; Willman, David A.; Mountford, Philip; Radius, Udo

doi:10.1002/chem.200204656

Cited by 80 publications

(88 citation statements)

References 87 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Instead, the products of [2 + 2] cycloaddition of the isocyanate N@C p-bond to the U@N bond were observed, yielding the j 2 -N,N 0 -ureato complexes, R = Mes (4), Dipp (5), in 53% yield (Scheme 1). The cycloaddition of isocyanates with M = NR bonds to yield isolable ureato-ligated metal complexes has been reported with multiple metals (Groups 3-5 [36][37][38][39], Group 6 [40][41][42][43], Groups 7-9 [44,45]) however, such reactivity on uranium has only been postulated as an intermediate in the imido exchange reaction that occurs when U(N t Bu) 2 I 2 (tppo) 2 is treated with PhNCO [46]. In fact, only one structurally characterized uranium ureato complex has been reported in the literature, and it was prepared by insertion of CO 2 into uranium imido bonds, followed by a complicated, binuclear rearrangement [7].…”

Section: Resultsmentioning

confidence: 99%

[2 + 2] cycloaddition reactions at terminal imido uranium(IV) complexes to yield isolable cycloadducts

Jilek

Tomson

Scott

et al. 2014

Inorganica Chimica Acta

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

[2 + 2] cycloaddition reactions at terminal imido uranium(IV) complexes to yield isolable cycloadducts

Jilek

Tomson

Scott

et al. 2014

Inorganica Chimica Acta

View full text Add to dashboard Cite

“…The remaining solid was washed with hexane (3 × 5 mL) and dried to yield 800 mg (1.15 mmol, 64%) of 3 as a bright orange solid. 1 H NMR (600 MHz, C 6 D 6 , 296 K): δ −0.09, 0.25 (s,6 H,Si(CH 3 ) 2 ), 0.80 (s,18 H, ) 3 ), 1.13 (s, 3 H, CH 3 ), 2.45 (s, 3 H, p-CH 3 ), 2.83 (s,6 H, ), 3.50 (d, 2 J HH = 12.5 Hz, 2 H, CHH), 3.99 (d, 2 J HH = 12.5 Hz, 2 H, CHH), 6.43 (t, 3 J H5pyH6py/Hpy4 = 6.0 Hz, 1H, H5 py ), 6.50 (t, 3 J m-Hpyo-Hpy/p-Hpy = 6.0 Hz, 2 H, m-H py ), 6.80−6.86 (m, 2 H, H3 py , p-H py ), 7.03 (dt, 3 J H4pyH3py/5py = 7.9 Hz, 4 J H4pyH6py = 1.7 Hz, 1 H, H4 py ), 7.20 (s, 2 H, m-H mes ), 8.98 (d, 3 J o-Hpym-Hpy = 6 Hz,2H,9.37 (d,3 J H6pyH5py = 5.8 Hz, H6 py ). Preparation of [Zr(N 2 TBS N py )(N Ph N 2 N DIPP )] (4).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The crude product was washed with hexane (3 × 5 mL) and dried to yield 220 mg (0.30 mmol, 72%) of 4 as a bright yellow solid. 1 H NMR (600 MHz, THF-d 8 , 296 K): δ −0.06, 0.12 (s,6 H,Si(CH 3 ) 2 ), 0.70 (s,18 H, ) 3 ), 1.07, 1,23 (d, 3 J HH = 6.7 Hz, 6 H, CH(CH 3 ) 2 ), 1.73 (s, 3 H, CH 3 ), 3.51 (sep, 3 J HH = 6.7 Hz, 2 H, CH(CH 3 ) 2 ), 3.63 (d, 2 J HH = 12.7 Hz, 2 H, CHH), 4.24 (d, 2 J HH = 12. 7 Hz, 2 H, CHH), 6.79 (t, 3 J p-HPhm-HPh = 0.7.6 Hz, 1H, p-H Ph ), 7.05−7.10 (m, 2 H, H6 py , H5 py ), 7.73 (t, 3 J m-HPho-HPh/m-HPh = 7.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The NMR tube was transferred immediately to the spectrometer, and a set of 1 H and 15 N NMR spectra were recorded. 1 H NMR (600 MHz, C 6 D 6 , 296 K): δ −0.10, 0.28 (s,6 H,Si(CH 3 Preparation of [Zr(κN,N,N,N, TBS N py )(HN Mes N 2 N Mes )] (7). To a stirred solution of [Zr(N 2 TBS N py )(N Mes )(py)] (3; 300 mg, 0.43 mmol) in toluene (15 mL) was added a solution of mesityl azide (70 mg, 0.43 mmol) in 5 mL of toluene.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Single crystals for X-ray diffraction were grown from a saturated toluene solution at room temperature. 1 H NMR (600 MHz, C 6 D 6 , 296 K): δ −0.10, 0.21 (s,6 H,Si(CH 3 (1.00 mg, 1.8 mmol) in toluene (40 mL) was added a suspension of lithium 2,4,6-trimethylaniline (255 mg, 1.8 mmol) in 5 mL of toluene. The reaction mixture was stirred for 2 days at 60°C, and then pyridine (150 μL, 1.8 mmol) and a solution of lithium hexamethyldisilazide (303 mg, 1.8 mmol) in 5 mL of toluene was added and the mixture was stirred for 2 days at 80°C.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis, Characterization, and Thermal Rearrangement of Zirconium Tetraazadienyl and Pentaazadienyl Complexes

et al. 2012

View full text Add to dashboard Cite

Reaction of the zirconium dichloro complex [Zr(N 2 TBS N py )Cl 2 ] (1) with 1 molar equiv of ArNHLi (Ar = Mes, DIPP) yielded the zirconium imido complexes [Zr-(Ph )] (5) by addition of phenyl azide, whereas the reaction of 2 or 3 with mesityl azide gave the alternative product 7, in which the azide is coupled with the CH activated ancillary tripod ligand. Reaction of 1 molar equiv of trimethylsilyl azide or 1-adamantyl azide with the previously reported hydrazinediido complex [Zr(N 2 TBS N py )(NNPh 2 )(py)] (9) at ambient temperature resulted in the formation of the five-membered zirconaacacycles [Zr(N 2 TBS N py )(N TMS N 3 NPh 2 )] (10) and [Zr(N 2 TBS N py )(N Ad N 3 NPh 2 )] (11). Complex 11 was thermally converted into the diazenido complex 12 via loss of 1 molar equiv of molecular N 2 . The direct formation of the analogous side-on-bonded diazenido analogue 13 was observed upon reaction of 9 with 1 equiv of mesityl azide at ambient temperature. On the basis of 15 N labeling and DFT modeling (DFT(B3PW91/6-31 g(d))) a mechanism for the reaction pathway leading to 12 and 13 is proposed. ■ INTRODUCTIONTetraazadiene complexes have been studied for many d-block metals in different formal oxidation states. 1 The bonding within the N 4 fragment has been of special interest. It may be regarded as a neutral tetraazadiene donor (a), as part of a delocalized π system including the metal atom (b), or as a dianionic tetraazene-1,4-diido ligand with an isolated NN double bond (c).Evidence for all three cases has been reported in the literature on the basis of structural data as well as theoretical studies. 2 While the N 4 unit coordinated to late transition metals tends to be best represented by resonance structures a and b, the bonding situation in early-transition-metal complexes is adequately represented by resonance form c.Several preparative routes to tetraazadiene complexes have been described in the literature, including the coupling of diazonium cations at the metal center, 3 salt metathesis of dihalides with Li 2 N 4 R 2 , 4 andmost commonlythe cycloaddition of organic azides with imido complexes. 5 The latter may be either isolated starting materials or species generated in situ by thermal fragmentation of azides at low-valent metal centers and subsequent reaction with excess azide to give the cycloaddition product. Furthermore, ruthenium tetrazene intermediates have been proposed to play a key role in the catalyst deactivation in ruthenium-catalyzed "click"-azide− alkyne cycloadditions. 6 We also note the insertion of an azide into a nitrogen−silicon bond to form an N 4 species 7 as well as the formation of an iron hexazene complex by reductive dimerization of two molecules of azide reported by Holland and co-workers. 8 Bergman and co-workers first reported the synthesis of the zirconium tetraazadienido complex [Cp 2 Zr(N 4 t Bu 2 )] by reaction of [Cp 2 Zr(N t Bu)(thf)] with tert-butyl azide. 9 In the presence of phenyl azide the N-bonded phenyl and tertbutyl groups underwent exchange, a process which...

show abstract

A New Family of Zirconium Complexes Anchored by Dianionic Cyclam‐Based Ligands: Syntheses, Structures, and Catalytic Applications

Martins

Munhá

Alves

et al. 2013

Advances in Organometallic Chemistry and Catalysis

View full text Add to dashboard Cite

Synthesis and Reactivity of Calix[4]arene‐Supported Group 4 Imido Complexes

Cited by 80 publications

References 87 publications

[2 + 2] cycloaddition reactions at terminal imido uranium(IV) complexes to yield isolable cycloadducts

[2 + 2] cycloaddition reactions at terminal imido uranium(IV) complexes to yield isolable cycloadducts

Synthesis, Characterization, and Thermal Rearrangement of Zirconium Tetraazadienyl and Pentaazadienyl Complexes

A New Family of Zirconium Complexes Anchored by Dianionic Cyclam‐Based Ligands: Syntheses, Structures, and Catalytic Applications

Contact Info

Product

Resources

About