Carbene Iridium(I) and Iridium(III) Complexes Containing the Metal Center in Different Stereochemical Environments

Ortmann, Dagmara A.; Weberndörfer, Birgit; Ilg, Kerstin; Laubender, Matthias; Werner, Helmut

doi:10.1021/om020069a

Cited by 57 publications

(33 citation statements)

References 56 publications

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“…[10] The Ir1 À B1 bond of 7 (1.892 (3) ) is significantly shorter than bonds of known iridium boryl complexes (1.991 (6)-2.093(7) ) [14] and is consistent with a borylene complex. The Ir1ÀB1 bond (1.892 (3) (5) ), [15] but significantly longer than that of terminal borylene complex [(h 5 -C 5 H 5 )Mn(=BCMe 3 )(CO) 2 ] (1.809 (9) ). [16] The central Ir-B-N axis is slightly bent, having an angle of 175.9(3)8.…”

Section: Holger Braunschweig* Melanie Forster Thomas Kupfer and Famentioning

confidence: 98%

Borylene Transfer under Thermal Conditions for the Synthesis of Rhodium and Iridium Borylene Complexes

et al. 2008

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The recent development of the photochemical transfer of borylene ligands from chromium and tungsten borylene complexes to inorganic, [1] and more recently, organic [2] substrates has shown the "DBX" fragment to be a useful synthon. As is the case for many reactive species, the feisty nature of the difficult-to-generate free borylenes [3] is tempered by coordination to a transition metal, so that their reactivity, which is reminiscent of the neighboring carbene species, [4] can be harnessed in conventional syntheses.In particular, the above-mentioned transfer reaction has proven a boon for the synthesis of borylenes with other metal centers, and has uncovered a surprising synthesis of borirenes from terminal or internal alkynes. However, with the exception of one example, [5] this reaction requires activation by UV light, and is thus limited to photochemically inert substrates. Herein we describe the use of a terminal molybdenum borylene complex [6] which performs this task without irradiation and at ambient temperatures. This new reactivity is borne out in the synthesis of the first terminal borylene complexes of the Group 9 elements rhodium and iridium. These two metals have been the subject of intense investigation regarding their application in catalytic borylation reactions. A variety of boryl complexes have therefore been prepared, [7] however their complexes with lower-coordinate boron have been overlooked owing to the lack of reliable synthetic routes. The complexes presented herein go some way in addressing this deficiency.When the rhodium dicarbonyl complex 2 was added to an equimolar amount of 1 in C 6 D 6 at ambient temperature, multinuclear NMR spectroscopy revealed gradual consumption of the starting materials within 16 h and formation of what appeared to be the terminal borylene species [(h 5 -C 5 H 5 )(OC)Rh = BN(SiMe 3 ) 2 ] (4) with concomitant generation of [Mo(CO) 6 ], as indicated by a resonance at d = 201.49 ppm in the 13 C NMR spectrum for the latter [Eq.(1)]. After workup, 4 was isolated as an analytically pure dark orange oil in 67 % yield.The 11 B{ 1 H} NMR spectrum of 4 features a broad signal at d = 75 ppm (w 1/2 = 309 Hz) which is shifted upfield relative to the signal for 1 (d = 91 ppm), [6] suggesting the formation of a terminal borylene species. [8] The 1 H NMR spectrum shows a singlet for the trimethylsilyl group at d = 0.21 ppm, which is deshielded with respect to that of the molybdenum borylene precursor (d = 0.15 ppm).[6] A single conspicuous band at ñ = 1955 cm À1 in the solution IR spectrum of 4 suggests that a lone CO ligand at rhodium was terminally coordinated. Unfortunately, owing to its oily consistency, it was not possible to obtain single crystals of 4 suitable for X-ray diffraction.Borylene 4 is unstable in solution, which was revealed by 11 B{ 1 H} NMR spectroscopy. The 11 B{ 1 H} NMR spectrum indicated the formation of a new boron-containing product even under mild conditions (hexane at À35 8C). Conversion into the new product was complete after about 15 days, at wh...

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Section: Holger Braunschweig* Melanie Forster Thomas Kupfer and Famentioning

confidence: 98%

Borylene Transfer under Thermal Conditions for the Synthesis of Rhodium and Iridium Borylene Complexes

et al. 2008

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“…A twist to these reactions is the oxidative addition of HCl to the Ir C bond of an Ir(I) carbene complex 46, affording the Ir(III) alkyl chloride 47 quantitatively (Table 4, entry 6) [34].…”

Section: Synthesis By Oxidative Addition 3141 Oxidative Addition mentioning

confidence: 99%

“…An example is seen in the complex 48, which HCl N/A [34] has been extensively studied by Bergman and co-workers [36]. A variety of cationic iridium alkyl carbonyl complexes 49 were prepared as racemic mixtures by the tandem C-H bond activation and decarbonylation reactions of aldehydes over the iridium center (Scheme 9).…”

Section: Synthesis By Oxidative Addition 3141 Oxidative Addition mentioning

confidence: 99%

Half-sandwich iridium complexes—Synthesis and applications in catalysis

Liu

Iggo

et al. 2008

Coordination Chemistry Reviews

100

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“…[10] Die Ir1-B1-Bindung von 7 (1.892(3) ) ist deutlich kürzer als in bekannten Iridiumborylkomplexen (1.991 (6)-2.093(7) ) [14] und stimmt somit mit den Erwartungen für einen Borylenkomplex überein. Der Ir1-B1-Abstand ist sehr ähnlich zu der Ir=C-Bindungslänge in dem verwandten Halbsandwich-Carbenkomplex [(h 5 -C 5 H 5 )Ir(=CPh 2 )(PiPr 3 )] (1.904 (5) ), [15] aber deutlich größer als im terminalen Borylenkomplex (9) ). [16] Die zentrale Achse Ir-B-N ist leicht gewinkelt (175.9 (3)8 [1b] (V À B 1.959(6) ), dem einzigen weiteren strukturanalytisch charakterisierten neutralen Halbsandwichkomplex mit einem terminalen Aminoborylenliganden.…”

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Thermischer Borylentransfer zur Synthese von Rhodium‐ und Iridiumborylenkomplexen

et al. 2008

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Carbene Iridium(I) and Iridium(III) Complexes Containing the Metal Center in Different Stereochemical Environments

Cited by 57 publications

References 56 publications

Borylene Transfer under Thermal Conditions for the Synthesis of Rhodium and Iridium Borylene Complexes

Borylene Transfer under Thermal Conditions for the Synthesis of Rhodium and Iridium Borylene Complexes

Half-sandwich iridium complexes—Synthesis and applications in catalysis

Thermischer Borylentransfer zur Synthese von Rhodium‐ und Iridiumborylenkomplexen

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