The first silyl- and germylboryl complexes: synthesis from novel (dichloro)silyl- and (dichloro)germylboranes, structure and reactivity

Braunschweig, Holger; Colling, Miriam; Kollann, Carsten; Englert, Ulli

doi:10.1039/b201100j

Cited by 69 publications

(52 citation statements)

References 41 publications

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“…Surprisingly, however, none of these attempts, in particular reactions of Na 2 [M(CO) 5 ] (M= Mo, W) with Cl 2 BSiA C H T U N G T R E N N U N G (SiMe 3 ) 3 , were met with success. Only the addition of Cl 2 BGeA C H T U N G T R E N N U N G (SiMe 3 ) 3 , which had already proven to be a suitable precursor for chloroA C H T U N G T R E N N U N G (germyl)boryl complexes, [20] to a suspension of Na 2 [Cr(CO) 5 ] in toluene at À78 8C yielded the corresponding borylene complex [(OC) 5 Cr=BÀGeA C H T U N G T R E N N U N G (SiMe 3 ) 3 ] as indicated by multinuclear NMR spectroscopy ( [5, 6b, 21] corresponding studies on the metal centered reactivity in such complexes, in particular with respect to co-ligand substitution, were not performed. It should be noted though, that our recent investigations on semibridging borylene complexes of the type [22] led to the structural characterization of trans-[(Cy 3 P)(OC) 4 Cr=B=NA C H T U N G T R E N N U N G (SiMe 3 ) 2 ] (5 a), which was isolated in low yields as a one of the products stemming from the deg- The observed selectivity of the ligand exchange may be partially attributed to steric constraints imposed by the bulky cyclohexyl and SiMe 3 groups, but provides also evidence for a certain trans-influence of the borylene ligand (see below).…”

Section: Resultsmentioning

confidence: 99%

Aminoborylene Complexes of Group 6 Elements and Iron: A Synthetic, Structural, and Quantum Chemical Study

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Colling-Hendelkens²,

Kollann

et al. 2007

Chemistry A European J

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Transition-metal-borylene complexes of the type [(OC)(5)M=BR] {M=Cr, Mo, W; R=N(SiMe(3))(2), 1a-3a, Si(SiMe(3))(3), 4a} and [(OC)(4)Fe=B=N(SiMe(3))(2)] (8) were prepared by salt elimination reactions. Synthesis of the latter complex was accompanied by the formation of substantial amounts of an unusual dinuclear iron complex [Fe(2){mu-C(2)O(2)(BN(SiMe(3))(2))}(2)(CO)(6)] (9). The aminoborylene complexes of Group 6 metals were converted to trans-[(Cy(3)P)(CO)(4)M=B=N(SiMe(3))(2)] (5a-7a) by irradiation in the presence of PCy(3). Structural and spectroscopic parameters were discussed with respect to the trans-effect of the borylene ligand and the degree of M-B d(pi)-p(pi)-backbonding. Computational studies were performed on Group 6-borylene complexes. The population and topological analyses as well as the molecular orbital composition are consistent with the presence of both sigma-and pi-type interactions. There are, however, indications that the d(pi)-p(pi)-backbonding in the silylborylene complex is significantly more pronounced than in the aminoborylene complexes.

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Section: Resultsmentioning

confidence: 99%

Aminoborylene Complexes of Group 6 Elements and Iron: A Synthetic, Structural, and Quantum Chemical Study

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Colling-Hendelkens²,

Kollann

et al. 2007

Chemistry A European J

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“…Such a discussion may be expanded to the difference in the bonding situation between borane adduct complexes and tricoordinate borane derivatives (e.g. [(MeCp)Mn(CO) 2 A C H T U N G T R E N N U N G (HBX 2 )], [37,43] [Cp 2 TiA C H T U N G T R E N N U N G (HBcat) 2 ], [44] and [Cp 2 TiA C H T U N G T R E N N U N G (HBcat)A C H T U N G T R E N N U N G (PMe 3 )], [45] HBcat = catecholborane), the latter of which involve short contact between metal and boron. In these compounds, the boron atom can utilize a free p orbital to accept electron density from metal and thereby expands its coordination number from three to four.…”

Section: Full Papermentioning

confidence: 99%

Investigation of the Stability of the M‐H‐B Bond in Borane σ Complexes [M(CO)₅(η¹‐BH₂R⋅L)] and [CpMn(CO)₂(η¹‐BH₂R⋅L)] (M=Cr, W; L=Tertiary Amine or Phosphine): Substituent and Lewis Base Effects

Kawano

Yamaguchi

Miyake

et al. 2007

Chemistry A European J

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We investigated the influence of a substituent and a Lewis base on boron upon the thermodynamic stability of metal complexes of borane-Lewis base adducts, [M(CO)5(eta1-BH(2)R.L)] (M=Cr, W) and [CpMn(CO)2(eta1-BH2R.L)], where R=Cl, I, m-C6H4F, Ph, H, Me, Et; L=PMe3, PPh3, NMe3, quinuclidine. In these compounds, the stability of the metal-borane linkage was enhanced by increasing the electron-releasing ability of the substituent on boron. A stronger base L additionally stabilized the complexes. The strength of the borane-metal interaction is thus mainly ascribed to the electron donation from the BH sigma orbital to metal rather than the back-donation into the BH sigma* orbital. This result supports the bonding model for the B-H-M linkage in the borane complexes suggested by MO calculations, where the borane-to-metal electron donation is predominant while the metal back-donation into the BH sigma* orbital is negligible. Such a stability trend of the borane complexes makes a sharp contrast to that of many silane and dihydrogen complexes.

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“…Eine (2) hin, [10] während ein 11 B-NMR-Signal bei d = 144 ppm, das im Vergleich zu dem der zweikernigen Ausgangsverbindung (d = 170 ppm) hochfeldverschoben, aber im Verleich zu terminalen Aminoborylenkomplexen (d % 100 ppm) [3, 8b] [12] sind um 22 bzw. 33 pm größer.…”

Section: Holger Braunschweig* Michael Burzler Thomas Kupfer Krzyszunclassified

Synthese und Elektronenstruktur eines terminalen Alkylborylenkomplexes

et al. 2007

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Die Chemie der Borylenkomplexe hat sich in den letzten Jahren deutlich weiterentwickelt.[1] Basierend auf einem genaueren Verständnis der Bindungssituation von BR-Liganden wurde mittlerweile erkannt, dass sperrige und elektronenliefernde Substituenten R notwendig für die Synthese terminaler Borylenkomplexe [L x M = B À R] sind. Dies ist darauf zurückführen, dass trotz der ¾hnlichkeit zum synergistischen Bindungsschema der CO-Komplexe die Koordination von BR an ein Metallzentrum zu einer Konzentration von positiver Ladung am Boratom führt, und das Borylenzentrum daher durch den Substituenten R elektronisch und sterisch gegen einen nukleophilen Angriff geschützt werden muss.[2] Aus diesem Grund haben sich sperrige Aminogruppen bei der Synthese von Borylenkomplexen besonders bewährt, [3] wohingegen ähnliche Verbindungen mit Mesityl-, [4] Hypersilyl- [5] oder Metallsubstituenten [6] eher selten sind. Während die NR 2 -Substituenten einerseits für die Synthese vorteilhaft sind, beeinträchtigen sie andererseits die Reaktivität der neutralen Komplexe [L x M = B = NR 2 ], und abgesehen von wenigen Ausnahmen [7] ist die Chemie dieser Spezies auf photochemisch induzierte Borylentransferreaktionen beschränkt.[8] Es wäre daher wünschenswert, weniger stark stabilisierende Substituenten, vorzugsweise Alkylgruppen, einzuführen. Bisher waren aus dieser Substanzklasse nur die Zweikernkomplexe [m-BtBu{(h 5 -C 5 H 4 R)Mn(CO) 2 } 2 ] (1 a, R = H; 1 b, R = Me) bekannt.[9] Hier berichten wir nun über den ersten terminalen Alkylborylenkomplex, der durch eine neuartige phosphaninduzierte Spaltung aus einer zweikernigen Vorstufe hergestellt wurde.Eine [12] sind um 22 bzw. 33 pm größer. Der B1-C21-Abstand von 1.531(11) gleicht dem Wert von 1.547(5) in tBu À B = C(SiMe 3 ) 2 , [13] das ein vergleichbares Substitutionsmuster an einem zweifach koordinierten Borzentrum aufweist.Erste Informationen über die Reaktivität der neuen Verbindung konnten durch die Umsetzung von 3 mit

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The first silyl- and germylboryl complexes: synthesis from novel (dichloro)silyl- and (dichloro)germylboranes, structure and reactivity

Cited by 69 publications

References 41 publications

Aminoborylene Complexes of Group 6 Elements and Iron: A Synthetic, Structural, and Quantum Chemical Study

Aminoborylene Complexes of Group 6 Elements and Iron: A Synthetic, Structural, and Quantum Chemical Study

Investigation of the Stability of the M‐H‐B Bond in Borane σ Complexes [M(CO)₅(η¹‐BH₂R⋅L)] and [CpMn(CO)₂(η¹‐BH₂R⋅L)] (M=Cr, W; L=Tertiary Amine or Phosphine): Substituent and Lewis Base Effects

Synthese und Elektronenstruktur eines terminalen Alkylborylenkomplexes

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The first silyl- and germylboryl complexes: synthesis from novel (dichloro)silyl- and (dichloro)germylboranes, structure and reactivity

Cited by 69 publications

References 41 publications

Aminoborylene Complexes of Group 6 Elements and Iron: A Synthetic, Structural, and Quantum Chemical Study

Aminoborylene Complexes of Group 6 Elements and Iron: A Synthetic, Structural, and Quantum Chemical Study

Investigation of the Stability of the M‐H‐B Bond in Borane σ Complexes [M(CO)5(η1‐BH2R⋅L)] and [CpMn(CO)2(η1‐BH2R⋅L)] (M=Cr, W; L=Tertiary Amine or Phosphine): Substituent and Lewis Base Effects

Synthese und Elektronenstruktur eines terminalen Alkylborylenkomplexes

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Investigation of the Stability of the M‐H‐B Bond in Borane σ Complexes [M(CO)₅(η¹‐BH₂R⋅L)] and [CpMn(CO)₂(η¹‐BH₂R⋅L)] (M=Cr, W; L=Tertiary Amine or Phosphine): Substituent and Lewis Base Effects