Synthese und Struktur siebenfach koordinierter Bismut(v)‐Komplexe mit benzoiden und nichtbenzoiden Arenliganden: Tri(aryl)tropolonatobismut(V)‐Komplexe
Abstract:ZUSCHRIFTENwurden mit dem DISCOVER-Kraftfeldprog~amm durchgefuhrt. In allen Berechnungen wurden entfernungsabhlngige Dielektriritltskonstanten verwendet. Die von DGEOM erzeugten Strukturen wurden 100 Schritte mit dem ,,Steepest-descent"-Algorithmus, gefolgt vom VA09A-Algorithmus, minimiert, bis alle Ableitungen unter 0.001 k c a l m o l -' k ' lagen. Eingegangen am 24. Juli 1995 [Z 82421 Stichworte: Lanthionine . Peptidmimetica [I] Fur neuere Beispiele siehe a) M. Goodman. S. Telefax: Int. + 6221/564955 schen … Show more
“…In all compounds, 1 and 2 , the O−Bi−O/Br angles are close to 180° (174.1(2)−179.4(2)°). The Bi−O distances are shorter than the ones found by Yamamoto for hexacoordinate Bi(V) compounds 9 and the Bi−O distance in Dittes' ditropolonato complexes …”
Section: Resultsmentioning
confidence: 55%
“…Complexes have been previously synthesized which have an alkoxide ligand attached to bismuth(V), but these complexes are stabilized by chelation of the bismuth by other donor groups on the alkoxide ligand. For example, Dittes et al recently reported tris(aryl)bismuth(V) tropolonato complexes which have a seven-coordinate bismuth, and Barton, Yamamoto, and co-workers have produced hexacoordinate bismuth species. , To avoid problems with oxidation and arylation reactions, the alkoxides OR (R = C 6 F 5 , C 6 Cl 5 ) were chosen for initial study. En route to producing the species Bi(OR) 5 , we decided to establish the ability of these OR groups to support the bismuth(V) oxidation state by preparing the complexes Ar 3 Bi(OR) 2 and Ar 4 Bi(OR) via salt metathesis reactions and alcoholysis, respectively.…”
The six new pentavalent Bi(V) alkoxide complexes
Ph3Bi(OR)2, 1,
Ph3BiBr(OR), 2, and
Ph4Bi(OR), 3 (a, R =
C6F5; b R =
C6Cl5) have been prepared.
Ph4Bi(OR) was synthesized
by alcoholysis of BiPh5 with ROH.
Ph3Bi(OR)2 and
Ph3BiBr(OR) were products of the
salt
elimination reaction between Ph3BiBr2 and
NaOR. These compounds were characterized
spectroscopically and by single-crystal X-ray diffraction. In the
solid state, they possess
distorted trigonal bipyramidal coordination geometries. Although
the mixed species
Ph3BiBr(OR) may be isolated in pure form as
crystalline solids, they do not exist as pure
compounds in solution owing to the very rapid redistribution
equilibrium Ph3Bi(OR)2
+
Ph3BiBr2 ⇌
2Ph3BiBr(OR). The equilibrium constants were
measured using VT NMR spectroscopy. For comparison, the equilibrium constants for the
previously unreported cross-exchange reactions between the dihalides
Ph3BiX2 (X = F, Cl, Br) were also
measured at
226 K. Trends observed in the values of K
eq
correlate with the difference in the electronegativity of the mixed X species. The thermal stabilities of
Ph3Bi(OR)2 were examined
in
toluene solution and in the solid state. Pyrolysis results in
elimination of ROPh for both R
= C6F5 and
C6Cl5.
“…In all compounds, 1 and 2 , the O−Bi−O/Br angles are close to 180° (174.1(2)−179.4(2)°). The Bi−O distances are shorter than the ones found by Yamamoto for hexacoordinate Bi(V) compounds 9 and the Bi−O distance in Dittes' ditropolonato complexes …”
Section: Resultsmentioning
confidence: 55%
“…Complexes have been previously synthesized which have an alkoxide ligand attached to bismuth(V), but these complexes are stabilized by chelation of the bismuth by other donor groups on the alkoxide ligand. For example, Dittes et al recently reported tris(aryl)bismuth(V) tropolonato complexes which have a seven-coordinate bismuth, and Barton, Yamamoto, and co-workers have produced hexacoordinate bismuth species. , To avoid problems with oxidation and arylation reactions, the alkoxides OR (R = C 6 F 5 , C 6 Cl 5 ) were chosen for initial study. En route to producing the species Bi(OR) 5 , we decided to establish the ability of these OR groups to support the bismuth(V) oxidation state by preparing the complexes Ar 3 Bi(OR) 2 and Ar 4 Bi(OR) via salt metathesis reactions and alcoholysis, respectively.…”
The six new pentavalent Bi(V) alkoxide complexes
Ph3Bi(OR)2, 1,
Ph3BiBr(OR), 2, and
Ph4Bi(OR), 3 (a, R =
C6F5; b R =
C6Cl5) have been prepared.
Ph4Bi(OR) was synthesized
by alcoholysis of BiPh5 with ROH.
Ph3Bi(OR)2 and
Ph3BiBr(OR) were products of the
salt
elimination reaction between Ph3BiBr2 and
NaOR. These compounds were characterized
spectroscopically and by single-crystal X-ray diffraction. In the
solid state, they possess
distorted trigonal bipyramidal coordination geometries. Although
the mixed species
Ph3BiBr(OR) may be isolated in pure form as
crystalline solids, they do not exist as pure
compounds in solution owing to the very rapid redistribution
equilibrium Ph3Bi(OR)2
+
Ph3BiBr2 ⇌
2Ph3BiBr(OR). The equilibrium constants were
measured using VT NMR spectroscopy. For comparison, the equilibrium constants for the
previously unreported cross-exchange reactions between the dihalides
Ph3BiX2 (X = F, Cl, Br) were also
measured at
226 K. Trends observed in the values of K
eq
correlate with the difference in the electronegativity of the mixed X species. The thermal stabilities of
Ph3Bi(OR)2 were examined
in
toluene solution and in the solid state. Pyrolysis results in
elimination of ROPh for both R
= C6F5 and
C6Cl5.
“…When 1,2-dioxo ligands have been used, e.g., tropolonato moieties in (4-MeC 6 H 4 ) 3 Bi(OC 7 H 5 O-2) 2 (Figure ) and (4-MeC 6 H 4 ) 3 Bi(OC 7 H 4 O-2-NO 2 -5) 2 , the differences (range 0.15−0.28 Å) between primary and secondary bismuth−oxygen bonds are smaller. As a consequence, the O−Bi−O bond angles (formed by primary Bi−O bonds) are considerably diminished while the C−Bi−C angles have the closest values to the ideal apical−apical and apical−equatorial angles in a pentagonal bipyramid observed for this type of compound.…”
Section: Compounds Of the Type R3bix2 (X =
Chalcogenato Ligand)mentioning
confidence: 99%
“…As a consequence, the O−Bi−O bond angles (formed by primary Bi−O bonds) are considerably diminished while the C−Bi−C angles have the closest values to the ideal apical−apical and apical−equatorial angles in a pentagonal bipyramid observed for this type of compound. 113 Molecular structure of (4-MeC 6 H 4 ) 3 Bi(OC 7 H 5 O-2) 2 …”
Section: Compounds Of the Type R3bix2 (X =
Chalcogenato Ligand)mentioning
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