Sulfur Induced Coordination at Phosphorus and Silicon

Holmes, Robert L.; Prakasha, T. K.; Srinivasan, Srikanth; Day, Roberta O.

doi:10.1080/10426509408545380

Cited by 24 publications

(46 citation statements)

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“…In studies − of related cyclic pentaoxyphosphoranes containing potential donor sulfur atoms as bridging groups in place of the sulfonyl group, the same two types of ring conformational orientations as found with use of the sulfonyl group prevail, i.e ., the chairlike and boatlike ring conformations giving penta- and hexacoordinated geometries similar to those illustrated for A and B . Examples with the presence of sulfur atoms are E 4 and F , representing these two geometrical possibilities, respectively.…”

Section: Introductionmentioning

confidence: 69%

“…An indication that the sulfone component as a bridge between aryl substituents acts as a poorer donor group compared to a sulfur atom in this position in related derivatives is found by contrasting the geometries of specific members. − For example, with sulfur as a donor atom, L 6 with aryl methyl substituents is hexacoordinate due to sulfur donor action, while the identically composed sulfone-containing phosphorane, 5 , other than insertion of the bridging SO 2 group in place of the sulfur atom, is pentacoordinate lacking any donor coordination. The same conclusion is reached on comparing the trigonal bipyramidal geometries for the ring sulfone members A 1 2 and A 2 2 with octahedral geometries achieved for analogous sulfur donor phosphorane, F 5 and M …”

Section: Resultsmentioning

confidence: 99%

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Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination¹

1997

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The new cyclic phosphine O 2 S[(t-Bu)MeC 6 H 2 O] 2 PPh (1) was used to prepare the new cyclic tetraoxyphosphoranes O 2 S[(t-Bu)MeC 6 H 2 O] 2 PPh(O 2 C 6 Cl 4 ) (2) and O 2 S[(t-Bu)MeC 6 H 2 O] 2 PPh(O 2 C 6 H 4 ) (3) by oxidative addition reactions. In similar reactions, the new cyclic pentaoxyphosphoranes O 2 S[(t-Bu)MeC 6 H 2 O] 2 P(OCH 2 CCl 3 ) 3 (4), O 2 S-[Me 2 C 6 H 2 O] 2 P(OPh) 3 (5), and O 2 S[(t-Bu)MeC 6 H 2 O] 2 P(OC 6 F 5 ) 3 ( 6) were formed from acyclic phosphites and the appropriate diol. Yields ranged from 51% to 66%. X-ray studies revealed hexacoordinated representations for 2 and 6 while 3-5 are pentacoordinate in trigonal bipyramidal geometries. For 3 and 4, the eight-membered rings are positioned diequatorially in anti chair conformations, whereas for 5, this ring occupies axial-equatorial sites in a syn twist-boat form. Tetraoxyphosphorane 3 is unique in locating the least electronegative ligand, the phenyl group, in an axial position. Oxygen donor action from the sulfone SO 2 group led to a displacement from a square pyramid to an octahedron to the extent of 82.2% for the highly fluorinated member 6 in comparison with 27.9% for the tetrachlorocatecholate derivative 2. These two pentaoxyphosphoranes provide the longest and shortest P-O distance thus far from a sulfone donor group, 2.646 (5) Å for 2 and 1.936 (7) Å for 6. In comparison with oxyphosphoranes having bridging sulfur atoms in the eight-membered ring, it is apparent that sulfur atom coordination is greater than oxygen atom coordination from the sulfone group as measured by the tendencies toward hexacoordination. 31 P and 1 H NMR data indicate the presence of two isomeric forms for each of the phosphoranes 2-4. Structural comparisons are made with related cyclic phosphoranes containing sulfur atoms and sulfone groups relative to steric and electronic factors that influence the formation of hexacoordination.

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Section: Introductionmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination¹

1997

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“…In previous work, we have found that sulfur atoms − and sulfonyl groups in ring containing pentaoxyphosphoranes are capable of donor action which leads to neutral hexacoordinated phosphorus. These derivatives form a range of structures along a coordinate from a square pyramid to an octahedral geometry.…”

Section: Introductionmentioning

confidence: 99%

Hexacoordination via Sulfur Donor Action in Nitrogen and Chlorine Bonded Bicyclic Tetraoxyphosphoranes¹

et al. 1997

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Oxidative addition reactions of a quinone with the sulfur containing cyclic chlorophosphine S[(t-Bu)MeC6H2O]2PCl (1) yielded the new bicyclic tetraoxyphosphoranes, S[(t-Bu)MeC6H2O]2PCl(O2C6Cl4) (2) and S[(t-Bu)MeC6H2O]2PCl(O2C14H8) (5). Further new derivatives of this class were prepared by chlorine displacement reactions of 2 and 5 to give S[(t-Bu)MeC6H2O]2P(NHC6H4Me)(O2C6Cl4) (3), S[(t-Bu)MeC6H2O]2P(NMe2)(O2C6Cl4) (4), S[(t-Bu)MeC6H2O]2P(NHCH2C6H5)(O2C14H8) (6), and S[(t-Bu)MeC6H2O]2P(NMe2)(O2C14H8) (7). X-ray studies of 2−6 revealed hexacoordination due to donor action by sulfur which is present as part of an eight-membered ring system. The series 2−6 formed geometries that were displaced along a coordinate from a square pyramid to an octahedron, ranging from 24% to 71%. The respective P−S distance decreased along this series from 3.04 to 2.48 Å as the octahedral character increased. Increased 31P NMR shielding accompanied the chloro derivatives 2 and 5, while increased π P−N back-bonding resulted in the least shielded members 4, 6, and 7 containing the less electronegative nitrogen atom. These changes in 31P chemical shift correlate with the extent of octahedral character where the more shielded phosphorus atom has the greater octahedral character. The analysis allows a lower limit in the phosphorus atom electrophilicity to be established that will allow hexacoordination in this series of bicyclic tetraoxyphosphoranes provided by a variation in ligand properties.

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“…In work in our laboratory, we have employed sulfur atoms to act as donors in promoting hexacoordination in structural studies of cyclic pentaxoyphosphoranes. − These compounds form a series of structures extending from a square pyramid toward an octahedron ranging from 44 to 70%. The respective P−S distances varied from 2.88 to 2.36 Å.…”

Section: Introductionmentioning

confidence: 99%

Isomeric Intraconversion among Penta- and Hexacoordinate Cyclic Oxyphosphoranes via Oxygen Atom Coordination¹^,²

1997

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The synthesis of a series of cyclic pentaoxyphosphoranes containing a sulfonyl group was carried out by the reaction of either P(OCH2CF3)3 or P(OPh)3 with the appropriate diol in an oxidative addition reaction: O2S[(t-Bu)MeC6H2O]2P(OCH2CF3)3 (1), O2S[(t-Bu)MeC6H2O]2P(OPh)3 (2), O2S[(t-Bu)2C6H2O]2P(OCH2CF3)3 (4), and O2S[(t-Bu)2C6H2O]2P(OPh)3 (5). Reaction of 2 with catechol yielded O2S[(t-Bu)MeC6H2O]2P(OPh)(C6H4O2) (3). X-ray studies provided the structures of 1−5, although 4 was badly disordered. The geometries of 2, 3, and 5 are octahedral due to P−O coordination provided by the sulfonyl group, whereas 1 and 4 are trigonal bipyramidal. Solution 31P, 1H, and 19F NMR spectra demonstrate that 1 and 4 exist in isomeric modifications. These are formulated as a pentacoordinate structure, as in the solid state, and a hexacoordinate structure. This represents the first study establishing intramolecular intraconversion between penta- and hexacoordinate isomers of phosphorus. An activation free energy of 17 kcal/mol for the exchange process for 1 and 4 was obtained from variable temperature 1H NMR spectra.

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Sulfur Induced Coordination at Phosphorus and Silicon

Cited by 24 publications

References 0 publications

Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination¹

Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination¹

Hexacoordination via Sulfur Donor Action in Nitrogen and Chlorine Bonded Bicyclic Tetraoxyphosphoranes¹

Isomeric Intraconversion among Penta- and Hexacoordinate Cyclic Oxyphosphoranes via Oxygen Atom Coordination¹^,²

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Sulfur Induced Coordination at Phosphorus and Silicon

Cited by 24 publications

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Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination1

Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination1

Hexacoordination via Sulfur Donor Action in Nitrogen and Chlorine Bonded Bicyclic Tetraoxyphosphoranes1

Isomeric Intraconversion among Penta- and Hexacoordinate Cyclic Oxyphosphoranes via Oxygen Atom Coordination1,2

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Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination¹

Sulfonyl-Containing Eight-Membered Rings Varying in Ring Conformation in Oxyphosphoranes. Hexacoordination vs Pentacoordination¹

Hexacoordination via Sulfur Donor Action in Nitrogen and Chlorine Bonded Bicyclic Tetraoxyphosphoranes¹

Isomeric Intraconversion among Penta- and Hexacoordinate Cyclic Oxyphosphoranes via Oxygen Atom Coordination¹^,²