Evidence for the existence of the dianion of cyclobutadiene

McKennis, J. S.; Brener, Lazaro; Schweiger, J. R.; Pettit, R.

doi:10.1039/c39720000365

Cited by 19 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dianion 1 has been claimed to exist as a labile intermediate in solutions of THF which suffers from ready protonation by the solvent. 167 The related species 452" and 462" are stable in solution and can be studied via NMR.91, 92 Quenching experiments (i.e., incorporation of two electrophiles) together with the symmetry inherent in the 13C NMR spectrum of 452" exclude the possible existence of monoanions (49,50). Moreover, the resonance of Cj (C2) of 452" at 8 84 is not compatible with a ring-opened valence isomer such as 452"a.…”

Section: Structure Proof Of Ionic Species a Constitution And Chargementioning

confidence: 99%

Reduction and oxidation of annulenes

Muellen¹

1984

Chem. Rev.

144

View full text Add to dashboard Cite

Section: Structure Proof Of Ionic Species a Constitution And Chargementioning

confidence: 99%

Reduction and oxidation of annulenes

Muellen¹

1984

Chem. Rev.

144

View full text Add to dashboard Cite

“…The formal oxidation state of the platinum atom is also uncertain. Although some chemical evidence has been reported demonstrating the existence of a salt of C4Z+,22 and C42- 23 as an intermediate, we prefer to regard cyclobutadiene as a neutral ligand. It is interesting to note that if the cyclobutadiene ligand were ionically bound as C42-, the e orbitals would be filled, and if the local site symmetry of the ring were lower than C2v the degeneracy of the e orbitals would be removed.…”

Section: Discussionmentioning

confidence: 99%

Crystal and molecular structure of tetramethylcyclobutadienetrifluoromethylbis(dimethylphenylphosphine)platinum(II) hexafluoroantimonate

Crump¹,

Payne²

1973

Inorg. Chem.

View full text Add to dashboard Cite

A single-crystal X-ray diffraction study of the compound [(C4(CH3)4)CF3Pt(P(CH3)2C6H5)2]SbF6, tetramethylcyclobutadienetrifluoromethylbis(dimethylphenylphosphme)platinum(II) hexafluoroantimonate, shows that it crystallizes in the monoclinic space group P2Jc, with unit cell dimensions a = 8.622 (6), b = 18.359 (13), c = 20.323 (13) A, and ß = 102.97 (8)°; d(measd) = 1.871 (1) g cm'3 and d(calcd) = 1.869 g cm"3 for Z = 4. A three-dimensional structure determination was based upon 2866 observed reflections measured on a four-circle diffractometer. Refinement by full-matrix leastsquares methods on F gave a conventional R factor of 0.049. Assuming tetramethylcyclobutadiene to be a monodentate ligand, the angles P-Pt-P = 95.2 (1)°and P-Pt-C = 98.7 (5) and 93.0 (5)°would indicate a distorted tetrahedral geometry t about the platinum atom. This is an unusual geometry for a tetracoordinate Pt(II) complex, and the ambiguity in assigning a formal oxidation state to platinum in this compound is discussed. The cyclobutadiene ring is square planar, within the accuracy of the experiment, with a mean C-C bond length of 1.47 (2) A. The fourfold axis of the cyclobutadiene ring is approximately coincident with the pseudo-threefold axis of the platinum atom. The substituent methyl carbon atoms are bent out of the plane of the cyclobutadiene ring away from the platinum atom an average of 14 (1)°, and the mean distance between the Pt atom and the four carbon atoms in the substituted cyclobutadiene ring is 2.220 (48) A. The hexafluoroantimonate anion is disordered about two positions and has been refined as two rigid groups with octahedral symmetry and antimony-fluorine bond lengths of 1.83 A.

show abstract

“…3-Carbethoxybicyclo[5.3.0]deca-4,6-diene (8). To an icecooled solution of the enone 7 (4.44 g, 0.02 mol) in ethanol (50 mL) was added sodium borohydride (0.40 g, 0.01 mol) in portions.…”

Section: Methodsmentioning

confidence: 99%

“…Stirring was continued for 6 h, and the mixture was left overnight (8) Wolinsky, J.; Erickson, K. L. J. Org. Chem.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

A new synthesis of azulene-5-carboxylic acid

Ravikumar¹,

Swaminathan²,

Rajagopalan³

1985

J. Org. Chem.

View full text Add to dashboard Cite

5867(CDC13) 6 1.4 (d, 3 H, J = 3 Hz), 1.48 (9, 3 HI, 1.50 (9, 3 H), 3.75-4.35 (m, 2 H), 9.75 (d, 1 H); MS, m / z 162 (M'), 159, 129, 115, 99, 85, 73, 59; IR (liquid film) 1730 IR (liquid film) , 1760 (b) From D-Threonine (See Preparation of the 4s-Trans Enantiomer from L-Threonine).(45)trans-2f,5-Trimethyl-1,3-dioxolane-4-carboxaldehyde (IC). L-Threonine (220 g, 1.85 mol) suspended in 500 mL of water at -5 "C was treated simultaneously while stirring with a solution of 138 g of NaN02 (2 mol) in 200 mL of water and 55.7 mL of concentrated H2S04 (1 mol) in 150 mL of water. The two solutions were added at such a rate that the temperature remained between 0 and 5 "C. The solution was then stirred at room temperature overnight. The water was evaporated under vacuum and the remaining mixture treated with 300 mL of EtOH. The salts were then filtered and the solution evaporated to dryness again. Absolute MeOH (200 mL) was then added and the solution saturated with gaseous HCl and refluxed for 6 h.

show abstract

Evidence for the existence of the dianion of cyclobutadiene

Abstract: Evidence is presented for the generation of cyclobutadiene dianion, a Huckel aromatic, from cisdichlorocyclobutene and sodium naphthalide ; although highly reactive, the dianion can be deuteriated to afford 3,4-dideuteriocyclobutene.

Cited by 19 publications

References 0 publications

Reduction and oxidation of annulenes

Reduction and oxidation of annulenes

Crystal and molecular structure of tetramethylcyclobutadienetrifluoromethylbis(dimethylphenylphosphine)platinum(II) hexafluoroantimonate

A new synthesis of azulene-5-carboxylic acid

Contact Info

Product

Resources

About