The First and Second Recoupled Pair Bonds in Sulfoxy Species Tyler Takeshita, D. E. Woon, T. H. Dunning, Jr. Department of Chemistry University of Illinois at Urbana-Champaign

Outline  Recoupled pair bonding in SX, X=F, OH, O  Trends in electron affinity  Importance of pi bonding  Addition of F and O to SF (second recoupled pair bond)  SF 2 vs. FSO  Future work

Methodology  MRCI+Q and RCCSD(T)  Correlation consistent basis sets aug-cc-pVXZ  X= T, Q  X = T+d, Q+d for S

Covalent and Recoupled Pair Bonds in SF S S F F F S S F SF 4 Σ - SF 2 Π SF 4 Σ - SF 2 Π RCCSD(T)/AVQZ D. E. Woon; T. H. Dunning, Jr; Molecular Physics; 107, 2009, p. 991

Covalent and Recoupled Pair Bonds in SF S S F F F S S F 4 Σ - r SF : Å 2 Π r SF : Å SF 4 Σ - SF 2 Π SF 4 Σ - SF 2 Π RCCSD(T)/AVQZ D. E. Woon; T. H. Dunning, Jr; Molecular Physics; 107, 2009, p. 991

O S O S SOH( 4 A ’’ ) S O S O SO( 3 Π) Recoupled Pair Bonds in SO, SOH

O S O S SOH( 4 A ’’ ) S O S O SO( 3 Π) De: 12.3 kcal/mol r e : Å De: 12.4 kcal/mol r SO : Å r OH : Å Recoupled Pair Bonds in SO, SOH

Effect of Electron Affinity F S De: 36.4 kcal/mol r e : Å F electron affinity: 3.40 eV SF( 4 Σ - ) O S De: 12.3 kcal/mol r e : Å O electron affinity: 1.46 eV SO( 3 Π) RCCSD(T)/AVQZ

Effect of Electron Affinity F S De: 36.4 kcal/mol r e : Å F electron affinity: 3.40 eV SF( 4 Σ - ) O S De: 12.3 kcal/mol r e : Å O electron affinity: 1.46 eV SO( 3 Π) RCCSD(T)/AVQZ How important is pi bonding?

The Importance of Pi Bonding F S De: 36.4 kcal/mol r e : Å F electron affinity: 3.40 eV SF( 4 Σ - ) O S De: 12.3 kcal/mol r e : Å O electron affinity: 1.46 eV SO( 3 Π) RCCSD(T)/AVQZ O S De: 12.4 kcal/mol r SO : Å r OH : Å OH electron affinity: 1.53 eV H SOH( 4 A ’’ ) How important is pi bonding?

The Importance of Pi Bonding F S De: 36.4 kcal/mol r e : Å F electron affinity: 3.40 eV SF( 4 Σ - ) O S De: 12.3 kcal/mol r e : Å O electron affinity: 1.46 eV SO( 3 Π) RCCSD(T)/AVQZ O S De: 12.4 kcal/mol r SO : Å r OH : Å OH electron affinity: 1.53 eV H SOH( 4 A ’’ ) How important is pi bonding? Pi bonding reduces bond length. No significant difference in bond energy.

The Addition of F to SF F 3A23A2 F S F S F 3B13B1 S F F S 4Σ-4Σ- S F 2Π2Π 1A11A1 R e = Å θ = 83.1° R e = Å θ = 162.7° R e = Å θ = 97.9° D. E. Woon; T. H. Dunning, Jr; J. Phys, Chem; 113, 2009, p RCCSD(T)/AVQZ

Recoupled Pair Bonding Predictions for SF + O F S 4Σ-4Σ- S F 2Π2Π S F 2 A’’ O F S O 2Π2Π F S O FSO 2 A’

F SF 2 3 A 2 F S R e = Å θ = 83.1° F S F SF 2 3 B 1 R e = Å θ = 162.7° S F R e = Å θ = 97.9° SF 2 1 A 1 S F FSO 2 A’’ O F SO FSO 2 Π R FS = Å R SO = Å θ = 180° R FS = Å R SO = Å θ = 108° RCCSD(T)/AVQZ R FS = Å R SO = Å θ = 95.2° F S O FSO 2 A’ D. E. Woon; T. H. Dunning, Jr; J. Phys, Chem; 113, 2009, p. 7915

F SF 2 3 A 2 F S R e = Å θ = 83.1° F S F SF 2 3 B 1 R e = Å θ = 162.7° S F R e = Å θ = 97.9° SF 2 1 A 1 S F FSO 2 A’’ O F SO FSO 2 Π R FS = Å R SO = Å θ = 180° R FS = Å R SO = Å θ = 108° R FS = Å R SO = Å θ = 95.2° F S O FSO 2 A’ D. E. Woon; T. H. Dunning, Jr; J. Phys, Chem; 113, 2009, p RCCSD(T)/AVQZ

F S F SF 2 3 B 1 R e = Å θ = 162.7° F SO FSO 2 Π R FS = Å R SO = Å θ = 180° Occ: Occ: Occ: Occ: Occ: 1.992

F SF 2 3 A 2 F S R e = Å θ = 83.1° F S F SF 2 3 B 1 R e = Å θ = 162.7° S F R e = Å θ = 97.9° SF 2 1 A 1 S F FSO 2 A’’ O F SO FSO 2 Π R FS = Å R SO = Å θ = 180° R FS = Å R SO = Å θ = 108° R FS = Å R SO = Å θ = 95.2° F S O FSO 2 A’ D. E. Woon; T. H. Dunning, Jr; J. Phys, Chem; 113, 2009, p RCCSD(T)/AVQZ

F SF 2 3 A 2 F S R e = Å θ = 83.1° F S F SF 2 3 B 1 R e = Å θ = 162.7° S F R e = Å θ = 97.9° SF 2 1 A 1 S F FSO 2 A’’ O F SO FSO 2 Π R FS = Å R SO = Å θ = 180° R FS = Å R SO = Å θ = 108° R FS = Å R SO = Å θ = 95.2° F S O FSO 2 A’ D. E. Woon; T. H. Dunning, Jr; J. Phys, Chem; 113, 2009, p RCCSD(T)/AVQZ

F SF 2 3 A 2 F S R e = Å θ = 83.1°  SF 2 3 A 2 singly occupied antibonding orbital compresses bond angle in SF 2 Occ: Occ: R FS = Å R SO = Å θ = 95.2° F S O FSO 2 A’

Summary of Current Work  Comparison of SX; X=F, OH, O recoupled structures  Electron affinity predicts ligands recoupling ability  O and OH recoupled bonds follow trends in electron affinity  Addition of Oxygen to SF 4 Σ -  Linear structure with two recoupled pair bonds  More localized antibonding orbital in structure containing one recoupled pair bond.

Ongoing Work: Addition to SO 3 Π and Effect of Electron Affinity F SO FSO 2 Π H SO HSO S F FSO 2 A’’ S O HSO  Addition of H to SO 3 Π is a covalent bond  Addition of F to SO 3 Π is a second recoupled pair bond R HS = Å R SO = Å θ = 93.0° R HS = Å R SO = Å θ = 105.0° R FS = Å R SO = Å θ = 180.0° R FS = Å R SO = Å θ = 108.0° O RCCSD(T)/AVQZ

Ongoing Work: Addition to SO 3 Π and Effect of Electron Affinity F SO FSO 2 Π H SO HSO S F FSO 2 A’’ S O HSO  Addition of H to SO 3 Π is a covalent bond  Addition of F to SO 3 Π is a second recoupled pair bond  Effect of electron affinity? R HS = Å R SO = Å θ = 93.0° R HS = Å R SO = Å θ = 105.0° R FS = Å R SO = Å θ = 180.0° R FS = Å R SO = Å θ = 108.0° O RCCSD(T)/AVQZ

Acknowledgements  Thom H. Dunning, Jr.  Dr. David E. Woon, Dr. Lina Chen, Jeff Leiding, Beth Lindquist, Lu Xu.  Support for this work was provided by funding from the Distinguished Chair for Research Excellence in Chemistry at the University of Illinois at Urbana-Champaign.