FUDAN UNIVERSITY 72 th International Symposium on Molecular

FUDAN UNIVERSITY 72 th International Symposium on Molecular Spectroscopy June 19 -23, 2017, UIUC Infrared Spectroscopy of New Molecules and Clusters Mingfei Zhou(周鸣飞) Department of Chemistry, Fudan University (复旦大学化学系激光化学研究所)

Research Interests How to create the world as or even better than Him ？ ---make new & useful molecules Ø What constitutes a chemical bond Ø What kinds of chemical bonds can be formed Ø What structures molecules can have Preparation, infrared spectroscopic and theoretical characterization of structure, bonding and reactivity of new molecules and clusters

Outline Ø High Oxidation State • Iridium tetroxide cation with a formal oxidation state +IX Nature, 2014, 514, 475 • Oxidation state +V of lanthanides Angew. Chem. Int. Ed. 2016, 55, 6896; Chem. Sci. 2017, 8, 4035 • Fe(+VII) oxidation state in Fe. O 4 - Phys. Chem. Phys. 2016, 18, 31125. Ø Donor-Acceptor Bonding Carbonyl Complexes • CO bonding with Lewis acids Be. O and Be. CO 3 Angew. Chem. Int. Ed. 2015, 54, 124 • Electron sharing or donor-acceptor bonding in B(CO)2 Angew. Chem. Int. Ed. 2015, 54, 11078 • B 3(CO)3+ complex featuring the smallest -aromatic B 3+ Angew. Chem. Int. Ed. 2016, 55, 2078 • One electron donor CO ligand Chem. Eur. J. 2016, 22, 2376 • Carbonyl complexes featuring metal-metal triple bonding Angew. Chem. Int. Ed. DOI: 10. 1002/anie. 201703525

Infrared Photodissociation Spectroscopy AB+ ~ l Collinear Tandem Time-of-Flight Mass Spectrometer

Matrix Isolation Infrared Absorption Spectroscopy Detector Pulsed Laser Target 4 K Cs. I Reagents inlet Spectral assignment-Isotopic substitution IR Source Trapping reactive intermediates and free radicals G. C. Pimentel et al. J. Chem. Phys. 1954, 22, 1943

1. High Oxidation State Ø The term "oxidation" was first used by Antoine Lavoisier to mean reaction of a substance with oxygen; The substance loses electrons upon being oxidized; Ø The “oxidation state” concept was introduced by Latimer in 1938; Ø Oxidation states were one of the intellectual stepping stones that Mendeleev used to derive the PT； Ø An indicator of the degree of oxidation (loss of electrons) of an atom in a chemical compound A central concept in chemistry

1. High Oxidation State What is the highest achievable oxidation state of any chemical elements in the Periodic Table? The highest experimentally known oxidation state of any chemical element so far is +VIII Ru+VIIIO 4 Os+VIIIO 4 Xe+VIIIO 4 M. Kaupp et al. , Coord. Chem. Rev. , 2009, 253, 606 Is a higher possible? oxidation state than +VIII

1. High Oxidation State The element iridium (5 d 7 6 s 2) with nine valence electrons would have the greatest chance of being oxidized beyond the +VIII oxidation state The probable candidates are the cationic species [Ir. O 4]+ and the anionic species [Ir. O 5]- C. K. Jørgensen, Oxidation numbers and Oxidation States, Springer, New York, 1969

1. 1 +IX Oxidation State of Iridium There is some evidence for a short-lived [Ir. O 4]+ species generated by decay of the unstable 193 Os isotopomer of Os. O 4 P. Rother et al. Radiochim. Acta, 1969, 11, 203 Quantum chemical calculations predicted that iridium tetroxide cation is stable D. Himmel, et al. Chem. Phys. Chem. 2010, 11 , 865 The existence of Ir. IXO 4+ requires experimental verification

1. 1 +IX Oxidation State of Iridium Preparation and spectroscopic characterization of Ir. O 4+ in gas phase IR photon energy in 900− 1200 cm− 1 region: 10. 8− 14. 4 k. J mol− 1 Rare gas atom tagging Mass spectra of the iridium oxide cations produced by pulsed laser vaporization of iridium in expansion of (a) O 2/He, and (b) O 2/Ar

1. 1 +IX Oxidation State of Iridium Ir. O 4+, Td: one IR active T 2 mode Ar-induced symmetry reduction & mode splitting C 3 v: E + A 1 (2: 1) Ar-coordination mode: ü Face ( 3) Edge ( 2) Vertex( 1) Infrared photodissociation spectrum of [193 Ir. O 4]+∙Ar

1. 1 +IX Oxidation State of Iridium Infrared photodissociation spectra of [193 Ir. O 4]+∙Arn

1. 1 +IX Oxidation State of Iridium Molecular orbital pictures of singlet Ir. O 4+ HOMO (T 1) HOMO-2 (A 1) HOMO-1 (T 2) HOMO-3 (T 2) HOMO-4 (E) the same as Os. O 4 HOMO-5 (T 2) HOMO-6 (A 1) Ir. O 4+ with Td symmetry has an d 0 electron configuration with iridium in oxidation state +IX

1. 1 +IX Oxidation State of Iridium Computed potential energy diagram (B 3 LYP results) of the isomers of [Ir. O 4]+ G. J. Wang et al. Nature, 2014, 514, 475

Is Oxidation State Higher Than +IX Possible? Pt. O 42+ is in fact a Pt(+VI) species!!!

Is Oxidation State Higher Than +IX Possible? Pt. O 4+ is a Pt(+II) species d-shell collapses in radius and energy +IX is the highest experimentally achievable oxidation state for stable chemical elements in PT

1. 2 +V Oxidation State of Lanthanides Ln: 4 f 5 d 6 s Contracted radial distribution of 4 f orbitals

1. 2 +V Oxidation State of Lanthanides Is a higher oxidation state than +IV possible for lanthanides? Pr: 4 f 3 6 s 2 (+V) IPs: Pr: 5. 42, 10. 55, 21. 62, 38. 95, 57. 45 e. V V: 6. 74, 14. 65, 29. 31, 46. 71, 65. 23 e. V Nd: 4 f 3 5 d 1 6 s 2 (+V, +VI)

1. 2 +V Oxidation State of Lanthanides Ø Praseodymium is also quadri- valent, possibly occasionally pentavalent S. Hopkins, J. Chem. Edu. 1936, 13, 363. Ø Y 2 O 3 should promote the oxidation of praseodymium to the pentavalent state by forming the compound YPr. O 4 W. Prandtl & G. Rieder, Z. Anorg. Chem. 1938, 225 Ø The claimed Pr(+V) in solid states were later refuted J. D. Mc. Cullough, J. Am. Chem. Soc. , 1950, 72 , 1386; J. Kleinberg, J. Chem. Educ. , 1952, 29, 324 Ø After 50 years, the Pr(+V) was believed to exist in gas-phase Pr. O 3 S. P. Willson & L. Andrews J. Phys. Chem. A, 1999, 103, 3171 Ø Pr. O 3 - is in fact a Pr(+IV) species J. Su et al. Sci. China Chem. 2016, 59, 442.

1. 2 +V Oxidation State of Lanthanides 2 , Pr (4 f 1) The removal or oxidization of the remaining 4 f electron from Pr. O 2 would lead to the [Pr. O 2]+ cation with Pr(+V) oxidation state • [(Pr. VO 2)+(O 2)x] and [(Nd. VO 2)+(O 2)x] cation complexes in gas phase • [( 2 -O 2)Prv. O 2] and NPr. O neutral molecules in noble gas matrices

1. 2 +V Oxidation State of Lanthanides Preparation of praseodymium oxide cation complexes in gas phase Mass spectra of the praseodymium oxide cation complexes

1. 2 +V Oxidation State of Lanthanides Experimental and simulated IR spectra of [(Pr. O 2)+(O 2)6]

1. 2 +V Oxidation State of Lanthanides Pr. O 2+ is a Pr(+V) species HOMO (2 u) HOMO-1(2 u) HOMO-2 (1 g) HOMO-3(1 g) HOMO-1(2 u) Pr: 4 f/5 d O: 2 p HOMO-3(1 g) Frontier canonical Kohn−Sham valence MO envelopes of the linear singlet Pr. O 2+ cation

1. 2 +V Oxidation State of Lanthanides Pr. O 2 neutral can be oxidized by O 2 in forming [(O 2 -)(Pr. O 2)+] Anneal at 30 K UV irradiation Anneal at 25 K Deposition at 4 K Preparation of Pr. O 4 neutral molecule in solid argon

1. 2 +V Oxidation State of Lanthanides C 2 v, 2 A 2 HOMO SOMO Pr. O 4 is a Pr(+V) species Zhou & Li et al. Angew. Chem. Int. Ed. 2016, 55, 6896.

1. 2 +V Oxidation State of Lanthanides Preparation of praseodymium nitride-oxide in noble gas matrices Pr-N Pr-O Visible irradiation Anneal at 12 K Anneal at 10 K Deposition at 4 K Pr + NO NPr. O in Ne

1. 2 +V Oxidation State of Lanthanides NPr. O is a pentavalent species B 3 LYP CCSD(T) 1 Mayer bond order Covalent triple bond radii: Pr + N = 1. 28 + 0. 54= 1. 82 Å Pr+ O = 1. 28 + 0. 53= 1. 83 Å P. Pyykko, et al. Chem. Eur. J. 2005, 11, 3511 Li & Zhou et al. Chem. Sci. 2017, 8, 4035

1. 2 +V Oxidation State of Lanthanides Nd. O 2+ is a Nd(+V) species IR spectra of the [Nd. On]+ cation complexes MO envelopes of the 2 state Nd. O 2+

2. Donor-Acceptor Bonding Carbonyl Complexes Dewar−Chatt−Duncanson bonding model synergic donation backdonation CO: (1σ)2(2σ)2(3σ)2(4σ)2(1π)4(5σ)2(2π)0 • One electron donor CO ligand • Carbonyl complexes featuring U-Fe triple bonding

2. 1 One-Electron Donor Carbonyl Ligand The terminally bonded CO ligands are classical two-electron donors Octet rule: [B(CO)3]+: 2 e (B) + 2 e (CO)× 3 = 8 e B(CO)3: 9 e X Anneal at 35 K Anneal at 30 K Deposition at 4 K Infrared spectra of boron carbonyls in solid argon

2. 1. One-Electron Donor Carbonyl Ligand Optimized geometry at CCSD(T)/cc-p. VDZ level B(CO)3 → B(CO)2 + CO Density of the unpaired electron De = 10. 9 kcal/mol The tilted CO ligand serves as a one-electron donor ligand

2. 1 One-Electron Donor Carbonyl Ligand Energy levels of the frontier Kohn−Sham valence MOs of B(CO)3

2. 1 One-Electron Donor Carbonyl Ligand C(CO)3+---B(CO)3 isoelectronic Mass spectrum of C(CO)n+ complexes IR spectra of C(CO)3+ and C(CO)4+ Graphite + CO/He Zhou & Frenking, Chem. Eur. J. 2016, 22, 2376

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding Actinide-transition metal multiple bonding Cotton, F. A. et al. Science 1964, 145, 1305 Nguyen, T. et al. Science 2005, 310, 844 Liddle, S. T. et al. Angew. Chem. Int. Ed. , 2009, 48, 1077; Chem. Eur. J. 2011, 17, 6909

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding Fe(CO)3 - --- building block Mass spectrum of iron−uranium carbonyl anion complexes

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding 13 CO 12 CO Mass spectra of iron−uranium carbonyl anion complexes

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding Infrared photodissociation spectra of UFe(CO)3 - and OUFe(CO)3 -

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding Experimental spectrum and PBE simulated IR spectra of UFe(CO)3 - isomers (The relative energies are given in

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding Bond length 2. 21 2. 16 2. 0 2. 6 Mayer bond order C 3 v, 4 A 1 C 3 v, 2 A 2 Covalent triple bond radii: U + Fe = 1. 18 + 1. 02= 2. 20 Å P. Pyykko, et al. Chem. Eur. J. 2005, 11, 3511

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding U 5 f U 7 s Fe 3 d CO 2 * U (6 d/5 f) - Fe (3 d) KS molecular orbitals of the quartet ground state UFe(CO) 3 -

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding U (5 f)3(6 d)1(7 s)2 + Fe(CO)3 - (2 A 1) U+IFe-II(CO)3 • One electron sharing bond • Two Fe U dative bonds Bonding scheme of the C 3 v structure of 4 A 1 -UFe(CO)3 -

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding UO (5 f)1(6 d)1(7 s)2 + Fe(CO)3 - (2 A 1) OU+IIIFe-II(CO)3 SOMO (2 a 2) U 5 f HOMO (12 a 1) U 7 s HOMO-1 (10 e) Fe 3 d CO 2 * HOMO-2 (11 a 1) U (6 d/5 f) - Fe (3 d) HOMO-3 (9 e) U (6 d/5 f) - Fe (3 d) KS molecular orbitals of OUFe(CO)3 - • One electron sharing bond • Two Fe U dative bonds

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding Energy decomposition analysis of UFe(CO)3 - and OUFe(CO)3 at the PBE/TZ 2 P level interaction fragments U-Fe(CO)3 - OU-Fe(CO)3 - U (5 K, f 2 f 16 dσ17 s 2) UO (3 H, fσ1 f 17 s 2) + Fe(CO)3 - (2 A 1) Eint -135. 0 -141. 0 EPauli 388. 9 372. 9 Eelstat -285. 3 (54. 5%) -268. 0 (52. 2%) Eorb -238. 5 (45. 5%) -245. 9 (47. 8%) Eorb( ) -84. 4 -59. 7 Eorb( ) -41. 5 -56. 4 Eorb( //) -41. 5 -56. 4

2. 2. Carbonyl Complexes Featuring U-Fe Triple Bonding OUFe(CO)3 - UFe(CO)3 ( ) Deformation densities of the pairwise orbital interactions Li & Zhou, Angew. Chem. Int. Ed. 2017, in press

Conclusions Ø Infrared spectroscopic experiments on massselected [Ir. O 4]+ Arn (n = 1 -4) cations show that the iridium tetroxide cation is formed with iridium in the formal oxidation state +IX; Ø Infrared spectroscopic studies on Pr. O 2+ and Nd. O 2+ complexes and the Pr. O 4 and NPr. O molecules confirm that formal oxidation state +V is viable for some lanthanide elements; Ø Some new carbonyl complexes have been prepared via donor-acceptor bonding strategy that exhibiting unusual bonding characters.

Acknowledgements Research group Collaborators Gernot Frenking (Marburg) Jun Li (Tsinghua) Financial support from NNSFC and MST Sebastian Riedel (Berlin) Chaoxian Chi (ECUT)

Thank you very much for your attention!