Actinide Metal Atom (Th and U) Reactions to Form Novel Molecules Metal-Carbon Multiple Bonds Actinide Metal Hydrides Lester Andrews, Chemistry Department, University of Virginia, Charlottesville, Virginia Also Jon Lyon, Han-Gook Cho, Xuefeng Wang, Bjorn Roos, Han-shi Hu, Jun Li, Colin Marsden, Laura Gagliardi

Apparatus for Laser Ablation and Matrix Isolation CsI window for IR

YAG laser ablation of Zr

Novel Organometallic Molecules M + CH 4  CH 3 —MH ↔ CH 2 =MH 2 ↔ HC≡MH 3 M + CH 3 X  CH 3 —MX ↔ CH 2 =MHX ↔ HC≡MH 2 X M + CH 2 X 2  CH 2 X—MX  CH 2 =MX 2  HC≡MHX 2 M + CHX 3  CHX 2 —MX  CHX=MX 2  HC≡MX 3 M + CX 4  CX 3 —MX  CX 2 =MX 2  XC≡MX 3

B3LYP density functional calculated structures for methylidene molecules

Infrared spectra of the Th + CH 4 reaction product J. Phys. Chem. A 2005, 105, Dep at 7 K nm > 220 nm Anneal 26 K > 420 nm

Observed and Calculated (B3LYP/ G(3df,3pd)/SDD) Frequencies for CH 2 =ThH 2 Approximate Mode Description CH 2 =ThH 2 13 CH 2 =ThH 2 CD 2 =ThD 2 Obs.Calc.Int.Obs.Calc.Int.Obs.Calc.Int. CH 2 stretch CH 2 stretch ThH 2 stretch b ThH 2 stretch b CH 2 bend C=Th stretch CH 2 wag ThH 2 bend ThH 2 rock CH 2 twist ThH 2 wag CH 2 rock

CH 2 =ThH 2, CH 2 =ThHF, CH 2 =UH 2, CH 2 =UHF CH 2 =UHF CH 2 =ThHF

Structures calculated with different theoretical methods Inorg. Chem. 2007, 46, BPW91/PW91/CASPT2

One singly-occupied U 5f orbital in CH 2 =UH 2

Reactions of laser-ablated U atoms with CH 2 XY (XY = F 2, FCl, and Cl 2 ) lead to a series of new actinide methylidene complexes CH 2 =UF 2, CH 2 =UFCl, and CH 2 =UCl 2, which have agostic structures stabilized by interaction through the open-shell U 6d-5f orbitals. Angew. Chem. Intl. Ed. 2007, 46, 9045.

Structures for Th, U and NH 3 Reaction Products Chem. Eur. J. 2007, 13, B3LYP/CCSD

H-N=ThH 2 H-N=UH % d 30.1% f HOMO 46.2% d 48.5% f HOMO CH 2 =ThH CH 2 =UH Small amount of triple bond character

Novel Organometallic Molecules M + CH 4  CH 3 —MH ↔ CH 2 =MH 2 ↔ HC≡MH 3 M + CH 3 X  CH 3 —MX ↔ CH 2 =MHX ↔ HC≡MH 2 X M + CH 2 X 2  CH 2 X—MX  CH 2 =MX 2  HC≡MHX 2 M + CHX 3  CHX 2 —MX  CHX=MX 2  HC≡MX 3 M + CX 4  CX 3 —MX  CX 2 =MX 2  XC≡MX 3

Th atom reactions with CHF 3, CHF 2 Cl, CHFCl 2, and CHCl 3 CHF 3

Approximate HC÷ThF 3 DC÷ThF 3 ModeObs.(argon matrix)B3LYP Calc. (int.)Obs.(argon matrix)B3LYP Calc. (int.) C-H stretch, a (5) (0) Th-F stretch, a (17) (30) Th-F stretch, e (419) (404) C-Th stretch, a (180) (160) H-C-Th bend, e425.9 (68)328.3 (56) F-Th-F bend, a (1)117.4 (4) F-Th-F bend, e117.5 (27)115.4 (27) C-Th-F bend, e106.0 (37)102.0 (17) Observed and Calculated Fundamental Frequencies for HC÷ThF 3 in C 3v Symmetry in the Triplet Ground Electronic State Eur. J. Inorg. Chem. 2008, in press.

Energies of Th and U atom reactions with CHF 3 and CF Å 2.16 Å 2.41 Å 2.13 Å 1.94 Å CHF 2 --ThF  CHF=ThF 2  HC—ThF 3 CHF=UF 2  HC≡UF kcal/mol + 46 kcal/mol 0 kcal/mol + 23 kcal/mol 0 kcal/mol 2.26 Å 2.47 Å 2.40 Å CF 2 =ThF 2  CF 2 —ThF 2  FC—ThF kcal/mol + 51 kcal/mol 0 kcal/mol 2.45 Å 2.40 Å 2.01 Å CF 2 —UF 2  CF 2 =UF 2  FC≡UF kcal/mol + 20 kcal/mol 0 kcal/mol

B3LYP Structures for HC-ThX 3 and XC-ThX 3 Complexes

Uranium atom reaction products Proc. Natl. Acad. Sci. 2007, 104, U+CDF 3 U+CF 4 U + CDF 3 U + CF 4 U + CDF 3 U + CHF 3

Observed and calculated (PW91/TZ2P) fundamental vibrational frequencies for the C 3v F 3 U≡CX (X = H, D, F) molecules Mode descriptionF 3 U≡CHF 3 U≡ 13 CHF 3 U≡CDF 3 U≡CF Obs.Calc.Obs.Calc.Obs.Calc.Obs.Calc. C-X str, a (0.1)2969(0.2)–2200(1.5)–1268(312) U≡CX str, a 1 –747(46)--721(42)–717(41)–441(34) U-F sym str, a (122)--585(123) (123) (118) U-F antisym str, e (284) (280) (207) (177) U≡C-X bend, e (34)--506(24)--412(49)–311(28)

Calculated structures of (a) F 3 U≡CH, (b) Cl 3 U≡CH, (d) Br 3 U≡CH, and (d) F 3 U≡CF

Comparison of the molecular orbitals of ethyne HC≡CH and the uranium- methylidyne F 3 U≡CH and F 3 U≡CF complexes (isosurface =0.05 atomic unit) HC≡CH F 3 U≡CH F 3 U≡CF π 1 -MO π 2 -MO σ-MO

Uranium atom reaction products CHCl 3 13 CHCl 3 CDCl 3 CHBr 3

Observed and calculated (PW91/TZ2P) fundamental vibrational frequencies for the C 3v X 3 U≡CH (X = Cl, Br) molecules Mode descriptionCl 3 U≡CHCl 3 U≡ 13 CHCl 3 U≡CDBr 3 U≡CH Obs. b Calc.Obs.Calc.Obs.Calc.Obs.Calc. C-H str, a (2)2991(2)2219(7)3005(3) U≡CX str, a 1 –c–c 770(69)–c–c 744(65)–c–c 738(64)–c–c 777(70) U≡C-H bend, e (224) (218) (216) (178) U-X sym str, a 1 339(29) 225(84) d U-X antisym str, e329(140)– –326(100)216(10) d

Carbon-Uranium Triple Bonds Å Å Å C≡U≡O HC≡UCl 3 PW91 bond lengths Zhou, Andrews, Li, Bursten, Lyon, Hu, Andrews, Li, J. Am. Chem. Soc. 1999, 121, Proc. Natl. Acad. Sci. U.S. Earlier work: 2007, 104(48), Tague, Andrews, Hunt, J. Phys. Chem. 1993, 97, Pyykko, Li, Runeberg, J. Phys. Chem. 1994, 98, 4809.

Reactions of Mo atoms with CHX 3 molecules: HC ≡ MoX 3

Reactions of Mo atoms with CHX 3 molecules Organometallics, 2007, 26, CHF 3 CHF 2 Cl CHFCl 2 CHCl 3 Natural Mo isotopic splittings

Approximate Description HC ≡ MoCl 3 DC ≡ MoCl 3 HC ≡ MoF 3 obscalcint obs calcint obs calcint C-H str, a HC ≡ Mo str, a b b c Mo-X str, e x x x2 Mo-X str, a H-C-Mo def, e x x x2 C-Mo-X def, e237.77x x x2 Mo-X 3 umb, a Mo-X 2 bend, e x2 Observed and Calculated [B3LYP/ G(2d,p) ] Fundamental Frequencies of HC≡MoX 3 Complexes in the Ground 1 A 1 Electronic State with the C 3v Structure

Span the periodic table U + H 2

U in solid para-hydrogen at 4 K J. Phys. Chem. A, 2007, 111, 6383.

Th in solid H 2, HD, and D 2 at 4 K J. Phys. Chem. A, 2008, in press.

Ground state total CASSCF electron density WH 4 (triplet) ThH 4 (singlet) UH 4 (triplet) WH 4 4H 2 (singlet) ThH 4 4H 2 (singlet) UH 4 6H 2 (triplet)

Ball Game!!! We have investigated reactions of the laser- ablated actinide metal atoms Th and U with small molecules, and assigned the new reaction products from matrix infrared spectra and comparison with DFT calculated isotopic frequencies. These new molecules are important for their unique bonding and structure and their unusual chemistry. We thank NSF for support and you for your kind attention.

Matrix-Isolation Spectroscopy Synthesis Gas-Phase Theory PERSPECTIVE