Matrix preparation and spectroscopic and theoretical investigation of small high oxidation-state complexes of groups 3–12, 14, lanthanide and actinide metal atoms: Carbon-metal single, double and triple bonds

A diuranium carbide cluster stabilized inside a C80 fullerene cage

“…In fact, the shortest U–C bond distance in poly-coordinated U-complexes to date is 2.184(3) Å, reported by Liddle et al for the U(VI) carbene complex U=[C(Ph 2 PNSiMe 3 ) 2 ](O)Cl 2 27 . Interestingly, the U–C bond lengths of the UC 0 U unit are between the 2.067(7) Å and 1.948(7) Å, theoretically calculated distances for uranium alkylidene and alkylidyne complexes U=CH 2 (H)F and U≡CH(Cl) 3 35 – 37 , and are nearly identical to the 2.01 Å distance calculated from the sum of the covalent radii 49 . Furthermore, the U–C 0 distances in 1 are longer than the triple bond of the U≡O unit (1.78 Å) in the uranyl dication UO 2 2+ , the U≡NR bonds (1.844(6) Å) of U(N t Bu) 2 (I) 2 (THF) 2 ), and the terminal U≡N bond (1.83(2) Å for the uranium nitride complex (Tren TIPS )UN), even when accounting for differences in the atomic radii of O, N, and C of ca.…”

“…The α-carbon bonded heteroatom(s) (e.g., phosphorous) aids the delocalization of the carbon-centered charge accumulation. While compounds possessing unsupported U=C bonds are difficult to prepare under typical synthetic conditions, Andrews and co-workers have identified alkylidene and even alkylidyne species such as H 2 C=UX 2 and HC≡UX 3 (X= H, F, Cl or Br) in low-temperature noble-gas matrix isolation experiments, providing evidence for such bonding motifs 35 – 37 . However, these compounds are too reactive to be isolated under typical synthetic conditions.…”

Double dative bond between divalent carbon(0) and uranium

“…Indeed, some of the uranium carbene species in the literature might be considered to contain non-negligible carbone character in their bonding 49,56,54 . In addition, species containing a U−C double bond, triple bond, or even quadruple bond were identified by matrix infrared spectroscopy and/or relativistic density functional calculations 64–69 . Very recently, a diuranium carbide cluster (U=C=U) was also stabilized inside a C 80 fullerene cage 50 .…”

Observation and Characterization of CH3CH2–MH, (CH2)2–MH2, and CH3–C≡MH3 Prepared in Reactions of Ethane with Laser-Ablated Group 6 Metal Atoms

“…Previous investigations have shown that metal atoms, including coinage metals and actinides, are reactive with methane and halomethanes . These new complexes, small versions of the larger complexes, often show agostic distortions, which are similar to those observed from their larger relatives, and photochemistry, including reversible photoisomerizations.…”

“…Many synthetic reactions and catalytic processes are also based upon bond insertion and the following rearrangements . Recent investigations have demonstrated that laser-ablated metal atoms are effective C–H­(X) bond insertion agents for methane and methyl halides, and the following H­(X)-migration also leads to generation of high oxidation-state products, methylidene and methylidynes (e.g., CH 2 MH 2 and HCMH 3 ) …”