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IBr2 is Cyanogen Chloride-derived structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is zero-dimensional and consists of two IBr2 clusters. I is bonded in a linear geometry to two equivalent Br atoms. Both I–Br bond lengths are 2.65 Å. Br is bonded in a single-bond geometry to one I atom.
Tb4Co is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Tb4Co clusters. Tb is bonded in a single-bond geometry to one Co atom. The Tb–Co bond length is 2.48 Å. Co is bonded in a tetrahedral geometry to four equivalent Tb atoms.
CsLa crystallizes in the hexagonal P6_3mc space group. The structure is zero-dimensional and consists of two CsLa clusters. Cs is bonded in a distorted single-bond geometry to one La atom. The Cs–La bond length is 3.58 Å. La is bonded in a distorted single-bond geometry to one Cs atom.
Radical-radical abstractions in hydrocarbon oxidation chemistry are disproportionation reactions that are generally exothermic with little or no barrier yet are underappreciated and poorly studied. Such challenging multireference electronic structure problems are tackled here using the recently developed state-specific multireference coupled cluster methods Mk-MRCCSD and Mk-MRCCSD(T), as well as the companion perturbation theory Mk-MRPT2 and the established MRCISD, MRCISD+Q, and CASPT2 approaches. Reaction paths are investigated for five prototypes involving radical-radical hydrogen abstraction: H + BeH → H 2 + Be, H + NH 2 → H 2 + NH, CH 3 + C 2 H 5 → CH 4 + C 2 H 4 , H + C2H 5 → H 2 + C 2 H 4 , and H + HCO → H 2 + CO. Full configuration interaction (FCI) benchmark computations for the H + BeH, H + NH 2 , and H + HCO reactions prove that Mk-MRCCSD(T) provides superior accuracy for the interaction energies in the entrance channel, with mean absolute errors less than 0.3 kcal mol(-1) and percentage deviations less than 10% over the fragment separations of relevance to kinetics. To facilitate combustion studies, energetics for the CH 3 + C 2 H 5 , H + C 2 H 5 , and H + HCO reactions were computed at each level of theory with correlation-consistent basis sets (cc-pVXZ, X = T, Q 5) and extrapolated to the complete basis set (CBS) limit. These CBS energies were coupled with CASPT2 projected vibrational frequencies along a minimum energy path to obtain rate constants for these three reactions. The rigorous Mk-MRCCSD(T)/CBS results demonstrate unequivocally that these three reactions proceed with no barrier in the entrance channel, contrary to some earlier predictions. Mk-MRCCSD(T) also reveals that the economical CASPT2 method performs well for large interfragment separations but may deteriorate substantially at shorter distances.
Si3N2 is alpha Po structured and crystallizes in the cubic Pm-3m space group. The structure is zero-dimensional and consists of one Si3N2 cluster. Si+1.33+ is bonded in a bent 120 degrees geometry to two equivalent N2- atoms. Both Si–N bond lengths are 1.76 Å. N2- is bonded in a trigonal planar geometry to three equivalent Si+1.33+ atoms.
Ba4Al is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ba4Al clusters. Ba is bonded in a single-bond geometry to one Al atom. The Ba–Al bond length is 3.19 Å. Al is bonded in a tetrahedral geometry to four equivalent Ba atoms.
Ca4Ni is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ca4Ni clusters. Ca is bonded in a single-bond geometry to one Ni atom. The Ca–Ni bond length is 2.59 Å. Ni is bonded in a tetrahedral geometry to four equivalent Ca atoms.
TcB is alpha carbon monoxide-like structured and crystallizes in the hexagonal P6_3mc space group. The structure is zero-dimensional and consists of two TcB clusters. Tc3- is bonded in a single-bond geometry to one B3+ atom. The Tc–B bond length is 1.77 Å. B3+ is bonded in a single-bond geometry to one Tc3- atom.
Ce4Fe is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ce4Fe clusters. Ce is bonded in a single-bond geometry to one Fe atom. The Ce–Fe bond length is 2.41 Å. Fe is bonded in a tetrahedral geometry to four equivalent Ce atoms.
Ba4Pd is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ba4Pd clusters. Ba is bonded in a single-bond geometry to one Pd atom. The Ba–Pd bond length is 2.98 Å. Pd is bonded in a tetrahedral geometry to four equivalent Ba atoms.
NiO6(ClO3)2 crystallizes in the cubic Pa-3 space group. The structure is zero-dimensional and consists of eight ClO3 clusters and four NiO6 clusters. In each ClO3 cluster, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.51 Å. Cl is bonded in a trigonal non-coplanar geometry to three equivalent O atoms. In each NiO6 cluster, Ni is bonded in an octahedral geometry to six equivalent O atoms. All Ni–O bond lengths are 1.92 Å. O is bonded in a single-bond geometry to one Ni atom.
LiCa4 is diamond structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight LiCa4 clusters. Li is bonded in a tetrahedral geometry to four equivalent Ca atoms. All Li–Ca bond lengths are 2.86 Å. Ca is bonded in a distorted single-bond geometry to one Li atom.
Ca4Pd is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ca4Pd clusters. Ca is bonded in a single-bond geometry to one Pd atom. The Ca–Pd bond length is 2.70 Å. Pd is bonded in a tetrahedral geometry to four equivalent Ca atoms.
AuBi4 is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight AuBi4 clusters. Au is bonded in a tetrahedral geometry to four equivalent Bi atoms. All Au–Bi bond lengths are 2.76 Å. Bi is bonded in a single-bond geometry to one Au atom.
Ca4Rh is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ca4Rh clusters. Ca is bonded in a single-bond geometry to one Rh atom. The Ca–Rh bond length is 2.58 Å. Rh is bonded in a tetrahedral geometry to four equivalent Ca atoms.
CeSe2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Ibam space group. The structure is zero-dimensional and consists of four CeSe2 clusters. Ce4+ is bonded in a linear geometry to two equivalent Se2- atoms. Both Ce–Se bond lengths are 2.53 Å. Se2- is bonded in a single-bond geometry to one Ce4+ atom.
Sc4Al is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Sc4Al clusters. Sc is bonded in a distorted single-bond geometry to one Al atom. The Sc–Al bond length is 2.61 Å. Al is bonded in a tetrahedral geometry to four equivalent Sc atoms.
Ce4Ni is Iron carbide-like structured and crystallizes in the cubic Fd-3m space group. The structure is zero-dimensional and consists of eight Ce4Ni clusters. Ce is bonded in a single-bond geometry to one Ni atom. The Ce–Ni bond length is 2.52 Å. Ni is bonded in a tetrahedral geometry to four equivalent Ce atoms.