Hybridization relativistic

The electronic structure calculations were carried out using the hybrid density functional method B3LYP [15] as implemented in the GAUSSIAN-94 package [16], in conjunction with the Stevens-Basch-Krauss (SBK) [17] effective core potential (ECP) (a relativistic ECP for Zr atom) and the standard 4-31G, CEP-31 and (8s8p6d/4s4p3d) basis sets for the H, (C, P and N), and Zr atoms, respectively. 

On the other hand, high-level computational methods are limited, for obvious reasons, to very simple systems.122 Calculations are likely to have limited accuracy due to basis set effects, relativistic contributions, and spin orbit corrections, especially in the case of tin hydrides, but these concerns can be addressed. Given the computational economy of density functional theories and the excellent behavior of the hybrid-DFT B3LYP123 already demonstrated for calculations of radical energies,124 we anticipate good progress in the theoretical approach. We hope that this collection serves as a reference for computational work that we are certain will be forthcoming. 

By analyzing the density matrix composition of planar and 3D structures of seven atom clusters (II and IV of Fig 1), calculated using scalar relativistic pseudo-potential at the GGA theory level, Fernandez and coworkers conclude that the planarity of An clusters is driven by the hybridization of the half-filled 6s orbital with the fully occupied 5d 2 orbital, which is favored by relativistic effects. Thus, the three valence electrons in the orbitals 6s and 5d 2, form a sticky-waist cylinder , where the cylinder is due to the almost filled s + d 2 hybrid, and the sticky-waist is due to the nearly half-filled s — d 2 hybrid orbital. 

Hz in complexes of [Hg Hg]2+ with crown ethers. In solid state minium, Pb304, the Pb4+-Pb2+ isotropic coupling, J(Pb, Pb), of 2.3 0.1 kHz is reported.457 The existence of this coupling is suggested to be a result of relativistically enhanced 6s- 6p promotion that seems to take place in heavy elements, which results in decreased hybridization efficiency and increased stability of lower oxidation states. It seems that such effects are to be expected for other relativistically bound molecular ions like [Hg2]2+. 

The geometry of coordination number 2 would be expected to be linear, either from the point of view of simple electrostatics or from the use of sp hybrids by the metal bot there are exceptions see Chapter 6). If the (n - l)d orbitals of the metal are sufficiently dose in energy to the ns and np orbitals, the dg orbital can enter into this hybridization to remove electron density from the region of the ligands. The tendency for this to occur will be in the order Hg = Au > Ag > Cu because of relativistic effects4 (see Chapter 18). This, in turn, may be partially responsible for the increased softness of Au(I) and Hg(ll) (see Chapter 9). 

Aurophilicity presumably arises from relativistic modification of the gold valence AOs energies, which brings the 5d and 6s orbitals into close proximity in the energy level diagram. In more recent theoretical studies, the effect is primarily attributed to electron correlation, which takes precedence over 6s/5d hybridization. To date, the origin of the aurophilicity has not yet been unambiguously established. 

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