Orbital octahedral

A theoretical basis for the description of the cationic complex [Cp Ru(PR3)2 = = SiR2]+ can also be given. For a d6 CpML2 system, a complete splitting of the three orbitals (octahedral symmetry) is to be expected. Consequently, a coordinated silylene ligand (without any base) should prefer the indicated (Fig. 10) conformation. 

Divalent nickel forms two main types of complexes. The first consists of complexes of the spin-free ( ionic or outer orbital) octahedral type (see also Ligand for their discussion) in which the ligands are principally H2O, NH3, and various amines such as ethylenediamine and its derivates, e.g., Ni(H20>62+. Ni(NH3)e2+, Ni(en)62+. These complexes usually have colors toward the high-frequency side of the spectrum, i.e., violet, blue, and green. The other class consists of tetracovalent square complexes with ligands such as CN, the dioximes and their derivatives, and other chelates, which usually have colors on the low frequency side of the spectrum, i.e., red. orange, and yellow. The structure of the nickel-climethylglyoxime complex is... 

In the case of the inner-orbital octahedral complexes, the six d sp hybrid orbitals are occupied by six electron pairs from ligands. The electrons of the central metal occupy the t2g orbitals. The inner orbital octahedral complexes which contain at least one d-orbital of t2g set empty are known to be labile. Probably, this empty d-orbital is used to accept the electron pair from the incoming hgand during the formation of an activated complex with a higher coordination number. In the inert inner-orbital octahedral complexes, every d-orbital of % set contains at least one electron. 

Explain inert and labile inner orbital octahedral complexes according to VBT. 

Silicon, germanium, tin and lead can make use of unfilled d orbitals to expand their covalency beyond four and each of these elements is able (but only with a few ligands) to increase its covalency to six. Hence silicon in oxidation state -f-4 forms the octahedral hexafluorosilicate complex ion [SiFg] (but not [SiCl] ). Tin and lead in oxidation state -1-4 form the hexahydroxo complex ions, hexahydroxostannate(IV). [Sn(OH) ] and hexahydroxoplum-bate(IV) respectively when excess alkali is added to an aqueous solution containing hydrated tin(IV) and lead(IV) ions. 

The ions and have 7 and 6 d electrons respectively. Where there are orbitals of the same (or nearly the same) energy, the electrons remain unpaired as far as possible by distributing themselves over all the orbitals. In the case of [CofNHj) ] -, the energy split in the d orbitals due to octahedral attachment of the six... 

Figure 7.38 Splitting of d orbitals in a regular octahedral field...

The chemistry of Cr(III) in aqueous solution is coordination chemistry (see Coordination compounds). It is dominated by the formation of kineticaHy inert, octahedral complexes. The bonding can be described by Ss]] hybridization, and HteraHy thousands of complexes have been prepared. The kinetic inertness results from the electronic configuration of the Cr ion (41). This type of orbital charge distribution makes ligand displacement and... 

Fig. 2. Simplified molecular orbital diagram for a low spia octahedral complex, such as [Co(NH3 )g, where A = energy difference a, e, and t may be antisymmetric (subscript ungerade) or centrosymmetric (subscript, gerade) symmetry orbitals. See text.

Figure 19.14 Molecular orbital diagram for an octahedral complex of a first series transition metal (only a interactions are considered in this simplified diagram).

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