Hapticity of a ligand

The hapticity of a ligand is the number of atoms that are directly bonded to the metal centre. Structures 1.1a and 1.1b show two representations of an [η⁵-C₅H₅]^- (cyclopentadienyl, Cp^-) ligand. For clarity in the diagrams in this chapter, we adopt 1.1b and similar representations for π-ligands such as η³-C₃H₅ and η⁶-C₆H₆.

(1.1a)          (1.1b)

Bridge ligand

Counting electrons provided by bridging ligands, metal–metal bonds and net charges requires care. When bridging between two metal centres, an X˙ (X = Cl, Br, I) or R₂P˙ ligand uses the unpaired electron and one lone pair to give an interaction formally represented by structure 1.26, i.e. one electron is donated to M, and two to M’. In a doubly bridged species such as(CO)₂Rh(μ-Cl)₂Rh(CO)₂, the μ-Cl atoms are equivalent as are the Rh atoms, and the two Cl bridges together contribute three electrons to each Rh. A bridging H˙ provides only one electron in total, shared between the metal atoms it bridges, e.g. in [HFe₂(CO(₈]^-, (1.2). Example 1.2 also illustrates that the formation of anM^_Msingle bond provides each M atom with one extra electron; an M¼M double bond contributes two electrons to each metal.

(1.2)

مواضيع ذات صلة

كيمياء القصدير

تطبيقات الطبقات الثنائية الهيدروكسيد

تطبيقات عملية التبادل الأيوني

مواد التبادل الأيوني Ion exchanger

ظاهرة التبادل الايوني Ion Exchange

تاريخ التبادل الايوني Ion Exchange History

كيمياء البلاتين ومعقداته

كيمياء البلاديوم ومعقداته

طرائق تقدير النحاس

كيمياء النحاس ومعقداته

طرائق تقدير النيكل

كيمياء النيكل ومعقداته