Bond properties coordinate covalent

In this chapter, we ll look at the properties and chemical behavior of transition metal compounds, paying special attention to coordination compounds, in which a central metal ion (or atom)—usually a transition metal—is attached to a group of surrounding molecules or ions by coordinate covalent bonds (Section 7.5). 

A is correct. Sodium chloride is a protolypic example of an ionic bond. In a coordinate covalent bond, both shared electrons come from the same atom for instance, a Lewis base (i.e., ammonia) or oxygen-containing compound (i.e., water). Although both shared electrons come from the same atom, a coordinate covalent bond is a single bond similar in chemical properties to a covalent bond. 

The use of transition metals or transition metal clusters to act as nodes for the modular self-assembly of diamondoid networks that are sustained by coordinate covalent bonds is also well established. Such architectures are of more than aesthetic appeal. Indeed, such structures have resulted in a class of compound with very interesting bulk and functional properties. Metal-organic diamondoid structures in which the spacer moiety has no center of inversion are predisposed to generate polar networks since there would not be any inherent center of inversion. Pyridine-4-carboxylic acid is such a ligand and bis(isonicotinato)zinc exists as a three-fold diamondoid structure that is thermally stable and inherently polar.33... 

From the valence bond point of view, formation of a complex involves reaction between Lewis bases (ligands) and a Lewis acid (metal or metal ion) with the formation of coordinate covalent (or dative) bonds between them. The model utilizes hybridization of metal s, p, and d valence orbitals to account for the observed structures and magnetic properties of complexes. For example, complexes of Pd(ll) and Pt(Il) are usually four-coordinate, square planar, and diamagnetic, and this arrangement is often found for Ni(II) complexes as well. Inasmuch as the free ion in the ground state in each case is paramagnetic (d, F), the bonding picture has to... 

The B—N bond in the above compound is different from the covalent bonds discussed so far in the sense that both electrons are contribnted by the N atom. This type of bond is called a coordinate covalent bond (also referred to as a dative bond), defined as a covalent bond in which one of the atoms donates both electrons. Although the properties of a coordinate covalent bond do not differ from those of a normal covalent bond (because all electrons are alike no matter what their sonrce), the distinction is useful for keeping track of valence electrons and assigning formal charges. 

The photophysical properties of 33 +, 34+ and 35 + were investigated in DMF and the results are here summarized [72,75]. In these systems the redox active porphyrins are on different parts of the structure which are held together by the coordinated metal in 33 + and 35 +, whereas in 34+ they are held together only by mechanical bonds and no covalent electron-transfer pathways exist. These systems are characterized by some flexibility of the polyether gold porphyrin appended macrocycle which could cause, upon... 

Pseudorotaxane is produced when the linear molecule of the object penetrates the cyclic subject. While functional groups or compositions are attaching both ends of the object through the covalent bond or coordinate bond, the formation of a stopper shape blocks the separation of pseudorotaxane from the main body, generating rotaxane. Rotaxane and pseudorotaxane are both supramolecules maintained by the weak interaction of noncovalent bonds. The imit molecule determines the properties of the whole large molecule. The rotaxane is composed of a linear molecule and a cyclic molecule. N-rotaxane is formed when a linear molecule passes through n-1 cyclic molecules. Due to the special noncovalent supramolecular structure, this sort of supramolecule demonstrates the special character and has potential for application [48]. 

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