Answer:
Just like all bonds between metals and nonmetals, the bond present in Copper II Chloride is ionic.
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Oh, really? All bonds between metals and nonmetals are ionic? Oversimplifications like this make it difficult for students to learn what is actually going on. No, not all metal/nonmetal bonds are ionic. In fact, very few bonds are ionic enough to call them that. There are a few 100% covalent bonds, as between the atoms in a molecule of a diatomic element, and no 100% ionic bonds, although bonds between the most electronegative nonmetals (i.e. F) and the metals of groups IA and IIA are pretty close.
In reality, the vast majority of bonds lie along a continuum between these two extremes -- ionic and covalent. Therefore, it make more sense to talk about the percent ionic character of a bond. Those bonds with high electronegativity differences behave more like they would if they were actually ionic. Bonds with low electronegativity difference are more covalent-like.
The bonds in copper chloride have an electronegativity difference of 1.26 giving the bonds a percent ionic character of about 33%. Clearly, the Cu-Cl bond is more covalent than it is ionic. Then what is it that gives CuCl2 its relatively high melting and boiling points?
As it turns out, the high melting points and boiling points of substances are due to their network structure, not to their internal bonding. The fact that CuCl2 exists as a network solid is what accounts for the melting and boiling points. Many compounds bonds with even higher covalent character which exist as networks have very high melting and boiling points. Diamond, with 100% covalent bonds, and a network structure, has the highest boiling point of any substance.