Quinquivalent is a related term of quantivalence.

In chemistry|lang=en terms the difference between quinquivalent and quantivalence

is that quinquivalent is (chemistry) having a valence of five while quantivalence is (chemistry) valence; the atomic or combining power of an element or radical expressed in terms of the number of atoms of hydrogen with which it will unite.

As an adjective quinquivalent

is (chemistry) having a valence of five.

As a noun quantivalence is

(chemistry) valence; the atomic or combining power of an element or radical expressed in terms of the number of atoms of hydrogen with which it will unite.