== Error in "Elementary constructions" section == 

 It seems to me that there is a mistake in the "general expression of a 2 × 2 unitary matrix" under section "Elementary constructions". To my understanding, Pauli Matrices do not fit into this form, even they are widely recognized to be unitary matrices (https://en.wikipedia.org/wiki/Pauli_matrices). I suspect that the general is restricted to a specific determinant value, but as chemist I prefer do not edit the main article. 

 Regards, HRS