split matrices over two lines using array

Question

I was wondering if there is anyway to split across two lines the following eigenvalue , eigenvector pair which I have listed below? I have tried \bigskip, \par, \newline within the array environment, but these all give me an error (more precisely " missing $ inserted" for which I do not understand). A minimum working example is given below along with a picture of the output. I would like to keep the output I have now, but loose the error which latex gives me. Also, is it possible to add some vertical space after the matrices at the bottom? I tried using \vspace{}, but I did not succeed.

\documentclass[a4paper,twoside,12pt,openany]{report}
\begin{document}
\usepackage{mathtools}
\usepackage{graphicx}
\usepackage[T1]{fontenc} 
\usepackage{placeins}
\usepackage{amssymb}
\usepackage{amsmath,scalefnt}   


 Eigenvalues, Eigenvectors \par
(D126) & {\small \begin{equation}
  \left[\left(\begin{array}{c} 1\\ -d\\ -\frac{\sqrt{3}\,d}{3}\\ \frac{\sqrt{3}\,d} 
 {3} 
  \end{array}\right),   \left(\begin{array}{cccc} 1 & -1 & 1 & 1\\ 1 & 0 & - 
 \frac{\left(2\,\sqrt{3}+3\right)\,\left(d+3\right)}{3\,\left(d-1\right)} & 
\frac{\left(2\,\sqrt{3}-3\right)\,\left(d+3\right)}{3\,\left(d-1\right)}\\ 1 & 0 & 
 \frac{3\,d+2\,\sqrt{3}\,d+2\,\sqrt{3}+5}{d-1} & \frac{3\,d-2\,\sqrt{3}\,d- 
 2\,\sqrt{3}+5}{d-1}\\ 1 & 1 & 1 & 1 \end{array}\right) \right] 
 \nonumber
 \end{equation}} \\ \hline

Answer 1

Something like this? (Note that I've gotten rid of all \left and \right sizing directives and all \, spacing directives.)

\documentclass[a4paper,twoside,12pt,openany]{report}
\usepackage{mathtools}
\usepackage[T1]{fontenc}

\begin{document}
Eigenvalues, Eigenvectors D126
\begin{gather*}
\renewcommand\arraystretch{1.35}
  \begin{pmatrix}
    1 \\ -d \\ -\frac{\sqrt{3}d}{3} \\  \frac{\sqrt{3}d}{3} 
  \end{pmatrix},  \\[2ex] % <-- induce a line break
  \begin{pmatrix}
    1 & -1 & 1 & 1  \\ 
    1 & 0 
          & -\frac{(2\sqrt{3}+3)(d+3)}{3(d-1)} 
          &  \frac{(2\sqrt{3}-3)(d+3)}{3(d-1)} \\ 
    1 & 0 
          & \frac{3d+2\sqrt{3}d+2\sqrt{3}+5}{d-1} 
          & \frac{3d-2\sqrt{3}d-2\sqrt{3}+5}{d-1} \\ 
    1 & 1 & 1 & 1 
  \end{pmatrix}
\end{gather*}
\end{document}