><a name="l00181"></a><span class="lineno">  181</span>&#160;                                              <span class="stringliteral">&#39;C2C&#39;</span>,  <span class="comment"># cu-cl-cu linkage</span></div><div class="line"><a name="l00182"></a><span class="lineno">  182</span>&#160;                                              <span class="stringliteral">&#39;NA&#39;</span>,  <span class="comment"># sodium ion</span></div><div class="line"><a name="l00183"></a><span class="lineno">  183</span>&#160;  