如何将 H_2 置于 N 之上？（天冬氨酸和谷氨酰胺金属配合物）

Question

请考虑以下代码

\documentclass{article} 
\usepackage{chemfig} 
\newcommand*\circleatom[1]{\tikz\node[circle,draw,fill=green!30]{\printatom{#1}};}

\begin{document}
\definesubmol{&}{-[:90,,,,draw=none]}
\definesubmol{8anta}{-[:-80,,,,draw=none]}

\setlewisdist{4pt}
\definesubmol{Gly}{
  H_{2}
  -[:-90]\lewis{0:,N}
  -[:225]H_{2}C 
  -[:-45]C(=[:-90]O)
  -[:13]\lewis{3:1:7:,O}!&\circleatom{Me}}
\definesubmol{Aspartic}{
  O=[:-90]C(-[:-25]\lewis{1:5:7:,O}!{8anta}\circleatom{Me}) 
  -[:230]H_{2}C 
  -[:-90,,2,2]HC(-[:30,,,2]H_{2}N)
  -[:-50]C(=[:-90]O) 
  -[:25]\lewis{1:3:7:,O}}
\definesubmol{Glutammic}{
  O=[:-90]C(-[:-25]\lewis{1:5:7:,O}!{8anta}\circleatom{Me}) 
  -[:230]H_{2}C 
  -[:-90,,2,2]H_{2}C
  -[:-90,,2,2]HC(-[:30,,,2]H_{2}N)
  -[:-50]C(=[:-90]O) 
  -[:25]\lewis{1:3:7:,O}}

\schemestart
\chemname{\chemfig{!{Gly}}}{Glycine}
\arrow{0}
\chemname{\chemfig{!{Aspartic}}}{Aspartic  acid}
\arrow{0}
\chemname{\chemfig{!{Glutammic}}}{Glutammic acid}
\schemestop
\end{document}

在第二个和第三个分子中，我想显示 N 上的电子，但我尝试使用宏 \lewis{...} 失败了。每次我在 N 附近插入 \lewis 时，我总是得到一个混乱的分子。我怀疑我没有在正确的位置写括号。

另外，我想把两个氢写在 N 上。我尝试使用“幻影”键（手册中名为“&”），但我无法弄清楚如何缩短该键。

Answer 1

\chemabove并\chembelow可能有帮助：

\documentclass{article}
\usepackage{chemfig}
\newcommand*\circleatom[1]{\tikz\node[circle,draw,fill=green!30]{\printatom{#1}};}
\begin{document}
\setlewisdist{4pt}
\schemestart
\chemname{%
    \chemfig{%
        H_{2}
        -[:-90]\lewis{0:,N}
        -[:225]H_{2}C
        -[:-45]C(=[:-90]O)
        -[:13]\lewis{3:1:7:,O}-[:90,1,,,draw=none]\circleatom{Me}
        }%
    }
    {Glycine}
\arrow{0}
\chemname{%
    \chemfig{%
        O=[:-90]C(-[:-25]\lewis{1:5:7:,O}-[:-80,.8,,,draw=none]\circleatom{Me})
        -[:230]H_{2}C
        -[:-90,,2,2]HC(-[:30]\chemabove[3pt]{\lewis{0:,N}}{H\kern1.5pt H})
        -[:-50]C(=[:-90]O)
        -[:30]\lewis{1:3:7:,O}
        }%
    }
    {Aspartic  acid}
\arrow{0}
\chemname{%
    \chemfig{%
        O=[:-90]C(-[:-25]\lewis{1:5:7:,O}-[:-80,,,,draw=none]\circleatom{Me})
        -[:230]H_{2}C
        -[:-90,,2,2]H_{2}C
        -[:-90,,2,2]HC(-[:30]\chembelow[3pt]{\lewis{0:,N}}{H\kern1.5pt H})
        -[:-50]C(=[:-90]O)
        -[:25]\lewis{1:3:7:,O}
        }%
    }
    {Glutammic acid}
\schemestop
\end{document}

编辑：另一个解决方案，对\chemabove和进行了稍微修改\chembelow：

\documentclass{article}
\usepackage{chemfig}
\newcommand*\circleatom[1]{\tikz\node[circle,draw,fill=green!30]{\printatom{#1}};}
\newcommand\stackabove[3][3pt]{\vbox{\offinterlineskip\vbox to0pt{\vss\hbox{\printatom{#2}}\kern#1}\hbox{#3}}}
\newcommand\stackbelow[3][3pt]{\vtop{\offinterlineskip\hbox{#3}\vbox to0pt{\kern#1\hbox{\printatom{#2}}\vss}}}
\begin{document}
\setlewisdist{4pt}
\schemestart
\chemname{%
    \chemfig{%
        H_{2}
        -[:-90]\lewis{0:,N}
        -[:225]H_{2}C
        -[:-45]C(=[:-90]O)
        -[:13]\lewis{3:1:7:,O}-[:90,1,,,draw=none]\circleatom{Me}
        }%
    }
    {Glycine}
\arrow{0}
\chemname{%
    \chemfig{%
        O=[:-90]C(-[:-25]\lewis{1:5:7:,O}-[:-80,.8,,,draw=none]\circleatom{Me})
        -[:230]H_{2}C
        -[:-90,,2,2]HC(-[:30]\stackabove{H_2}{\lewis{0:,N}})
        -[:-50]C(=[:-90]O)
        -[:30]\lewis{1:3:7:,O}
        }%
    }
    {Aspartic  acid}
\arrow{0}
\chemname{%
    \chemfig{%
        O=[:-90]C(-[:-25]\lewis{1:5:7:,O}-[:-80,,,,draw=none]\circleatom{Me})
        -[:230]H_{2}C
        -[:-90,,2,2]H_{2}C
        -[:-90,,2,2]HC(-[:30]\stackbelow{H_2}{\lewis{0:,N}})
        -[:-50]C(=[:-90]O)
        -[:25]\lewis{1:3:7:,O}
        }%
    }
    {Glutammic acid}
\schemestop
\end{document}