\documentclass[10pt,border=1pt,tikz,class=scrartcl,multi=false]{standalone}
\usepackage{times}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage{amssymb,siunitx}
\usepackage{pgfplots}
\pgfplotsset{compat=1.13}
\usepackage{chemfig,chemmacros}
\renewcommand*{\familydefault}{\sfdefault}
\renewcommand*\printatom[1]{\ensuremath{\mathsf{#1} } }
\setatomsep{2.5em}
\setdoublesep{.6ex}
\setarrowdefault{,1,ultra thick}
\setbondstyle{thick,cap=round}

\usetikzlibrary{positioning,calc,arrows,fit,backgrounds,decorations,shapes}

\pgfdeclaredecoration{ddbond}{initial}
{
	\state{initial}[width=4pt]
	{
		\pgfpathlineto{\pgfpoint{4pt}{0pt} }
		\pgfpathmoveto{\pgfpoint{2pt}{2pt} }
		\pgfpathlineto{\pgfpoint{4pt}{2pt} }
		\pgfpathmoveto{\pgfpoint{4pt}{0pt} }
	}
	\state{final}
	{
		\pgfpathlineto{\pgfpointdecoratedpathlast}
	}
}
\tikzset{lddbond/.style={decorate,decoration=ddbond} }
\tikzset{rddbond/.style={decorate,decoration={ddbond,mirror} } }
\newcommand\namebond[4][5pt]{\chemmove{\path(#2)--(#3)node[midway,sloped,yshift=#1]{#4};} }
\newcommand\arcbetweennodes[3]{%
	\pgfmathanglebetweenpoints{\pgfpointanchor{#1}{center} }{\pgfpointanchor{#2}{center} }%
	\let#3\pgfmathresult}
\newcommand\arclabelA[6][stealth-stealth,shorten <=1pt,shorten >=1pt]{%
	\chemmove[red]{%
		\arcbetweennodes{#4}{#3}\anglestart \arcbetweennodes{#4}{#5}\angleend
		\draw[#1]([shift=(\anglestart:#2)]#4)arc(\anglestart:\angleend:#2);
		\pgfmathparse{(\anglestart+\angleend)/2}\let\anglestart\pgfmathresult
		\node[shift=(\anglestart:#2+1pt)#4,anchor=\anglestart+180,rotate=\anglestart-90,inner sep=0pt, outer sep=0pt]at(#4){#6};
	}
}
\newcommand\arclabelB[6][stealth-stealth,shorten <=1pt,shorten >=1pt]{%
	\chemmove[red]{%
		\arcbetweennodes{#3}{#4}\anglestart \arcbetweennodes{#5}{#4}\angleend
		\draw[#1]([shift=(\anglestart:-#2)]#4)arc(\anglestart:\angleend:-#2);
		\pgfmathparse{(\anglestart+\angleend)/2}
		\let\anglestart\pgfmathresult
		\node[shift=(\anglestart:-#2-1pt)#4,anchor=\anglestart+0,rotate=\anglestart+90,inner sep=0pt, outer sep=0pt]at(#4){#6};
	}
}

\pagestyle{empty}
\thispagestyle{empty}
\begin{document}
\schemestart[][west]
	\chemfig{
		@{0}O
		(-[::147]@{1}N(-[::66.5,,,,rddbond]O)-[::-66.5,,,,lddbond]O)
		-[::33]@{2}N(-[@{a1}::66.5,,,,rddbond]O)-[@{a2}::-66.5,,,,lddbond]O
	}
	\arclabelA{.4cm}{1}{0}{2}{\tiny114\si\degree}
	\arclabelB{.4cm}{a2}{2}{a1}{\tiny133\si\degree}
\end{document}