Perkembangan dunia dalam segi kimia memiliki detail yang beragam, salah satunya aturan 18 elektron, yang aturan tersebut mirip dengan kaidah [[Kaidah oktet|duplet]] ataupun [[Kaidah oktet|oktet]]. Aturan 18 elektron dirancang untuk memprediksi struktur dan reaktifitas kompleks untuk kompleks logam yang stabil, khususnya [[Kimia organologam|organologam]].<ref>{{Cite journal|last=Okuniewski|first=Andrzej|last2=Rosiak|first2=Damian|last3=Chojnacki|first3=Jarosław|last4=Becker|first4=Barbara|date=2015-04-18|title=Coordination polymers and molecular structures among complexes of mercury(II) halides with selected 1-benzoylthioureas|url=https://www.sciencedirect.com/science/article/pii/S0277538715000625|journal=Polyhedron|language=en|volume=90|pages=47–57|doi=10.1016/j.poly.2015.01.035|issn=0277-5387}}</ref> Senyawa [[Koordinasi sferis|koordinasi]] atau [[Kompleks (kimia)|kompleks]] terdiri dari [[logam]] atau ion logam sebagai atom pusat yang terikat secara ikatan kovalen koordinasi ke satu atau lebih atom donor dalam suatu [[ligan]].<ref>{{Cite journal|last=K|first=Alieva G.|last2=A|first2=Kadirova Sh|last3=A|first3=Nuralieva G.|last4=M|first4=Ashurov J.|date=/26/2021|title=Synthesis and Study of Complex Compounds with Benzotriazole Products of 3d-Metals|url=http://article.sapub.org/Complex%20compounds%20of%20Cu%20(II),%20Zn%20(II),%20Ni%20(II)%20and%20Co%20(II)%20chloride,%20nitrate%20and%20acetate%20salts%20were%20synthesized%20on%20the%20basis%20of%201,2,3-benzotriazole%20derivatives.%20Composition%20of%20synthesized%20complex%20compounds,%20structure%20element%20analysis,%20EQ%20spectroscopy,%20RCA,%20chromato-mass%20spectrometry,%20energy-dispersion%20analysis,%20electron%20diffusion%20reduction%20spectrum,%20individuality%20of%20newly%20synthesized%20complex%20compounds%20on%20the%20basis%20of%20modern%20quantum%20chemical%20calculations%20and%203d%20metals%20of%20heterocyclic%20ligands%20the%20laws%20of%20coordination%20were%20determined.|journal=International Journal of Materials and Chemistry|language=en|volume=11|issue=1|pages=1–9|issn=2166-5354}}</ref> {{Lead missing|date=Oktober 2022}}
