In 1933 H. Hartmann started the study of chemistry in Munich, where he got strongly influenced and supported by Arnold Sommerfeld.  1939 he continued his studies in Frankfurt where he received his PhD 1941. In 1943 he habilitated on the applications of the Hückel theory. 1946 he became Docent in Frankfurt. Together with F. Ilse, his first student, he developed Ligand field theory a mayor advance in the understanding of complex compounds.  In 1951 he became leader of a division in the Max-Planck-Institute for Physical Chemistry in Göttingen but returned to Frankfurt a year later.