  Single crystals of Sc5Rh6Sn18 were grown from Sn-flux. The crystal structure
(SG: I41/acd, a = 13.5529(2) {\AA}, c = 27.0976(7) {\AA}) was studied by
high-resolution X-ray diffraction on powder and single crystal material as well
as by TEM. All methods confirm it to crystallize with Sc5Ir6Sn18 (space group
I41/acd) type of structure. The performed structural studies suggest also the
presence of local domains with broken average translational symmetry. Analysis
of the chemical bonding situation reveal highly polar Sc2-Sn1, Sn-Rh and Sc2-Rh
bonds, two- and three-center bonds involving Sn-atoms as well as ionic nature
of Sc1 bonding. The thermopower of Sc5Rh6Sn18 is isotropic, small and negative
(i.e. dominance of electron-like charge carriers). Due to structural disorder,
the thermal conductivity is lowered in comparison with regular metallic
systems.
