  SrRh2As2 exhibits structural phase transitions reminiscent to those of
BaFe2As2, but crystallizes with three polymorphs derived from the tetragonal
ThCr2Si2-type structure. The structure of \alpha-SrRh2As2 is monoclinic with a
= 421.2(1) pm, b = 1105.6(2) pm, c = 843.0(1) pm and \beta = 95{\deg} and was
refined as a partially pseudo meroedric twin in the space group P21/c with R1 =
0.0928. \beta-SrRh2As2 crystallizes with a modulated structure in the (3+1)
dimensional superspace group Fmmm(10\gamma)\sigma 00 with the unit cell
parameters a = 1114.4(3) pm, b = 574.4(2) pm and c = 611.5(2) pm and an
incommensurable modulation vector q = (1, 0, 0.3311(4)). High temperature
single crystal diffraction experiments confirm the tetragonal ThCr2Si2-type
structure for \gamma-SrRh2As2 above 350{\deg}C. Electronic band structure
calculations indicate that the structural distortion in alpha-SrRh2As2 is
caused by strong Rh-Rh bonding interactions and has no magnetic origin as
suggested for isotypic BaFe2As2.
