  Ba4NbIr3O12, a previously unreported material with a triangular planar
geometry of Ir3O12 trimers, is described. Magnetic susceptibility measurements
show no magnetic ordering down to 1.8 K despite the Curie-Weiss temperature of
-13 K. The material has a very low effective magnetic moment of 0.80
{\mu}B/f.u. To look at the lower temperature behavior, the specific heat (Cp)
was measured down to 0.35 K; it shows no indication of magnetic ordering and
fitting a power law to Cp vs. T below 2 K yields the power {\alpha} = 3/4.
Comparison to the previously unreported trimer compound made with the 4d
element Rh in place of the 5d element Ir, Ba4NbRh3O12, is presented. The
analysis suggests that Ba4NbIr3O12 is a candidate spin liquid material.
