Fourier-transform microwave spectroscopy of the H2-HCN complex

► The J = 1-0 rotational transition of H2-HCN has been observed with FTMW spectroscopy. ► The para-H2 is attached to the H end of HCN, while ortho-H2 to the N end of HCN. ► The nuclear spin-spin coupling constant has been determined for (ortho)H2-HCN.