We report analytical solutions to the unitary bound problem for coherence/polarization transfer in IS two-spin-1/2 systems by means of unitary operations. Theoretical upper bounds for the transfer efficiency along with the associated optimum transformation operators are obtained analytically by decomposing the unitary operator as a product of exponentials in the special unitary Lie group SU(4). Addressing NMR spectroscopy as a specific example, the method is demonstrated for the non-Hermitian transfers I--->S- and 2I(-)S(z)-->S-being relevant for heteronuclear single-quantum coherence (HSQC) experiments as well as the double- to single-quantum transfer I-S--->(I-Sbeta)+(IS-)-S-beta being representative for coherence-order and spin-state-selective transfer in INADEQUATE CR experiments. Furthermore, using a Lagrangian function approach it is demonstrated how the method enables analytical description of two-dimensional bounds for I-z-->S-z cross polarization.