With the lone exception of the bis(trifluoromethyl) derivative, the dominant reaction of phosphinous acids is tautomerization:
:PROH  →  OPRH
Even the pentafluorophenyl compound P(CF)OH is unstable with respect to the phosphine oxide.
Although phosphinous acids are rare, their P-bonded coordination complexes are well established, e.g.  Mo(CO)P(OH).