Tetraphosphorus ligands for catalytic hydroformylation and related reactions

A catalyst comprising a ligand and a transition metal salt, wherein the metal of said metal salt is selected from the group consisting of:

• Fe, Zn, Mn, Co, Cu, Ag, Ni, Pt, Pd, Rh, Ru and Ir;
• and wherein the ligand has the following formula:
• wherein i, j, k, l, m and n are, independently, H, R, Ar, substituted Ar, OR, OAr, COOEt, halide, SO2R, SO3H, SO2NHR, POR2, POAr2 or NR2, where R is an alkyl, substituted alkyl, aryl or substituted aryl and Ar is an aryl;
• X1-X4 are, independently, O, or CH2;
• and Y1, Y′1, Y2, Y′2, Y3, Y′3, Y4, Y′4, are, independently, R, Ar, OR, OAr, pyrrole or substituted pyrrole, or where R, Ar, OR, OAr, pyrrole and substituted pyrrole are linked with a carbon to carbon bond, CH2, NH, NR or O.