Abstract: The present invention relates to the preparation of novel catalysts made from transition metal compounds and “tridentate” 4,5-diphosphinoacridine ligands (“acriphos”). The novel ligands employed herein are diphosphine compounds of 4,5-disubstituted acridine which coordinate transition metals in a three-fold way with the two phosphorus atoms and the acridine nitrogen. The invention also relates to the use of the novel catalysts for the catalysis of carbon monoxide conversion via the water-gas shift reaction (WGSR: CO+H2O→CO2+H2) and for the catalysis of the following reactions: hydroformylation, carbonylation, carboxylation, hydrogenation, hydrocyanogenation, hydrosilylation, polymerization, isomerization, cross-couplings and metathesis.