(where azi = 7-azaindolate, L = polar phosphine) were isolated from the reaction of [Rh(µ-Cl)(CO) 2 ] 2 with 7-azaindolate followed by some polar mono-and bis-phosphines (L 1 -L 8 ). A relationship between δ 31 P-NMR and ν(CO) values was considered to define the impact of polar-groups on σ -donor properties of the phosphines. These compounds were evaluated as catalyst precursors in the hydroformylation of 1-hexene and 1-dodecene both in mono-and biphasic aqueous organic systems. While the biphasic hydroformylations (water + toluene) gave exclusively the aldehydes, the monophasic one (aqueous ethanol) showed propensity to form both aldehydes and alcohols. The influence of bimetallic cooperative effects, and σ -donor and hydrophilic properties of the phosphines with pendant polar-groups in enhancing the yields and selectivity of hydroformylation products was emphasized. In addition, when strong σ -donor phosphine was used, the π -acceptor nature of pyridine ring of 7-azaindolate spacer was found to be a considerable factor in facilitating the facile cleavage of CO group during hydroformylation and in supplementing the cooperative effects. Copyright