N,N-Dimethylethanolamine reacts with (CO)5Mo(PPh2Cl) to give (CO)5Mo(PPh2OCH2CH2NMe2) which has been characterized as a BF3 adduct and by heating to form the mixed donor (P,N) chelate complex (CO)4Mo(PPh2OCH2CH2NMe2). The chromium and tungsten analogs of the Mo chelate complex have been made by photochemical reaction between the hexa carbonyls and the uncomplexed (P,N) ligand. A combination of chloride displacemetn and photochemical chelation were used to obtain cis-(CO)4Mo(PPh2NHCH2CH2NMe2). With cis-(CO)4Mo(PPh2Cl)2, HOCH2CH2NME2 gives cis-(CO)4Mo(PPh2OCH2CH2NMe2)(PPh2OH) and not the expected disubstituted product. Ethylenediamine, N-methylethylenediamine and N,N-dimethylethylenediamine react with cis-(CO)4Mo(PPh2Cl)2 in a straight forward manner to yield cis-(CO)4Mo(PPh2NHCH2CH2NR2)2 where R2 = H2, HMe, and Me2, respectively. N,N′-Dimethylethylenediamine yields only the chelate complex (CO)4Mo(PPh2NMeCH2CH2NMePPh2). The 1H NMR spectra of these complexes reveal some interesting examples of PH and HH virtual coupling. © 1980.