The stable phosphinato complexes [μ-R2PO2Re(CO)3L]n (1, 2b-f) [L = THF (a), py (b), NH3 (c), P(C6H5)3 (d), As(C6H5)3 (e), P(C6H11)3 (f), O(C2H5)2 (g)] are obtained by addition of the ligands L to the compounds [μ-R2PO2Re(CO)3]n (1, 2) [R = CH3 (1), C6H5 (2)] at 20-40 °C (1, 2c: -35 °C). 1, 2b, d, e are also formed when THF in 1, 2a is substituted by the ligands b, d, and e. The unstable ether adducts 1, 2 g which result photochemically from Re2(CO)10 and the acids R2PO2H, are transformed to 1, 2 by elimination of ether. At 20 °C 1, 2 a react with liquid ammonia to give the ionic complexes [(OC)3Re(NH3)3][O2PR2] (1, 2h). On the basis of their mass and vibrational spectra, and a crystallographic investigation, the methyl [1a-f] and phenyl compounds [2a-f] are dimeric and oligomeric, respectively. The rhenium atoms are bridged via R2PO2- ligands (phosphinato-O,O′). 1a crystallizes monoclinic in the space group C2/m with Z = 2.