The reaction of [Cp*MCl4] (M = Nb, Ta; Cp* = C5Me5) with PH2R in toluene at room temperature gives the primary phosphine complexes [Cp*MCl4(PH2R)] [Cp* = C5Me5; M = Nb: R = But (1a), Ad (2a), Cy (3a), Ph (4a), 2, 4, 6-Me3C6H2 (Mes) (5a); M = Ta: R = But (1b), Ad (2b), Cy (3b), Ph (4b), Mes (5b)] in high yield. 1—5 were characterized spectroscopically (NMR, IR, MS) and by crystal structure determinations. The starting material [Cp*TaCl4] is monomeric in the solid state, as shown by crystal structure determination. Metallorganische Niob- und Tantal-Komplexe mit primaren Phosphanliganden: Synthese und Molekulstrukturen von [Cp*MCl4(PH2R)] (M = Nb, Ta; Cp* = C5Me5;R = But, Ad, Cy, Ph, 2, 4, 6-Me3C6H2 (Mes)) Die Komplexe [Cp*MCl4] (M = Nb, Ta; Cp* = C5Me5) reagieren bei Raumtemperatur in Toluol mit den primaren Phosphanen PH2R unter glatter Bildung der Verbindungen [Cp*MCl4(PH2R)] [Cp* = C5Me5; M = Nb: R = But (1a), Ad (2a), Cy (3a), Ph (4a), 2, 4, 6-Me3C6H2 (Mes) (5a); M = Ta: R = But (1b), Ad (2b), Cy (3b), Ph (4b), Mes (5b)]. 1—5 wurden spektroskopisch (NMR, IR, MS) und rontgenstrukturanalytisch charakterisiert. Die Ausgangsverbindung [Cp*TaCl4] ist im Festkorper monomer.