Two new dialkoxy‐substituted nido‐platinaundecaboranes: [(PPh 3 ) 2 PtB 10 H 10 ‐8,10–2(OCH 2 CH 3 )] ± CH 2 Cl 2 (I), { (PPh 3 ) 2 ‐PtB 10 H 10 ‐8,10–2[OCH(CH 3 ) 2 ]} (II)

Two title nido‐11‐vertex platinaundecaboranes, 7,7‐bis‐(triphenylphosphine‐P)‐8, 10‐diethoxy‐8, 9:10, 11‐bis‐μ‐ H ‐7‐platina‐nido‐undecaborane‐dichloromethane (I) and 7,7‐bis‐(triphenylphosphine‐P) ‐8, 10‐di( i ‐propoxy) ‐8,9:10,11‐bis‐μ‐ H ‐7‐platina‐nido‐undecaborane (II), were prepared and their structures were determined by single crystal X‐ray diffraction method. Each of them has an 11‐vertex nido‐polyhedral skeleton. {PtB 10 } cage is substituted by two ethoxy or i ‐propoxy groups at 8 and 10 positions, respectively.