DEPROTONATION OF MN2(MU-H)(MU-PR2)(CO)8 (R = PH, CY) FOR SYNTHESIS OF HETERONUCLEAR MANGANESE-GOLD CLUSTERS WITH MN2AUN CORES (N = 1-3)

The dimanganese complexes Mn2(mu-H)(mu-PR2)(CO)8 (R = Ph, Cy) have been deprotonated with 1,8-diazabicyclo[5.4.0]undec-7-en (DBU) in tetrahydrofuran solution at 20-degrees-C to give the anions [Mn2(mu-PR2) (CO)8]-, which were isolated as tetraethyl-ammonium salts. Both dimanganese complexes and the related anions were measured by cyclic voltammetry. The treatment of the aforementioned dimanganese complexes in thf solution with LiR' (R = Me, Ph) and subsequently with PPh3AuCl gave at 20-degrees-C three types of products: Mn2(mu-PR2(CO)8(AuPPh3),Mn2(mu-PR2)(mu-C(R')O(CO)6- (AuPPh3)2 and Mn2(mu-PR2)(CO)6(AuPPh3)3. The newly prepared substances were characterized by means of IR-, UV/VIS, P-31 NMR data. The results of single X-ray analyses showed for the three-membered metal ring compound Mn2(mu-PPh2)(CO)8(AuPPh3) an uni-fold bridged sigma(Mn-Mn) bond length of 306.7(3) pm, the metallatetrahedron complex Mn2(mu-PPh2)(mu-C(Ph)O)(CO)6(AuPPh3)2 a two-fold bridged sigma(Mn-Mn) bond length of 300.6(4) pm and the trigonal-bipyramidal cluster Mn2(mu-PPh2)(CO)6(AuPPh3)3 an uni-fold bridged pi(Mn-Mn) bond length of 274.7(3) pm. The Mn-Au bonds of these substances are accompanied by semi-bridging CO ligands which are signified through short Au...C contact lengths in the range of 251 to 270 pm. In the substance with the Mn2Au2 metallatetrahedron core exists, additionally, such a contact with the acyclic C atom of C(Ph)O bridging group of 263.4(18) pm. Such contact lengths were compared for corresponding dimanganese and dirhenium complexes.