In metallacarborane chemistry, 16 and/or 18 elec tron cationic complexes of the general formula [M(L,L´) n ] + [7 R´ 8 R″ 7,8 nido C 2 B 9 H 10 ] -(M = Rh; R´ and R″ = H, Alk, Ar, PhS, PPh 2 ; L and L´ = P(Alk) 3 , PPh 3 , P(Alk)Ph 2 , etc., n = 3 or 4; M = Ir, R´, R″ = H; L = η 4 COD, L´ = (PAr 3 ) 2 , n = 0) have been represented earlier only by rhodium 1,2 and iridium 3 compounds. The only salt of this type with the complex nido carborane anion, [Rh(PPh 3 ) 3 ] + [7 {(1´ (closo 1´,2´ C 2 B 10 H 11 )} 7,8 nido C 2 B 9 H 11 ] -, was structurally characterized 4 by X ray diffraction. The aim of the present study was to synthesize new cationic ruthenium(II) diphosphine complexes with the nido dicarbaundecaborate anions.When studying the replacement of PPh 3 ligands in triply bridged exo nido ruthenacarboranes, exo nido 5,6,10 [RuCl(PPh 3 ) 2 ] 5,6,10 µ (H) 3 10 H 7,8 R 2 7,8 C 2 B 9 H 6 (1: R = H (a); R = Me (b)), 5 with the chelating diphosphine ligands Ph 2 P(CH 2 ) n PPh 2 (n = 2 (2a, dppe); 3 (2b, dppp)), we found that the reaction in benzene at 22 °C afforded predominantly the cationic complexes [RuCl(Ph 2 P(CH 2 ) n PPh 2 ) 2 ] + [7,8 R 2 7,8 nido C 2 B 9 H 10 ] -(3a: R = H, n = 2; 3b: R = H, n = 3; 3c: R = Me, n = 3), in which the nido dicarbaundecaborate anions serve as counterions.
Scheme 1Interestingly, in the course of the reactions of com plexes 1a,b with 2b in a ratio of 1 : 1 not only 3b,c but also intermediate diphosphine substituted exo nido complexes as mixtures of symmetrical (S) and asymmetrical (AS) isomers, viz., exo nido 5,6,10 [Cl(dppp)Ru] 5,6,10 µ
