Synthesis of cationic ruthenium diphosphine complexes with nido-dicarbaundecaborate anions. Molecular structure of [RuCl(dppe)2]+[7,8-nido-C2B9H12]−

Abstract

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

Ruthenium carborane complexes in the controlled radical polymerization of methyl methacrylate

“…The second reaction product was eluted from the column by more polar CH 2 Cl 2 , which was removed in vacuo to give 0.05 g (11%) of complex 6. The data of 1 H, 31 P{ 1 H}, and 11 B NMR spectra of complex 6 fully coincided with the published data, 24 . The structure was solved by the direct method and refined by the full matrix least squares method on F 2 hkl with anisotropic ther mal parameters for all nonhydrogen atoms.…”

Chiral paramagnetic closo-ruthenacarboranes via phosphine–diphosphine displacement reaction of “three-bridge” exo-nido-ruthenacarboranes: Molecular Structure of (−)-[closo-3-Cl-3,3-{(Ph2PCHCH3)2CH2}-3,1,2-RuC2B9H11] and its ortho-cycloboronated derivative

“…These compounds were found to display high catalytic activity in the cyclopropanation reactions of alkenes and dienes [3], and they can be used as the versatile building-block reagents in the construction of mono-and/or low-nuclearity metallacarboranes of different types and structures [4]. Recently, we have found that the PPh 3 groups in 6, P) 2 Ru}-5,6,10-l-(H) 3 -10-H-7,8-R 2 -7,8-C 2 B 9 H 6 ] (1, R = H; 2, R = Me) can easily be replaced by chelating diphosphines such as dppe or dppp in the course of the room-temperature displacement reaction in benzene affording stable cationic salts [RuCl{Ph 2 P(CH 2 ) n PPh 2 } 2 ] + [nido-7,8-R 2 -7,8-C 2 B 9 H 10 ] À (R = H, Me; n = 2 or 3) [5]. In the work that we now report, we have examined thermal replacement of PPh 3 ligands in the exo-nido ruthenium complex 1 with the (2S,4S)-(À)-2,4-bis-(diphenylphosphino)pentane (3,BDPP) and, as a result, three novel optically active 18-and 17-electron closo diphosphine-ruthenacarborane complexes have been obtained.…”

“…Reaction of the ruthenium complex 1 with a 10% molar excess of diphosphine 3 in refluxing toluene for 1 h afforded a mixture of three ruthenacarborane products (4), (5) and (6) in ca. 54% (total content).…”

“…2 and 3). It is of interest to note that the Ru-Cl bond lengths in 5 (2.3637 Å ) and 6 (an average 2.3843(14) Å ) are marginally shorter compared to the average Ru-Cl distances (2.443-2.456 Å ) found in the known Cp-and Cp*-containing Ru(II) complexes with chelated diphosphine ligands [12][13][14], being rather close to those found in the cationic five-coordinate Ru(II) complexes of the type [RuCl{R 2 P(CH 2 ) n PR 2 } 2 ][An] (for instance, n = 2, R = Ph, An = PF 6 , 2.394(3) Å [15]; n = 2, R = Cy, An = PF 6 , 2.386(3) Å [16]; n = 2, R = Ph, An = nido-C 2 B 9 H 12 , 2.391(1) [5]). …”

Isolation and characterization of the chelate exo-nido-ruthenacarborane intermediates formed in the thermal exo-nido-to-closo conversion of [exo-nido-5,6,10-{Cl(Ph3P)2Ru}-5,6,10-(μ-H)3-10-H-7,8-R2-7,8-C2B9H6] (R=H or Me) upon the triphenylphosphine ligand displacement with the chiral (2S,4S)-(−)-2,4-bis(diphenylphosphino)pentane

“…Such an extension could, in principle, be accomplished by varying of either the phosphine ligands attached to the metal atom or the carborane cage substituents. For this reason, we have recently examined the room-temperature phosphine-diphosphine displacement reactions of 6, 2 6, 3 R = Me) using chelating diphosphines Ph 2 P(CH 2 ) 2 PPh 2 and Ph 2 P(CH 2 ) 3 PPh 2 [5] as well as thermal reaction of 1 with the chiral diphosphine (2S,4S)-(À)-2,4-bis(diphenylphosphino)pentane (3, S, S-bdpp) [6]. From the latter reaction, in refluxing toluene, a series of 18-and 17-electron closo-(S, S-bdpp)ruthenacarborane species were isolated, of which two were formulated as [closo-3,3-(S, S-bdpp)-3-Cl-3-H-3,1,2-RuC 2 B 9 H 11 ] (4) and [closo-3,3-(S, S-bdpp)-3-Cl-3,1,2-RuC 2 B 9 H 11 ] (5), and the third was ortho-cycloboronated derivative of 5, [closo-3-Cl-3,3-{(S, S)-Ph 2 PCH(CH 3 )CH 2 CH(CH 3 )PPh-ortho-C 6 H 4 }-3,1,2-RuC 2 B 9 H 10 ] (6).…”