The charge-compensated monocarbon carboranes nido-7-NR3-7-CB10H12 react with [Ru3(CO)12] in toluene at reflux temperatures to give the triruthenium complexes [Ru3(CO)8(η5-7-NR3-7-CB10H10)] [NR3 = NMe3 (1a), NH2But (1b), and NMe2But (1c)]. The molecular structure of 1a has been established by X-ray crystallography. The metal atoms form an essentially isosceles triangle. One Ru atom carries two terminal CO groups and the nido-7-NMe3-7-CB10H10 cage, coordinated in a pentahapto manner. The two boron atoms in the β-sites with respect to the carbon in the CBBBB ring form exopolyhedral three-center, two-electron B−H⇀Ru bonds to the other two Ru atoms. These metal atoms also carry three essentially terminally attached CO ligands. Treatment of 1a with PPh3 in toluene gave, after column chromatography of the mixture, [Ru3(μ-H)(μ3-σ: η5-7-NMe3-7-CB10H9)(CO)7(PPh3)] (2), whereas reaction with CNBut affords [Ru3(CO)7(CNBut)(η5-7-NMe3-7-CB10H10)] (3). The structure of 2 has been established by X-ray crystallography. The molecule has a triangular array of ruthenium atoms. As in 1a, one metal center Ru(1) carries two CO groups and forms a closo-icosahedral RuCB10 framework by coordination in a pentahapto manner to the open face of a nido-CB10 fragment. A second Ru atom is ligated by two CO molecules and the PPh3 group, the latter being transoid to Ru(1), while the third Ru atom is terminally attached to three CO molecules. The Ru(2)−Ru(3) connectivity is bridged by a hydrido ligand, and in addition both of these metal atoms are linked to the CB10 framework through boron atoms in the β-sites of the CBBBB ring coordinated to Ru(1). Atom Ru(2) forms a three-center, two-electron B−H⇀Ru bond, while atom Ru(3) forms an Ru−B σ-bond, with the result that the nido-7-NMe3-7-CB10H9 group bridges the Ru3 triangle via η5-CBBBB, B−H⇀Ru, and B−Ru interactions. The NMR data for the new compounds are reported and discussed in relation to their structures.
Treatment of [Ru(CO) 3 (η 5 -7,8-C 2 B 9 H 11 )] (1) with Me 3 NO in THF (tetrahydrofuran) affords [Ru(CO) 2 (NMe 3 )(η 5 -7,8-C 2 B 9 H 11 )] (3b), while the salt [NEt 4 ][RuI(CO) 2 (η 5 -7,8-C 2 B 9 H 11 )] (2) reacts with NCMe in the presence of AgBF 4 to give [Ru(CO) 2 (NCMe)(η 5 -7,8-C 2 B 9 H 11 )] (3c). Related complexes [Ru(CO) 2 (L)(η 5 -7,8-C 2 B 9 H 11 )] (L ) CNBu t (3d), PPh 3 (3e)) are obtained by displacement of THF from [Ru(CO) 2 (THF)(η 5 -7,8-C 2 B 9 H 11 )] (3a) with CNBu t and PPh 3 , respectively. Alkenes and 3a afford the complexes [Ru(CO) 2 (alkene)(η 5 -7,8-C 2 B 9 H 11 )] (alkene ) C 2 H 4 (4a), MeCHdCH 2 (4b), Me 3 SiCHdCH 2 (4c), and C 7 H 10 (norbornene) (4d)), whereas alkynes RCtCR (R ) Me, Ph) give the species [Ru(CO) 2 (RCtCR)(η 5 -7,8-C 2 B 9 H 11 )] (R ) Me (5a), Ph (5b)). The reaction of complex 5a with K[BH(CHMeEt) 3 ], in Et 2 O solution, followed by addition of 18-crown-6, gives the salt [K(18-crown-6)][Ru{C(Me)dC(H)Me}(CO) 2 (η 5 -7,8-C 2 B 9 H 11 )] ( 6), while PPh 3 in CH 2 Cl 2 affords the ylide complex [Ru{C(Me)dC(Me)PPh 3 }(CO) 2 -(η 5 -7,8-C 2 B 9 H 11 )] ( 7). Reactions between 3a and the alkynes RCtCH (R ) Bu t , SiMe 3 ) yield a variety of products, in all of which the carborane ligand adopts a nonspectator role. Complex 3a and 1 mol equiv of Bu t CtCH gives a mixture of isomers [Ru(CO) 2 (η 2 :η 5 -9-C(H)dC(H)Bu t -7,8-C 2 B 9 H 10 )] (8a) and [Ru(CO) 2 (η 2 :η 5 -10-C(H)dC(H)Bu t -7,8-C 2 B 9 H 10 )] ( 8b). An X-ray diffraction study on 8a revealed that the ruthenium atom is η 5 -coordinated by the open CCBBB face of the nido-C 2 B 9 cage and by the CdC bond of the BCHdC(H)Bu t group. The reaction between 3a and 1 mol equiv of Me 3 SiCtCH is more complex due to SiMe 3 group cleavage. Isomeric mixtures of [Ru(CO) 2 (η 2 :η 5 -9-C(H)dC(H)R-7,8-C 2 B 9 H 10 )] (R ) H (9a), SiMe 3 (10a)) and [Ru(CO) 2 (η 2 :η 5 -10-C(H)dC(H)R-7,8-C 2 B 9 H 10 )] (R ) H (9b), SiMe 3 (10b)) are obtained. Addition of PMe 2 Ph in heptane to 9b gives [Ru(CO) 2 (σ,η 5 -10-C(H)(PMe 2 Ph)-CH 2 -7,8-C 2 B 9 H 10 )] (11b), the ylide structure of which was confirmed by X-ray crystallography.The Ru(CO) 2 fragment is linked to the nido-C 2 B 9 cage system by η 5 bonding to the CCBBB face and by a Ru-CH 2 σ-bond to the CH 2 C(H)(PMe 2 Ph)B fragment. Reactions between 3a and RCtCH, employing an excess of the latter, give the compounds [Ru(CO) 2 {η 2 :ηwhich all boron atoms in the open CCBBB face of the cage bonded to the ruthenium carry C(H)dC-(H)R substituents. Treatment of the complexes 12 with PMe 3 yields respectively [Ru(CO) 2 -(PMe 3 ){η 5 -9,10,11-[C(H)dC(H)Bu t ] 3 -7,8-C 2 B 9 H 8 }] (13) and [Ru(CO) 2 {σ,η 5 -9-C(H)(PMe 3 )C-(H)SiMe 3 -10,11-[C(H)dC(H)SiMe 3 ] 2 -7,8-C 2 B 9 H 8 }] (14). The structure of 13 was established by X-ray diffraction. The Ru atom is coordinated by a PMe 3 molecule and the two CO groups and by the nido-9,10,11-[C(H)dC(H)Bu t ] 3 -7,8-C 2 B 9 H 8 cage. All boron atoms in the pentagonal CCBBB ring ligating the metal carry C(H)dC(H)Bu t substituents. In addition to X-...
The complex [Ru(THF)(CO)2(η5-7,8-C2B9H11)] (1a, THF = tetrahydrofuran) reacts with the alkylidyne reagents [M(⋮CC6H4Me-4)(CO)2(η5-C5H5)] (M = Mo or W) to give the compounds [MRu(μ-CC6H4Me-4)(CO)4(η5-7,8-C2B9H11)(η5-C5H5)] (M = W (2a), Mo (2b)), which readily isomerize to the species [MRu(CO)4{σ,η5-9-CH(C6H4Me-4)-7,8-C2B9H10}(η5-C5H5)] (M = W (3a), Mo (3b)). The structure of 3b was established by X-ray diffraction. The Mo(CO)2(η5-C5H5) fragment is attached to the closo-RuC2B9 framework by a Mo−Ru bond and a three-center two-electron B−H⇀Mo linkage involving a boron atom in an α site in the CCBBB ring ligating the ruthenium. The CH(C6H4Me-4) moiety bridges between the Ru(CO)2 group and the B atom located in the other α site in the CCBBB ring. The oxo complex [WRuO{μ-σ,η5-9-CH(C6H4Me-4)-7,8-C2B9H10}(CO)2(η5-C5H5)] (4a) is a side product in the formation of 3a, and it also was characterized by X-ray diffraction. Treatment of the species 3 with PMe3 affords the zwitterionic compounds [MRu(CO)4{η5-9-CH(PMe3)(C6H4Me-4)-7,8-C2B9H10}(η5-C5H5)] (M = W (5a), Mo (5b)). A single-crystal X-ray diffraction study of 5a revealed that the (OC)2W−Ru(CO)2 unit is bridged by the nido-9-CH(PMe3)(C6H4Me-4)-7,8-C2B9H10 group. The open C2B3 face is pentacoordinated to the Ru atom, and there is an exopolyhedral B−H⇀W bond involving a Bα atom in the CCBBB ring. The other Bα site carries the CH(PMe3)(C6H4Me-4) substituent. Reactions between the ruthenium reagent [Ru(THF)(CO)2(η5-7,8-Me2-7,8-C2B9H9)] (1b) and [W(⋮CC6H4Me-4)(CO)2(η5-C5H5)] gave [WRuO{μ-σ,η5-7,8-Me2-10-CH(C6H4Me-4)-7,8-C2B9H8}(CO)2(η5-C5H5)] (4b), [WRu(μ-H){μ-η5,η‘5-7,8-Me2-9-C5H4-10-CH2(C6H4Me-4)-7,8-C2B9H7}(CO)5] (6a), and [WRu{μ-σ,η5-2,7-Me2-8-CH2(C6H4Me-4)-9-C(H)O-2,7-C2B9H6}(CO)4(η5-C5H5)] (7a) that were separated by column chromatography. The corresponding reaction between 1b and [W(⋮CC6H4Me-2)(CO)2(η5-C5H5)] afforded [WRuO{μ-σ,η5-7,8-Me2-n-CH(C6H4Me-2)-7,8-C2B9H8}(CO)2(η5-C5H5)] (n = 9 (4c), 10 (4d)) and [WRu{μ-σ,η5-2,7-Me2-8-CH2(C6H4Me-2)-9-C(H)O-2,7-C2B9H6}(CO)4(η5-C5H5)] (7b). Treatment of 1b with [Mo(⋮CC6H4Me-n)(CO)2(η5-C5H5)] (n = 4 or 2) yielded [MoRu(μ-H){μ-η5,η‘5-7,8-Me2-9-C5H4-10-CH2(C6H4Me-n)-7,8-C2B9H7}(CO)5] (n = 4 (6b), 2 (6c)). The structures of 4b, 6b, and 7b were established by X-ray diffraction. In 6b, the (OC)3Mo(μ-H)Ru(CO)2 unit is bridged by a 7,8-Me2-9-C5H4-10-CH2(C6H4Me-4)-7,8-C2B9H7 moiety, a structure resulting from a linking of C5H5 and nido-C2B9 groups. The C5 ring is η5-coordinated to the molybdenum, while the open CCBBB face of the carborane cage is similarly attached to the ruthenium. In complex 7b, a nido-2,7-Me2-8-CH2(C6H4Me-2)-9-C(H)O-2,7-C2B9H6 cage system bridges the Ru−W bond with an η5-CB4 ring coordinated to the Ru atom and with the cage joined to the W atom by a B−W bond. In addition, the C(H)O group forms a second bridge linking the cage to the tungsten, with the latter coordinated by the formyl O atom.
The compounds [Ru 3 (CO) 12 ] and nido-7,8-Me 2 -7,8-C 2 B 9 H 11 react in CH 2 Cl 2 to yield a mixture of [Ru(CO) 3 (η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] (1b) and [Ru 3 (CO) 8 (η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] (2) in a ratio of ca. 1:2. The tri-and dinuclear ruthenium complexes) PPh 3 (4), PMe 2 Ph (5)), [Ru 2 (CO) 4 (PMe 3 ) 2 (η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] ( 7), and [Ru 3 (µ-dppm)-(CO) 6 (η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] (8) have been prepared by treating 2 with tertiary phosphines. A single-crystal X-ray diffraction study on 5 revealed the structure as one in which a triangular array of ruthenium atoms is bridged by a nido-7,8-Me 2 -7,8-C 2 B 9 H 8 group. The latter is pentahapto coordinated to one Ru atom, which carries two CO ligands, and is linked to the other metal atoms by a Ru-B and a B-HFRu bond, respectively. These two ruthenium atoms are each coordinated by two CO groups and one PMe 2 Ph group. Treatment of 2 with Me 2 NCH 2 NMe 2 in CH 2 Cl 2 affords a mixture of the complexes [Ru 2 (µ-η 5 -7,8-Me 2 -10-CH 2 NMe 2 -7,8-C 2 B 9 H 8 )(CO) 5 ] ( 9) and [Ru 2 (CO) 5 (NHMe 2 )(η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] (10). The structures of both diruthenium compounds were established by X-ray diffraction. In 9 the Ru-Ru bond is bridged by the 7,8-Me 2 -10-CH 2 NMe 2 -7,8-C 2 B 9 H 8 cage system. The open pentagonal CCBBB face is coordinated to one Ru atom, which also carries two CO molecules, while the exopolyhedral CH 2 NMe 2 group is coordinated to the other Ru atom which is also ligated by three CO molecules. In 10 a Ru(CO) 2 (η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 ) moiety with a closo-3,1,2-RuC 2 B 9 framework is linked by exopolyhedral Ru-Ru and B-HFRu bonds to a Ru-(CO) 3 (NHMe 2 ) group. The reaction between 2 and pyridine affords a mixture of [Ru 2 (CO) 5 -(NC 5 H 5 )(η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] ( 11) and [Ru 2 (CO) 4 (NC 5 H 5 ) 2 (η 5 -7,8-Me 2 -7,8-C 2 B 9 H 9 )] ( 12). An X-ray diffraction study on 11 revealed a molecular structure similar to that of 10. The new compounds have been characterized by NMR spectroscopy in addition to the X-ray diffraction studies. * To whom correspondence should be addressed. † In the compounds described in this paper ruthenium atoms and nido-C2B9 cages form closo-1,2-dicarba-3-ruthenadodecaborane structures. However, use of this numbering scheme leads to a complicated nomenclature for the polynuclear metal complexes reported. Following precedent (Mullica, D.
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