Reactions of the Rhenacarborane [N(PPh3)2]2[Re(CO)3(5-7-CB10H11
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- 作者：John C. Jeffery ; Paul A. Jelliss ; Leigh H. Rees ; and F. Gordon A. Stone
- 刊名：Organometallics
- 出版年：1998
- 出版时间：May 25, 1998
- 年：1998
- 卷：17
- 期：11
- 页码：2258 - 2270
- 全文大小：182K
- 年卷期：v.17,no.11(May 25, 1998)
- ISSN：1520-6041
文摘
The rhenium salt[N(PPh3)2]2[Re(CO)3(
5-7-CB10H11)](1a) reacts with the group 9 transition-metal complexes[M(NCMe)3(5-C5Me5)][BF4]2(M = Rh, Ir) to form neutral binuclearmetal compounds[ReM(CO)3(5-C5Me5)(5-7-CB10H11)](M = Rh (3a), Ir (3b)). Complex3awas characterized by X-ray diffraction as having aRh(5-C5Me5) fragmentattached to theicosahedral closo-2,1-ReCB10 framework by aRe-Rh bond and two B-H
Rh linkages. Thelatter involve boron atoms in 
- and 
-sites with respect to thecage carbon atom of the43a10001">CBBB B face of the cage ligating the Re atom.At ambient temperatures, the complex ishighly dynamic in solution, although significant exopolyhedral mobilityof the Rh(5-C5Me5) fragment was suppressed by cooling solutions to -88
C, as determined by a variable-temperature NMR study. Treatment of 3a with phosphinesPR3 (PR3 = PMe3,PMe2Ph)yields the complexes[ReRh(CO)3(PR3)(5-C5Me5)(5-7-CB10H11)](PR3 = PMe3 (4b),PMe2Ph(5)). Product 4b exists only in the form ofone green isomer, which contains aB-HRhagostic bond, whereas 5 consists of a mixture of red andgreen isomers 5a and 5b,respectively. Red crystals of 5a were isolated, andX-ray diffraction revealed that the 5-C5Me5 ligand carried by the rhodium atomlies in an anti configuration with respect to thecage carbon atom of thenido-7-CB10H11 ligand, which is5-bound to the rhenium atom.The rhodium atom is also connected to the cage through aB-HRh system, involving aboron atom in a position to the cage carbon atom of 43a10002">theCBBB B face of the cage. Insolution,an equilibrium exists between the syn and anti isomers of 5aand those of the green complex5b. The latter contain a B-HRhbonded system. Although 3b could not be isolated,itcould be formed at temperatures below 0 C and reacted in situ withthe phosphines PMe3and PMe2Ph to yield the stable species[ReIr(CO)3(PR3)(5-C5Me5)(5-7-CB10H11)](PR3 = PMe3(6), PMe2Ph (7)). For both6 and 7 it was possible to separate the - and-isomeric formsby column chromatography to give 6a/7a and6b/7b, respectively. Complex 6awasdetermined by X-ray diffraction to be the anti isomer with aB-HIr bond. In solution,both 6a and 6b exist as mixtures of syn and antiisomers. The structure of 7b determinedby X-ray diffraction showed it to have a B-HIrlinkage and to be the syn isomer, theonly isomeric form in solution, while 7a had aB-HIr exopolyhedral bond and was amixture of both syn and anti isomeric species.
5-7-CB10H11)](1a) reacts with the group 9 transition-metal complexes[M(NCMe)3(5-C5Me5)][BF4]2(M = Rh, Ir) to form neutral binuclearmetal compounds[ReM(CO)3(5-C5Me5)(5-7-CB10H11)](M = Rh (3a), Ir (3b)). Complex3awas characterized by X-ray diffraction as having aRh(5-C5Me5) fragmentattached to theicosahedral closo-2,1-ReCB10 framework by aRe-Rh bond and two B-HRh linkages. Thelatter involve boron atoms in - and -sites with respect to thecage carbon atom of the5-C5Me5) fragment was suppressed by cooling solutions to -88C, as determined by a variable-temperature NMR study. Treatment of 3a with phosphinesPR3 (PR3 = PMe3,PMe2Ph)yields the complexes[ReRh(CO)3(PR3)(5-C5Me5)(5-7-CB10H11)](PR3 = PMe3 (4b),PMe2Ph(5)). Product 4b exists only in the form ofone green isomer, which contains aB-HRhagostic bond, whereas 5 consists of a mixture of red andgreen isomers 5a and 5b,respectively. Red crystals of 5a were isolated, andX-ray diffraction revealed that the 5-C5Me5 ligand carried by the rhodium atomlies in an anti configuration with respect to thecage carbon atom of thenido-7-CB10H11 ligand, which is5-bound to the rhenium atom.The rhodium atom is also connected to the cage through aB-HRh system, involving aboron atom in a position to the cage carbon atom of -HRhbonded system. Although 3b could not be isolated,itcould be formed at temperatures below 0 C and reacted in situ withthe phosphines PMe3and PMe2Ph to yield the stable species[ReIr(CO)3(PR3)(5-C5Me5)(5-7-CB10H11)](PR3 = PMe3(6), PMe2Ph (7)). For both6 and 7 it was possible to separate the - and-isomeric formsby column chromatography to give 6a/7a and6b/7b, respectively. Complex 6awasdetermined by X-ray diffraction to be the anti isomer with aB-HIr bond. In solution,both 6a and 6b exist as mixtures of syn and antiisomers. The structure of 7b determinedby X-ray diffraction showed it to have a B-HIrlinkage and to be the syn isomer, theonly isomeric form in solution, while 7a had aB-HIr exopolyhedral bond and was amixture of both syn and anti isomeric species.