Article

Formation of Intramolecular Rings in Ferramonocarbollide Complexes

Department of Chemistry & Biochemistry, Baylor University, Waco, Texas 76798-7348, USA.
Inorganic Chemistry (Impact Factor: 4.76). 10/2008; 47(19):8788-97. DOI: 10.1021/ic800780w
Source: PubMed

ABSTRACT

Addition of PPh 2Cl and Tl[PF 6] to CH 2Cl 2 solutions of [N(PPh 3) 2][6,6,6-(CO) 3- closo-6,1-FeCB 8H 9] ( 1) affords the isomeric B-substituted species [6,6,6-(CO) 3- n-(PHPh 2)- closo-6,1-FeCB 8H 8] [ n = 7 ( 2a) or 10 ( 2b)]. Deprotonation (NaH) of the phosphine ligand in 2a, with subsequent addition of [IrCl(CO)(PPh 3) 2] and Tl[PF 6], yields the neutral, zwitterionic complex [6,6,6-(CO) 3-4,7-mu-{Ir(H)(CO)(PPh 3) 2PPh 2}- closo-6,1-FeCB 8H 7] ( 3), which contains a B-P-Ir- B ring. Alternatively, deprotonation using NEt 3, followed by addition of HC[triple bond]CCH 2Br, affords [6,6,6-(CO) 3-7-(PPh 2CCMe)- closo-6,1-FeCB 8H 8] ( 4). Addition of [Co 2(CO) 8] to CH 2Cl 2 solutions of the latter gives [6,6,6-(CO) 3-7-(PPh 2-{(mu-eta (2):eta (2)-CCMe)Co 2(CO) 6})- closo-6,1-FeCB 8H 8] ( 5), which contains a {C 2Co 2} tetrahedron. In the absence of added substrates, deprotonation of the PHPh 2 group in compounds 2, followed by reaction of the resulting anions with CH 2Cl 2 solvent, affords [6,6,6-(CO) 3- n-(PPh 2CH 2Cl)- closo-6,1-FeCB 8H 8] [ n = 7 ( 6a) or 10 ( 6b)] plus [6,6-(CO) 2-6,7-mu-{PPh 2CH 2PPh 2}- closo-6,1-FeCB 8H 8] ( 7, formed from 2a), of which the latter species possesses an intramolecular B-P-C-P- Fe ring. Addition of Me 3NO to CH 2Cl 2 solutions of 2a causes loss of an Fe-bound CO ligand and formation of [6,6-(CO) 2-6,7-mu-{NMe 2CH 2PPh 2}- closo-6,1-FeCB 8H 8] ( 8), which incorporates a B-P-C-N- Fe ring. A similar reaction in the presence of ligands L yields [6,6-(CO) 2-6-L-7-(PPh 2CH 2Cl)- closo-6,1-FeCB 8H 8] [L = PEt 3 ( 9) or CNBu (t) ( 10)], in addition to 8.

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    ABSTRACT: Photolysis of THF solutions of 10-vertex [N(PPh3)2][6,6,6-(CO)3-closo-6,1-FeCB8H9] (1) in the presence of PEt3 results in [N(PPh3)2][6-CO-6,6-(PEt3)2-closo-6,1-FeCB8H9] (2), which readily oxidizes in air to form the neutral and paramagnetic, 17-electron Fe(III) species [6-CO-6,6-(PEt3)2-closo-6,1-FeCB8H9] (3). Substitution of one PEt3 ligand by cyanide occurs on addition of [NBun4][CN] and Me3NO to 3 in CH2Cl2, giving [NBun4][6-CO-6-CN-6-PEt3-closo-6,1-FeCB8H9] (4). When [IrCl(CO)(PPh3)2] and Tl[PF6] (1:1) are added to CH2Cl2 solutions of 4, the neutral, paramagnetic complex [6-{(μ-CN)Ir(CO)(PPh3)2}-6-CO-6-PEt3-closo-6,1-FeCB8H9] (5) is obtained. Results of X-ray diffraction studies carried out on 3 and 5 are presented herein.
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