Article

Formation of intramolecular rings in ferramonocarbollide complexes

Department of Chemistry & Biochemistry, Baylor University, Waco, Texas 76798-7348, USA.
Inorganic Chemistry (Impact Factor: 4.79). 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: Addition of Me3NO to CH2Cl2 solutions of [1-OH-2,2,2-(CO)3-closo-2,1,10-FeC2B7H8] (1a) affords [2,2-(CO)2-1,2-μ-{OCH2NMe2}-closo-2,1,10-FeC2B7H8] (2), which contains a five-membered FeNCOC unit. The same reaction in MeCN as solvent gives [2,2-(CO)2-1,2-μ-{OC(R)NH}-closo-2,1,10-FeC2B7H8] (3a, R = Me). Analogous derivatives [R = CH═C(H)Me (3c), p-C6H4NO2 (3d), p-C6H4Br (3f), p-C6H4C(H)O (3g), p-C6H4C≡CH (3h), p-C5H4N (3i), or NH2 (3j)] are obtained from treatment of CH2Cl2 solutions of 1a with other cyano-containing substrates and Me3NO. The μ-imidate species 3 undergo a variety of subsequent reactions. Thus, oxidative coupling of compound 3h in CH2Cl2, in the presence of CuCl−TMEDA (TMEDA = Me2NCH2CH2NMe2), affords dimeric [2,2-(CO)2-closo-2,1,10-FeC2B7H8-1,2-μ-{OC(NFeH)-p-C6H4-C≡C}]2 (4), which reacts with [Co2(CO)8] in CH2Cl2 to give the tetracluster species [2,2-(CO)2-closo-2,1,10-FeC2B7H8-1,2-μ-{OC(NFeH)-p-C6H4-{(μ-η2:η2-C≡C)Co2(CO)6}}]2 (5). Conversely, 3f forms a bis(cluster) species, [2,2′-dppb-{2-CO-1,2-μ-{OC(C6H4Br)NH}-closo-2,1,10-FeC2B7H8}2] (6), upon reaction with dppb (0.5 mol equiv) in refluxing THF (dppb = Ph2P(CH2)4PPh2; THF = tetrahydrofuran). Compound 3a in CH2Cl2 with PHPh2 and Me3NO yields [2-CO-2-PHPh2-1,2-μ-{OC(Me)NH}-closo-2,1,10-FeC2B7H8] (7), which, upon reaction with wet NEt3 in CH2Cl2, gives [NHEt3][2-CO-2-{P(O)Ph2}-1,2-μ-{OC(Me)NH}-closo-2,1,10-FeC2B7H8] (8). When a mixture of C6H6−CH2I2 was used in the latter reaction, the product was [2-CO-2-PIPh2-1,2-μ-{OC(Me)NH}-closo-2,1,10-FeC2B7H8] (9), which itself reacts with AgO2CMe, forming [2-CO-2-{P(O2CMe)Ph2}-1,2-μ-{OC(Me)NH}-closo-2,1,10-FeC2B7H8] (10). Compound 3a reacts with excess [NBun4]CN in CH2Cl2 to form the anionic complex [1-OH-2,2-(CO)2-2-CN-closo-2,1,10-FeC2B7H8]−, isolated as its [N(PPh3)2]+ salt (11), in which the intramolecular imidate portion of the precursor has been lost. The anion of 11 readily coordinates via the cyano group to the cationic {Ir(CO)(PPh3)2}+ fragment (formed from [IrCl(CO)(PPh3)2] and TlPF6), affording [2-{(μ-CN)Ir(CO)(PPh3)2}-1-OH-2,2-(CO)2-closo-2,1,10-FeC2B7H8] (12). Oxidative addition of MeI to the Ir(I) center in 12 gives the corresponding Ir(III) species [2-{(μ-CN)Ir(I)(Me)(CO)(PPh3)2}-1-OH-2,2-(CO)2-closo-2,1,10-FeC2B7H8] (13). The novel structural features of these compounds—including hydrogen-bonding interactions—were confirmed by single-crystal X-ray diffraction studies.
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    ABSTRACT: Reaction between [NBun4][closo-1-CB7H8] and [Mn2(CO)10] in THF (THF = tetrahydrofuran) at reflux temperatures, or at room temperature with ultraviolet irradiation, followed by addition of [N(PPh3)2]Cl, affords the manganese−dicarbollide salt [N(PPh3)2][1-OH-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8] (1). Addition of NOBF4 to 1 gives the neutral species [1-OH-2,2-(CO)2-2-NO-closo-2,1,10-MnC2B7H8] (2), which readily undergoes CO substitution with PEt3 in the presence of Me3NO to yield [1-OH-2-CO-2-NO-2-PEt3-closo-2,1,10-MnC2B7H8] (3). Protonation of 1 in the presence of dialkyl sulfides SR2 affords the neutral complexes [1-SR2-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8] [R = Me (4); SR2 = S(CH2)4 (5); R = {CH2CHCH2} (6)]; the synthesis of 5 is accompanied by formation of a boron-substituted relative, [1-OH-6-{S(CH2)4}-2,2,2-(CO)3-closo-2,1,10-MnC2B7H7] (7). Addition of Me3NO to 6 in CH2Cl2 produces the anions [1-(SCH2CHCH2)-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8]− and [1,2-σ:η2-(SCH2CHCH2)-2,2-(CO)2-closo-2,1,10-MnC2B7H8]−, isolated as the [N(PPh3)2]+ salts 10 and 11, respectively. Iodinated derivatives of 1 are obtained by direct reaction with I2: an equimolar reaction yields two species, [N(PPh3)2][1-I-2,2,2-(CO)3-closo-2,1,10-MnC2B7H8] (12) and [N(PPh3)2][1-OH-6-I-2,2,2-(CO)3-closo-2,1,10-MnC2B7H7] (13), whereas treatment with excess I2 affords [N(PPh3)2][1,6,9-I3-2,2,2-(CO)3-closo-2,1,10-MnC2B7H6] (14) as the only product. When 12 was heated with Cu powder in refluxing DMF (DMF = N,N-dimethylformamide) the “parent” unsubstituted compound [N(PPh3)2][2,2,2-(CO)3-closo-2,1,10-MnC2B7H9] (15) was the sole product. Further cluster functionalization was achieved by treating 14 with the Grignard reagent (p-tol)MgBr (p-tol = 4-Me-C6H4-), leading to [N(PPh3)2][6,9-(p-tol)2-2,2,2-(CO)3-closo-2,1,10-MnC2B7H7] (16). The latter reacts with NOBF4 in CH2Cl2 to form neutral [6,9-(p-tol)2-2,2-(CO)2-2-NO-closo-2,1,10-MnC2B7H7] (17). X-ray diffraction studies have confirmed the structural details of compounds 1, 2, 7, 8, 11−13, 15, and 17.
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