TY - JOUR
T1 - Pyrazolyl-Bridged Iridium Dimers. 7.1 Synthesis and Properties of Bridge-Substituted Analogues of [Ir(COD)(μ-pz)]2 (pzH = Pyrazole), the “Mixed-Bridge” Complex [Ir2(COD)2(μ-pz)(μ-fpz)] (fpzH = 3, 5-Bis(trifluoromethyl)pyrazole), and the “Mixed-Metal” Dimer [IrRh(COD)2(μ-pz)2]. Crystal and Molecular Structures of Bis(cyclooctadiene)bis(μ-3-phenyl-5-methylpyrazolyl)-diiridium(I) (Dissymmetric Isomer) and Bis(cyclooctadiene)bis(μ-3, 4, 5-trimethylpyrazolyl)diiridium(I)
AU - Bushnell, Gordon W.
AU - Kimberley Fjeldsted, D. O.
AU - Stobart, Stephen R.
AU - Zaworotko, Michael J.
AU - Knox, Selby A.R.
AU - Macpherson, Kirsty A.
PY - 1985/6
Y1 - 1985/6
N2 - Fifteen diiridium(I) complexes [Ir(COD)(μ-L)]2 (2–16) (COD = cycloocta-1, 5-diene) related to the prototypal compound [Ir(COD)(μ-pz)]2 (1, pzH = pyrazole) have been synthesized by Cl displacement by LH from [Ir(COD)(μ-Cl)]2 (L = 4-methylpyrazolyl (2), 3-methylpyrazolyl (3), 3, 5-dimethylpyrazolyl (4), 3, 5-diphenylpyrazolyl (5), 3-phenyl-5-methylpyrazolyl (6), 3-(trifluoromethyl)-5-methylpyrazolyl (7), 3, 5-bis(trifluoromethyl)pyrazolyl (8), 3, 4, 5-trimethylpyrazolyl (9), 3, 5-dimethyl-4-bromopyrazolyl (10), indazolyl (11), 3-(heptafluoropropyl)-5-tert-butylpyrazolyl (12), 3-(trifluoromethyl)-5-phenylpyrazolyl (13), 4-chloropyrazolyl (14), 4-iodopyrazolyl (15), and 4-nitropyrazolyl (16)). The products have been characterized by 1H and 13C NMR spectroscopy and UV/visible absorption spectrophotometry and have been subjected to study by cyclic voltammetry. Among complexes incorporating unsymmetrically substituted bridging ligands, dimers 3, 7 and 11 exist as diastereoisomeric mixtures, while for 6 one diastereomer predominates and 12 and 13 appear to be formed as single isomers. The predominant diastereomer of compound 6 has been identified as the dissymmetric isomer (C2 molecular symmetry); monoclinic, of space group P21/n with a = 13.690 (4) Å, b = 14.617 (4) Å, c = 15.749 (10) Å, and β = 96.42 (4)°, in which the Ir2 separation = 3.079 (2) Å. Intramolecular nonbonding approach to within 2.2 A of hydrogen atoms attached to opposing terminal COD ligands has been identified in crystals of compound 9, triclinic, of space group P1, a = 11.116 (4) Å, b = 13.502 (5) Å, c = 11.006 (4) Å, α= 105.45 (4)°, β= 62.16 (3)°, and y = 110.07 (4)°, in which the Ir2 separation is 3.096 (1) A. A marked increase in P1/2 is observed compared with the parent compound 1 accompanying either 3, 5 or 4 substitution with electron-withdrawing groups (CF3 or NO2) of the bridging pyrazolyl unit. Synthesis of the “mixed-bridge” analogue [Ir(COD)(μ-pz)(μ-fpz)Ir(COD)] (17) and of the “mixed-metal” complex [RhIr(COD)2(μ-pz)2] (18) is described, and stability and NMR properties of both these products are reported.
AB - Fifteen diiridium(I) complexes [Ir(COD)(μ-L)]2 (2–16) (COD = cycloocta-1, 5-diene) related to the prototypal compound [Ir(COD)(μ-pz)]2 (1, pzH = pyrazole) have been synthesized by Cl displacement by LH from [Ir(COD)(μ-Cl)]2 (L = 4-methylpyrazolyl (2), 3-methylpyrazolyl (3), 3, 5-dimethylpyrazolyl (4), 3, 5-diphenylpyrazolyl (5), 3-phenyl-5-methylpyrazolyl (6), 3-(trifluoromethyl)-5-methylpyrazolyl (7), 3, 5-bis(trifluoromethyl)pyrazolyl (8), 3, 4, 5-trimethylpyrazolyl (9), 3, 5-dimethyl-4-bromopyrazolyl (10), indazolyl (11), 3-(heptafluoropropyl)-5-tert-butylpyrazolyl (12), 3-(trifluoromethyl)-5-phenylpyrazolyl (13), 4-chloropyrazolyl (14), 4-iodopyrazolyl (15), and 4-nitropyrazolyl (16)). The products have been characterized by 1H and 13C NMR spectroscopy and UV/visible absorption spectrophotometry and have been subjected to study by cyclic voltammetry. Among complexes incorporating unsymmetrically substituted bridging ligands, dimers 3, 7 and 11 exist as diastereoisomeric mixtures, while for 6 one diastereomer predominates and 12 and 13 appear to be formed as single isomers. The predominant diastereomer of compound 6 has been identified as the dissymmetric isomer (C2 molecular symmetry); monoclinic, of space group P21/n with a = 13.690 (4) Å, b = 14.617 (4) Å, c = 15.749 (10) Å, and β = 96.42 (4)°, in which the Ir2 separation = 3.079 (2) Å. Intramolecular nonbonding approach to within 2.2 A of hydrogen atoms attached to opposing terminal COD ligands has been identified in crystals of compound 9, triclinic, of space group P1, a = 11.116 (4) Å, b = 13.502 (5) Å, c = 11.006 (4) Å, α= 105.45 (4)°, β= 62.16 (3)°, and y = 110.07 (4)°, in which the Ir2 separation is 3.096 (1) A. A marked increase in P1/2 is observed compared with the parent compound 1 accompanying either 3, 5 or 4 substitution with electron-withdrawing groups (CF3 or NO2) of the bridging pyrazolyl unit. Synthesis of the “mixed-bridge” analogue [Ir(COD)(μ-pz)(μ-fpz)Ir(COD)] (17) and of the “mixed-metal” complex [RhIr(COD)2(μ-pz)2] (18) is described, and stability and NMR properties of both these products are reported.
UR - http://www.scopus.com/inward/record.url?scp=0000437980&partnerID=8YFLogxK
U2 - 10.1021/om00125a029
DO - 10.1021/om00125a029
M3 - Article
AN - SCOPUS:0000437980
SN - 0276-7333
VL - 4
SP - 1107
EP - 1114
JO - Organometallics
JF - Organometallics
IS - 6
ER -