(PENTAMETHYLCYCLOPENTADIENYL)NITROSYL(ETHYLENE)IRIDIUM TETRAFLUOROBORATE, [(ETA-5-C5ME5)IR(NO)(C2H4)][BF4] - SYNTHESIS, CHARACTERIZATION, AND SOME REACTIONS - X-RAY CRYSTAL-STRUCTURES OF THE TITLE COMPOUND AND ITS DERIVATIVES (ETA-5-C5ME5)IR(NO)(CH2CH2OET) AND (ETA-5-C5ME5)2IR2X2(MU-X)(MU-NO) (X=BR, I)

[(eta5-C5Me6)Ir(NO)(C2H4)][BF4] (1) has been synthesized from the reaction of (eta5-C5Me5)Ir(C2H4)2 with [NO] [BF4] in acetone at -10-degrees-C. Compound 1 crystallizes in the monoclinic space group P2(1)/n with Z = 4, a = 7.454(1) angstrom, b = 24.381(3) angstrom, c = 8.536(1) angstrom, beta = 93.85(l)-degrees, V = 1547.8 angstrom3, and the structure was refined to R(F) = 0.034 for 1922 data (I(o) greater-than-or-equal-to 2.0sigma(I(o))) and 161 variables. The Ir-NO group is 'linear'', with N-0 = 1.15(1) angstrom, Ir-N = 1.762(9) angstrom, and Ir-N-0 = 175.8(9)-degrees; the IR spectrum in ethanol exhibits nu(NO) = 1821 cm-1, confirmed by N-15 enrichment [nu((NO)-N-15) = 1786 cm-1]. The ethylene ligand is symmetrically bound to iridium with bond lengths Ir-C(1) = 2.19(1) angstrom, Ir-C(2) = 2.17(1) angstrom, and C(l)-C(2) = 1.37(2) angstrom and is oriented with the C(l)-C(2) axis approximately perpendicular to the plane defined by N and the centers of mass of the eta5-C5Me5 and eta2-C2H4 ligands, respectively. The barrier to ethylene rotation (DELTA G363double dagger = 68.7 +/- 0.2 kJ mol-1) was determined from variable-temperature H-1 NMR data at the coalescence temperature (T(c) = 353 K). Products of reaction of 1 with KI, KBr, KCl, NaOEt, and (eta5-C5Me5)Ir(CO)2 are described. Reaction with KI in ethanol at room temperature gives (eta5-C5Me5)Ir(NO)I and at 60-degrees-C gives the binuclear compound (eta5-C5Me5)2Ir2I2(mu-I)(mu-NO) (2). (eta5-C5Me5)Ir(NO)I has nu(NO) = 1761 cm-1 [nu((NO)-N-15) = 1717 cm-1] in CDC13 indicating a terminal -linear'' nitrosyl group. Compound 2 crystallizes from toluene as 2-toluene in the monoclinic space group P2(1)/c with Z = 4, a = 12.7738(11) angstrom, b = 13.5804(13) angstrom, c = 18.6110(23) angstrom, beta = 100.40(l)-degrees and V = 3175.5 angstrom3. The structure was refined to R(F) = 0.043 for 3045 data (I(o) greater-than-or-equal-to 2.5sigma(I(o))) and 134 variables. Complex 2 has mutually trans eta5-C5Me5 groups, trans terminal iodide ligands, and symmetrically bridging nitrosyl and iodide with Ir(l)-N = 2.029(12) angstrom, Ir(2)-N = 1.974(12) angstrom, and N-0 = 1.24(2) angstrom. The reaction of 1 with KBr in ethanol at room temperature produces (eta5-C5Me5)Ir(NO)Br in solution but this converts on attempted isolation to other products which include (eta5-C5Me5)Ir2Br2(mu-Br)(mu-NO) (3). Compound 3 crystallizes in the monoclinic space group P2(1)/n with Z = 2, a = 8.6364(8) angstrom, b = 9.3766(6) angstrom, c = 15.501(3) angstrom, beta = 101.753(11)-degrees, V = 1228.9 angstrom3, and the structure was refined to R(F) = 0.034 for 1120 data (I(o) greater-than-or-equal-to 2.5sigma(I(o))) and 99 variables. The structure of 3 is essentially similar to that of 2, but is disordered about a crystallographic inversion center. In contrast to these ethylene displacement reactions, NaOEt reacts with 1 to produce the ethoxyethyl derivative (eta5-C5Me5)Ir(NO)(CH2CH2OEt) (4), which crystallizes in the monoclinic space group P2(1)/n with Z = 4, a = 7.291(2) angstrom, b = 15.274(2) angstrom, c = 14.362(2) angstrom, beta = 96.90(2)-degrees and V = 1587.8 A3. The structure was refined to R(F) = 0.027 for 1960 data (I(o) greater-than-or-equal-to 2.5sigma(I(o))) and 128 variables. The reaction of 1 with (eta5-C5Me5)Ir(CO)2 in refluxing ethanol yielded [(eta5-C5Me5)2Ir2(mu-CO)(mu-NO)] [BF4], identified on the basis of analytical and spectroscopic data.