Thomas S. Janik

Formation of carboncarbon bonds on di(organo)iridium complexes, rr′Ir(CO)(PPh3)2X (R,R′ = Me, Ph, CH2Ph, C(O)CH3; X = Cl, I) and the crystal structure of cis,cis,trans-[Ir(CH3)2(CO)2(PPh3)2+][CF3SO3-]

Abstract The reactions of RX with trans -R′Ir(CO(PPh 3 ) 2 are reported. Addition of CH 3 C(O)Cl to trans -CH 3 Ir(CO)(PPh 3 ) 2 leads to acetone; addition of CH 3 I to trans -PhIr(CO)(PPh 3 ) 2 leads to toluene; and addition of CH 3 I to trans -C 6 H 5 CH 2 Ir(CO)(PPh 3 ) 2 leads to ethylbenzene. Reaction of C 2 H 5 Br with trans -CH 3 Ir(CO)(PPh 3 ) 2 leads to CH 4 and C 2 H 4 . The addition of CH 3 I to trans -CH 3 Ir(CO)(PPh 3 ) 2 leads to Ir(CH 3 ) 2 Ir(CO)(PPh 3 ) 2 I from which Ir(CH 3 ) 2 (CO)-(PPh 3 ) 2 + and Ir(CH 3 ) 2 (CO) 2 (PPh 3 ) 2 + can be prepared. These dimethyl complexes do not undergo reductive elimination of ethane, acetone or diacetyl under a variety of conditions (CH 4 and C 2 H 6 are formed at decomposition). Thus for these complexes the charge, the presence of a free coordination site and the cis stereochemistry do not facilitate reductive elimination reactions. To ascertain that no structural features were preventing reductive elimination from the dimethyl complex we have examined the structure of cis,cis,trans -[Ir(CH 3 ) 2 (CO) 2 (PPh 3 ) 2 + ][CF 3 SO 3 − ]. This crystallizes in the centrosymmetric triclinic space group P 1 ( C i 1 ; No. 2) with a 11.708(2), b 11.738(2) c 14.702(2) A, α 87.544(13), β 79.181(14), γ 76.963(15)°, V 1933.4(6) A 3 and D (calcd) 1.64 g cm −3 for mol. wt. 951.9 and Z = 2. x-ray diffraction data (Mo- K α , 2θ 4.5–50.0°) were collected with a Syntex P2 1 automated four-circle diffractometer and the structure was refined to R 3.5% for all 6835 reflections ( R 2.9% for those 6133 reflections with | F 0 | > 6σ(| F 0 |)). The central d 6 iridium(III) ion has a slightly distorted octahedral stereochemistry, with Ir-CO 1.943(5) and 1.956(5) A, Ir-CH 3 2.152(5) and 2.155(5) A and Ir-PPh 3 2.391(1) and 2.400(1) A; interligand angles include OC-Ir_CO 102.09(20), CH 3 -Ir-CH 3 89.70(19) and PPh 3 -Ir-PPh 3 174.68(4)°.

Crystal structures of trans-[Ru(dppe)2(CO)(Cl)](BF4)·2(toluene) and trans-[Ru(dppm)2(CO)(Cl)](BF4)·CH2Cl2: a study of the steric and electronic ligand effects of trans-positioned diphosphine ligands

Abstract Single-crystal X-ray diffraction studies were carried out on the complexes trans-[Ru(dppe)2(CO)(Cl)](BF4) ·2(toluene) (1) (where dppe = 1,2-bis(diphenylphosphino)ethane) and trans-[Ru(dppm)2(CO)(Cl)](BF4) ·CH2Cl2 (2) (where dppm = bis(diphenylphosphino)methane). Complex 1 crystallizes in the orthorhombic space group P21212 with a = 14.366(3), b = 17.075(3), c = 12.433(2) A , V = 3049.8(10) A 3 and Z = 2 . The structure was refined to R = 3.02% for 3233 reflections above 6σ (R = 4.46% for all 3991 point-group independent data); the Ru-cation lies on a site of C2 symmetry, leading to disorder of the Cl and CO ligands. Complex 2 crystallizes in the orthorhombic space group Pna2 1 , with a = 22.425(7), b = 11.515(4), c = 19.511(10) A , V = 5038(3) A 3 and Z = 4 . The structure was refined to R = 4.43% for 4770 reflections above 6σ (R = 7.09% for all 6631 point-group independent data). The crystal structure data suggest increased intramolecular interligand interactions with the trans-bis(dppe) complexes relative to the trans-bis(dppm) complexes. In order to furth assess the steric ligand effects of dppm and dppe on the redox chemistry of ruthenium complexes, the electrochemical data for complexes 1 and 2 as well as for trans-Ru(dppe)2(Cl)2 and trans-Ru(dppm)2(Cl)2 were analyzed. The Epa value for the oxidation of complex 1 was more positive than the Epa value for the oxidation of complex 2; similarly, the E 1 2 value for the oxidation of trans-Ru(dppe)2(Cl)2 was more positive than the E 1 2 value for the oxidation of trans-Ru(dppm)2(Cl)2. The increase in the redox potentials for the oxidation of the dope complexes may be due to the enhanced intramolecular interligand interactions of the dppe ligands, which is in agreement with the crystal structure data.

Catalytic homogeneous hydrogenation of terminal olefins by RCo(CO)2(P(OCH3)3)2 (R = CH3 or CH3C(O))

Abstract The complexes RCo(CO) 2 L 2 (R = CH 3 , CH 3 C(O), L = P(OCH 3 ) 3 ) show a marked activity (450 turnovers/h) for hydrogenation of terminal olefins at ambient conditions. There is very little activity for more hindered olefins. A number of reactions have been examined, which allow a mechanism for the catalytic cycle to be presented. This mechanism involves a series of methyl → acetyl interconversion which open coordination sites, very similar to η 3 · η 1 allyl interconversions.

Reaction of alkenes with trans-MeOIr(CO)(PPh3)2. Crystal and molecular structure of the pentacoordinate alkoxy-alkene iridium(I) complex, MeOIr(CO)(PPh3)2(TCNE)

Abstract The reaction of trans -MeOIr(CO)(PPh 3 ) 2 with TCNE (tetracyanoethylene) gives rise to the stable adduct MeOIr(CO)(PPh 3 ) 2 (TCNE), the structure of which has been determined via a single-crystal X-ray diffraction study. This complex crystallizes in the centrosymmetric orthorhombic space group Pbca ( D 15 2 h ; No. 61) with a 17.806(4), b 20.769(4), c 20.589(6) A, V 7614(3) A 3 and Z = 8. Diffraction data (Mo- K α , 2θ = 5–45°) were collected on a Syntex P2 1 automated four-circle diffractometer and the structure was solved and refined to R F 6.2% for 3502 data with | F 0 | > 3σ(| F 0 |) ( R F 4.3% for those 2775 data with | F 0 | > 6 σ(| F 0 |)). The central iridium atom has a distorted trigonal bipyramidal coordination geometry in which the methoxy group (Ir-OMe 2.057(8) A) and carbonyl ligand (Ir-CO 1.897(14) A) occupy axial sites with ∠MeOue5f8Irue5f8CO 174.7(4)°. The two triphenylphosphine ligands occupy equatorial sites (Irue5f8P(1) 2.399(3), Irue5f8P(2) 2.390(3) A, ∠P(1)ue5f8Irue5f8P(2) 110.32(11)° and the TCNE ligand is linked in an η 2 “face-on” fashion with the olefinic bond parallel to the equatorial coordination plane (Irue5f8C(4) 2.176(10), Irue5f8C(7) 2.160(12) A) and lengthened substantially from its value in the free olefin (C(4)ue5f8C(7) 1.539(17) A).

Crystal structure of 751-1751-1751-1751-2751-2751-2

AbstractThe title compound crystallizes in the centrosymmetric triclinic space groupn

Synthesis and crystal structure of a dinuclear organometallic phosphonium ylid complex, [(η5-C5H5(CO)C2(ε-CO)(ε-CHP(C6H5)3)+][PF – 6 ]

Pbar 1

Crystal and molecular structure of the triflate salt of diprotonated 1,4,8,11-tetrakis(2-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane, [C10H22N4(CH2CH2OH)4 2+]−[CF3SO3 −]2: geometry of a diprotonated octadenate ligand

n (No. 2) witha=10.818(1)Å,b=10.876(1)Å,c=11.072(2)Å, α=98.74(1)°, β=98.83(1)°, γ=96.61(1)°,V=125906(3)Å3 andZ=2. Interatomic distances include Fe−P=2.243(2)Å, Fe−CO=1.771(6)–1.781(5)Å, Fe−C(C5H5)=2.074(6)–2.103(5)Å and P−F=1.511(6)–1.571(4)Å.

Structural studies on ruthenium carbonyl hydrides: XIV. Synthesis, characterization, and crystal structure of (μ-H)2Ru3(η3-η2-CHC(O)OCH3)(CO)8(PPh3). An example of cis-labilization by an oxygen donor ligand☆

Abstract The molybdenum alkynyl complexes [Mo(Cue606CPh)(η3-allyl)(CO)2(bipy)] (1) and [Mo(Cue606CH)(η3-allyl)(CO)2(N–N)] (N–N=2,2′-bipyridine, 2a; 1,10-phenanthroline, 2b) react with dicobalt octacarbonyl to give the new tetrahedrane trimetallic complexes [Co2(CO)6(μ-η2:η2-M–Cue606CPh)], M={Mo(η3-C3H5)(CO)2(bipy)} (3) and [Co2(CO)6(μ-η2:η2-M–Cue606CH)], M={Mo(η3-C3H5)(CO)2(N–N)} (N–N=bipy, 4a; phen, 4b), respectively. These new compounds were characterized by analytical (C, H, N), spectroscopic (IR, 1H NMR) and crystallographic (single crystal X-ray diffraction) means.