Syntheses, x-ray structures, and cis-trans isomerism of (pentamethylcyclopentadienyl)dicarbonylrhenium dihalides (.eta.-C5Me5)Re(CO)2X2 (X = Cl, Br, I)

Abstract

Cis and trans isomers have been synthesized for the series of rhenium dicarbonyl dihalides Cp*Re(CO)2X2(Cp* = i)-C5Me5•, X = Cl, Br, I). The cis isomers were formed by reaction of Cp*Re(CO)2(N2) with HX and were converted to the trans isomers by UV irradiation in hexane. The structures of the isomers have been assigned from examination of r(CO) IR intensities and are supported by X-ray structure determinations on cts-Cp*Re(CO)3I2 and frans-Cp*Re(CO)2Br,. Crystal data for c¿s-Cp*Re(CO)2I2: monoclinic P21/n, a = 7.201 (3) A, b = 27.254 (5) A, c = 8.682 (2) Á, ß = 110.04 (4)°, U = 1600.2 (2) A3 4, Z)calcd = 2.62 g cm"3, Dmeasd = 2.64 (1) g cm'3, Z = 4, X(Mo ) = 0.71069 A, µ( ) = 115.1 cm"1, RF = 0.046, Rwf = 0.058 for 1510 observed reflections (2081 measured with 3°< 2 < 45°). Crystal data for trons-Cp*Re(CO)2Br2: monoclinic P21/c, a = 8.512 (2) A, b = 12.610 (4) A, c = 13.794 (6) Á, ß = 102.40 (3)°, U = 1446.1 (3) A3, Scaled = 2.47 g cm"3, Dmeaad = 2.43 (1) g cm"3, Z = 4, ( ) = 0.71069 A, µ( ), = 139.8 cm"1, RF = 0.043, = 0.054 for 1509 reflections (2008 measured with 3 < 2 < 46°). cis-and frans-CpRe(CO)2Cl2 (the missing members of the cyclopentadienyl analogues CpRe(CO)2X2) have been synthesized from CpRe(CO)2(N2) and Cl2. The reaction of Cp*Re(CO)3 with I2 in hexane yields [Cp*Re(CO)3I][I3] thermally and irons-Cp*Re(CO)2I2 after irradiation.

The photochemistry of cylopentadienylmolybdenum complexes including the mechanism of the cis-trans photoisomerism of (η5-C5H5)Mo(CO)2LX, X = Cl Br, I; L = PPh3, PBu3

“…For this series of rhenium complexes we found that cis-trans isomerism was a result of dissociative loss of CO to generate a single intermediate, regardless of the starting isomer used, which reacted with free CO to produce a trans geometry in the product, reaction [I]. This was in agreement with reports of the room temperature solution studies which indicated the observation of only cis-trans isomerism for these Re complexes (2).…”

“…The reaction, given by reaction [2], is a geometrical isomerism of the basal ligands. Unlike the rhenium complexes, the molybdenum complexes were reported to undergo isomerism in either direction via photochemical initiation.…”

Carben- und Carbin-Komplexe des Technetiums und Rheniums - Synthese, Struktur und Reaktionen / Carbene and Carbyne Complexes of Technetium and Rhenium - Synthesis, Structure and Reactions

“…: 78 °C (Zers.)) [7] [8], während wir für die purpurfarbenen Kristalle auf der Basis IR-spektroskopischer Befunde (feh lende r(C O )-, charakteristische v(CH)-, v(CC)-und v(R e-C l)-A bsorptionen) und in Analogie zum homologen Cp2ReCl die Struktur Cp*2ReCl vorschlagen [9], Die Acyl-Komplexe 2 a und 2 b lassen sich direkt in Verbindungen mit einer Metall-KohlenstoffDreifachbindung überführen. So führt die Um set zung von 2 b mit Oxalylbromid in C H 2C12 bei -6 0 °C direkt zum Carbin-Komplex [Cp*(CO)2-R e=C P h]B r (5b), welcher nach chrom atographi scher Reinigung an silanisiertem Kieselgel bei -3 0 °C mit 80% Ausbeute als leuchtend-gelber, in C H 2C12 sehr gut, in Pentan dagegen unlöslicher Feststoff isoliert wird (Gl.…”

“…: 9 7 -9 8 °C. EI-MS (70 eV), m /z (% ): 424,3 (17,9) [Cp*(CO)2TcC (O Et)Ph]+, 396,3 (27,3) [C p*(C O )TcC (O Et)Ph]+, 368,4 (5,4) [Cp*TcC(O Et)Ph]+, 339,2 (24,8) …”

“…C21H 250 3Re (511,63). EI-MS (70 eV), m /z (%)'■ 512, 3 (27,7) [Cp*(CO)2R eC (O E t)Ph]+, 484,3 (17,1) [C p*(C O )R eC (O Et)Ph]+, 456,3 (1,7) [Cp*ReC(OEt)Ph]+, 427,1 (13,7) [Cp*(CO)RePh]+, 399,0 (45,9) [Cp*RePh]+, 350,1 (4,6) [Cp*Re(CO)]+, 322,1 (1,4) (1,2) [Cp*3TcCl]+, 404,0 (3,3) [Cp*2TcCl]+, 368, 2 (6 ,8) [Cp*2Tc]+, 367,2 (27,3) [Cp*(CO)2TcPh]+, 339,2 (3,8) [Cp*(CO)TcPh]+, 324,1 (2,9) [Cp*(CO)2TcCl]+, 322,1 (100,0) [Cp*TcCl2(O H )]+, 318,1 (25,2) [Cp*Tc(CO)3]+, 307,1 (15,8) [Cp*Tc(CO)2(O H )]+, 290,1 (8,9) [Cp*Tc(CO)2]+, 268,5 (68,7) [Cp*TcCl]+, 262,1 (22,9) [Cp*Tc(CO)]+, 234,1 (22,1) …”