Estrada, Alexander Louis (2022-10). New Rhodium and Rhenium Coordination Chemistry: From Molecular Gyroscopes to Chiral Lewis Acids. Doctoral Dissertation.
Thesis
Square planar trans-Rh(CO)(Cl)[P((CH2)6CH=CH2)3]2 (2c), trans-Rh(CO)(Cl)-[P(p-C6H4O(CH2)mCH=CH2)3]2 (19; m = 5/b, 6/c, 7/d), and octahedral mer,trans-Re(CO)3(X)[P(p-C6H4O(CH2)6CH=CH2)3]2 (X = Cl, 23; Br, 24) undergo C=C meta-thesis/hydrogenation sequences to generate trans-Rh(CO)(Cl)[P((CH2)14)3P] (4c, 41%), trans-Rh(CO)(Cl)[P(p-C6H4O(CH2)nO-p-C6H4)3P] (n = 2m+2, 15b-d; 26-41%), and mer,trans-Re(CO)3(X)[P(p-C6H4O(CH2)14O-p-C6H4)3P] (X = Cl, 25c, 19%; Br, 26c, 61%). Additions of NaBr, NaI, KSCN, ZnPh2, MeLi, or NaBH4 to 4c give the substitution products trans-Rh(CO)(X)[P((CH2)14)3P] (X = Br/I/-NCS, 5c/6c/7c, 97-44%), trans-Rh(CO)(R)[P((CH2)14)3P] (R = Ph/Me, 8c/9c, ~94-89%) or trans-Rh(CO)- (H2BH2)[P((CH2)14)3P] (10c, 99%). Reactions with BrCCl3 or CO give octahedral or trigonal bipyramidal addition products trans-Rh(CO)(Cl)(Br)(CCl3)[P((CH2)14)3P] (11c, 97%) or trans-Rh(CO)2(I)[P((CH2)14)3P] (12c, ~98%). Addition of LiC?CAr to 15b gives trans-Rh(CO)(C?CAr)[P(p-C6H4O(CH2)12O-p-C6H4)3P] (Ar = C6H5/p-C6H4CH3, 21b/22b, 22-37%). Addition of excess PMe3 to 4c or 15c,d gives P((CH2)14)3P (1c, 58%) or P(p-C6H4O(CH2)nO-p-C6H4)3P (27c,d, 83-75%). Diphosphines 1c and 27d react with [(Rh(CO)2(u-Cl)]2 to regenerate 4c (58%) and 15c (87%). Both in,in and out,out isomers of 27c,d are possible, but low temperature NMR spectra show one set of signals, consistent with rapid homeomorphic isomerizations. Crystallographic and spectroscopic data are used to interpret dynamic properties. While 4c-6c and 9c-10c exhibit a single set of seven CH2 ^13C NMR signals at room temperature, 7c-8c exhibit two sets, while 11c exhibits three. Additionally, the barrier to Rh(CO)2(I) rotation in 12c is bounded as higher than that of Rh(CO)(I) rotation in 6c, but the rotamers preferentially interconvert via CO dissociation/addition. Steric interactions with the PC6H4O linkages are analyzed in 15b-d, 21b, and 22b. The Cl-Rh-CO and ArC?C-Rh-CO rotators of 15b-d and 21b rapidly rotate on the NMR time scale, but in 22b the longer p-CH3C6H4C?C group is confined between two (CH2)12 bridges even at 120 ?C. Diphenyldiazomethane and [(?^5-C5H5)Re(NO)(PPh3)(ClC6H5)]^+ BF4^- react to give the ?^1 adduct [(?5-C5H5)Re(NO)(PPh3)(NNCPh2)]+ BF4- (73%). In the presence of copper powder, a 3-phenyl-1H-indazole complex derived from carbon-hydrogen bond activation, [(?^5-C5H5)Re(NO)(PPh3)(N=C(Ph)C=CHCH=CHCH=CNH)]+ BF4- (65%) is obtained. Subsequent reaction with NaOCH3 gives indazolyl complex (?5-C5H5)-Re(NO)(PPh3)(NC=CH-CH=CHCH=CC(Ph)=N) (85%), derived from NH deprotonation and a 1,2-rhenium shift. DFT calculations are used to probe the mechanism of the 1,2-shift, energetics of alternative rotamers and linkage isomers, and assign bond orders and dominant resonance formulations.
