TY - JOUR
T1 - Better understanding of the species with the shortest Re2 6+ bonds and related Re27+ species with tetraguanidinate paddlewheel structures
AU - Cotton, F. Albert
AU - Dalal, Naresh S.
AU - Huang, Penglin
AU - Ibragimov, Sergey A.
AU - Murillo, Carlos A.
AU - Piccoli, Paula M.B.
AU - Ramsey, Chris M.
AU - Schultz, Arthur J.
AU - Wang, Xiaoping
AU - Zhao, Qinliang
PY - 2007/3/5
Y1 - 2007/3/5
N2 - A series of compounds has been made containing quadruply bonded Re 2(hpp)4X2 species (hpp = the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2a]pyrimidine), where X is CF 3SO3 (1), CF3CO2 (2), and F (3). The distances of 2.1562(7), 2.1711(5), and 2.1959(4) Å for 1-3 show significant effects of the σ and π electron donating ability of the axial ligands on the metal-metal distance. With the weakly coordinating triflate ligand the Re-Re distance is the shortest for any quadruple bonded species known. In addition to examining the effects of axial ligands on the Re 2(hpp)42+ core, our study of the Re 2(hpp)43+ core is being extended beyond the preliminary results previously reported in only one compound [Re 2(hpp)4Cl2]PF6 (Dalton Trans. 2003, 1218). We now report the structural characterization by both X-ray and neutron diffraction of the compound [Re2(hpp)4F](TFPB) 2, 4 (TFPB = the anion tetrakis[3,5-bis(trifluoromethyl)phenyl] borate), and a detailed study by EPR spectroscopy of [Re2(hpp) 4Cl2]PF6 at 9.5, 34.5, and 95 GHz frequencies, using dilute fluid solutions, frozen glass, and neat powder, show that the unpaired electron in the [Re2(hpp)4Cl2] + ion is in an MO of predominant metal character with little mixing from the guanidinate ligands.
AB - A series of compounds has been made containing quadruply bonded Re 2(hpp)4X2 species (hpp = the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2a]pyrimidine), where X is CF 3SO3 (1), CF3CO2 (2), and F (3). The distances of 2.1562(7), 2.1711(5), and 2.1959(4) Å for 1-3 show significant effects of the σ and π electron donating ability of the axial ligands on the metal-metal distance. With the weakly coordinating triflate ligand the Re-Re distance is the shortest for any quadruple bonded species known. In addition to examining the effects of axial ligands on the Re 2(hpp)42+ core, our study of the Re 2(hpp)43+ core is being extended beyond the preliminary results previously reported in only one compound [Re 2(hpp)4Cl2]PF6 (Dalton Trans. 2003, 1218). We now report the structural characterization by both X-ray and neutron diffraction of the compound [Re2(hpp)4F](TFPB) 2, 4 (TFPB = the anion tetrakis[3,5-bis(trifluoromethyl)phenyl] borate), and a detailed study by EPR spectroscopy of [Re2(hpp) 4Cl2]PF6 at 9.5, 34.5, and 95 GHz frequencies, using dilute fluid solutions, frozen glass, and neat powder, show that the unpaired electron in the [Re2(hpp)4Cl2] + ion is in an MO of predominant metal character with little mixing from the guanidinate ligands.
UR - http://www.scopus.com/inward/record.url?scp=33947364273&partnerID=8YFLogxK
U2 - 10.1021/ic062319b
DO - 10.1021/ic062319b
M3 - Article
AN - SCOPUS:33947364273
SN - 0020-1669
VL - 46
SP - 1718
EP - 1726
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 5
ER -