TY - JOUR
T1 - Combined Experimental and Theoretical Study on Hampered Phosphine Dissociation in Heteroleptic Ni/Zn Complexes
AU - Heiß, Patricia
AU - Hornung, Julius
AU - Zhou, Xiaoyu
AU - Jandl, Christian
AU - Pöthig, Alexander
AU - Gemel, Christian
AU - Fischer, Roland A.
N1 - Publisher Copyright:
© 2019 American Chemical Society.
PY - 2020/1/6
Y1 - 2020/1/6
N2 - Heterometallic Ni/Zn complexes can serve as molecular models for the semihydrogenation of acetylene catalyzed by heterogeneous Ni/Zn phases. Pursuing this target, we present the synthesis of the series [Ni(ZnCp*)n(ZnMe)n(PEt3)4-n] (n = 1-3; 1, 2, 3) which is obtained via E/Zn exchange from [Ni(ECp*)n(PEt3)4-n] (n = 1-3, E = Al, Ga; P1, P2, P3). The isolation of the intermediate compound [Ni(GaCp*)(ZnCp*)(ZnMe)(PEt3)2] (2a) supports the assumption of a stepwise Ga/Zn exchange in the formation of 3. The dissociation behavior of PEt3 in 2 and 3 was investigated experimentally using variable temperature (VT) UV-vis spectroscopy indicating suppressed phosphine dissociation in both cases. For comparison, the absorption spectra of the saturated and unsaturated compounds were calculated using time dependent DFT calculations (TDDFT). Energy decomposition analysis with the natural orbital for chemical valence extension (EDA NOCV) calculations shows a bond strengthening of the Ni-P bond by successive substitution of the phosphines with (ZnR)2 units. The influence of different phosphines (PMe3, PEt3, PPh3, P(OEt)3) on Ni-P bond length and on Zn-Zn interactions in [Ni(ZnR)2n(PR′)4-n] (R = Cp*, Me; R′ = Me, Et, Ph, OEt) was also studied by DFT calculations. A correlation of increasing sterical demand of the phosphine ligand and a shortening of the Zn-Zn distances is observed.
AB - Heterometallic Ni/Zn complexes can serve as molecular models for the semihydrogenation of acetylene catalyzed by heterogeneous Ni/Zn phases. Pursuing this target, we present the synthesis of the series [Ni(ZnCp*)n(ZnMe)n(PEt3)4-n] (n = 1-3; 1, 2, 3) which is obtained via E/Zn exchange from [Ni(ECp*)n(PEt3)4-n] (n = 1-3, E = Al, Ga; P1, P2, P3). The isolation of the intermediate compound [Ni(GaCp*)(ZnCp*)(ZnMe)(PEt3)2] (2a) supports the assumption of a stepwise Ga/Zn exchange in the formation of 3. The dissociation behavior of PEt3 in 2 and 3 was investigated experimentally using variable temperature (VT) UV-vis spectroscopy indicating suppressed phosphine dissociation in both cases. For comparison, the absorption spectra of the saturated and unsaturated compounds were calculated using time dependent DFT calculations (TDDFT). Energy decomposition analysis with the natural orbital for chemical valence extension (EDA NOCV) calculations shows a bond strengthening of the Ni-P bond by successive substitution of the phosphines with (ZnR)2 units. The influence of different phosphines (PMe3, PEt3, PPh3, P(OEt)3) on Ni-P bond length and on Zn-Zn interactions in [Ni(ZnR)2n(PR′)4-n] (R = Cp*, Me; R′ = Me, Et, Ph, OEt) was also studied by DFT calculations. A correlation of increasing sterical demand of the phosphine ligand and a shortening of the Zn-Zn distances is observed.
UR - http://www.scopus.com/inward/record.url?scp=85077458521&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.9b02798
DO - 10.1021/acs.inorgchem.9b02798
M3 - Article
C2 - 31874031
AN - SCOPUS:85077458521
SN - 0020-1669
VL - 59
SP - 514
EP - 522
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 1
ER -