Studies of polyaromatic phosphines and their coordination to noble metals
File(s)
Author(s)
Müller, Thomas E.
Type
Thesis
Abstract
Gold and platinum complexes of the polyaromatic tertiary phosphine ligands PArPh2, PAr?Ph, PApa (Ar = naphthyl (Np), anthracenyl (An)) and PFc2Ph (Fc = ferrocenyl) have been synthesised and their chemical and structural properties are described. These ligands, which have previously been neglected, show interesting differences in their coordination properties compared to PPI13.
Specifically they have provided an unusual environment around the ethyne moiety in R3P-Au-C=C-Au-PR3- The molecular structures of the chloroform solvates of the ethynediyl digold complexes NpPh2P-Au-G=C-Au- PNpPh2-2CHC13 and Np2PhP-Au-C=C-Au-PNp2Ph-6CHCl3 have been determined by X-ray techniques. These compounds exhibit novel C-H-ut interactions between the protons of CHCI3 molecules and the n -electron system of the C=C bond. The results have provided the first examples of C-H-t:(C=C) interactions which have the optimal theoretically predicted T-shaped geometry However the H•••7t distances observed here (2.42Á-2.58Á) are significantly shorter than those observed in organic systems. Their strength is comparable to typical hydrogen bonding energies.
Reduction of platinum complexes with polyaromatic phosphines has resulted in the formation of new platinum clusters. The first direct synthesis of the platinum dimers [Pt2Cl2(CO)2(PR3)2] (PR3 = PNpPh2 and PFc2Ph) from monometallic precursors is reported and the X-ray crystal structure of [Pt2Cl2(CO)2(PFc2Ph)2] has been determined. Slight variation of the reaction conditions lead to the isolation of the triangulo- cluster compounds [Pt3(|i-CO)3(PR3)3] (PR3 = PNpPh2 and PNp2Ph).
The ability of these ligands to adapt their steric requirements by adopting alternative ring conformations is useful in the context of coordination and organometallic chemistry and has raised the question of whether the Tolman cone angle can adequately describe these variations. A new structural definition of the cone angle introduced here has enabled us to access the crystallographic database and has resulted for the first time in a statistical analysis of the Tolman cone angle.
Specifically they have provided an unusual environment around the ethyne moiety in R3P-Au-C=C-Au-PR3- The molecular structures of the chloroform solvates of the ethynediyl digold complexes NpPh2P-Au-G=C-Au- PNpPh2-2CHC13 and Np2PhP-Au-C=C-Au-PNp2Ph-6CHCl3 have been determined by X-ray techniques. These compounds exhibit novel C-H-ut interactions between the protons of CHCI3 molecules and the n -electron system of the C=C bond. The results have provided the first examples of C-H-t:(C=C) interactions which have the optimal theoretically predicted T-shaped geometry However the H•••7t distances observed here (2.42Á-2.58Á) are significantly shorter than those observed in organic systems. Their strength is comparable to typical hydrogen bonding energies.
Reduction of platinum complexes with polyaromatic phosphines has resulted in the formation of new platinum clusters. The first direct synthesis of the platinum dimers [Pt2Cl2(CO)2(PR3)2] (PR3 = PNpPh2 and PFc2Ph) from monometallic precursors is reported and the X-ray crystal structure of [Pt2Cl2(CO)2(PFc2Ph)2] has been determined. Slight variation of the reaction conditions lead to the isolation of the triangulo- cluster compounds [Pt3(|i-CO)3(PR3)3] (PR3 = PNpPh2 and PNp2Ph).
The ability of these ligands to adapt their steric requirements by adopting alternative ring conformations is useful in the context of coordination and organometallic chemistry and has raised the question of whether the Tolman cone angle can adequately describe these variations. A new structural definition of the cone angle introduced here has enabled us to access the crystallographic database and has resulted for the first time in a statistical analysis of the Tolman cone angle.
Version
Open Access
Date Issued
1995
Date Awarded
1995
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Mingos, Professor D.M.P
Publisher Department
Department of Chemistry
Publisher Institution
University of London - Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)