Ewch i’r prif gynnwys
Dr Paul Newman

Dr Paul Newman

Research Fellow

Yr Ysgol Cemeg

Email:
newmanp1@cardiff.ac.uk
Telephone:
+44 (0)29 2087 0464
Fax:
+44 (0)29 2087 4030

Links

Research Group: Inorganic Chemistry

Research Interests

  • Development of new ligand frameworks for application in coordination chemistry and homogeneous catalysis
  • Phosphacyclic chemistry particularly the design and synthesis of structurally elaborate polycyclic phosphines as novel ligands
  • Chiral metal complexes
  • Rigid bicyclic N-heterocyclic carbenes with secondary donors as supporting ligands for high oxidation state metal centes
  • Asymmetric transition metal catalysed oxidations

Most of our work encompasses aspects of synthetic organic, inorganic and organometallic chemistry with an emphasis on preparing new ligands and exploring their coordination chemistry and deployment in homogeneous catalysis.   Inherently chiral phosphines and N-heterocyclic carbenes (NHCs) are of particular interest as discussed under the $acirc; research$acirc; tab above.

For more information, click on the 'Research' tab above.

Teaching

CH3102 Foundations of Inorganic Chemistry

CH3408 Modern Catalytic Processes

CHT215 Key skills in catalysis

CHT221 Mechanism and ligand design in homogeneous catalysis

CHT222 Homogeneous catalysts in industry

MSc (1988, R. D. Gillard) and PhD (1991, P. A. Williams), University of Wales Cardiff. Post -doctoral research associate, University of Wales Cardiff (1991-2, R. D. Gillard), University of Glasgow (1993-96, R. D. Peacock and R. J. Cross), Cardiff University (1997-2002, P. G. Edwards). Appointed Cardiff University Research Fellow 2002 and Cardiff Catalysis Institute (CCI) research officer (2009).

2019

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1998

Phosphacycles

Unlike acyclic phosphines and azacycles, the coordination chemistry of cyclic phosphines (phosphacycles) is relatively poorly developed. We are interested in the synthesis of innately asymmetric, structurally elaborate phosphines derived from readily available $acirc; chiral pool$acirc; precursors. The structure of one such ligand (phenop) is shown below. Phenop has eight stereogenic carbon centres (four of which derive from the camphor starting material and four of which are generated stereoselectively during the synthesis) and a pseudo-chiral phosphorus. Phenop forms numerous complexes with a range of transition metals in various oxidation states and undergoes facile cyclometallation (internal C-H activation) with Pd(II) and Pt(II) to give P,C chelates as shown in 2. The observed cyclometallation is unusual for two reasons: firstly the activated C-H bond is of an alkyl type rather than the more common aryl; and secondly, the actual site of C-H activation depends on the nature of the metal precursor. For example the use of Na2[PdCl4] gives the complex 1 whereas palladium(II) acetate produces 2.

i) nBuLi, 0.5. PhPCl2, H2O2, 87%; ii) NaBH4, 93%; iii) TsCl, 52%; iv) HSiCl3, 93%.
Fig.1. and Fig.2.

We are also interested in other fused cyclic systems, a bicyclic example of which is shown in 3 together with a bidentate derivative (4) and the molecular structure of its complex with Mo(CO)4.

Fig.3. and Fig.4.
Fig.5.

Fused expanded-ring NHCs

N-heterocyclic carbenes (NHCs) have achieved great prominence in recent years as ligands of outstanding promise and application in coordination chemistry and homogeneous catalysis. NHCs where the constituent heterocyclic ring(s) is >5 membered are referred to as expanded-ring derivatives and they possess unusual properties such as increased basicity / nucleophilicity and enhanced sterics that may lead to novel reactivity in their metal complexes. We (together with Prof Cavell) are interested in fused 6/7-membered NHCs with exo-cyclic N-substituents containing other potential donors such as those derived from azolium salts of the type shown below (5). The N,N$acirc; -dipyridyl derivative of 5 undergoes room temperature oxidative addition to Ni(1,5-COD)2 to give the pincer complex shown in the figure below. This is unusual chemistry for expanded-ring azolium salts which do not tend to undergo oxidative addition as readily as 5-membered NHCs.

Fig.6.