 Professor
Andrew S. Weller
Chemistry Research Laboratory
Telephone: 01865 285 151
Research in the Weller group is based upon synthetic organometallic
chemistry, and in particular the generation and stabilisation
of transition metal complexes with a low coordination number or
which are “operationally unsaturated”. Through this we are
interested in topics related to catalysis (e.g. weakly
coordinating anions, hemi-labile ligands), C-H, C-C, B-H complexes
and activation (via agostic or sigma interactions) and
the self-assembly of metal fragments to form novel clusters that
show promise as models for hydrogen on metal surfaces and new hydrogen
storage devices. Our research themes broadly encompass organometallic,
inorganic chemistry and catalysis. Close links with members of
the organic section gives the possibility that joint inorganic/organic
projects related to this area can be pursued. Collaborations with
theoretical chemists (especially Professors Jennifer Green,
Oxford and Stuart
Macgregor, Heriot-Watt) also lead to a deeper understanding
of structures and reactivity of many of the new complexes made.
Please visit our Research Web Pages for more
details, as well as our latest publications/news.
Selected recent highlights of this research include:
(i) The synthesis of a new class of unsaturated metal clusters [1,2],
by a kinetically-controlled self-assembly process, which have an
extraordinarily high hydride content (Figure 1); are also models
for hydrogen attachment on a metal surface; uptake and release
H2; undergo a variety of electrochemical processes due
their unsaturated electronic structure and act as redox-switchable
hydrogen storage materials – which we believe is a new concept
for the storage and rapid release of H2 at room temperature
and pressure.
 
Figure 1. Example of a high-hydride content molecular
cluster, [Rh6(PiPr3)6H12]2+,
(left); Cartoon showing the concept of Redox-Switchable Hydrogen
Storage.
(ii) The synthesis and definitive characterisation of late
transition metal C-C and B-H sigma complexes. These complexes
also undergo C-C or B-H activation in solution, making them genuine
intermediates in these transformations of growing synthetic utility.
[3]
Figure 2. Example of a cationic Rh(III) complex
that shows an agostic C-C interaction as well as an agostic C-H
interaction with the metal centre.
(iii) Understanding the role of weakly coordinating
anions in catalysis by late transition metals.[4] Particular
highlights include the development of catalysts partnered with
weakly coordinating carborane mononanions, [closo-CB11H6X6]- (Figure
3), that show excellent turnover numbers or resistance to decomposition;
and uncovering unusual structural motifs for anion binding, for
example a rare example of coordinated [BArF4]-.
 
Figure 3. Example of a cationic iridium phosphine
complex stabilised by a weakly coordinating carborane anion (left);
and a rare example of a coordinated [BArF4]- complex
(right).
(iv) The role of hemilabile ligands in stabilising
latent vacant coordination sites on transition metal systems. A
recent important result from this work is the development (with Willis, Oxford)
of hydroacylation catalysts for challenging substrates (C-H activation)
in which each steps on the catalytic cycle has been characterized.[5]
Figure 4. Catalytic cycle for the hydroacylation
of alkenes as elucidated by NMR spectroscopy, X-ray crystallography
and ESI-MS.
(v) Remarkable (sometimes acceptorless) intramolecular
alkyl dehydrogenation processes (Figure 5), that have applicability
to alkane activation, and the succinct generation of new catalysts.[6]
References
[1] (a) J. Am. Chem. Soc. 2007, 129,
1793; (b) Angew. Chem. Int. Ed. 2006, 45, 6005;
(c) J. Am. Chem. Soc. 2006, 128, 6247;
(d) Angew. Chem. Int. Ed. 2005, 44,
6875; (e) J. Am. Chem. Soc. 2004, 126, 4784; (f) Inorg.
Chem. 2005, 44, 3162; (g) Angew.
Chem. 2007, 46, 7844; (f) Inorg. Chem. 2008, 47,
778
[2] Highlighted work: Nature, 2006, 442,
850; ibid. 443, 400; Angew. Chem. 2004, 43,
6028; ibid. 2005, 44, 5772; Green Chem. 2006, 8,
941
[3] (a) Angew. Chem. Int. Ed. 2006, 45, 452
; (b) Proc. Nat. Acad. Sc. 2007, 104, 6921;
(c) J. Am. Chem. Soc. 2008, in the press.
[4] (a) Organometallics, 2007, 26, 463; (b) Dalton
Trans. 2006, 5492; (c) Chem. Commun. 2005, 3609;
(d) Organometallics, 2004, 23, 428; (e) Dalton
Trans., 2003, 4437; (f) Organometallics, 2002,
21, 2842; (g) Chem. Eur. J., 2002, 8,
2088; (h) Chem. Commun., 2001, 2286; (i) Dalton
Trans. 2007, 1759
[5] (a) Dalton Trans., 2004, 3383; (b) Eur. J.
Inorg. Chem., 2006, 4068; (c) Angew. Chem.
Int. Ed. 2006, 45, 7618; (d) Chem.
Eur. J. 2008, 14, 8383
[6] (a) Chem. Commun. 2006, 3408; (b) Chem.
Eur. J. 2008, 14, 1004; (c) N. J. Chem. 2008, 32,
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