Olefin metatheses in metal coordination spheres: Novel trans-spanning bidentate and facially-spanning tridentate macrocyclic phosphine complexes

Article abstract of DOI:10.1039/b007405p

The title reaction is applied to square-planar rhodium and platinum complexes with trans PPh₂(CH₂)₆CH=CH₂ ligands, and square-planar platinum or octahedral tungsten complexes with trans or facial PPh[(CH₂

Full text of DOI:10.1039/b007405p

Olefin metatheses in metal coordination spheres: novel trans-spanning
bidentate and facially-spanning tridentate macrocyclic phosphine complexes
Eike B. Bauer,a Johannes Ruwwe,ab José Miguel Martín-Alvarez,b Thomas B. Peters,b James C. Bohling,b
Frank A. Hampel,a Slawomir Szafert,ac Tadeusz Lisc and J. A. Gladysz*a
a Institut für Organische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, 91054
Erlangen, Germany. E-mail: john.gladysz@organik.uni-erlangen.de
b Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
c
Department of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland
Received (in Cambridge, UK) 12th September 2000, Accepted 2nd October 2000
First published as an Advance Article on the web
The title reaction is applied to square-planar rhodium and
platinum complexes with trans PPh2(CH2)6CHNCH2 li-
gands, and square-planar platinum or octahedral tungsten
complexes with trans or facial PPh[(CH2)6CHNCH2]2 li-
gands. Ring-closing (poly)macrocyclizations occur.
ties.10 Fig. 1 shows the crystal structure of 5b,† highlighting the
basket-handle-like trans-spanning ligand.
New applications of olefin metathesis are rapidly appearing in
nearly every area of organic synthesis.1 However, there have
been few reports of olefin metatheses in metal coordination
spheres.2–7 Some early observations of Rudler and coworkers2
were followed by elegant applications in catenane syntheses3,4
and ferrocenophane polymerizations.5 We recently showed that
Grubbs’ catalyst, Cl2(Cy3P)2Ru(NCHPh) 1, can be applied to a
variety of coordinatively saturated and unsaturated, neutral and
charged, alkene-containing phosphine or thioether com-
plexes—unequivocally demonstrating general applicability.6
From this beginning, we sought to develop directed syntheses of
more sophisticated organometallic targets. Here, we present
three innovative and progressively more topologically challeng-
ing extensions: (1) monomacrocyclizations involving trans
phosphine ligands, each with one terminal alkene moiety, (2)
dimacrocyclizations involving trans phosphine ligands, each
with two terminal alkene moieties, and (3) trimacrocyclizations
involving facial phosphine ligands, each with two terminal
alkene moieties.
Fig. 1 Crystal structure of 5b.
Next, the phosphine-dialkene PPh[(CH2)6CHNCH2]2 6 was
prepared in 78% yield from H2PPh, BunLi (2.1 equiv), and
Br(CH2)6CHNCH2 (2.0 equiv.). Reaction with [Pt(m-
Cl)(C6F5)(SR2)]2
gave
trans-Pt(Cl)(C6F5)-
{PPh[(CH2)6CHNCH2]2}2 7 (91%), which could give two types
of metathesis/hydrogenation products, 8 and 9, as shown in
Scheme 2. The latter features two macrocyclic monop-
hosphines, an efficient cyclization mode for 1+1 metal com-
plexes of 6.11 The former features one macrocyclic diph-
osphine, with two diastereomers differing in the orientations of
the phenyl groups (8a,b). Under conditions similar to those in
The phosphine-monoalkene PPh2(CH2)6CHNCH2 2,6 bridg-
ing chloride complex [Rh(m-Cl)(cod)]2, and CO were combined
under conditions previously used to prepare rhodium bis-
phosphine complexes trans-Rh(Cl)(CO)(L)2.8 Workup gave
trans-Rh(Cl)(CO)[PPh2(CH2)6CHNCH2]2 3a as a yellow pow-
der in 83% yield. The reaction of 2 and the tetrahydrothiophene
9
(SR2) complex [Pt(m-Cl)(C6F5)(SR2)]2 similarly led to the
platinum
bis-phosphine
complex
trans-Pt(Cl)(C6F5)-
[PPh2(CH2)6CH = CH2]2 3b, (90%). As shown in Scheme 1,
CH2Cl2 solutions of 3a or 3b (0.0027–0.0025 M) and 1 (5.0–7.0
mol%) were refluxed. Workups gave macrocycles 4 (M/X =
Rh/CO a, Pt/C6F5 b) in 83–90% yields and as 90–83+10–17
mixtures of E/Z CNC isomers, as assayed by standard 13C or 1H
NMR criteria.3b,6 Hydrogenations over 10% Pd/C (1 atm) gave
the corresponding saturated macrocycles 5a (yellow oil, 35%)
and 5b (white powder, 90%). The structures of all the preceding
compounds followed readily from their spectroscopic proper-
Scheme 1 Monomacrocyclizations catalyzed by Cl2(Cy3P)2Ru(NCHPh) 1.
M/X = a, Rh/CO; b, Pt/C6F5.
Scheme 2 A dimacrocyclization reaction.
DOI: 10.1039/b007405p
Chem. Commun., 2000, 2261–2262
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Fig. 2 Crystal structure of 8a.
Fig. 3 Crystal structure of 11aA.
strated the utility of Grubbs’ catalyst 1 for the construction of
topologically novel organometallic (poly)macrocycles from
easily accessed precursors in a single step.
We thank the Deutsche Forschungsgemeinschaft (DFG; GL
300-1/1) and US National Science Foundation for support.
Scheme 3 A trimacrocyclization reaction
Notes and references
† Crystal
C63H93O3P3W, M
hexagonal,
data;
5b/8a/11aA:
964.30/1006.47/1175.13, monoclinic/monoclinic/
31.7963(7)/24.8121(3)/18.900(8),
C44H48ClF5P2Pt/C46H66ClF5P2Pt/
Scheme 1, reactions of 7 and 1 gave 84–65% yields of
metathesized products, which were hydrogenated and chroma-
tographed on alumina. The two least polar products were
isolated in 31 and 7% yields, and shown by X-ray crystallog-
raphy to be 8a and 8b, respectively.† The structure of the former
is given in Fig. 2. Some diplatinum products form, and the
conditions for this sequence are still being optimized. However,
no traces of 9 have been detected to date—a surprising and
highly exploitable selectivity.
=
=
a
b
=
10.7342(3)/10.5438(2)/18.900(8), c = 24.9213(6)/18.0730(4)/9.842(3) Å,
V = 8311.2(4)/4575.32(14)/3045(2) Å3, T = 173(2)/173(2)/95(2) K, space
groups C2/c, P21/c, P3, Z = 8/4/2, m(Mo-Ka) = 3.570/3.246/2.017 mm21
,
=
¯
15944/17699/14105 reflections measured, 9273/10322/3555 unique (Rint
0.0683/0.0549/0.0796), which were used in calculations. Final R values: R1
[I 2s(I)] 0.0435/0.0404/0.1018; wR2 (all data)
>
=
=
0.1278/0.0796/0.1647. Two CH2 groups in 5b were disordered and could
not be fully resolved. Refined partial occupancy (C10/C10A, C11/C11A):
55+45. CCDC 182/1815. See http://www.rsc.org/suppdata/cc/b0/
b007405p/ for crystallographic files in .cif format.
We sought to attempt even more speculative types of
macrocyclizations. Many tungsten triphosphine complexes fac-
W(CO)3(L)3 are known, and 10 (Scheme 3) was prepared by a
standard method.12 This could give three different types of
metathesis products, each with a plethora of CNC and/or PPh
isomers (a: one triphosphine, 16 isomers; b: one diphosphine
and one monophosphine, 18 isomers; c: three monophosphines,
4 isomers). Reaction with 1 as above and chromatography gave
a sample of empirical formula W(CO)3{PPh[(CH2)6CHN]2}3 11
(83%), as assayed by NMR and mass spectrometry. HPLC
showed three overlapping regions of many partially resolved
peaks. Hydrogenation could be effected (94%), but under no
1 Top. Organomet. Chem., ed. A. Fürstner, Springer, Berlin, 1998, vol. 1.
2 C. Alvarez Toledano, A. Parlier, H. Rudler, J. C. Daran and Y. Jeannin,
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Parlier, H. Rudler and J. C. Daran, Organometallics, 1987, 6, 1057.
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Int. Ed. Engl., 1997, 36, 1308; (b) M. Weck, B. Mohr, J.-P. Sauvage and
R. H. Grubbs, J. Org. Chem., 1999, 64, 5463.
4 C. Dietrich-Buchecker, G. Rapenne and J.-P. Sauvage, Chem. Com-
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10 New complexes were characterized by IR, NMR (1H/13C/31P), and MS.
All except 3b and 7 gave correct microanalyses. Representative
procedures have been described earlier.6
conditions was
a preparatively meaningful purification
achieved. Nonetheless, two macrocyclic triphosphine com-
plexes (11aA, 11aB) could be crystallized from the mixture
before hydrogenation, and X-ray structures of both were
determined.† That of 11aA, which is representative, is shown in
Fig. 3. All PPh groups are anti to the W(CO)3 moiety in 11aA,
whereas one is syn in 11aB. Each has three E-CNC linkages.
The preceding syntheses have many noteworthy features.
First, a variety of complexes with trans-spanning diphosphines
are known.13 However, our route is the first to link two existing
monophosphines with a hydrocarbon tether. Second, doubly
trans-spanning diphosphines such as in 8 are to our knowledge
unknown. However, a conceptually similar two-fold ring-
closing metathesis involving trans 2,6-disubstituted pyridine
ligands has recently been reported.7a Here, the pyridine
geometry favors the formation of trans-spanning bridges,
whereas 7 lacks a structure-based driving force. Third, in
contrast to the surprisingly selective conversion of 7 to 8, 10
appears to give virtually every possible product. Such behavior,
disparaged in the past, is now praised as an efficient route to a
combinatorial library. Importantly, other strategies have been
used to effect high-yield template syntheses of 10–15 mem-
bered facially-spanning triphosphine complexes from tris-
monophosphine complexes.14 In conclusion, we have demon-
5
11 J. M. Martín-Alvarez and C. H. Horn, unpublished results with [(h -
C5Me5)Re(NO)(6)(L)]n+ systems.
12 G. J. Kubas, Inorg. Chem., 1983, 22, 692.
13 Recent lead references to trans-spanning phosphine ligands: D.
Armspach and D. Matt, Chem. Commun., 1999, 1073; W. J. Perez, C. H.
Lake, R. F. See, L. M. Toomey, M. R. Churchill, K. J. Takeuchi, C. P.
Radano, W. J. Boyko and C. A. Bessel, J. Chem. Soc., Dalton Trans.,
1999, 2281.
14 B. N. Diel, P. F. Brandt, R. C. Haltiwanger, M. L. J. Hackney and A. D.
Norman, Inorg. Chem., 1989, 28, 2811; P. G. Edwards, P. D. Newman
and D. E. Hibbs, Angew. Chem., Int. Ed., 2000, 39, 2722 and extensive
earlier work cited therein.
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