Olefin metatheses in metal coordination spheres: A new strategy for cyclic and macrocyclic organometallic compounds

Article abstract of DOI:10.1021/om9808920

The cationic and neutral rhenium and platinum complexes [(t]5-C5Hs)Re(NO)(PPh3)(S(CH2CH= CH2)2)]+TfO-,fac-(OC)3Re(Br){PPh2(CH2)6CH=CH2}2, and cis-Pt(Cl)2{PPh2(CH2)6CH=CH2}2, which contain sulfide or phosphine ligands with (CH2)nCH=CH2 substituents, undergo efficient intramolecular metatheses with (Cl)2(PCy3)2Ru(=CHPh) to give new sulfide and chelating diphosphine complexes with 5- and 17membered rings.

Full text of DOI:10.1021/om9808920

Organometallics 1999, 18, 955-957
955
Olefin Meta th eses in Meta l Coor d in a tion Sp h er es: A
New Str a tegy for Cyclic a n d Ma cr ocyclic Or ga n om eta llic
Com p ou n d s
J ose´ Miguel Mart´ın-Alvarez,† Frank Hampel,‡ Atta M. Arif,† and
J . A. Gladysz*,†,‡
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, and Institut fu¨r
Organische Chemie, Friedrich-Alexander Universita¨t Erlangen-Nu¨rnberg, Henkestrasse 42,
91054 Erlangen, Germany
Received October 30, 1998
Summary: The cationic and neutral rhenium and plati-
num complexes [(η5-C5H5)Re(NO)(PPh3)(S(CH2CHd
CH2)2)]+TfO-, fac-(OC)3Re(Br){PPh2(CH2)6CHdCH2}2,
and cis-Pt(Cl)2{PPh2(CH2)6CHdCH2}2, which contain
sulfide or phosphine ligands with (CH2)nCHdCH2 sub-
stituents, undergo efficient intramolecular metatheses
with (Cl)2(PCy3)2Ru(dCHPh) to give new sulfide and
chelating diphosphine complexes with 5- and 17-
membered rings.
In principle, olefin metathesis can be applied within
or between ligands. As a test of the former, CH2Cl2
solutions of the previously reported cationic rhenium
diallyl sulfide complex [(η5-C5H5)Re(NO)(PPh3)(S(CH2-
CHdCH2)2)]+TfO- (2; 0.0026 M)8 and 1 (2 mol %, 0.0015
M) were combined (Scheme 1). After 3 h at reflux, NMR
spectra of the homogeneous mixture showed the es-
sentially quantitative formation of a product. Workup
gave the crystalline dihydrothiophene complex [(η5-
Over the past decade, the olefin metathesis reaction
has been applied in virtually every arena of chemical
synthesis.1,2 This has been in large part prompted by
the commercial availability of catalysts and significant
air, moisture, and functional group tolerance.2 The
recent development of enantioselective catalysts should
further accelerate activity.3 However, applications in
organometallic synthesis remain scant.4-6 We were
curious whether olefin metathesis might be a viable
approach to complex target molecules currently under
pursuit in our group. Thus, we set out to investigate a
selection of model reactions. In this communication, we
report that it is possible to utilize the popular Grubbs
catalyst (Cl)2(PCy3)2Ru(dCHPh) (1)7 for a variety of
ring-closing olefin metatheses in metal coordination
spheres.
C5H5)Re(NO)(PPh3)(SCH2CHdCHCH2)]+TfO- (3) in 75%
yield. The structure of 3 followed from its spectroscopic
properties,9 which were similar to those of many related
diallyl sulfide complexes characterized earlier.8 Inter-
estingly, ring-closing metatheses of free diallyl sulfide
with catalysts similar to 1 fail, presumably due to
catalyst deactivation.10 In this regard, it should be noted
that sulfide ligands are easily detached from the rhe-
nium Lewis acid in 2 and 3.8
We next sought to attempt macrocyclizations involv-
ing alkenes on different ligands. Reaction of (OC)5Re-
(Br) and the phosphine PPh2(CH2)6CHdCH2 (4)11 in
refluxing CHCl3 (Scheme 1) gave the neutral rhenium
(8) Cagle, P. C.; Meyer, O.; Weickhardt, K.; Arif, A. M.; Gladysz, J .
A. J . Am. Chem. Soc. 1995, 117, 11730.
* To whom correspondence should be addressed at Friedrich-
Alexander Universita¨t Erlangen-Nu¨rnberg.
(9) All new complexes were characterized by microanalysis and IR,
NMR (1H/13C/31P), and mass spectrometry, as detailed in the Support-
ing Information. Representative procedure: A Schlenk flask was
charged with 5 (0.286 g, 0.303 mmol) and CH2Cl2 (110 mL). Another
Schlenk flask was charged with 1 (0.005 g, 0.006 mmol) and CH2Cl2
(10 mL). The purple solution was added by cannula to the colorless
solution of 5. The mixture was refluxed (3 h). Solvent was removed by
rotary evaporation. The residue was chromatographed on a silica
column (CH2Cl2). The solvent was removed by rotary evaporation to
give 6 as a white powder (0.221 g, 0.242 mmol, 80%), mp 184-185 °C.
NMR (CDCl3, major trans CdC isomer): 1H (δ) 7.62-7.23 (m, 4C6H5),
5.39 (m, CHdCH), 2.77 (m, 2PPh2CHH′), 2.07 (m, 2PPh2CHH′ +
CH2CHdCH), 1.56-1.18 (m, 8CH2); 13C{1H} (ppm) 190.0, 189.3 (2 t,
1:2, J CP ) 28.7, CO), 131.1 (s, CHdCH), 134-133 (complex i-Ph), 133.2,
132.8 (2 virtual t, J CP ) 4.5, o-Ph), 130.1, 130.1 (2 s, p-Ph), 128.7, 128.3
(2 virtual t, J CP ) 4.1, m-Ph), 32.3 (s, CH2CHdCH), 30.5 (virtual t,
J CP ) 5.6), 29.2 (s), 28.7 (s), 25.5 (virtual t, J CP ) 12.1), 24.4 (br s);
31P{1H} -8.2 (s) ppm.
† University of Utah.
‡ Friedrich-Alexander Universita¨t Erlangen-Nu¨rnberg.
(1) Ivin, K. J .; Mol, J . C. Olefin Metathesis and Metathesis Poly-
merization; Academic Press: New York, 1997.
(2) (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413. (b)
Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037;
Angew. Chem. 1997, 109, 2124.
(3) (a) Alexander, J . B.; La, D. S.; Cefalo, D. R.; Hoveyda, A. H.;
Schrock, R. R. J . Am. Chem. Soc. 1998, 120, 4041. (b) La, D. S.;
Alexander, J . B.; Cefalo, D. R.; Graf, D. D.; Hoveyda, A. H.; Schrock,
R. R. J . Am. Chem. Soc. 1998, 120, 9720.
(4) (a) Mohr, B.; Weck, M.; Sauvage, J .-P.; Grubbs, R. H. Angew.
Chem., Int. Ed. Engl. 1997, 36, 1308; Angew. Chem. 1997, 109, 1365.
(b) Dietrich-Buchecker, C.; Rapenne, G.; Sauvage, J .-P. J . Chem. Soc.,
Chem. Commun. 1997, 2053.
(5) Ferrocene-based examples: (a) Gamble, A. S.; Patton, J . T.;
Boncella, J . M. Makromol. Chem., Rapid Commun. 1993, 13, 109. (b)
Buretea, M. A.; Tilley, T. D. Organometallics 1997, 16, 1507.
(6) There are, of course, many examples of LnMdC + CdC met-
atheses in metal coordination spheres, but catalyzed CdC + CdC
metatheses are very rare.4
(10) Armstrong, S. K.; Christie, B. A. Tetrahedron Lett. 1996, 37,
9373.
(11) The new phosphine 4 was isolated in 88% yield from the
reaction of LiPPh2 and commercial Br(CH2)6CHdCH2. The lower
homologue PPh2(CH2)4CHdCH2 has been characterized previously:
J ackson, W. R.; Perlmutter, P.; Suh, G.-H. J . Chem. Soc., Chem.
Commun. 1987, 724.
(7) Compound 1 has been designated as the 1998 “Reagent of the
Year” by Fluka, one of several commercial vendors. The Schrock
molybdenum catalyst is also now commercially available.
10.1021/om9808920 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 02/20/1999

956 Organometallics, Vol. 18, No. 6, 1999
Communications
Sch em e 1. Rin g-Closin g Olefin Meta th esis in
Meta l Coor d in a tion Sp h er es
The crystal structures of 6 and 7 were determined as
described in the Supporting Information, and selected
results are given in Figure 1. The data confirm the
macrocyclic nature of 6 and 7, which exhibit remarkably
similar Ph2P(CH2)6CHnCHn(CH2)6PPh2 conformations
(despite some disorder in 7), identical space groups (P21/
c, Z ) 4), and nearly equal unit cell dimensions. The
metrical parameters are routine, but van der Waals
representations show some void space within the mac-
rocycles. NMR spectra of crystalline 6 show both CdC
isomers. Interestingly, either trans or cis isomers can
dominate in macrocyclizations catalyzed by 1.12
We next sought to attempt macrocyclizations involv-
ing different metals. Accordingly, a reaction of Pt(Cl)2-
(COD) and 4 in CH2Cl2 (Scheme 1) gave the neutral
platinum bis(phosphine) complex cis-Pt(Cl)2{PPh2(CH2)6-
CHdCH2}2 (8) in 70% yield.9 This test substrate is also,
in contrast to those above, coordinatively unsaturated.
Solutions of 8 (0.0027 M) and 1 (2 mol %; 0.0012 M) in
CH2Cl2 were combined and refluxed (3 h). Workup gave
an analytically pure complex of empirical formula cis-
Pt(Cl)2{PPh2(CH2)6CHdCH(CH2)6PPh2} (9) in 71% yield.
The dCHCH2 13C NMR chemical shift (32.2 ppm)
indicated a trans isomer.12 Careful analysis showed a
minor second component (31P NMR: 91:9 in CDCl3 (7.7,
7.9 ppm) or acetone). On the basis of precedent with
other Pt(Cl)2 adducts of chelating phosphines,13 we
suspected that one component was a dimer formed by
bridging two phosphines between two platinums, as
shown in Scheme 1.
Indeed, FAB mass spectra showed strong ions with
masses corresponding to (9 - Cl)+ and (9 + 9 - Cl)+
(63% and 46%). However, an osmotic molecular weight
determination established that the major species in
solution was the monomer (calcd, 830.8; found (CHCl3),
844). As depicted in Figure 1, a crystal structure showed
only the monomer 9. The unit cell dimensions of six
additional crystals were determined, and all were
identical. Nonetheless, crystals were dissolved in ac-
etone that had been cooled to -80 °C, and a 31P NMR
spectrum was immediately recorded. Interestingly, both
isomers were present (91:9).
There are two highly significant previous reports of
related chemistry.4 Sauvage and Grubbs have found
that cationic alkene-substituted copper 1,10-phenan-
throline complexes and 1 can react to give macrocycles
that are easily elaborated to novel catenanes or molec-
ular knots. In conclusion, the preceding data show that
1 is able to catalyze olefin metatheses in the coordina-
tion spheres of both cationic and neutral, and coordi-
natively saturated and unsaturated, metal complexes.
Given our success with phosphine and sulfur donor
ligands, we extrapolate that a wide variety of alkene-
bearing ligands can be utilized. The conversion of 2 to
3 further demonstrates that transition metals can be
employed as protecting groups for functionality that
would otherwise deactivate the catalyst. These findings
open up an exciting range of new architectural possibili-
ties for directed organometallic synthesis. Applications
to complex targets will be reported soon.
bis(phosphine) complex fac-(OC)3Re(Br){PPh2(CH2)6-
CHdCH2}2 (5) in 72% yield.9 Then CH2Cl2 solutions of
5 (0.0028 M) and 1 (2 mol %; 0.0012 M) were combined
and refluxed (3 h). Workup gave the macrocycle fac-
(OC)3Re(Br){PPh2(CH2)6CHdCH(CH2)6PPh2} (6) in 80%
yield as an (83-80):(17-20) mixture of geometric iso-
1
mers, as evidenced by two CHdCH H NMR signals (δ,
acetone-d6, decoupling: 5.42, 5.37). The dCHCH2 13C
NMR chemical shifts (32.3, 29.5 ppm) showed the major
species to be a trans isomer.12 Hydrogenation (1 atm,
Pd/carbon, toluene/ethanol) gave the saturated macro-
cycle fac-(OC)3Re(Br){PPh2(CH2)14PPh2} (7) in 98%
yield.
(12) (a) Fu¨rstner, A.; Langemann, K. J . Org. Chem. 1996, 61, 3942.
(b) Fu¨rstner, A.; Langemann, K. Synthesis 1997, 792.
(13) Hill, W. E.; Minahan, D. M. A.; Taylor, J . G.; McAuliffe, C. A.
J . Am. Chem. Soc. 1982, 104, 6001.

Communications
Organometallics, Vol. 18, No. 6, 1999 957
F igu r e 1. Molecular structures of 6 (top left), 7 (top right), and 9 (bottom). Key bond lengths (Å) and angles (deg) are as
follows. 6/7: Re-Br, 2.6614(14)/2.6540(12); Re-C39, 1.899(10)/1.949(11); Re-C40, 1.912(11)/2.054(13); Re-C41, 1.901-
(8)/1.936(10); Re-P1, 2.499(2)/2.487(3); Re-P2, 2.534(2)/2.520(3); P1-C1, 1.830(8)/1.819(10); C1-C2, 1.507(13)/1.526(14);
C2-C3, 1.520(18)/1.53(3); C3-C4, 1.30(3)/1.53(3); C4-C5, 1.45(2)/1.58(2); C5-C6, 1.43(3)/1.48(2); C6-C7, 1.48(3)/1.53(2);
C7-C8, 1.23(2)/1.50(2); C8-C9, 1.59(2)/1.52(2); C9-C10, 1.525(16)/1.502(14); C10-C11, 1.518(16)/1.52(2); C11-C12, 1.512-
(13)/1.511(13); C12-C13, 1.530(12)/1.521(14); C13-C14, 1.506(12)/1.529(13); P2-C14, 1.840(8)/1.826(9); P1-Re-P2, 97.48-
(7)/97.97(8); C1-P1-Re, 114.9(3)/115.5(4); C2-C1-P1, 114.6(7)/114.4(7); C1-C2-C3, 111.5(11)/113(10); C4-C3-C2,
123.5(19)/112(3); C3-C4-C5, 127(3)/111(10); C6-C5-C4, 116(2)/116.6(11); C5-C6-C7, 120.1(19)/114.6(12); C8-C7-C6,
126(2)/116.8(12); C7-C8-C9, 129(2)/115.3(11); C10-C9-C8, 109.7(13)/112.4(10); C11-C10-C9, 114.9(11)/114.5(9); C12-
C11-C10, 112.4(9)/115.3(9); C11-C12-C13, 115.7(9)/114.1(9); C14-C13-C12, 111.5(7)/111.9(8); C13-C14-P2, 113.5(6)/
114.1(7); C14-P2-Re, 121.2(3)/122.3(3). 9: Pt-P1, 2.261(2); Pt-P2, 2.2492(13); Pt-Cl1, 2.337(2); Pt-Cl2, 2.3586(13);
P1-C1, 1.818(4); C1-C2, 1.546(6); C2-C3, 1.544(7); C3-C4, 1.532(7); C4-C5, 1.527(7); C5-C6, 1.524(8); C6-C7, 1.445-
(9); C7-C8, 1.353(9); C8-C9, 1.472(8); C9-C10, 1.522(8); C10-C11, 1.509(7); C11-C12, 1.519(8); C12-C13, 1.528(6);
C13-C14, 1.527(7); P2-C14, 1.829(5); P1-Pt-Cl2, 84.86(5); P2-Pt-Cl1, 89.85(5); Cl1-Pt-Cl2, 87.10(5); P2-Pt-P1, 98.22-
(5); C1-P1-Pt, 107.7(2); C2-C1-P1, 119.6(3); C1-C2-C3, 111.3(4); C4-C3-C2, 112.7(4); C5-C4-C3, 114.1(5); C4-
C5-C6, 115.3(5); C7-C6-C5, 113.7(5); C8-C7-C6, 124.1(6); C7-C8-C9, 127.0(6); C8-C9-C10, 111.3(5); C11-C10-
C9, 115.4(5); C10-C11-C12, 113.9(5); C13-C12-C11, 112.5(5); C14-C13-C12, 112.8(4); C13-C14-P2, 113.5(3); C14-
P2-Pt, 116.1(2).
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
Ack n ow led gm en t. We thank the NSF for support
cedures and tables of crystallographic data for 6, 7, and 9. This
of this research, the Ministerio de Educacio´n y Ciencia
material is available free of charge via the Internet at
(Spain), and the Fulbright Commission for Fellow-
http://pubs.acs.org.
ships (J .M.M.-A.) and Dr. J . Ruwwe for supporting
observations.
OM9808920