Phosphine-substituted porphyrins as supramolecular building blocks

Article abstract of DOI:10.1039/b000482k

A route to alkyne-phosphine-substituted metalloporphyrins is presented. The X-ray structure of the methanol adduct of a diphenylphosphine Zn(II) porphyrin reveals solid state dimerisation accompanied by proton transfer from coordinated methanol to phosphine in a process reminiscent of carbonic anhydrase. The ability of the phosphine-substituted porphyrins to form non- covalent arrays with a Ru(II) porphyrin was explored using ¹H/³¹P NMR and UV/vis spectroscopy as well as MALDI-TOF mass spectrometry.

Full text of DOI:10.1039/b000482k

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Phosphine-substituted porphyrins as supramolecular building blocks
Scott L. Darling, Eugen Stulz, Neil Feeder, Nick Bampos and Jeremy K. M. Sanders*
Cambridge Centre for Molecular Recognition, University Chemical L aboratory, L ensÐeld Road,
Cambridge, UK CB2 1EW . E-mail: jkms=cam.ac.uk
L e t t e r
Received (in Montpellier, France) 17th January 2000, Accepted 20th March 2000
A route to alkyne-phosphine-substituted metalloporphyrins is
presented. The X-ray structure of the methanol adduct of a
diphenylphosphine Zn(II) porphyrin reveals solid state dimer-
isation accompanied by proton transfer from coordinated meth-
metal chloride to produce a Grignard-type alkynyl complex.¤
The reactivity of alkynyl metal complexes was found to
increase in the order Na \ Li B Cu(II) B Zn(II) @ Mg(II) B
Ce(III) @ Cd(II). This reagent reacts in situ with an electrophilic
anol to phosphine in
a
process reminiscent of carbonic
phosphorus such as ClPPh to give, after acidic workup,
2
anhydrase. The ability of the phosphine-substituted porphyrins
to form non-covalent arrays with a Ru(II) porphyrin was
explored using 1H/31P NMR and UV/vis spectroscopy as well
as MALDI-TOF mass spectrometry.
H -1, H -2 or Ni-2, respectively.” The phosphines were pro-
2
2
tected in situ by treatment with a slight excess of BH SMe at
3
2
[30 ¡C to prevent oxidation during work-up and puriÐ-
cation.7 Nevertheless, the reactions are best carried out using
standard Schlenk techniques. Changing the central metal from
Zn(II) to Ni(II) did not prevent phosphine oxidation, but the
reaction was signiÐcantly retarded. The phosphine oxides,
In pursuit of new building blocks capable of forming supra-
molecular arrays via non-covalent interactions,1 we have
begun to explore the coordination of phosphines to Ru(II)
porphyrins. In particular, we describe here the synthesis of
metalloporphyrins linked via rigid alkynes to phosphine
groups, which can then generate oligoporphyrin arrays by
coordinating to Ru(II) porphyrins. To our knowledge no such
compounds have been reported previously.
Phosphine donors are known to coordinate strongly to
Ru(II).2 In porphyrins, the octahedral geometry of Ru is satis-
Ðed by the four equatorial nitrogens of the heterocyclic core,
CO and a molecule of solvent, which can be exchanged by a
suitable ligand at ambient temperature to produce
mono(phosphine) complexes, while bis(phosphine) complexes
are obtained via thermal displacement of the CO ligand.3 To
date, Ru(II) porphyrins have been used to study the oxidation
of phosphines to phosphine oxides;4 if the porphyrin has a
chiral superstructure, then enantioselectivity can be obtained
when binding racemic phosphines.5
however, can be reduced using Cl SiH in toluene.8 Metalla-
3
tion of the free base porphyrin phosphines is easily achieved
by standard procedures using the metal acetates to yield
quantitatively the corresponding Zn and Ni porphyrins.
The 31P NMR shifts for the phosphine porphyrins are diag-
nostic for distinguishing the phosphines (d [ 32.2) from the
phosphine oxides (d 8.9); the nature of the metal and the sub-
stitution pattern did not show any inÑuence on the chemical
shift of either the phosphine or phosphine oxide. The 31P
NMR resonance for the zinc phosphine series was slightly
broadened in CDCl at room temperature, but sharpened
3
either upon cooling to [20 ¡C or by recording the spectrum
in C D N. This indicates a dynamic yet weak complexation of
5
5
Bis(triarylphosphine) complexes of ruthenium porphyrins
have been reported to be labile in solution and dissociate to
the corresponding mono-phosphine complex as revealed by
UV/vis studies.3a After mixing 1 : 1 or 1 : 2 ratios of Ru-1
with PPh or PFu (Fu \ 2-furyl), both 1H and 31P NMR
3
3
spectra exhibited extremely broad lines at room temperature,
indicating a dynamic exchange between free and bound
species on the chemical shift timescale, thus conÐrming the
lability of these systems. In contrast, a sterically less hindered
tertiary phosphine such as diphenylphosphinoacetylene (DPA)
showed, upon addition of 1 equiv. to Ru-1, rapid formation of
the mono-substituted complex at room temperature,
exhibiting sharp signals in the 31P NMR spectrum [d(free)
[34, d(bound) [15]. A bis(phosphine) complex was observed
when using 2 equiv. of DPA and the sample was warmed to
40 ¡C, as judged by the appearance of a sharp signal at
d (31P) 2. As we have already synthesised alkyne-substituted
porphyrins in our laboratory,6 these porphyrins seem to be
the precursors of choice to attach a diphenylphosphine, thus
creating a supramolecular building block with reduced steric
hindrance compared with triarylphosphines.
To synthesise phosphine-substituted porphyrins, we envis-
aged deprotonation of the alkynes Zn-1, Zn-2 or Ni-1 using
lithium hexamethyldisilazane (LiHMDS) in THF ([78 ¡C,
Scheme 1), followed by transmetallation using a transition
Scheme 1 Reagents and conditions: (i) LiHMDS, CdCl , THF,
2
[78 ¡C; (ii) ClPPh , [78 ¡C ] rt; (iii) BH SMe , [30 ¡C;
2
3
2
(iv) HNEt , 50 ¡C; (v) M(OAc) , CHCl ÈMeOH, heat.
2
2
3
DOI: 10.1039/b000482k
New J. Chem., 2000, 24, 261È264
261
This journal is ( The Royal Society of Chemistry and the Centre National de la Recherche ScientiÐque 2000

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phine ligands on zinc porphyrins cause large red shifts (* ca.
10 nm) and substantial changes in the intensity ratios (* ca.
0.3) due to their r-donor properties.9 Also the free base and
nickel phosphines exhibited essentially identical absorption
spectra as their phosphine oxide counterparts.
In the solid state, however, formation of a dimeric structure
was observed by X-ray analysis of a suitable crystal of Zn-4
(Fig. 1),° where the most striking observation is deprotonation
of a metal-bound methanol by the phosphine; the proton
bound to the phosphorus could be located from signiÐcant
residual electron density in the di†erence Fourier map and
(isotropically) reÐned. The dimer is cooperatively supported
by two equivalent hydrogen bonds between the protonated
phosphine and the zinc bound methoxide (PÈHÉ É ÉO, 2.67 A;
PÈH, 1.36 A). The PÈH bond length is consistent with that in
other reported protonated phosphines.10 Although there are
reported examples of deprotonated zinc-bound alcohols,11 the
structure of Zn-4 is to our knowledge the Ðrst zinc-bound
methoxide to be deprotonated by a phosphine and held
together by PÈHÉ É ÉO bonds. Indeed, the structure is remi-
niscent of the active sites of some of the hydrolytic zinc
enzymes such as carboxypeptidase A and carbonic anhy-
drase.12
Fig. 1 X-Ray structure of the Zn-4 dimer. Thermal ellipsoids are
drawn at the 50% probability level. H atoms (except for phosphine
and Zn-bound methanol) and hexyl sidechains are omitted for clarity;
dashed line indicates H bonding. Alternative disordered orientations
are not shown.
the phosphine to the zinc to give dimerisation; this was not
observed in the free base or nickel series. The UV/vis spectra
of Zn-4 (10~6 M in toluene) did not show a red shift of the
B-band absorption compared to its oxide, which does not
form any complexes with Ru-1 in solution (as judged by 31P
NMR). The Q-bands are red shifted by 2 nm, and the ratio of
the intensities Q(a)/Q(b) increased from 0.56 for the oxide to
0.64 for Zn-4. Since these di†erences are small, dimerisation is
a negligible phenomenon in dilute solutions, because phos-
When phosphine porphyrins are mixed with 1 equiv. of
Ru-1 in CDCl , complexes [Ru-1/Por-PPh ] (Por \
3
2
porphyrin) are readily formed with a distinct 1 : 1 stoichiom-
etry, showing sharp lines in the 31P NMR spectra. The reso-
nances for the complexed phosphines are downÐeld shifted
and appear at d(31P) [13.2. Again, the nature of the metal in
the phosphine porphyrin and the substitution pattern had no
inÑuence on the chemical shift di†erence (*d 19 upon
complexation), but complexation of the phosphines to ruthe-
nium leads to more stable complexes compared to complex-
ation to zinc, as indicated by the narrower resonance. The
proton signals of the phosphine residue were typically upÐeld
shifted in the complexes as a result of the ring current of the
aromatic porphyrin core, and the observation of diagnostic
nOe connectivities between the phosphine porphyrin and
Ru-1 in the NOESY spectrum of [Ru-1/Zn-4] conÐrmed the
coordination, presumably at an angle as depicted in Fig. 2.
Inequivalency of the a and b sides of the Ru-1 moiety can be
seen by the di†erent proton chemical shifts of the H-15 and
H-16 But groups at the periphery of Ru-1, whereas the H-14
But groups of the phosphine porphyrin moiety appear equiva-
lent. The UV/vis spectra of 1 : 1 mixtures of the phosphine
porphyrins with Ru-1 proved to be a superposition of the
absorption spectra of the individual components; therefore
the conjugates do not exhibit exciton coupling in the elec-
tronic ground state.13 We attribute the absence of electronic
communication to the relatively large distance between the
chromophores, as conÐrmed by the una†ected NÈH NMR
Fig. 2 Selected nOe connectivities for [Ru-1/Zn-4].
resonance in [Ru-1/H -2].
2
Mixing 2 equiv. of phosphine porphyrin with Ru-1 and
boiling the CDCl solution for 5 h resulted in formation of a
3
new species assigned to trimeric porphyrin arrays of the com-
position [Por-PPh /Ru-1/Por-PPh ] and showing
a 31P
2
2
NMR resonance at d 3.0. As no free phosphine was detected
in the 31P NMR spectra, the formation of the trimeric com-
plexes was virtually complete. The even larger downÐeld shift
compared to the dimeric arrays is indicative of the much
weaker p-backbonding ability of a phosphine ligand on the
ruthenium compared to a CO ligand in a trans position. The
diagnostic proton resonances were again the aryl proton
signals of the phosphine residues, which have essentially iden-
tical chemical shifts as in the dimeric arrays. The isochronic
resonances of H-15 and H-16 are indicative of an equivalent
trans coordination of the two phosphines to Ru-1. As in the
dimeric arrays, the measured UV/vis spectra of the trimeric
complexes could be perfectly reproduced by calculation of the
additive superposition of the individual components.
Fig. 3 MALDI-TOF mass spectrum of a 5 : 1 mixture (CHCl ) of
3
Ni-2 with Ru-1, neat sample. H tpp (m/z 615.25) served as internal
2
reference; for peak assignments see text.
262
New J. Chem., 2000, 24, 261È264

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The MALDI-TOF mass spectrum of a 1 : 1 mixture of Ni-2
with Ru-1 showed signals at m/z 955 (Ru-1 [ CO, calcd. 955),
1234 (Ni-2, calcd. 1231), 1913 [(Ru-1 [ CO) dimer, calcd.
1910] and 2191 ([Ru-1/Ni-2], calcd. 2186). Raising the
amount of phosphine to a 5 : 1 ratio did not increase the rela-
tive amount of complex detected in the mass spectrum, nor
were peaks observed that would indicate formation of the
bis(phosphine) complex in the gas phase, but signiÐcantly Ru
dimerisation was completely inhibited (Fig. 3).14 This result
shows that stable arrays between phosphine-substituted
porphyrins and ruthenium porphyrins are not only readily
formed in solution, but remain intact in the gas phase and can
even be detected by MALDI-TOF mass spectrometry.
In summary, we have developed a general synthetic route to
phosphine porphyrins, and an X-ray structure revealed unex-
pected deprotonation of Zn-bound methanol. The phosphine
porphyrins are capable of forming dimeric and trimeric
hetero-dimetallic porphyrin arrays in solution, the former
being also stable in the gas phase, and contribute new supra-
molecular building blocks exhibiting orthogonal, non-
covalent binding motifs when combined with suitable central
metals.
144.7 (s), 143.4 (s), 143.1 (s), 141.5 (s), 141.4 (s), 140.9 (s), 136.6
(s), 136.3 (s, J 6.3 Hz), 135.7 (s), 133.1 (d), 132.8 (d), 132.6 (d),
PvC
131.0 (d), 129.1 (d), 128.7 (d, J
7.5 Hz), 127.5 (d), 122.6 (s),
PvC
121.1 (d), 119.6 (s), 116.3 (s, C3 C, J 28.8 Hz), 96.7 (d), 86.4 (s,
C3 C), 34.9 (t), 33.0 (t), 31.7 (t), 31.6 (t), 31.4 (q), 29.7 (t), 29.6 (t),
PvC
26.5 (t), 22.5 (t), 22.4 (t), 14.8 (q), 14.0 (q), 13.9 (q). 31P NMR
(CDCl , 161.97 MHz): d \ [32.2. MALDI-TOF MS: calcd.
3
1176, found 1174.
An analogous reaction using Ni-1 yielded directly Ni-2 in
75% yield.
Metallation reactions. Metallation of H -2 was achieved by
2
reÑuxing a CHCl ÈMeOH solution (5 ] 1 ml) of H -2 (100
3
2
mg, 0.085 mmol) with Zn(OAc) Æ 2H O (187 mg, 0.85 mmol)
2
2
or Ni(OAc) Æ 4H O (211 mg, 0.85 mmol) for 1 h (Zn) or 4 h
2
2
(Ni). After evaporation of the solvent, the residue was
extracted with CHCl until the Ðltrate appeared colourless.
3
Crystallisation from CHCl ÈMeOH (1 ] 15 ml) at [20 ¡C
3
overnight gave the pure metallated phosphine porphyrins in
quantitative yields.
Selected data for Zn-4: UV/vis (toluene, j/nm, lg e): 414
(5.53), 538 (4.28), 574 (4.09). 1H NMR (CDCl , 400 MHz):
3
d \ 10.20 (s, 2 H, meso-H), 8.10 (d, J 8.0 Hz, 2 H, H-8), 7.96 (d,
J 1.8 Hz, 2 H, H-9), 7.94 (d, J 8.0 Hz, 2 H, H-7), 7.81 (m, 4 H,
H-4), 7.78 (d, J 1.8 Hz, 1 H, H-10), 7.46 (m, 6 H, H-5/6), 3.99
[m, 8 H, CH (CH ) CH ], 2.51 (s, 6 H, H-12), 2.46 (s, 6 H,
Experimental
2
2 4
3
All experiments and manipulations were performed under an
Ar atmosphere using freshly distilled and carefully degassed
solvents. Standard Schlenk techniques in appropriate glass-
ware were used throughout the experiments and analysis. The
molecular mass of Ru-1 (1014.42) was calculated as the MeOH
solvate.
H-13), 2.21 [m, 8 H, CH CH (CH ) CH ], 1.78 [m, 8 H,
2 3
(CH ) CH (CH ) CH ], 1.54 (s, 18 H, H-14), 1.49 [m, 8 H,
2 2 2 2
(CH ) CH CH CH ], 1.37 [m, 8 H, (CH ) CH CH ], 0.91 [t,
2 3 3 4
2
2
3
2
2
3
2
3
2
3
3
J 7.3 Hz, 12 H, (CH ) CH ]. 31P NMR (CDCl , 161.97
MHz): d \ [32.2. MALDI-TOF MS: calcd. 1240, found
1237.
2 5
3
Selected data for Ni-3: UV/vis (toluene, j/nm, lg e): 410
(5.35), 530 (4.19), 564 (4.33). 1H NMR (CDCl , 500 MHz):
Syntheses
3
d \ 9.42 (s, 2 H, meso-H), 7.83 (d, J 8.0 Hz, 2 H, H-8), 7.79 (d,
J 8.0 Hz, 2 H, H-7), 7.76 (m, 4 H, H-4), 7.68 (d, J 1.7 Hz, 2 H,
H-9), 7.67 (d, J 1.7 Hz, 1 H, H-10), 7.42 (m, 6 H, H-5/6), 3.63
[t, J 7.6 Hz, 8 H, CH (CH ) CH ], 2.25 (s, 6 H, H-12), 2.23 (s,
H -2. A solution of Zn-2 (500 mg, 0.474 mmol) and dry
2
2
CdCl (261 mg, 1.42 mmol) in THF (20 ml) was cooled to
2
2 4
3
[78 ¡C, and after addition of LiHMDS (1.42 ml, 1 M THF)
6 H, H-13), 2.20 [qn, J 7.1 Hz, 8 H, CH CH (CH ) CH ], 1.58
2 3
[p, J 7.5 Hz, 8 H, (CH ) CH (CH ) CH ], 1.42 (s, 18 H, H-14),
2 2 2 2
1.34 [m, 16 H, (CH ) CH CH CH /(CH ) CH CH ], 0.88
2 3 3 4
2
3
2
3
the mixture was stirred for 2 h. Then ClPPh (313 mg, 1.42
2
2
2
mmol) in THF (10 ml) was added dropwise at [78 ¡C and the
2
3
2
3
red solution stirred for 30 min, warmed to rt and stirred for
another 30 min. The mixture was again cooled to [30 ¡C,
BH SMe (108 mg, 1.42 mmol) was added, and the solution
[dt, J 2.3 Hz, J 7.2 Hz, 12 H, (CH ) CH ]. 31P NMR
(CDCl , 161.97 MHz): d \ [32.2. MALDI-TOF MS: calcd.
1
2
2 5
3
3
1233, found 1231.
3
2
stirred for 45 min. The reaction was quenched by addition of
H OÈ10 N HCl (20 ] 2 ml) and stirred vigorously until
2
homogenously green. Extraction from CH Cl ÈNa CO sat.
Coordination compounds
2
2
2
4
3
(50 ] 100 ml) and evaporation of the dried (MgSO ) organic
phase yielded a brownish-red solid, which was chromato-
graphed on silica (hexaneÈEtOAcÈCHCl 15 : 1 : 1). The H -
[Ru-1/Ni-3]. NMR: Ru-1 (5.00 mg, 4.93 lmol) in CDCl
3
2
3
(0.4 ml) and Ni-3 (6.08 mg, 4.93 lmol) in CDCl (0.3 ml) were
3
2-BH complex was dissolved in HNEt (5 ml), heated to
3
2
50 ¡C for 45 min. and the solvent evaporated in vacuo. The
mixed in a NMR tube Ðtted with a teÑon seal and left to
solid was three times coevaporated with CHCl (5 ml) and
equilibrate for 1 h. 1H NMR (500 MHz): d \ 9.87 (s, 2 H,
Ru-1 meso-H), 9.44 (s, 2 H, Ni-3 meso-H), 7.83 (br s, 2 H, H-1),
7.76 (d, J 7.9, 2 H, H-8), 7.69 (d, J 1.6 Hz, 2 H, H-3), 7.68 (d, J
1.6 Hz, 1 H, H-10), 7.43 (br s, 2 H, H-9), 7.24 (d, J 7.9 Hz, 2 H,
H-7), 7.15 (m, 2 H, H-2), 6.84 (br t, 2 H, H-6), 6.53 (br t, 4 H,
H-5), 4.29 (br t, 4 H, H-4), 3.87 (q, J 7.4 Hz, 8 H, Ru-1
CH CH ), 3.66 [q, J 8.6, 8 H, Ni-3 CH (CH ) CH ], 2.29 (s, 6
3
precipitated from tolueneÈacetonitrile (2 ] 15 ml) at [20 ¡C
overnight. Crystallisation from CHCl Èmethanol (2 ] 15 ml)
3
at [20 ¡C gave H -2 (380 mg, 0.322 mmol, 68%) as brown
2
crystals. R (hexaneÈEtOAc 5 : 1): Zn-2 0.70, H -2 0.68, H -2-
f
2
2
BH 0.52.
3
Selected data for H -2: UV/vis (toluene, j/nm, lg e): 412
2
2
3
2
2 4
3
(5.39), 506 (5.01), 540 (3.79), 576 (3.95), 584 (3.85). 1H NMR
H, H-12), 2.25 (s, 12 H, H-11), 2.20 (s, 6H, H-13), 1.90 [m, 8 H,
(CDCl , 500 MHz): d \ 10.23 (s, 2 H, meso-H), 8.08 (d, J 7.5
Ni-3 CH CH (CH ) CH ], 1.80 [t, J 7.4 Hz, 12 H, Ru-1
3
2
2
2 3
3
Hz, 2 H, H-8), 7.92 (d, J 7.5 Hz, 2 H, H-7), 7.91 (s, 2 H, H-9),
CH CH ], 1.62 [m, 8 H, Ni-3 (CH ) CH (CH ) CH ], 1.51 (s,
2
3
2 2
2
2 2
3
7.83 (d, J 7.7 Hz, 4 H, H-4), 7.81 (s, 1 H, H-10), 7.47 (dd, J 7.7
18 H, H-16), 1.47 (s, 18 H, H-15), 1.43 (s, 18 H, H-14), 1.35 [m,
1
Hz, J 6.8 Hz, 4 H, H-5), 7.43 (d, J 6.8 Hz, 2 H, H-6), 3.98 [br
2
16 H, Ni-3 (CH ) CH CH CH /(CH ) CH CH ], 0.89 [dt, J
2 3
2
2
3
3 4
2
3
1
s, 8 H, CH (CH ) CH ], 2.53 (s, 6 H, H-12), 2.50 (s, 6 H, H-13),
3.2 Hz, J 7.3 Hz, 12 H, Ni-3 (CH ) CH ]. 31P NMR (161.97
2
2 4
3
2
2 5
3
2.19 [br s, 8 H, CH CH (CH ) CH ], 1.73 [t, J 6.5 Hz,
2 3
(CH ) CH (CH ) CH ], 1.50 (s, 18 H, H-14), 1.49 [m, 8 H,
2 2 2 2
(CH ) CH CH CH ], 1.36 [m, 8 H, (CH ) CH CH ], 0.90 [t,
2 3 3 4
MHz): d \ [13.2. MALDI-TOF MS: calcd. 2186, found
2191. UV/vis: One hundred microliters each of Ru-1 and Ni-3
solutions (2 mM in toluene) were mixed and diluted with 800
ll toluene. After equilibration for 1 h, 15 ll of the mixture
were injected into 3.0 ml of toluene in a quartz cuvette. UV/vis
2
2
3
2
2
3
2
3
2
3
J 7.1 Hz, 12 H, (CH ) CH ], [2.39 and [2.41 (2 ] s, 2 H,
2 5
3
NH). 13C NMR (CDCl , 125.7 MHz): d \ 149.9 (s), 145.3 (s),
3
New J. Chem., 2000, 24, 261È264
263

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° Crystals were grown from layered addition of methanol to a sat.
(j/nm, lg e): 406 (5.61), 526 (4.49), 560 (4.41). Calcd:Ò 406
CH Cl solution. Crystal data for
C
H
N OPZn, Zn-4:
(5.61), 526 (4.50), 560 (4.42).
2
2
83 105
4
M \ 1271.05, triclinic, a \ 15.835(2), b \ 17.762(2), c \ 14.503(2) A,
a \ 92.220(1)¡, b \ 97.390(1)¡, c \ 99.47(1)¡, U \ 3631.6(8)
AŽ 3,
T \ 180 K, space group P1, Z \ 2, k(Mo-Ka) \ 0.408 mm~1, 17 797
total reÑections, 11 350 independent reÑections, R \ 0.0903, R \
[Ni-3/Ru-1/Ni-3]. NMR: Ru-1 (3.00 mg, 2.95 lmol) and
Ni-3 (7.30 mg, 5.90 lmol) were dissolved in CDCl (1.0 ml)
int
1
3
0.1040, R(r) 0.1553, wR \ 0.3015 (all data). Non-H atoms were
and heated to reÑux for 5 h. The resulting solution was
2
reÐned anisotropically; H atoms were reÐned isotropically using a
directly used for measurements. 1H NMR (500 MHz):
d \ 9.53 (br s, 2 H, Ru-1 meso-H), 9.46 (br s, 4 H, Ni-3
meso-H), 7.75 (d, J 7.9 Hz, 4 H, H-8), 7.72 (d, J 1.5 Hz, 2 H,
H-3), 7.70 (d, J 1.7 Hz, 2 H, H-10), 7.61 (br s, 2 H, H-1), 7.41
(d, J 1.7 Hz, 4 H, H-9), 7.30 (d, J 7.9 Hz, 4 H, H-7), 7.17 (m, 2
H, H-2), 6.83 (t, J 7.2 Hz, 4 H, H-6), 6.55 (t, J 7.5, 8 H, H-5),
4.59 (m, 8 H, H-4), 3.74 (q, J 7.5, 8 H, Ru-1 CH CH ), 3.68 [m,
riding model except for the P-bound proton, which was reÐned iso-
tropically from electron density. The hexyl sidechains, one aryl residue
on P and the di-But-aryl substituent showed disorder and could be
reÐned in two non-equally populated positions. CCDC reference
number 440/174. See http://www.rsc.org/suppdata/nj/b0/b000482k/
for crystallographic Ðles in .cif format.
Ò UV/vis data for Ru-1 (toluene, j/nm, lg e): 404 (5.36), 524 (4.21), 554
(4.04).
2
3
16 H, Ni-3 CH (CH ) CH ], 2.36 (s, 12 H, H-12), 2.22 (s, 12
2
2 4
3
1
2
(a) C. C. Mak, N. Bampos and J. K. M. Sanders, Chem. Commun.,
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J. K. M. Sanders, N. Bampos, Z. ClydeÈWatson, S. L. Darling, J.
C. Hawley, H.-J. Kim, C. C. Mak and S. J. Webb, in T he Porphy-
rin Handbook, eds. K. M. Kadish, K. M. Smith and R. Guilard,
Academic Press, London, 2000, vol. 3, pp. 1È48.
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Acta, 1989, 160, 115.
B. R. James, A. Pacheco, S. J. Rettig, I. S. Thorburn, R. G. Ball
and J. A. Ibers, J. Mol. Catal., 1987, 41, 147.
H, H-13), 2.10 (br s, 12 H, H-11), 2.04 [m, 16 H, Ni-3
CH CH (CH ) CH ], 1.77 (t, J 7.5 Hz, 12 H, Ru-1 CH CH ),
2
2
2 3
3
2
3
1.65 [m, 16 H, Ni-3 (CH ) CH (CH ) CH ], 1.50 (s, 36 H,
2 2
2
2 2
3
H-15/H-16), 1.45 (s, 36 H, H-14), 1.44 [m, 16 H, Ni-3
(CH ) CH CH CH ], 1.36 [m, 16 H, (CH ) CH CH ], 0.92
2 3
1
2
2
3
3 4
2 5
2
3
[dt, J 1.4 Hz, J 7.2 Hz, 12 H, Ni-3 (CH ) CH ]. 31P NMR
2
3
3
(161.97 MHz): d \ 3.0. UV/vis: One hundred microliters of a
Ru-1 solution (2 mM in toluene) and 200 ll Ni-3 solution (2
mM in toluene) were mixed and diluted with 700 ll toluene.
After equilibration for 5 h at 70 ¡C, 15 ll of the mixture were
injected into 3.0 ml of toluene in a quartz cuvette. UV/vis
(j/nm, lg e): 408 (5.78), 526 (4.75), 564 (4.75). Calcd:Ò 408
(5.78), 526 (4.67), 560 (4.67).
4
5
(a) P. Le Maux, H. Bahri and G. Simonneaux, Inorg. Chem.,
1995, 34, 4691; (b) P. Le Maux, H. Bahri and G. Simonneaux, J.
Chem. Soc., Chem. Commun., 1994, 1287.
L. J. Twyman and J. K. M. Sanders, T etrahedron L ett., 1999, 40,
6681.
6
7
8
F. Langer and P. Knochel, T etrahedron L ett., 1995, 36, 4591.
R. Engel, in Handbook of Organophosphorus Chemistry, ed. R.
Engel, Marcel Dekker Inc., New York, 1992, ch. 5.
Acknowledgements
We thank Dr Yiu-Fai Ng for NMR measurements and the
Swiss National Science Foundation and EPSRC for Ðnancial
support.
9
M. Nappa and J. S. Valentine, J. Am. Chem. Soc., 1978, 100, 5075.
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Notes and references
¤ The Na` alkynyl reagent was formed by deprotonation of the
alkyne using NaH, while the Mg2` complex was formed by treatment
of the alkyne with EtMgBr.
” Preliminary experiments showed that reaction of the alkynyl-
Grignard reagent with chloro diethyl phosphate followed by
reduction using LAH yields the corresponding primary phosphine,
which is also a potentially useful building block.
14 E. Stulz, C. C. Mak and J. K. M. Sanders, in preparation.
264
New J. Chem., 2000, 24, 261È264