A stable cooper(I)-triazacyclononane complex with an intramolecularly coordinated alkyne group

Article abstract of DOI:10.1021/om000999z

A 1,4,7-triazacyclononane copper(I) complex with an intramolecularly coordinated pendant alkyne has been synthesized and characterized spectroscopically and by X-ray studies. This complex is air-stable indefinitely in the solid state and stable in acetone

Full text of DOI:10.1021/om000999z

Organometallics 2001, 20, 2161-2166
2161
A Sta ble Cop p er (I)-Tr ia za cyclon on a n e Com p lex w ith a n
In tr a m olecu la r ly Coor d in a ted Alk yn e Gr ou p
Murray V. Baker,*,1 David H. Brown, Neil Somers, and Allan H. White
Department of Chemistry, The University of Western Australia, Crawley, WA 6009, Australia
Received November 21, 2000
A 1,4,7-triazacyclononane copper(I) complex with an intramolecularly coordinated pendant
alkyne has been synthesized and characterized spectroscopically and by X-ray studies. This
complex is air-stable indefinitely in the solid state and stable in acetone solutions in air for
several days.
Sch em e 1a
In tr od u ction
1,4,7-Triazacyclonane metal complexes with intramo-
lecularly coordinated pendant functional groups (espe-
cially those with O, N, S, and P donors) have received
much attention.2,3 In contrast, complexes of 1,4,7-
triazacyclononanes containing intramolecularly coordi-
nated carbon-carbon multiple bonds are rare. Despite
recent reports of metal complexes of alkynyl-function-
alized 1,4,7-triazacyclononanes,4,5 there appear to be no
reports of intramolecularly coordinated pendant alkynes
in such systems. There has been one report of a
triazacyclononane complex containing an intramolecu-
larly coordinated alkene,6 but this complex was ex-
tremely air sensitive and only characterized by infrared
spectroscopy. In the broader area of facially coordinating
ligands (arenes, cyclopentadienyls, N tripods, etc.) bear-
ing pendant functional groups, the only reports of
complexes containing an intramolecularly coordinated
pendant alkyne appear to be the (η8-alkynylarene)-
dicarbonylchromium complexes of Krivykh and co-
workers.7-9
We have synthesized a family of triazacycles with
pendant alkynyl groups and explored their reactions
with metals,5,10 with a view toward intramolecular
coordination and subsequent coupling of pendant alkynes
to form organometallic cage complexes. In our previous
studies, we were unable to isolate any complex contain-
ing an intramolecularly coordinated alkyne, apparently
because the alkynes either competed poorly with other
ligands for the metal center or underwent subsequent
reactions that led to complex mixtures of products. In
a
Reagents: (i) CuI, CH3OH, NaBPh4; (ii) [Cu(CH3CN)4]PF6,
THF.
this paper, we report on the coordination of a 1,4,7-
trialkynyl-1,4,7-triazacyclononane to copper(I), which
results in the first example of a stable, well-defined
TACN complex with an intramolecularly coordinated
alkynyl group.
(1) To whom correspondence should be addressed. Fax: +61 8 9380
1005. E-mail: mvb@chem.uwa.edu.au.
(2) Chaudhuri, P.; Wieghardt, K. Prog. Inorg. Chem. 1987, 35, 329.
(3) Wainwright, K. P. Coord. Chem. Rev. 1997, 166, 35.
(4) Ellis, D.; Farrugia, L. J .; Peacock, R. D. Polyhedron 1999, 18,
1229.
(5) Baker, M. V.; Brown, D. H.; Skelton, B. W.; White, A. H. J . Chem.
Soc., Dalton Trans. 2000, 4607.
(6) Farrugia, L. J .; Lovatt, P. A.; Peacock, R. D. Inorg. Chim. Acta
1996, 246, 343.
(7) Krivykh, V. V.; Il’minskaya, E. S.; Rybinskaya, M. I. Bull. Acad.
Sci. USSR Div. Chem. Sci. (Engl. Transl.) 1981, 30, 1563.
(8) Rybinskaya, M. I.; Krivykh, V. V.; Gusev, O. V.; Il’minskaya, E.
S. Bull. Acad. Sci. USSR Div. Chem. Sci. (Engl. Transl.) 1981, 30,
2371.
Resu lts a n d Discu ssion
The reaction of 1,4,7-tri(5-phenyl-4-pentynyl)-1,4,7-
triazacyclononane 1 with CuI in methanol, followed by
the addition of NaBPh4, yielded the Cu(I) salt 2‚BPh4
(Scheme 1) as a colorless solid in high yield (86%).
Alternatively, 2 could be obtained as the hexafluoro-
phosphate salt 2‚PF6 by the reaction of 1 with [Cu(CH3-
CN)4]PF6 in THF. The structure of the cation 2 was
deduced by spectroscopic techniques and subsequently
(9) Taits, E. S.; Petrovskii, P. V.; Krivykh, V. V. Russ. Chem. Bull.
1999, 48, 1157.
(10) Baker, M. V.; Brown, D. H.; Skelton, B. W.; White, A. H. J .
Chem. Soc., Dalton Trans. 2000, 763.
-
1
confirmed by an X-ray study of the BPh4 salt. The H
and 13C NMR spectra of 2‚BPh4 in acetone-d6 showed
10.1021/om000999z CCC: $20.00 © 2001 American Chemical Society
Publication on Web 05/03/2001

2162 Organometallics, Vol. 20, No. 11, 2001
Ta ble 1. Selected Ca tion P a r a m eter s
Baker et al.
atoms
parameter
atoms
parameter
Distances (Å)
Cu-N(1)
Cu-N(4)
Cu-N(7)
2.041(1), 2.041(1)
2.248(1), 2.195(1)
2.087(1), 2.124(1)
Cu-C(14)
1.950(1), 1.955(2)
1.996(1), 2.002(2)
1.236(2), 1.234(2)
Cu-C(15)
C(14)-C(15)
Angles (deg)
N(1)-Cu-N(4)
N(1)-Cu-N(7)
N(1)-Cu-C(14)
N(1)-Cu-C(15)
N(4)-Cu-N(7)
Cu-N(1)-C(2)
Cu-N(1)-C(9)
Cu-N(4)-C(3)
C(13)-C(14)-C(15)
84.88(4), 85.80(5)
88.71(5), 86.85(5)
102.10(6), 103.75(5)
138.25(6), 140.07(5)
82.97(4), 83.83(4)
109.42(9), 108.51(9)
100.8(1), 102.87(7)
100.20(8), 98.48(7)
163.6(1), 167.0(2)
N(4)-Cu-C(14)
N(4)-Cu-C(15)
N(7)-Cu-C(14)
N(7)-Cu-C(15)
C(14)-Cu-C(15)
Cu-N(4)-C(5)
Cu-N(7)-C(6)
Cu-N(7)-C(8)
C(14)-C(15)-C(151)
117.29(5), 130.33(5)
115.17(5), 117.67(5)
157.51(5), 144.24(5)
128.04(6), 125.13(5)
36.49(7), 36.33(6)
106.97(8), 107.39(8)
105.77(8), 103.85(9)
104.58(9), 105.66(8)
156.9(1), 157.6(2)
Torsion Anglesb (deg)
2-1-9-8
68.1(2), 68.3(2)
-48.1(1), -47.5(1)
47.0(2), 46.3(2)
-17.8(1), -18.7(1)
-131.3(1), -130.7(1)
65.9(2), 66.1(2)
-46.9(1), -47.0(2)
105.7(2), 103.4(1)
48.7(2), 49.8(2)
9-1-2-3
-130.3(1), -134.0(1)
-19.6(2), -21.7(1)
47.5(2), 52.1(2)
-45.4(1), -49.8(1)
68.1(1), 63.3(2)
-132.8(1), -134.1(1)
-23.5(2), -23.9(2)
-167.6(1), -169.4(1)
49.7(2), -37.7(2)
28.3(1), 24.7(1)
Cu-1-9-8
1-9-8-7
Cu-1-2-3
1-2-3-4
9-8-7-Cu
9-8-7-6
8-7-6-5
Cu-7-6-5
11-1-2-3
4-5-6-7
15-Cu-4-41
1-11-12-13
12-13-14-15
2-3-4-Cu
2-3-4-5
3-4-5-6
Cu-4-5-6
11-1-9-8
Cu-1-11-12
15-Cu-7-71
11-12-13-14
4.9(1), 2.2(1)
-78.0(2), 76.1(2)
174.1(5), -148.1(6)
56.7(2), -69.0(2)
a
b
The two values in each entry are for unprimed and primed cations, respectively. C, N denoted by number only, N italicized.
features expected for a complex with one bound and two
free alkynes. The 13C NMR spectrum contained four
signals in the alkyne region (δ 81.9, 86.1, 89.4, 94.4).
Two of these signals had chemical shifts similar to those
of the alkyne carbons of free 1 (δ 81.4, 91.1 for 1 in
acetone-d6) and are thus attributed to the carbons of
the pendant alkyne groups, while the other two signals,
which were of lower intensity, are assigned to the
rameters of the coordination geometry between the two
molecules, and from the putative noncrystallographic
m-symmetries of the core environments (m through Cu,
N(1), C(14,15)). In terms of distances there are differ-
ences in Cu-N(4) and Cu-N(7) both within each
molecule and between the two molecules (Table 1), with
very large associated differences in derivative angles,
presumably a concomitant of different ring conforma-
tions, between the two molecules (Figure 1) and between
the two quasi-m-related halves of each molecule. Com-
paring the two molecules, the conformations of the
triazacyclononane components about the two metal
atoms are very similar (see torsion angles in Table 1),
despite the considerable differences in geometries of the
CuN3 arrays.
1
carbons of the coordinated alkyne group. The H NMR
spectrum showed signals at δ 2.28 and 2.91 (relative
areas 4H and 2H, respectively), which are attributed
to the methylene protons adjacent to the two free
alkynes and the single bound alkyne, respectively. The
infrared spectrum of 2‚BPh4 contained a weak signal
at 2229 cm-1, which, being similar in position to the
signal due to the CtC stretching mode for 1 (2227
cm-1), is attributed to the free alkyne groups in 2. A
slightly more intense signal at 2022 cm-1 is attributed
to CtC stretching of the coordinated alkyne group. The
decrease in stretching frequency (ca. 200 cm-1) on
coordination of the alkyne to the Cu(I) center in 2 is
within the range reported previously for other alkynes
on coordination to Cu(I) centers.11
Related systems with N3-donors of appropriate sym-
metry and simplicity with an (N3-donor)CuI(η2-C2) co-
ordination environment are rather few (Table 2). Di-
ethylenetriamine (H2N(CH2)2NH(CH2)2NH2, dien) is a
close analogue of the present triazacyclononane, lacking
the ring closure provided by the last (CH2)2 moiety; two
complexes are recorded of it, both with alkenes rather
than alkynes, viz. hex-1-ene12 and norbornadiene.13
A
Crystals of 2‚BPh4 suitable for X-ray studies were
grown from acetone/light petroleum solutions. The
results of the low-temperature single-crystal X-ray study
are consistent with the stoichiometry and connectivity
as given above. Two independent molecules, devoid of
crystallographic symmetry, comprise the asymmetric
unit of the structure. Within each molecule the copper
atom is coordinated by the three nitrogen atoms of the
triazacyclononane moiety, together with an η2-alkyne
group from one of the pendants. While in broad terms
the copper-ligand atom distances fall into the ranges
expected, there are surprising divergences in the pa-
further complex [{HB(pz)3}Cu(C2H4)] (pz ) pyrazolyl,
C2H4 ) ethylene)14 is also relevant. In all of these, a
“central” nitrogen atom may be discerned, either by
virtue of lack of closure of the ligand or the putative
symmetry of the situation. In all cases, presumably
because of the absence of a tether linking the coordi-
nated alkene to the N3 core, the CdC bond lies parallel
to the line joining the outer nitrogen donors, rather than
perpendicular to this line as for the CtC bond in 2. The
(12) Pasquali, M.; Floriani, C.; Gaetani-Manfredotti, A.; Chiesi-Villa,
A. Inorg. Chem. 1979, 18, 3535.
(13) Pasquali, M.; Floriani, C.; Gaetani-Manfredotti, A.; Chiesi-Villa,
A. J . Am. Chem. Soc. 1978, 100, 4918.
(11) Munakata, M.; Kitagawa, S.; Kawada, I.; Maekawa, M.; Shi-
mono, H. J . Chem. Soc., Dalton Trans. 1992, 2225.
(14) Thompson, J . S.; Harlow, R. L.; Whitney, F. J . J . Am. Chem.
Soc. 1983, 105, 3522.

A Stable Copper(I)-Triazacyclononane Complex
Organometallics, Vol. 20, No. 11, 2001 2163
F igu r e 1. Projections of the two independent molecules (unprimed, primed), showing 50% probability amplitude
displacement ellipsoids for the non-hydrogen atoms, hydrogen atoms having arbitrary radii of 0.1 Å. Note the different
conformations of the coordinated rings (cf. Table 1).
Ta ble 2. Com p a r a tive Geom etr ies for (N3-Don or )Cu (η2-C2) System s
b
c
complex
2a
[(dien)Cu(C6H12)]+
[(dien)Cu(C7H10)]+
[{HB(pz)3}Cu(C2H4)]d
Distances (Å)
Cu-N(central)
Cu-N(outer)
2.041(1), 2.041(1)
2.248(1), 2.195(1)
2.087(1), 2.124(1)
1.950(1), 1.955(2)
1.996(1), 2.002(2)
1.874(1), 1.880(1)
1.236(2), 1.234(2)
2.25(1), 2.21(2)
2.11(1), 2.13(2)
2.09(1), 2.14(1)
2.10(2), 2.03(2)
2.13(2), 2.10(2)
2.01(2), 1.98(2)
1.30(3), 1.18(3)
2.252(7)
2.008(6)
2.109(8)
2.19(1)
2.19(1)
2.08(1)
1.38(2)
2.160(4)
2.017(3)
2.041(3)
2.023(5)
2.004(6)
1.90(1)
Cu-C
Cu-C2(midpt)
C-C
1.329(9)
Angles (deg)
N(central)-Cu-N(outer)
84.88(4), 85.80(5)
88.71(5), 86.85(5)
82.97(4), 83.83(4)
120.4(1), 122.1(4)
117.7(1), 125.7(4)
144.0(1), 136.8(3)
83.2(7), 84.1(8)
83.5(6), 83.1(7)
108.0(7), 105.2(8)
121.1(9), 130.8(11)
127.4(9), 130.1(11)
119.7(9), 112.4(10)
83.3(3)
81.5(4)
105.6(3)
108.2(4)
125.6(4)
128.4(4)
89.8(1)
89.7(1)
92.4(1)
115.6(1)
129.9(1)
127.6(1)
N(outer)-Cu-N(outer)
C2(midpt)-Cu-N(central)
C2(midpt)-Cu-N(outer)
a
b
Two molecules of different conformation. Reference 12. Two molecules of different conformation. C6H12 ) hex-1-ene. c Reference 13.
d
Reference 14. The “central” nitrogen here is the “different” one (N(31) in ref 14), the CdC bond of the ethylene lying parallel to
N(11)‚‚‚N(21).
presence of the tether in 2 may also explain why in this
complex the Cu-N(central) bond is the shortest Cu-N
bond, by a considerable margin, whereas the Cu-
N(central) bond is the longest Cu-N bond in each
alkene complex. The N(outer)-Cu-N(outer) angles in
the three alkene complexes vary diversely, those of the
dien complexes greatly enlarged compared to those in
the [HB(pz)3]- complex and 2. To what extent these
differences may be a consequence of electronic factors
associated with the type of η2-C2 donor and its orienta-
tion, cf. the pendant constraint in 2, is unclear, but it
is noteworthy that in 2, regardless of which molecule,
the N-Cu-C angles are very divergent, suggestive of
some tension between the disposition of the CtC moiety
and its tether.
were consistent with a complex with C3 symmetry (i.e.,
three equivalent phenylpentynyl groups), while the 31P
NMR spectrum of the product showed a resonance at δ
6.8, which is close to that observed for the cation in
[(iPr3TACN)Cu(PPh3)]PF6 (δ 5.27 in dichloromethane-
d2).15 When an 8 mM solution of 2‚PF6 in acetone-d6
solution was purged with CO and maintained under an
atmosphere of CO, an equilibrium mixture containing
2 and a product tentatively assigned as the CO adduct
4 was formed (Scheme 1). The adduct 4 was identified
1
by new signals in the H and 13C NMR spectra of the
solution, and the ratio of 2 to 4 was ca. 1.4:1, respec-
tively (by 1H NMR). When the sample was purged with
N2, 4 was converted to 2, but when the CO atmosphere
was restored, the equilibrium between 2 and 4 was
reestablished. Other Cu(I) TACN complexes are known
to bind CO reversibly.16
The coordinated alkyne in 2 can be displaced. Addi-
tion of PPh3 to solutions containing 2‚BPh4 or 2‚PF6
resulted in quantitative displacement of the bound
alkyne and formation of a product identified as 3 on the
(15) Halfen, J . A.; Mahapatra, S.; Wilkinson, E. C.; Gengenbach, A.
J .; Young, V. G., J r.; Que, L., J r.; Tolman, W. B. J . Am. Chem. Soc.
1996, 118, 763.
1
basis of its NMR spectra. The H and 13C NMR spectra

2164 Organometallics, Vol. 20, No. 11, 2001
Baker et al.
F igu r e 2. 1H NMR spectra (500.1 MHz, acetonitrile-d3) for solutions of 2‚BPh4 at the temperatures indicated. Signals
marked 4 are due to adventitious moisture and the signal marked * is the solvent signal.
The 1H NMR spectra of acetonitrile-d3 solutions
containing 2‚BPh4 at ambient temperatures were broad-
ened, apparently due to exchange of free and coordi-
nated alkyne groups. Variable-temperature NMR stud-
ies (Figure 2) show that, at 233 K, this process is
essentially frozen out. The most dramatic change be-
tween spectra recorded at 233 and 343 K is that at the
higher temperature the six protons (R and R′) adjacent
to the alkyne groups appear as a singlet (albeit still
somewhat broad) resonance near δ 2.47, whereas at 233
K, the four protons (R) adjacent to the free alkyne groups
resonate as a triplet at δ 2.19 and the two protons (R′)
adjacent to the coordinated alkyne group resonate near
δ 2.8. The coalescence temperature for the signals due
to these protons is ca. 320 K. Assuming that the
difference in resonant frequencies of the R and R′
protons at this temperature is the same as at 233 K (305
Hz), we estimate17 the rate constant for the exchange
process as 610 s-1 at 320 K.
temperature is close to the population-weighted average
of the chemical shifts observed for the R and R′ protons
at low temperature (δ 2.39) suggests that if 5 is formed
it is not present in significant amounts at any given
instant. If the changes of the NMR spectra with tem-
perature were simply a consequence of acetonitrile
displacing the coordinated alkyne then we would expect
the signal due to the R/R′ protons to appear near δ 2.19
in the high-temperature spectra.
Triazacyclononane-Cu(I) complexes are generally
extremely sensitive to air and water,15,18 TACN-Cu(I)
adducts of alkynes particularly so. [Cu(η2-PhCtCPh)-
(η3-R3TACN)]BPh4 (R ) H or Me), formed by the
reaction of R3TACN with CuI, diphenylacetylene, and
NaBPh4 in methanol, decomposed in solution before a
13C NMR spectrum could be recorded.19 In contrast, the
(17) The commonly used expression for estimation of rate constants
at coalescence is kc ) 2.22∆ν, where ∆ν is the difference between the
resonant frequencies of the exchanging protons. The expression applies
when the exchange involves equally populated sites. In this study, the
R and R′ protons have relative populations 0.67 and 0.33, respectively,
We presume the acetonitrile solvate 5 to be an
intermediate in the exchange process responsible for the
temperature dependence of the NMR spectra. The fact
that the chemical shift of the R/R′ protons at high
and as a result the expression for the rate constant becomes kc
)
2.01∆ν. See: Sandstro¨m, J . Dynamic NMR Spectroscopy; Academic
Press: London, 1982; pp 81-82.
(18) Berreau, L. M.; Halfen, J . A.; Young, V. G., J r.; Tolman, W. B.
Inorg. Chem. 1998, 37, 1091.
(16) Berreau, L. M.; Halfen, J . A.; Young, V. G., J r.; Tolman, W. B.
Inorg. Chim. Acta 2000, 297, 115.
(19) Chaudhuri, P.; Oder, K. J . Organomet. Chem. 1989, 367, 249.

A Stable Copper(I)-Triazacyclononane Complex
Organometallics, Vol. 20, No. 11, 2001 2165
Cu(I) complex 2, as its PF6- or BPh4- salt, is remarkably
stable. Crystals of 2‚BPh4 exposed to the laboratory
atmosphere showed no signs of decomposition after
several months in the laboratory atmosphere at ambient
temperature. Solutions of 2‚BPh4 in acetone-d6 or 2‚PF6
in methanol-d4 prepared in the laboratory atmosphere
showed no changes in color or 1H NMR spectra even
after exposure to oxygen over several hours. Over the
course of several weeks, however, the solutions devel-
Australian National University, Canberra. Cyclic voltammo-
grams were recorded with a MacLab potentiostat controlled
by a Macintosh LC computer equipped with AD Instruments
Echem Software, using platinum working and counter elec-
trodes and a silver/silver chloride reference electrode. Each
solution was purged with argon and studied at ambient
temperatures.
Syn th esis of 2‚BP h 4. A solution of 1 (106 mg, 0.191 mmol)
in methanol (2 mL) was added to a suspension of CuI (33 mg,
0.17 mmol) in methanol (8 mL), and the mixture was stirred
for 3 h. A solution of NaBPh4 (84 mg, 0.25 mmol) in CH3OH
(2 mL) was then added, and a white precipitate formed
immediately. The precipitate was collected, washed with
methanol (3 mL), and dried in vacuo to yield 2‚BPh4 as a white
powder (139 mg, 86%) that was spectroscopically pure. A
sample of analytical purity was obtained by recrystallization
from acetone/ether. Anal. Calcd for C63H65BCuN3‚2(CH3)2CO:
C, 78.57; H, 7.36; N, 3.98. Found: C, 78.92; H, 7.31; N, 4.08.
HR-MS (FAB): m/z 618.2934 ([M - BPh4]+, exact mass calcd
for C39H45CuN3 618.2909). IR data (KBr, cm-1): 2229 (free Ct
1
oped a green color, and their H NMR spectra indicated
the presence of unidentified products.
The resistance of 2 to aerial oxidation is reflected in
the behavior of the complex in cyclic voltammetry
experiments (ca. 1 mM solutions of 2 in 0.1 M (Bu4N)-
(PF6) in acetonitrile, scan rate 200 mV/s). In these
experiments, 2 showed no redox activity over the range
-0.5 to +0.8 V (vs Ag/AgCl). Previously studies15,16 of
(R3TACN)Cu(I)L systems (L ) heterocyclic N-donor or
CH3CN) found that the complexes exhibited quasi-
reversible one-electron redox transformations with E1/2
values in the range -0.1 to +0.36 V vs SCE (i.e., ca.
-0.05 to +0.41 V vs Ag/AgCl). In experiments cycled
over the range -1.0 to +1.5 V, solutions of 2 showed an
oxidation wave centered near +1.1 V (vs Ag/AgCl) and
an associated reduction wave centered near +0.4 V. The
large separation between the waves suggests a compli-
cated redox behavior. We tentatively interpret these
results in terms of four steps: (i) a single-electron
oxidation of 2 to the Cu(II) form; (ii) displacement of
the coordinated alkyne leading to formation of [(R3-
TACN)Cu(CH3CN)]2+ (R ) 5-phenyl-4-pentynyl); (iii)
single-electron reduction of [(R3TACN)Cu(CH3CN)]2+
(R ) 5-phenyl-4-pentynyl) to form the acetonitrile
solvate 5; and (iv) subsequent displacement of coordi-
nated acetonitrile by an alkyne group to regenerate 2.
We note that the potential of the reduction wave is very
close to the E1/2 value (+0.36 vs SCE, ca. +0.41 V vs
Ag/AgCl) reported15 for [(iPr3TACN)Cu(CH3CN)]+. What-
ever the processes responsible for the observed cyclic
voltammograms, the absence of any redox behavior over
the range -0.5 to +0.8 V demonstrates that the Cu(I)
state is remarkably stable in 2 compared to related
TACN-Cu(I) complexes. This stability may be due in
part to the “soft” nature of the alkyne group,16 but the
notable instability of [Cu(η2-PhCtCPh)(η3-R3TACN)]-
BPh4 (RdH or Me),19 complexes with intermolecularly
coordinated alkynes, suggests that the chelate effect is
also a significant factor in the stability of 2.
1
C); 2022 (coordinated CtC). H NMR (acetone-d6, 295 K): δ
1.98 (6H, m, 3 × CH2CH2CtC), 2.28 (4H, m, 2 × CH2CtC),
2.91 (2H, m, 1 × CH2CtC), 2.95-3.11 (18H, m, 3 × NCH2-
CH2N and 3 × CH2CH2CH2CtC), 6.78 (4H, m, 4 × HBPh), 6.92
(8H, m, 8 × HBPh), 7.23-7.36 (21H, m, 8 × HBPh and 13 ×
H
≡CPh) and 7.48 (2H, m, 2 × H≡CPh); (acetonitrile-d3, 233 K):
δ 1.84 (6H, m, 3 × CH2CH2CtC), 2.19 (4H, t, J HH ) 6.8 Hz,
2 × CH2CtC), 2.75-2.95 (20H, m, 3 × NCH2CH2N, 3 × CH2-
CH2CH2CtC and 1 × CH2CtC), 6.81 (4H, m, 4 × HBPh), 6.98
(8H, m, 8 × HBPh), 7.12-7.35 (23H, m, 8 × HBPh and 15 ×
H
≡CPh); (acetonitrile-d3, 343 K): δ 1.91 (6H, quintet, J HH ) 7.0
Hz, 3 × CH2CH2CtC), 2.47 (6H, br, Wh/2 31 Hz, 3 × CH2Ct
C), 2.83-2.97 (12H, AA′BB′ pattern, 3 × NCH2CH2N), 2.99
(6H, apparent t, splitting 7.2 Hz, 3 × CH2CH2CH2CtC), 6.84
(4H, m, 4 × HBPh), 6.99 (8H, m, 8 × HBPh), 7.26-7.36 (23H, m,
8 × HBPh and 15 × H≡CPh). 13C NMR (acetone-d6, 295 K): δ
17.6 (2 × CH2CtC), 19.6 (1 × CH2CtC), 26.6 (2 × CH2CH2Ct
C), 26.8 (1 × CH2CH2CtC), 53.6, 54.1, 56.8 and 60.6 (2 × CH2-
CH2CH2CtC and 3 × NCH2CH2N), 61.9 (1 × CH2CH2CH2Ct
C), 81.9 (2 × C≡CPh), 86.1 (1 × C≡CPh), 89.4 (2 × CtCPh),
94.4 (1 × CtCPh), 122.2 (4 × CHBPh), 124.6 (2 × CPh), 125.2
(1 × CPh), 126.0 (8 × CHBPh), 128.7 (2 × CHPh), 129.21 (4 ×
CHPh), 129.23 (1 × CHPh), 129.8 (2 × CHPh), 131.4 (2 × CHPh),
132.2 (4 × CHPh), 137.0 (8 × CHBPh) and 164.9 (4 × CBPh).
Str u ctu r e Deter m in a tion for 2‚BP h 4. A full sphere of
CCD area-detector diffractometer data was measured (Bruker
AXS instrument; ω-scans, 2θmax ) 68°; monochromatic Mo KR
radiation, λ ) 0.71073 Å; T ca. 153 K) yielding 75 226
reflections, these merging to 38 319 (Rint ) 0.026) after
“empirical”/multiscan absorption correction (µMo ) 4.7 cm-1
;
specimen: 0.45 × 0.35 × 0.15 mm; ‘T’min,max ) 0.69, 0.80),
25986 with F > 4σ(F) being considered “observed” and used
in the full-matrix least-squares refinement, refining anisotro-
pic thermal parameter forms for the non-hydrogen atoms,
together with (x, y, z, Uiso)H. Final conventional residuals on
|F| at convergence were R () Σ(∆|F|)/Σ|Fo|) ) 0.039, Rw ) (Σ-
Exp er im en ta l Section
2
(w∆2)/Σ|Fo| )1/2 (w ) (σ2(F) + 0.0004F2)-1) ) 0.042. Neutral
Ma t er ia ls.
1,4,7-Tri(5-phenyl-4-pentynyl)-1,4,7-triaza-
atom complex scattering factors were employed within the Xtal
3.7 program system.20 Pertinent results are given below and
in Tables 1 and 2 and Figure 1.
cyclononane 1 was synthesized by reaction of 1,4,7-triaza-
cyclononane trihydroiodide with 5-iodo-1-phenyl-1-pentyne in
acetonitrile.5 Methanol was dried and distilled prior to use.
Reactions were performed in a N2-atmosphere drybox. NMR
spectra were recorded using a Bruker ARX 500 spectrometer
Cr ysta l d a ta : C63H65BCuN3, M ) 938.6; triclinic, space
group P1h(C1i , No. 2), a ) 13.0957(7) Å, b ) 19.682(1) Å, c )
20.655(1) Å, R ) 74.829(1)°, â ) 81.526(1)°, γ ) 89.799(1)°,
1
(500.1 MHz for H, 125.8 MHz for 13C, 202.5 MHz for 31P) and
were referenced with respect to solvent signals (1H, 13C) or
external 85% H3PO4 (31P). DEPT, COSY, and decoupling
experiments were used in assignment of 1H and 13C NMR
spectra. Mass spectra were obtained by Dr A. Reeder using a
VG Autospec mass spectrometer, using fast atom bombard-
ment (FAB) with a cesium ion source and m-nitrobenzyl
alcohol as the matrix. Microanalysis was performed by the
Microanalytical Laboratory, Research School of Chemistry,
V ) 5079 Å3, Dc (Z ) 4) ) 1.227 g cm-3. |∆Fmax| ) 0.8(1) e Å-3
.
Sp ectr a l Ch a r a cter iza tion of 3‚BP h 4. Triphenylphos-
phine (2.0 mg, 7.6 µmol) was added to a solution of 2‚BPh4
(6.7 mg, 7.1 µmol) in acetonitrile-d3 (1.0 mL). The product,
formed in quantitative yield (by 1H NMR), was identified as
(20) Hall, S. R.; du Boulay, D. J .; Olthof-Hazekamp, R., Eds. The
Xtal 3.7 System; The University of Western Australia: Nedlands, 2000.

2166 Organometallics, Vol. 20, No. 11, 2001
Baker et al.
3‚BPh4 on the basis of its NMR spectral data. 1H NMR
(acetonitrile-d6, 295 K): δ 1.76 (6H, m, 3 × CH2CtC), 1.80
(6H, m, 3 × CH2CH2CtC), 2.72 (6H, m, 3 × CH2CH2CH2-
CtC), 2.79-2.92 (12H, AA′BB′ pattern, 3 × NCH2CH2N), 6.83
(4H, m, 4 × HBPh), 6.98 (8H, m, 8 × HBPh), 7.23-7.33 (29H, m,
8 × HBPh and 21 × HPh) and 7.35-7.46 (9H, m, 9 × HPh). 13C
NMR (acetonitrile-d6, 295 K): δ 17.2 (3 × CH2CtC), 28.3
(3 × CH2CH2CtC), 54.9 (3 × NCH2CH2N), 61.8 (3 × CH2CH2-
CH2CtC), 81.6 (3 × C≡CPh), 89.7 (3 × CtCPh), 122.7 (4 ×
CHBPh), 124.5 (3 × CPh), 126.5 (8 × CHBPh), 128.8 (3 × CHPh),
129.4 (6 × CHPh), 130.3 (d, J PC ) 10 Hz, 6 × CHPPh), 131.5 (d,
J PC ) 2 Hz, 3 × CHPPh), 132.2 (6 × CHPh), 132.9 (d, J PC ) 37
Hz, 3 × CPPh), 134.0 (d, J PC ) 14 Hz, 6 × CHPPh), 136.7 (8 ×
CHBPh) and 164.7 (4 × CBPh). 31P NMR (acetonitrile-d6, 295
K): δ 6.8.
(6H, t, J ) 6.8 Hz, 3 × CH2CtC), 3.04-3.20 (12H, m, 3 ×
NCH2CH2N; partly obscured by resonances due to 2), 3.28 (6H,
m, 3 × CH2CH2CH2CtC), 7.25-7.38 (15H, m, 15 × HPh; partly
obscured by resonances due to 2). 13C NMR (acetone-d6, 295
K): δ 17.6 (3 × CH2CtC), 28.6 (3 × CH2CH2CtC), 55.1 (3 ×
NCH2CH2N), 61.6 (3 × CH2CH2CH2CtC), 81.9 (3 × C≡CPh),
89.6 (3 × CtCPh), 124.5 (3 × CPh), 128.8 (3 × CHPh), 129.3
(6 × CHPh), 132.2 (6 × CHPh) and 185.0 (CO).
Ack n ow led gm en t. We thank the Australian Re-
search Council for Small Grant funding and for an
Australian Postgraduate Research Award (to D.H.B.).
We thank the Crystallography Center of The Univer-
sity of Western Australia for a Ted Maslen Scholarship
(to N.S.).
Sp ectr a l Ch a r a cter iza tion of 4‚P F 6. Carbon monoxide
was bubbled through a solution of 2‚PF6 (6 mg) in acetone-d6
(1 mL) in an NMR tube fitted with a rubber septum. The
resulting sample was maintained under an atmosphere of CO
Su p p or tin g In for m a tion Ava ila ble: Full details of crys-
tallographic study of 2‚BPh4, including a figure showing the
unit cell array and tables giving all crystallographic data,
atomic positional parameters, bond distances and angles, and
anisotropic thermal parameters. This information is available
free of charge via the Internet at http://pubs.acs.org.
1
and was found (by integration of H NMR peaks) to contain
the cation 2 and the CO adduct 4 in
a ratio of 1.4:1,
respectively. The adduct 4 was identified on the basis of its
signals in the 1H and 13C NMR spectra of the sample. 1H NMR
(acetone-d6, 295 K): δ 2.14 (6H, m, 3 × CH2CH2CtC), 2.54
OM000999Z