A novel tetramer copper(I) complex containing diallylphosphine ligands: Synthesis, characterization and catalytic application in A3-coupling (Aldehyde-Amine-Alkyne) reactions

Article abstract of DOI:10.1016/j.ica.2017.07.038

A novel tetrameric copper(I) complex containing tert-butyldiallylphosphine ligands, [CuCl{^tBu-P(CH₂CH = CH₂)₂}]₄ (2), has been synthesized and characterized by structural and spectroscopic methods. X-ray diffraction analysis showed that 2 has a cubane-like solid structure of formula [CuCl{κ¹(P)-^tBu-P(CH₂CH = CH₂)₂}]₄. In solution, a dynamic behavior generated by the cubane ? chair isomerization was detected by variable temperature NMR analysis. DFT calculations have been performed to explain the observed dynamic equilibrium in solution. The use of copper(I) complex 2 as catalyst for the synthesis of propargylamines via A³-coupling reactions has been tested. Complex 2 is capable of promoting A³-coupling reactions of both aromatic and aliphatic aldehydes with cyclic secondary amines and phenylacetylene. The reaction proceeds under mild condition and absence of solvent.

Full text of DOI:10.1016/j.ica.2017.07.038

Accepted Manuscript
Research paper
A Novel Tetramer Copper(I) Complex Containing Diallylphosphine Ligands:
Synthesis, Characterization and Catalytic Application in A3-Coupling (Alde-
hyde-Amine-Alkyne) Reactions
Jennifer Rosales, Juan M. García, Edward Ávila, Teresa González, David
Santiago Coll, Edgar Ocando-Mavárez
PII:
S0020-1693(17)30546-7
http://dx.doi.org/10.1016/j.ica.2017.07.038
ICA 17761
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
7 April 2017
15 July 2017
17 July 2017
Please cite this article as: J. Rosales, J.M. García, E. Ávila, T. González, D.S. Coll, E. Ocando-Mavárez, A Novel
Tetramer Copper(I) Complex Containing Diallylphosphine Ligands: Synthesis, Characterization and Catalytic
Application in A3-Coupling (Aldehyde-Amine-Alkyne) Reactions, Inorganica Chimica Acta (2017), doi: http://
dx.doi.org/10.1016/j.ica.2017.07.038
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A Novel Tetramer Copper(I) Complex Containing
Diallylphosphine Ligands: Synthesis,
Characterization and Catalytic Application in A3-
Coupling (Aldehyde-Amine-Alkyne) Reactions
Jennifer Rosales,† Juan M. García,†* Edward Ávila,‡ Teresa González,‡ David Santiago Coll,§
and Edgar Ocando-Mavárez,† *
†Laboratorio de Físico-Química Orgánica, IVIC, Caracas 1020-A, Venezuela.
‡Laboratorio de Síntesis y Caracterización de Nuevos Materiales, IVIC, Caracas 1020-A,
Venezuela.
§Laboratorio de Físico-Química Teórica de Materiales, IVIC, Caracas 1020-A, Venezuela.
KEYWORDS: A3-coupling reactions; propargylamine; diallylphosphine ligands; tetramer
cobre(I) complex.
ABSTRACT: A novel tetrameric copper(I) complex containing tert-butyldiallylphosphine
ligands, [CuCl{tBu-P(CH2CH=CH2)2}]4 (2), has been synthesized and characterized by structural
and spectroscopic methods. X-ray diffraction analysis showed that 2 has a cubane-like solid
1
structure of formula [CuCl{ (P)-tBu-P(CH2CH=CH2)2}]4. In solution, a dynamic behavior
1

generated by the cubane
chair isomerization was detected by variable temperature NMR
analysis. DFT calculations have been performed to explain the observed dynamic equilibrium in
solution. The use of copper(I) complex 2 as catalyst for the synthesis of propargylamines via A3-
coupling reactions has been tested. Complex 2 is capable of promoting A3-coupling reactions of
both aromatic and aliphatic aldehydes with cyclic secondary amines and phenylacetylene. The
reaction proceeds under mild condition and absence of solvent.
1. Introduction
Propargylamines are generally used in organic chemistry as precursors and versatile building
blocks for the preparation of various nitrogen-containing heterocyclic compounds as well as key
intermediates for the synthesis of biologically active pharmaceuticals and natural products [1].
Furthermore, some propargylamines have been used for the treatment of neuropsychiatric
disorders such as Parkinson's and Alzheimer's disease [2]. Because of their importance, many
synthetic methods have been developed [3]. However, the most direct and efficient method for
the preparation of propargylamines is through transition-metal catalyzed three-component
coupling of an aldehyde, an amine and a terminal alkyne, which is known as an A3 coupling
reaction [4]. In recent years, various homogeneous and heterogeneous catalysts have been
employed in the synthesis of propargylamine via A3-coupling reaction, based on transition
metals such as Zr [8], Mn [9], Re [10], Fe [11], Ru [12], Co [13], Ir [14], Ni [15], Pd [16] Cu
[17], Ag [18], Au [19], Zn [20], Cd [21] and Hg [22]. Among the different transition metals,
copper have been widely studied because of its abundance, low cost, low toxicity and high
reactivity.
It is well-known that phosphines are versatile ligands capable of exerting a subtle control on
the metal center, which leads to metal catalysts with improved reactivity and stability [23].
2

However, there are few reports that describe the use of copper(I) catalysts bearing phosphines as
ligand in A3-coupling reactions [24]. We have recently reported a study concerning to hemilabile
properties of diallylphosphine ligands [25]. Ligands displaying this behavior enable to generate
active sites on the metal center and to stabilize reactive intermediates, which are features that
have been shown to enhance both activity and selectivity in catalytic reactions [26]. Now, we
feel motivated to explore the synthesis and catalytic potential of copper complexes with
diallylphosphine. Thus, herein we wish to report the synthesis of a novel tetrameric copper(I)
complex containing diallylphosphine ligands and its use as catalyst in the synthesis of
propargylamine via A3-coupling reaction.
2. Experimental
2.1. General Information
All reactions and manipulations were carried out under an inert atmosphere of argon by using
standard Schlenk techniques. Dry, oxygen-free solvents were employed. The elemental analysis
was performed (C, H, N) on a model EA1108 Fisons elemental analyzer. 1H, 13C, and 31P NMR
spectra were recorded with either Bruker Avance-300, Avance-500 or Avance-600
spectrometers. 1H and 13C NMR chemical shifts are reported in ppm relative to Me4Si as external
standard. 31P NMR chemical shifts are expressed in ppm relative to 85 % H
3
PO . tert-
4
butyldiallylphosphine was prepared by reported method [27].[CuCl(Ph3P)]4 (3) and
[CuCl(iPr3P)]4 (4) complexes were prepared following the reported procedure by Churchill [28].
CuCl complex and other chemicals were purchased from Sigma–Aldrich Co.
2.2. Preparation of [CuCl{tBu-P(CH2CH=CH2)2}]4 (2)
3

To a solution of CuCl (200 mg, 2.02 mmol) in CH2Cl2 (20 mL) was added a solution of the
tert-butyldiallylphosphine (1) (343.4 mg, 2.02 mmol) in 10 mL of CH2Cl2. The solution was
stirred for 24 h at RT. The solution was evaporated to dryness to give a white solid, which was
washed with pentane (15 mL) and dried under vacuum. Yield: 80% (435 mg) 1H NMR (500.03
MHz, CDCl3, 25 °C): δ 1.17 (d, 3JPH= 14.0 Hz, 36H, CH3tBu), 2.36-2.51 (m, 16H, PCH2), 5.05 (m,
16H, =CH2), 6.0 (br. s, 8H, CH=). 13C {1H} NMR (75.47 MHz, CDCl3, 25 °C): δ 27.3 (d, 2JCP =
5.7 Hz, 12C, CH3tBu), 28.1 (d, JCP = 14.1 Hz, 8C, PCH2), 30.3 (d, 4C, JCP = 17.2 Hz, PCtBu), 117.2
(br. s, 8C, =CH2), 132.9 (br. s, 8C, CH=). 31P {1H} NMR (202.41 MHz, CDCl3, 25 °C): δ 3.4 (br.
s). Anal. Calcd for C40H76P4Cu4Cl4: C, 44.61; H, 7.11. Found: C, 44.25; H, 7.08.
2.3. General Procedure for A3-Coupling Catalyzed by [CuCl{tBu-P(CH2CH=CH2)2}]4(2)
Under argon atmosphere, catalyst [CuCl{tBu-P(CH2CH=CH2)2}]4 2 (2.7 mg, 0.0025 mmol, 0.5
mol%), aldehyde (0.5 mmol), amine (0.55 mmol) and alkyne (0.75 mmol) were loaded in a
screw-cap test tube equipped with a stirring bar. The mixture was stirred at 50 °C for 6 h and
kept in the dark until completed the time of reaction. Then, the mixture was cooled, extracted
with ether (3x5 mL) and dried over MgSO4. The mixture was filtrated, concentrated (1H-NMR
spectroscopy showed quantitative conversion of aldehyde) and the residue was purified by flash
chromatography on silica gel (eluent: hexane/EtOAc= 3:1 V/V). The corresponding
propargylamines were obtained as a racemic mixture in form of light-yellow oil. Reported yields
are the average of at least two independent runs.
N-(1,3-Diphenyl-2-propynyl)piperidine (4a): Following the general procedure from 53 mg of
benzaldehyde, 47 mg of piperidina and 77 mg of phenylacetylene was obtained N-(1,3-Diphenyl-
2-propynyl)piperidina (4a) (128 mg, 93%). 1H NMR (600.13 MHz, CDCl3, 25ºC): = 1.49 (m,
2H, NCH2CH2CH2), 1.65 (m, 4H, NCH2CH2), 2.62 (br. s, 4H, NCH2CH2),4.85 (s, 1H, N-CH),
4

7.35-7.40 (m, 6H, CHAr), 7.57 (m, 2H, CHAr), 7.69 (m, 2H, CHAr). 13C{1H} NMR (150.91 MHz,
CDCl3, 25ºC): = 24.43 (s, 1C, NCH2CH2CH2), 26.17 (s, 2C, NCH2CH2CH2), 50.68 (s, 2C,
NCH2), 62.37 (s, 1C, N-CH), 86.07 (s, 1C, C•C-Ph), 87.81 (s, 1C, C•C-Ph), 123.33 (s, 1C, CAr),
127.40, 128.01, 128.23, 128.49, 131.77 (5 x s, 10C, CHAr), 138.59 (s, 1C, CAr).
N-(1,3-Diphenyl-2-propynyl)pyrrolidine (4b): Following the general procedure from 53 mg of
benzaldehyde, 39 mg of pyrrolidine and 77 mg of phenylacetylene was obtained N-(1,3-
Diphenyl-2-propynyl)pyrrolidine (4b) (118 mg, 90%). 1H NMR (600.13 MHz, CDCl3, 25ºC): =
1.79 (m, 4H, NCH2CH2), 2.69 (br. s, 4H, NCH2), 4.88 (s, 1H, N-CH), 7.23-7.36 (m, 6H, CHAr),
7.48 (m, 2H, CHAr), 7.60 (m, 2H, CHAr). 13C{1H} NMR (150.91 MHz, CDCl3, 25ºC): = 23.47 (s,
2C, NCH2CH2), 50.23 (s, 2C, NCH2), 59.09 (s, 1C, N-CH), 86.67 (s, 1C, C•C-Ph), 86.89 (s, 1C,
C•C-Ph), 123.21 (s, 1C, CAr), 128.04, 128.22, 128.25, 128.40, 129.16, 131.75 (6 x s, 10C, CHAr),
132.46 (s, 1C, CAr).
N-(1,3-Diphenyl-2-propynyl)morpholine (4c): Following the general procedure from 53 mg of
benzaldehyde, 48 mg of morpholine and 77 mg of phenylacetylene was obtained N-(1,3-
Diphenyl-2-propynyl)morpholine (4c) (114 mg, 83%). 1H NMR (300.20 MHz, CDCl3, 25ºC): =
2.65 (m, 4H, NCH2CH2), 3.75 (br. s, 4H, NCH2), 4.81 (s, 1H, N-CH), 7.31-7.38 (m, 6H, CHAr),
7.54 (m, 2H, CHAr), 7.65 (m, 2H, CHAr). 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): = 49.83 (s,
1C, NCH), 61.97 (s, 2C, NCH2CH2), 67.08 (s, 2C, CH2CH2O), 85.01 (s, 1C, C•C-Ph), 88.45 (s,
1C, C•C-Ph), 122.92 (s, 1C, CAr), 127.69, 128.15, 128.23, 128.50, 131.73 (5 x s, 10C, CHAr),
137.76 (s, 1C, CAr).
N-(1,3-Diphenyl-2-propynyl)tetramethylpiperidine (4d): Following the general procedure from
53 mg of benzaldehyde, 77 mg of 2,2,6,6-tetramethylpiperidine and 77 mg of phenylacetylene.
The analysis of crude mixture by 1H-NMR spectroscopy did not reveal the formation of desired
product.
5

N-(1,3-Diphenyl-2-propynyl)di-isopropylamine (4e): Following the general procedure from 53
mg of benzaldehyde, 56 mg of di-isopropylamine and 77 mg of phenylacetylene was obtained N-
(1,3-Diphenyl-2-propynyl)di-isopropylamine (4e) (22 mg, 15%). 1H NMR (300.20 MHz, CDCl3,
25ºC): = 1.05 (d, 3JHH = 6.7 Hz, 6H, CH3NiPr), 1.30 (d,3JHH = 6.6 Hz, 6H, CH3Nipr), 3.20 (sept,3JHH =
6.7 Hz, 2H, CHNipr), 5.02 (s, 1H, N-CH), 7.30-7.33 (m, 5H, CHAr), 7.46-7.49 (m, 3H, CHAr), 7.72-
7.75 (m, 2H, CHAr). 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): = 20.69 (s, 2C, CH3NiPr), 23.84
(s, 2C, CH3NiPr), 46.64 (s, 2C, CHNiPr), 50.50 (s, 1C, N-CH), 85.90 (s, 1C, C•C-Ph), 91.96 (s, 1C,
C•C-Ph), 123.94 (s, 1C, CAr), 126.76, 127.81, 127.88, 128.30, 131.33 (5 x s, 10C, CHAr), 142.19
(s, 1C, CAr).
N-(1,3-Diphenyl-2-propynyl)N-methylaniline (4f): Following the general procedure from 53
mg of benzaldehyde, 59 mg of methylaniline and 77 mg of phenylacetylene was obtained N-(1,3-
Diphenyl-2-propynyl)N-methylaniline (4f) (49 mg, 33%). 1H NMR (300.20 MHz, CDCl3, 25ºC):
= 2.81 (s, 3H, NCH3), 6.30 (s, 1H, N-CH), 6.86-6.91 (m, 1H, CHAr), 7.04 (m, 1H, CHAr), 7.07
(m, 1H, CHAr), 7.30-7.44 (m, 8H, CHAr), 7.48-7.51 (m, 2H, CHAr), 7.67 (m, 2H, CHAr). 13C{1H}
NMR (75.49 MHz, CDCl3, 25ºC): = 33..90 (s,, 1C, NCH3), 57.13 (s, 1C, N-CH), 85.84 (s, 1C,
C•C-Ph), 87.08 (s, 1C, C•C-Ph), 115.39, 118.81 (2 x s, 3C, CHAr),123.01 (s, 1C, CAr),127.67,
127.80, 128.33, 128.50, 129.24, 131.90 (6 x s, 12C, CHAr), 138.64 (s, 1C, CAr), 150.37 (s, 1C,
CAr).
1-(1-propyl-3-phenyl-2-propynyl)piperidine (4g): Following the general procedure from 36 mg
of butyraldehyde, 47 mg of piperidine and 77 mg of phenylacetylene was obtained 1-(1-propyl-
1
3-phenyl-2-propynyl)piperidine (4g) (119 mg, 99%). H NMR (300.20 MHz, CDCl3, 25ºC): =
0.95 (t, 3JHH = 7.2 Hz, 3H, CH3-CH2), 1.44-1.79 (m,10H, NCH2CH2CH2, CH3-CH2CH2), 2.49, 2.66
(2 x m, 4H, NCH2), 3.48 (dd, 3JHH = 5.4 Hz, 2JHH = 9.2 Hz, 1H, N-CH), 7.27 (m, 3H, CHAr), 7.41
(m, 2H, CHAr). 13C{1H} NMR (150.91 MHz, CDCl3, 25ºC): = 13.994 (s, 11C, CH3-CH2), 20.18 (s,
6

1C, CH3-CH2), 24.64 (s, 2C, NH2CH2CH2), 26.26 (s, 2C, NCH2CH2CH2), 35.65 (s, 1C, CH2-CH2 ),
50.62 (s, 2C, NCH2), 58.36 (s, 1C, NCH), 85.67 (s, 1C, C•C-Ph), 88.19 (s, 1C, C•C-Ph), 123.66
(s, 1C, CAr), 127.74, 128.20, 131.79 (3 x s, 3C, CHAr).
1-(1-propyl-3-phenyl-2-propynyl)pyrrolidine (4h): Following the general procedure from 36
mg of butyraldehyde, 39 mg of pyrrolidine and 77 mg of phenylacetylene was obtained 1-(1-
propyl-3-phenyl-2-propynyl)pyrrolidine (4h) (112 mg, 99%). 1H NMR (600.13 MHz, CDCl3,
25ºC): = 0.95 (t, 3JHH = 7.4 Hz, 3H, CH3-CH2), 1.48 (sept,3JHH = 7.2 Hz, 1H, CH3-CH2), 1.60
(sept,3JHH = 7.1 Hz, 1H, CH3-CH2), 1.70 (dd,3JHH = 7.7 Hz, 2H, CH2-CH2), 1.78 (br. s, 4H,
NCH2CH2), 2.68, 2.75 (2 x br. s, 4H, NCH2), 3.67 (t, 3JHH = 7.4 Hz, 1H, N-CH), 7.25 (m, 3H,
CHAr), 7.40 (m, 2H, CHAr). 13C{1H} NMR (150.91 MHz, CDCl3, 25ºC): = 13.89 (s, 1C, CH3-
CH2), 19.95 (s, 1C, CH3-CH2), 23.49 (s, 2C, NCH2CH2), 37.18 (s, 1C, CH2-CH2 ), 49.69 (s, 2C,
NCH2), 50.84 (s, 1C, N-CH), 85.28 (s, 1C, C•C-Ph), 88.24 (s, 1C, C•C-Ph), 123.48 (s, 1C, CAr),
127.28, 128.18, 131.18 (3 x s, 3C, CHAr).
1-(1-propyl-3-phenyl-2-propynyl)di-isopropylamine (4i): Following the general procedure
from 36 mg of butyraldehyde, 77 mg of di-isopropylamine and 77 mg of phenylacetylene was
obtained 1-(1-propyl-3-phenyl-2-propynyl)piperidine (4i) (39 mg, 30%). 1H NMR (300.20 MHz,
CDCl3, 25ºC): = 0.92 (t, 3JHH = 7.2 Hz, 3H, CH3-CH2), 1.02 (d, 3JHH = 6.7 Hz, 6H, CH3NiPr), 1.18
(d,3JHH = 6.5 Hz, 6H, CH3Nipr), 1.41-1.64 (m,4H, CH2-CH2), 3.20 (sept,3JHH = 6.6 Hz, 2H, CHNipr),
3.60 (t, 3JHH = 7.4 Hz, 1H, N-CH), 7.25 (m, 3H, CHAr), 7.35 (m, 2H, CHAr).13C{1H} NMR (75.49
MHz, CDCl3, 25ºC): = 13.97 (s, 1C, CH3-CH2), 19.92 (s, 1C, CH3-CH2), 20.47, 24.16 (2 x s, 4C,
CH3NiPr), 37.18 (s, 1C, CH2-CH2), 45.86, (s,1C, CHNipr), 46.42 (s, 1C, N-CH), 82.42 (s, 1C, C•C-
Ph), 94.34 (s, 1C, C•CC-Ph), 124.31 (s, 1C, CAr), 127.36, 128.17, 131.26 (3 x s, 3C, CHAr).
N-[1-(4-Methoxyphenyl)-3-phenyl-2-propynyl]pyrrolidine (4j): Following the general
procedure from 68 mg of p-methoxybenzaldehyde, 39 mg of pyrrolidine and 77 mg of
7

phenylacetylene was obtained N-[1-(4-Methoxyphenyl)-3-phenyl-2-propynyl]pyrrolidine (4j)
(143 mg, 98%). 1H NMR (300.20 MHz, CDCl3, 25ºC): = 1.78 (m, 4H, NCH2CH2), 2.67 (m,
4H, NCH2), 3.79 (s, 1H, OCH3), 4.82 (s, 1H, N-CH), 6.87, 6.90 (2x br. s, 2H, CHAr), 7.29 (m, 3H,
CHAr), 7.46-7.52 (m, 4H, CHAr). 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): = 23.44 (s, 2C,
NCH2CH2), 50.19 (s, 2C, NCH2), 55.22 (s, 1C, N-CH), 58.48 (s, 1C, OCH3), 86.65 (s, 1C, C•C-
Ph), 87.00 (s, 1C, C•CC-Ph), 113.55 (s, 2C, CHAr), 123.25 (s, 1C, CAr), 127.98, 128.19, 129.33,
131.71 (4 x s, 7C, CHAr), 132,44 (s, 1C, CAr), 159.02 (s, 1C, CAr).
N-[1-(4-Bromophenyl)-3-phenyl-2-propynyl]pyrrolidine (4k): Following the general procedure
from 93 mg of p-bromobenzaldehyde, 39 mg of pyrrolidine and 77 mg of phenylacetylene was
obtained N-[1-(4-Bromophenyl)-3-phenyl-2-propynyl]pyrrolidine (4m) (136 mg, 80%). 1H NMR
(300.20 MHz, CDCl3, 25ºC): = 1.84 (br. s, 4H, NCH2CH2), 2.72 (br. s, 4H, NCH2), 4.92 (s, 1H,
N-CH), 7.35 (m, 4H, CHAr), 7.53 (m, 5H, CHAr). 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): =
23.52 (s, 2C, NCH2CH2), 50.07 (s, 2C, NCH2), 58.37 (s, 1C, NCH), 85.82 (s, 1C, C•C-Ph), 87.40
(s, 1C, C•C-Ph), 121.47 (s, 1C, CAr), 122.92 (s, 1C, CAr), 128.23, 128.27, 128.39, 129.15, 129.94,
131.31, 131.76 (7 x s, 9C, CHAr), 138.51 (s, 1C, CAr).
N-[1-(3-Chlorophenyl)-3-phenyl-2-propynyl]pyrrolidine (4l): Following the general procedure
from 70 mg of m-chlorobenzaldehyde, 39 mg of pyrrolidine and 77 mg of phenylacetylene was
obtained N-[1-(3-Chlorophenyl)-3-phenyl-2-propynyl]pyrrolidine (4l) (123 mg, 83%). 1H NMR
(300.20 MHz, CDCl3, 25ºC): = 1.85 (br. s, 4H, NCH2CH2), 2.74 (m, 4H, NCH2), 4.94 (s, 1H,
N-CH), 7.35 (m, 5H, CHAr), 7.54 (m, 3H, CHAr), 7.68 (m, 1H, CHAr). 13C{1H} NMR (75.49 MHz,
CDCl3, 25ºC): = 23.61 (s, 2C, NCH2CH2), 50.16 (s, 2C, NCH2), 58.53 (s, 1C, N-CH), 85.72 (s,
1C, C•C-Ph), 87.56 (s, 1C, C•C-Ph), 122.98 (s, 1C, CAr), 126.45, 127.80, 128.32, 128.35, 128.39,
129.53, 131.86 (7 x s, 9C, CHAr), 134.22 (s, 1C, CAr), 141.66 (s, 1C, CAr).
8

N-[1-(4-Chlorophenyl)-3-phenyl-2-propynyl]pyrrolidine (4m): Following the general
procedure from 70 mg of p-chlorobenzaldehyde, 39 mg of pyrrolidine and 77 mg of
phenylacetylene was obtained N-[1-(4-Chlorophenyl)-3-phenyl-2-propynyl]pyrrolidine (4m)
(133 mg, 90%). 1H NMR (300.20 MHz, CDCl3, 25ºC): = 1.80 (br. s, 4H, NCH2CH2), 2.67 (m,
4H, NCH2), 4.87 (s, 1H, N-CH), 7.32 (m, 5H, CHAr), 7.50 (m, 4H, CHAr). 13C{1H} NMR (75.49
MHz, CDCl3, 25ºC): = 23.61 (s, 2C, NCH2CH2), 50.17 (s, 2C, NCH2), 58.42 (s, 1C, N-CH),
86.11 (s, 1C, C•C-Ph), 87.41 (s, 1C, C•C-Ph), 123.07 (s, 1C, CAr), 128.28, 128.36, 128.43,
129.63, 131.84 (5 x s, 9C, CHAr), 133.34 (s, 1C, CAr), 138.23 (s, 1C, CAr).
N-[1-(2-Chlorophenyl)-3-phenyl-2-propynyl]pyrrolidine (4n): Following the general
procedure from 70 mg of o-chlorobenzaldehyde, 39 mg of pyrrolidine and 77 mg of
phenylacetylene was obtained N-[1-(2-Chlorophenyl)-3-phenyl-2-propynyl]pyrrolidine (4n); (59
mg, 40%). 1H NMR (300.20 MHz, CDCl3, 25ºC): = 1.78 (br. s, 4H, NCH2CH2), 2.72 (m, 4H,
NCH2), 5.29 (s, 1H, N-CH), 7.30 (m, 5H, CHAr), 7.45 (m, 3H, CHAr), 7.77 (m, 1H, CHAr). 13C{1H}
NMR (75.49 MHz, CDCl3, 25ºC): = 23..54 (s,, 2C, NCCH2CH2), 50.42 (s, 2C, NCH2), 55.65 (s,
1C, N-CH), 86.50 (s, 1C, C•C-Ph), 86.56 (s, 1C, C•C-Ph), 123.12 (s, 1C, CAr), 126.71, 128.21,
128.30, 128.85, 129.69, 130.17, 131.83 (7 x s, 9C, CHAr), 133.86 (s, 1C, CAr), 137.26 (s, 1C, CAr).
N-(1,3-Diphenyl-2-propynyl)N-butylamine (4o): Following the general procedure from 53 mg
of benzaldehyde, 40 mg of N-butylamine and 77 mg of phenylacetylene was obtained N-(1,3-
Diphenyl-2-propynyl)N-butylamine (4o) (33 mg, 25%). 1H NMR (300.20 MHz, CDCl3, 25ºC):
= 0.86 (t, 3JHH = 7.2 Hz, 3H, CH3-CH2), 1.38 (m, 2H, CH3-CH2), 1.53 (m, 2H, N-CH2-CH2), 1.82
(br, 1H, N-H), 2.72 (m, 1H, N-CH2), 2.82 (m, 1H, N-CH2), 4.79 (s, 1H, N-CH), 6.86-6.91 (m,
1H, CHAr), 7.04 (m, 1H, CHAr), 7.07 (m, 1H, CHAr), 7.30-7.44 (m, 8H, CHAr), 7.24-7.59 (m, 10H,
CHAr) 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): = 13.96 (s, 1C, CH3-CH2), 20.49 (s, 1C, CH3-
CH2), 32.07 (s, 1C, N-CH2-CH2), 47.01 (s, 1H, N-CH2), 54.71 (s, 1C, N-CH), 85.33 (s, 1C, C•C-
9

Ph), 89.51 (s, 1C, C•C-Ph), 123.22 (s, 1C, CAr), 127.59, 127.69, 128.08, 128.22, 128.48, 131.69
(6 x s, 10C, CHAr), 140.54 (s, 1C, CAr).
1-(1-phenylhept-2-yn-1-yl)pyrrolidine (4p): Following the general procedure from 53 mg of
benzaldehyde, 39 mg of pyrrolidine and 62 mg of 1-hexyne was obtained 1-(1-phenylhept-2-yn-
1-yl)pyrrolidine (4p) (62 mg, 51%). 1H NMR (300.20 MHz, CDCl3, 25ºC): = 0.91 (t, 3JHH= 7.2
Hz, 3H, CH3); 1.50 (m, 4H, CH2CH2CH3), 1.76 (m, 4H, NCH2CH2), 2.27 (m, 2H, C•C-CH2), 2.60
(m, 4H, NCH2), 4.60 (t, JHH= 2.0 Hz, 1H, N-CH), 7.24-7.31 (m, 3H, CHAr), 7.50 (m, 1H, CHAr),
7.53 (m, 1H, CHAr). 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): = 13.57 (s, 1C, CH3), 18.44 (s,
1C, C•C-CH2), 21.96 (s, 1C, CH2CH3), 23.40 (s, 2C, NCH2CH2), 31.06 (s, 1C, C•CC-CH2CH2),
50.11 (s, 2C, NCH2), 58.74 (s, 1C, N-CH), 76.81 (s, 1C, C•C-CH2), 87.03 (s, 1C, C•C-CH2),
127.31, 128.05, 128.22 (3 x s, 5C, CHAr), 139.96 (s, 1C, CAr).
7-phenyl-7-(pyrrolidin-1-yl)hept-5-ynenitrile (4q): Following the general procedure from 53
mg of benzaldehyde, 39 mg of pyrrolidine and 70 mg of 5-hexynenitrile was obtained 7-phenyl-
7-(pyrrolidin-1-yl)hept-5-ynenitrile (4q) (91 mg, 72%). 1H NMR (300.20 MHz, CDCl3, 25ºC):
= 1.73 (m, 4H, NCH2CH2), 1.85 (m, 2H, N•C-CH2), 2.44 (m, 4H, C•C-CH2CH2), 2.54 (m, 4H,
NCH2), 4.54 (t, JHH= 2.0 Hz, 1H, N-CH), 7.24-7.33 (m, 3H, CHAr), 7.45 (m, 1H, CHAr), 7.48 (m,
1H, CHAr). 13C{1H} NMR (75.49 MHz, CDCl3, 25ºC): = 18.00 (s, 1C, C•CC-CH2), 17.76 (s, 1C,
C•C-CH2CH2), 23.20 (s, 2C, NCH2CH2), 24.62(s, 1C, N•C-CH2), 50.21 (s, 2C, NCH2), 58.62 (s,
1C, N-CH), 79.18 (s, 1C, C•C-CH2), 83.63 (s, 1C, C•C-CH2), 119.00 (s, 1C, N•C-CH2), 127.36,
127.89, 128.04 (3 x s, 5C, CHAr), 139.47 (s, 1C, CAr).
2.4. X-Ray Crystallography
One single crystal was mounted on a glass fiber and the crystallographic data were collected at
298(2) K on a Rigaku diffractometer, AFC-7, Mercury CCD-detector, Mo-K ( = 0.71073 Å)
10

radiation. Additionally, data collection using and scan was performed. Non-hydrogen atoms
are located from the difference E-maps by means of starting models for structure refinement
were found using direct methods with SHELXS program [29] (SHELXL-NT suite software [30]),
and the structural data were refined by full-matrix least-squares methods on F2 using the
SHELXL program [29] (SHELXL-NT suite software) [31]. Anisotropic thermal parameters were
used to refine all non-hydrogen atoms. The H atoms on the C atoms were included in calculated
positions. The H atoms on water molecules can be found from the weak residual electron peaks.
For distances and angles bonds and coordination sphere analysis was done with the PLATON
package of crystallographic software [32]. CCDC 1453471 for compound 2, contains the
supplementary crystallographic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Table 1. Crystallographic Parameters for 2
Crystal data
Chemical formula
Mr
C40H76Cl4Cu4P4
1076.85
Tetragonal, I-4 (No. 82)
295
14.130 (6), 13.268 (5)
2649 (19)
Crystal system, space group
Temperature (K)
a, c (Å)
V (Å3)
Z
2
Radiation type
Mo K , λ = 0.71070 Å
1.93
µ (mm−1)
Crystal size (mm)
Data collection
0.17 × 0.15 × 0.10
Rigaku AFC7S Mercury
diffractometer
Multi-scan methods
0.478, 0.521
Diffractometer
Absorption correction
Tmin, Tmax
No. of measured, independent and observed [I > 2 (I)] reflections
7160, 2540, 2299
0.025
0.661
Rint
(sin / )max (Å−1)
Refinement
R[F2 > 2 (F2)], wR(F2), S
No. of reflections
No. of parameters
H-atom treatment
0.036, 0.082, 1.11
2540
1118
H-atom parameters constrained
0.21, −0.29
,
min (e Å−3)
Ambasxolute structure
Flack parameter [33]
-0.003 (17)
Absolute structure parameter
11

2.5. Theoretical calculations.
Structures were optimized using DMol3 [34].This DFT based program permits determination of
the relative stability of all studied species based on their electronic structure. The calculations
were performed using the Kohn–Sham Hamiltonian with the Perdew–Wang 1991 gradient
correction [35] and the double-zeta plus (DNP) numerical basic set [34], which provides good
accuracy at a relatively low computational cost. The All Electron core treatment was used for all
the atoms. Frequency calculations of the structures showed that all frequencies were positive
indicating that all structures are real minima.
3. Results and discussion
3.1. Synthesis and characterization of [CuCl{tBu-P(CH2CH=CH2)2}]4 (2)
The reaction 1:1 of CuCl and tert-butyldiallylphosphine (1), in dichloromethane, resulted in
the formation of tetramer copper(I) complex [CuCl{tBu-P(CH2CH=CH2)2}]4 (2), which was
isolated as an off-white crystalline powder in 80% yield (Scheme 1).
Scheme 1. Synthesis of copper(I) complex [CuCl{tBu-P(CH2CH=CH2)2}]4 (2)
31P{1H} NMR spectrum at RT for 2 showed a broad signal slightly shifted to downfield with
respect to the free ligand [25] (Table 2). Meanwhile, 1H and 13C{1H} NMR spectra at RT reveal
1
the (P) coordination mode of the diallylphosphine ligand, as indicated by broad resonances for
olefin protons and carbons of the allyl groups, which exhibit similar values to those observed for
12

free ligand [25, 27c] (Table 2). Moreover, elemental analysis for 2 revealed a stoichiometric ratio
Cu/R3P 1:1.
Table 2. Spectral data for 2a
δ 1H
δ 1H
δ
13C{1H}
δ
13C{1H}
31P{1H}
Compounds
δ
(=CH) (=CH2) (=CH)
(=CH2)
1
2
-1.9
3.4
5.7
6.0
4.9
135.3
132.9
115.8
117.2
5.05
a Taken in CDCl3 at RT.
Copper(I) complex 2 was successfully isolated from concentrated pentane solution at RT as
white crystals, and the molecular structure was confirmed by X-ray diffraction analysis (Figure
1). Complex 2 has a tetrameric structure, which crystallizes in tetragonal space groups I-4 (No.
1
82) with asymmetric units containing [CuCl{ (P)-tBu-P(CH2CH=CH2)2}]4.
(b)
(c)
(a)
Figure 1. (a) Molecular structure of complex 2, with selected atom labeling scheme and ellipsoids drawn at the
30% probability level. Selected bond lengths (Å) and bond angles (deg): Cu1—P1 2.186(1), Cu1—Cl1i 2.333(1),
Cu1—Cl1ii 2.622(2), Cu1—Cl1iii 2.445(1); P1—Cu1—Cl1i 133.46(4), P1—Cu1—Cl1ii 105.37(4), P1—Cu1—Cl1iii
119.71(4), Cl1i—Cu1—Cl1ii 98.92(3), Cl1i—Cu1—Cl1iii 98.50(3), Cl1ii—Cu1—Cl1iii 91.13(3). (b) Coordination
1
sphere surrounded of Cu1 ion. (c) The “cubane-like” framework [CuCl{ (P)-tBu-P(CH2CH=CH2)2}]4.
Complex 2 has one crystallographically independent Cu(I) ion, surrounded by one phosphorus
atom (Cu1—P1 bond length 2.186 (1) Å) and three chlorine ligands (Cu1—Cl1, Cu1—Cl1i, and
Cu1—Cl1ii bond length 2.333 (1) Å, 2.622 (2) Å, and 2.445 (1) Å, respectively). This
environment describes a coordination sphere of a distorted tetrahedral for Cu1, as is shown in the
13

Figure 2b. The bond angle values range from 91.13° to 98.92° for Cl—Cu—Cl and from 105.37°
to 133.46° for P—Cu—Cl. In addition, each chlorine ion joins another Cu1 ion to form an
distorted "cubane-like" structure, as is shown in Figure 2c. The deformation of the Cu4Cl4 core is
evidenced by bond angles values Cl—Cu—Cl (ranging from 91.13° to 98.92°) and Cu—Cl—Cu
(ranging from 81.26° to 87.64°), which describe well the deviation from ideal cubane-like
structures. This cubane-like structure is in agreement with stoichiometric ratio Cu/L 1:1 and
confirms the monodentate coordination mode of tert-butyldiallylphosphine in 2. In addition,
cubane-like solid structures are well-known for phosphine copper(I) complexes. In fact, this
motif is present in 11 structures reported on the CSD data base [36]. A comparative analysis
indicates that bond distances and angles found for complex 2 are consistent with those in similar
reported structures.
Because of width of the signal in 31P{1H} NMR spectrum at RT, NMR analysis at variable
temperature was performed (Figure 2). This spectroscopic analysis revealed the existence of a
dynamic equilibrium in solution between two copper(I) species (labeled as 2' and 2''). In 31P{1H}
NMR spectra at variable temperature, the single broad signal around 3.4 ppm becomes into two
signals at 4.6 ppm (for 2') and - 3.2 ppm (for 2'') by decreasing the temperature from 35°C to -
90°C, whereas it remain unchanged by increasing from 25 °C to 75°C (Figure 2). Meanwhile, 1H
NMR spectrum at -90 °C (Figure S7 in supporting information) show the signals corresponding
to allyl protons for the two copper(I) species [ 6.04 for CH=; 4.94 (3JHH = 9.3 Hz) and 5.01 (3JHH
= 16.7 Hz) for =CH2] for 2'' and [ 5.8 for CH=; 5.17 and 4.41 (3JHH = 16.7 Hz) for =CH2] for 2'.
14

25°C
15°C
0°C
75°C
65°C
-15°C
-25°C
-35°C
55°C
45°C
35°C
-50°C
-70°C
-90°C
25°C
Figure 2. 31P{1H} NMR spectra at variable temperature for 2: from -90°C to 25°C in CD2Cl2 (left) and from 25°C to
75°C in toluene-d8 (right).
As we have mentioned above, cubane-like structure has been found to be the most common for
tetrameric phosphine copper(I) halides, however, open chair-like (or step) structure has been
also observed in several cases [28, 37]. Indeed, it has been established that the cube-like
structure is destabilized relative to the chair structure when large halogen atoms are accompanied
by bulky phosphine on the metal atom, thereby [Ph3PCuBr]4 and [Ph3PCuI]4 were isolated as
chair-like structures in solid state while [Ph3PCuCl]4 as a cubane-like structure. In addition, Teo
and Calabrese [38] have found that [Ph3PAgI]4 is capable of existing in both a highly distorted
cubane-like configuration and a chair-like structure in solid state. These authors have analyzed
steric interaction in (R3Y)4M4X4 (Y= P, As; M= Cu, Ag; X= Cl, Br, I) tetramers and concluded:
“As the steric hindrance among the ligands increases, the following stereochemical variation
inevitably occurs symmetrical cubane • distorted cubane • (cubane
chair ”. Therefore, observed dynamic equilibrium in solution for 2 can be ascribable to the
cubane chair isomerization as consequence of the low stability of the cube-like structure
chair isomerization) •
caused by the strong strain of the Cu4Cl4 core for steric reasons. In order to deep on this
hypothesis we have performed DFT calculations. Theoretical calculations indicates that the
experimentally isolated tetrameric structure 2'' is destabilized relative to the chair-like structure
15

2' by barely ca. 0.73 Kcal/mol (Figure 3). This result confirms that dynamic equilibrium is
1
generated by the isomerization of tetramer [CuCl{ (P)-tBu-P(CH2CH=CH2)2}]4 to give both the
cubane and the chair forms in solution.
PR3
Cl
Cu
Cl
R3P
Cl
PR3
Cu
R3P
Cu
R3P
Cl
Cl
Cu
Cu
Cu
Cl
Cl
Cu
PR3
Cu
R3P
Cl
PR3
2'
2''
(0.00)
(- 0.73)
tBu P
R3P:
Figure 3. Relative energies (kcal/mol) calculated for 2' and 2'' using Dmol3 are given in parentheses.
3.2. Catalytic Studies
We have examined the catalytic activity of copper(I) complex 2 in the A3-coupling reaction of
aldehyde, amine and alkyne for the preparation of propargylamines. In order to find optimized
reaction conditions, the coupling of benzaldehyde, piperidine and phenylacetylene was chosen as
model reaction in molar ratio 1:1.1:1.5 respectively. The results are summarized in Table 2. The
reaction was initially carried out under solvent free conditions at 25°C and 50°C. Almost total
conversion (96%) into desired product was achieved at 50°C within 6 hour using 0.5 mol% of 2
(Table 3, entries 8 and 9 ). When catalyst loading was decreased to 0.25 and 0.125 mol%, the
conversion was significantly lowered (Table 3. entries 8, 10 and 11). Meanwhile, solvents such
as toluene, petroleum ether, CHCl3, CH3OH, THF, CH3CN and water gave conversion lower than
that obtained under solvent free conditions (Table 3, entries 1-8). Thus, using 2 (0.5 mol%) at
50°C under solvent-free conditions (Table 3, entry 8) was selected as the optimum conditions
for the A3-coupling reaction of aldehyde, amine and alkyne.
16

Under the above optimized conditions, the model A3-coupling reaction was carried out using
analogous copper(I) complexes containing homofunctional phosphine [CuCl(Ph3P)]4 (3) and
[CuCl(iPr3P)]4 (4) as catalyst (Table 2, entries 8, 12 and 13). The results indicate that complex 2
shows higher catalytic activity than 3 and 4 (Table 3, entries 8, 12 and 13), which suggests that
tert-butyldiallylphosphine ligand might have a notable effect on the reactivity of copper(I) chloro
complexes involved in the A3-coupling reaction. However, to date we have not found any
evidence that correlates the best catalytic performance of complex 2 with the hemilabile behavior
of the ligand tert-butyldiallylphosphine.
Table 3. Optimization studies a
[Cu]
(mol%)
Time
(h)
Conversion
(%)b
Catalyst
Solvent
Temperature (°C)
Entry
1
2
2
2
Ph-CH3
Petroleum
ether
0.5
0.5
50
50
6
6
48
69
3
2
CHCl3
0.5
50
50
50
50
50
50
25
50
50
50
50
6
6
6
6
6
6
24
6
6
6
6
67
70
59
73
51
96
49
74
51
70
71
4
2
CH3OH
THF
CH3CN
water
neat
0.5
5
6
2
0.5
0.5
2
7
0.5
2
8
0.5
2
9
neat
0.5
2
10
11
12
13
neat
0.25
0.125
0.5
2
neat
2
neat
[CuCl(Ph3P)]4 (3)
[CuCl(iPr3P)]4 (4)
neat
0.5
aAll the reactions were carried out by using benzaldehyde (0.5 mmol), piperidine, (0.55 mmol) and phenylacetylene (0.75
mmol) in various solvent (0.5 mL). b Conversions were determined by 1H-NMR spectroscopy of the crude reaction and are
average of at least two independent runs.
In order to examine the scope of the reaction, we extended our investigation to different
combinations of aldehydes, amines and alkynes as depicted in Table 4. Initially, we studied the
17

reactivity of aromatic and aliphatic aldehydes with cyclic secondary amines and phenylacetylene
under the optimized reaction conditions (Table 4, entries 1-3, 7 and 8). Coupling of aromatic
benzaldehyde and aliphatic butyraldehyde using piperidine and pyrrolidine led to corresponding
propargylamines 4a-b and 4g-h in excellent yields. For a cyclic amine less nucleophilic as
morpholine, the corresponding propargylamine (4c) was obtained in good yield but at longer
reaction time than piperidine and pyrrolidine (Table 4, entry 3). It is interesting to note that for
the bulky 2,2,6,6-tetramethylpiperidine the expected reaction product was not obtained and
starting material remained intact (Table 4, entry 4).
Table 4. A3-coupling reactions catalyzed by [CuCl{tBu-P(CH2CH=CH2)2}]4 catalyst(2)a
yield
(%)b
Entry
Aldehyde
Amine
Alkyne
Product
1
2
C6H5CHO
C6H5CHO
Piperidine
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
phenylacetylene
1-hexyne
4a
4b
4c
4d
4e
4f
93
90
Pyrrolidine
Morpholine
2,2,6,6-Tetramethylpiperidine
iPr2NH
83c
NRd
15c
33c
99
3
C6H5CHO
4
C6H5CHO
5
C6H5CHO
6
C6H5CHO
Methylaniline
Piperidine
7
CH3(CH2)2CHO
CH3(CH2)2CHO
CH3(CH2)2CHO
4-MeOC6H5CHO
4-BrC6H5CHO
3-ClC6H5CHO
4-ClC6H5CHO
2-ClC6H5CHO
C6H5CHO
4g
4h
4i
8
Pyrrolidine
iPr2NH
99
30c
98
9
10
11
12
13
14
15
16
17
Pyrrolidine
Pyrrolidine
Pyrrolidine
Pyrrolidine
Pyrrolidine
n-Butylamine
Pyrrolidine
Pyrrolidine
4j
4k
4l
80
83
4m
4n
4o
4p
4q
90
40
25
C6H5CHO
C6H5CHO
51
72c
5-hexynenitrile
a All the reactions were carried out by using aldehyde (0.5 mmol), amine, (0.55 mmol), phenylacetylene (0.75 mmol) and 2 mol%
of catalyst 2 under free solvent conditions at 50°C for 6h. b Isolated yield based on aldehyde. c Reactions were carried out at 50°C
for 24h. d Verified by 1H-NMR spectroscopy of the crude reaction.
We also studied the influence of electron–donating or –withdrawing groups on the aromatic
ring of aldehyde. Aromatic aldehyde containing electron donating group as CH3O– at para–
18

position returned the corresponding product 4j in excellent yield (Table 4, entry 10). Also,
aromatic aldehydes possessing electron withdrawing groups such as Cl– and Br– at either meta–
and para–position gave good yields of the desired products 4k-4m (Table 4. entries 10-13).
However, aromatic aldehyde with chloro group at ortho–position gave low yield of the
corresponding product 4n (Table 4, entry 14). Subsequently, we screened additional secondary
amines such as isopropylamine and methylaniline with benzaldehyde and phenylacetylene,
which gave the desired products 4e and 4f in low yields (Table 4, entries 5 and 6). With
butyraldehyde, the reaction yield also resulted to be low (Table 4, entry 9). We then studied the
reactivity of the primary amine butylamine under the optimized reaction conditions, which led to
propargylamine 4o with only 25% yield (Table 4, entry 15).
Finally, we also evaluated the reactivity of aliphatic alkynes such as 1-hexyne and 5-
hexynenitrile with benzaldehyde and pyrrolidine under the optimized reaction conditions. The
use of 1-hexyne results in the formation of propargylamine 4p in 51% yield but in case of 5-
hexynenitrile, moderate yield of the corresponding propargylamine 4q was obtained after longer
reaction time (Table 4, entries 16 and 17).
Our catalyst 2 offer some advantages over previously reported Cu(I) catalysts bearing
phosphine-based ligands [24]. For instance, catalyst 2 operates under solvent free conditions,
moderate reaction temperature and lower catalyst loading.
4. Conclusions
In summary, we have synthesized and characterized a new copper(I) complex with tert-
butyldiallylphosphine ligands. X-ray crystallographic study confirmed the cubane-like structure
1
of the copper complex of formula [CuCl{ (P)-tBu-P(CH2CH=CH2)2}]4. However, spectroscopic
data at variable temperature indicated the existence of a dynamic behavior in solution generated
by the cubane
chair isomerization as consequence of the low stability of the cube-like
structure caused by the strong strain of the Cu4Cl4 core for steric reasons. DFT calculations
19

indicates that the experimentally isolated tetrameric structure is destabilized relative to the chair-
like structure. Catalytic ability of complex 2 was tested in A3-coupling reaction of aldehydes,
amines and alkynes. We found that complex 2 is an efficient catalyst for A3-coupling reactions of
both aromatic and aliphatic aldehydes with cyclic amine and phenylacetylene under mild
reaction condition and absence of solvent.
ASSOCIATED CONTENT
Supporting Information
Theoretical calculation, spectroscopic and crystallographic data. This material is available free
of charge via the Internet at https://www.journals.elsevier.com/inorganica-chimica-acta.
AUTOR INFORMATION
*E-mail: jmgarcia@ivic.gob.ve, eocando@ivic.gob.ve.
ACKNOWLEDGMENTS
We thank the Venezuelan Minister for Sciences and Technology (FONACIT G-2005000433,
G-2005000447) and the IVIC for financial support of this work. Dr. Rafael Rodriguez from
Centro de Química-IVIC for helpful discussions.
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26

GraphicalAbstract #1
tbu
P
Cl
Cu
tbu
P
Cu
Cl
CH2Cl2
24h, RT
t
4 CuCl
+ 4
Bu P
Cu
Cl
P
tbu
1
Cl
Cu
P
tbu
2
80%
GraphicalAbstract #2
27

Highlights:
A tetramer copper(I) complex with tert-butyldiallylphosphine has been synthesized and
characterized.
Tetramer copper(I) complex shows a cubane-like structure in solid state.
Isomerization of tetramer copper(I) complex was observed in solution.
A3-Coupling (Aldehyde-Amine-Alkyne) Reaction catalyzed by tetramer copper(I) complex.
28