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.Wcfrochimica Act.. Vol.4OA,No. 5, pp.433-436. 1984 Printed inGrcalBritain.
Copper (I) complexes
with some disubstituted acetylenes dimethylsulphoxide
and
A. C. UKWUEZE* and S. R. LANDOR Department of Chemistry, University of Lagos, Lagos, Nigeria (Received 28 September 1983)
copper (I) cyanide, bromide and chloride complexes with disubstituted acetylenes (RR’C(OH)C=C-X; R, R’ = CH3 or C,H5, X = Br, CN or Cl) and dimethylsulphoxide (DMSO) were
Abstract-Twelve
prepared and characterized. In all cases, the molar ratio of copper to dimethylsulphoxide and disubstituted acetylene was 4:2:1. The ‘HNMR, U.V.absorption and i.r. spectra (m cm-‘) of the copper (I) complexes were measured. The elemental analysis and spectral data suggest that the disubstituted acetylene is coordinated to the copper (I) atom via the x-bond using two-electron, three-centre carbon-metal bonds.
EXPERIMENTAL.
INTRODUCTION Extensive structural investigation of copper (I) complexes with disubstituted acetylenes had remained largely unexplored as a result of the lack of availability of single crystals suitable in size for X-ray analysis [ 11. However, it has been possible to obtain structural information based on i.r., u.v., NMR and elemental analysis for copper (I) and gold (I) complexes with disubstituted acetylenes [2-121. In this study, some disubstituted acetylenes (RR’C(OH)C=C-X, R, R’ = CH3 or C2H5, X = Br, CN or Cl) have been found to coordinate with copper (I) atoms via the n-bond, with DMSO molecules as ligand anions to copper (I) atoms. In the literature there is no information about the coordination of DMSO molecules to copper (I) atoms[2-121. We therefore report the characterization of copper (I) complexes [(CuY), (DMSO)* RR’C(OH)C%C-X, Y = CN, Br or Cl, R’,R’ = CH3 or C2Hs, X = CN, Br or Cl].
Physical methods
Preliminary work showed that thecomplexes were very airsensitive and so all preparations were made under a dry nitrogen atmosphere. Filtration and drying of complexes was done using a vacuum line. Infrared spectra were recorded using a Perkin-Elmer 257 grating spectrophotometer. Ultraviolet spectra were recorded in ethanolic solution using a path length of 1Omm on a Unicam SP800 electrophotometer. Proton NMR spectra were recorded on a Varian HA 100 or T60 spectrophotometer using TMS as external standard and CDCls as solvent. Melting points of the complexes (the temperatures at which ligands separate) were recorded on electrothermal melting point apparatus. Analysis
The amount of copper in the complexes was determined by complexometric titration [13]. The chloride and bromide were determined gravimetrically[l4]. The results of the elemental analysis are shown in Table 1. Preparation of disubstituted acetylenes
RR’C(OH)C C-X (R,R’ = CH,, C,Hs, X = Br, CN or Cl) were prepared according to methods in the literature [ 153. Preparation of complexes
*Correspondence to be addressed to: A. C. UKWUUE, School of Chemistry and Molecular Science, The University of Sussex, Brighton, Sussex BNl 9QJ, U.K.
Copper (I) cyanide (2.58 g, 0.04 M) was stirred into anhydrous DMSO (75ml) under nitrogen for 2 h. 1-Bromo-f methylbut-1-yn-3-01 (l&g, 0.01 M) was then added to the
Table 1. Elemental analysis of prepared copper (I) complexes Cu (%) Found talc. (CuCN),.(DMSO),.(CH,),C(OH)C=C-Br (CuBr),,~(DMSO),~(CH,),C(OH)CzC-Br (CuCl),~(DMSO),.(CH,),C(OH)C=C-Br (CuCN).+.(DMSO),C,H,(CH,)C(OH)C=C-Br (CuBr),.(DMS0)2.C2H,CH3C(OH)C=C-Br (CuCl),~(DMSO),C2H&H3C(OH)C&-Br (CuCN),.(DMSO),C,H,(CH,)C(OH)C=C’ZN (CuBr),.(DMSO),C,H,(CH,)C(OH)C=C-CN (CuCl),~(DMSO),~C,H,(CH,)C(OH)C=C-CN (CuCN),~(DMSO),C,H,(CH,)C(OH)C(OH)C=C-Cl (CuBr),.(DMS0)2.C2H5(CHJ)C(OH)C=GCl (CuCl),~(DMSO),C,H,(CH,)C(OH)C=C-Cl 433
36.95
27.90 35.05 36.20 27.50 34.10 39.15 29.25 37.05 36.40 28.95 36.40
37.23 28.22 35.25 36.47 27.79 34.59 39.56 29.54 37.33 36.82 29.22 36.82
Br, Cl, CN Found C&Z. 11.50 43.90
11.80 44.72
43.50
44.05
20.20
20.41
20.50
20.74
A. C. UKWUEZE and S. R. LANDOR
434
solution and stirred for another 2 h at 50°C under nitrogen. On cooling, the grey-yellow solid which separated from the solution was filtered in vacua and dried in cucuo, yield 5Sg, m.p. 125°C. All the other complexes were then prepared as above using the corresponding disubstituted acetylene and copper (I) compound. The yield and m.p. are shown in Table 2. The complexes were formed according to the equation:
RR’C(OH)C=C-X
+ CuY
DMSo > (CuY), (so,vent)
400&6OOcm-’ we can see that there are no remarkable differences in the frequencies of the peaks. This implies that the ligands have similar structure in both the bromo-, chloro- and cyano-complexes.
(DMSO)a . RR’C(OH)C=C-X.
(R’, R’ = CH3 or C2H5, X = CN, Br or Cl, Y = CN, Cl or Br.)
RESULTS AND DISCUSSION Infrared
spectra
The important i.r. frequencies of the ligands and the complexes are shown in Table 3. Vibrational assignments have been made for many of the observed frequencies on the basis of comparison with accepted assignments for certain modes in other compounds of close structural similarity. Thus, the features shown by some of the bands have been considered in the light of previous spectroscopic data interpretations. The V(S=O) occurs at 1020_1060cm-’ and this band is in close agreement with that observed for V(S=O) at 104~1060cm-i for organo-sulphur compounds [16]. The absence of V(C=C) at the expected region 21~-22OOcm-i suggests that the acetylenic ITbond is directly coordinated to copper (I) atom resulting in a decrease in bond order. The band then shifts to a lower frequency of 166&1640cm-‘. Reports have shown that copper (I) does not form discrete 2, 3 or 4 coordinate species in the solid form [ 171. The above observation is also in agreement with the two-electron three-centre bonds postulated for these complexes. The doublet structure observed for V(O-H) is due to the partial solubility with depolymerization in the Nujol mull used for the solid state spectra of the complexes [ 171. When we compare the i.r. spectra of the corresponding cyano, bromo- and chloro-complexes in the region
Ultraviolet
‘HNMR
prepared
(CuBr),.(DMSO),~(CH,)&(OH)C=C-Br (CuCl),.(DMSO),~(CH,),C(OH)C~C-Br (CuCN),.(DMSO),.C,H,(CH,)C(OH)C=CBr (CuBr),.(DMSO),,CZH,(CH,)C(OH)C=C-Br (CUCI),.(DMSO)~.C~H~(CH~)C(OH)C=C-B~ (CuCN),.(DMSO),C2H,(CH,)C(OH)C&CN (CuBr),~(DMSO),.C1H5(CH3)C(OH)C=CCN (CuCI),~(DMSO),.CZHS(CH,)C=CCN (CuCN),.(DMSO),~C,H,(CH,)C=CCl (CuBr),~(DMSO),.C2H,(CH,)C=CCl (CUCI),.(DMSO)~.C~H~(CH~)C=C-CI
spectra
The proton resonance shown in Table 5. CDCI, as reference. The quartet observed in the ethyl and
Table 2. Yield and m.p. of complexes
Complex
spectra
The U.V. absorption spectra of the prepared complexes are presented in Table 4. The band with the smallest molar absorptivity (E,,_) occurs at 294nm and it also has the smallest energy due to C-T interactions. Regular octahedral copper complexes are rare due to a very strong Jahn-Teller effect. Thus, the elongated distortion associated with copper complexes makes the structure more square-planar with increased distortion. The C-T spectrum exhibits only one band when the structure of copper complex is a regular octahedron. However, upon elongation, the octahedron splits this band into 224 bands which appears as a broad band. The centre of this broad band acquires higher energies in accordance with the degree of distortion [l&20]. The highest energy band observed for the complexes prepared above occurred at 275 nm and has Em,, 208. The near-u.v. absorption bands of all the complexes are very strong and agree with the expected behaviour of tetramers or polymers in the solid state and dimers in solution[21]. Thus we can conclude that the complexes are dimers in solution but tetramers in the solid state.
spectra of the complexes are was used as solvent and TMS and triplet structures usually methyl protons are represen-
used in this study
wt of cuy (0.04 mole) used
Yield
M.p. (“C)
5.14 3.96 3.58 5.74 3.96 3.58 5.74 3.96 3.58 5.74 3.96
2.4,26.9 % 4.562.9 % 5.5,79.6 % 3.1,34.20/; 4.5,61.7 “/, 5.0,79.5 “/ 4.2,49.8 y0 2.4,36.9 7, 4.6,12.3 7, 3.5,41.1 7; 4.3,63.7 ‘i,
122 115 125 123 118 126 120 129 125 117 115
Compounds
163&b 1650&b 165Os,b 163Os,b 165Os,b 164&b 165Ck,b
214ow, 2120s 22OOw,2180s
214ow, 2120s -
2130
351os, 3410s
342Os,3300s
342Os,3300s
3510%3420s
351Os,3420s
35OOs,3850s
351os, 3410s
351os, 3300s
351os, 3410s 215th~
165Os,b
-
351os, 3450s
165Os,b
-
35oos, 3400s
165Os,b
164Os,b
164Os,b
V(CzC)
21oow,214os
V(C=N)
35oos, 3400s
VP-H)
1460s
146os, 144om
164os, 144Om 1410w 1460s
1460s
146om, 1440s 1410w Was, 1410w
149om, 1440s 1410w 144os, 14oow
1460s
149Om,1460s 143ow 149onl. 1460s
CH, asym. def.
131orn
1380s
138Os,1320m
138Os,131Om
131om
138Os,132Om
1360s
137os, 1310m
138Os,1300m
138Os,132Om
137Os,1320m
137Os,1320m
CH2 sym. def.
950s
980s
950s
950s
940s
980s
950s
990s
CH2 wagging.
1030s.b
102Os,b
102Os,b
103Os,b
103Os,b
103Os,b
103Os,b
106Os,b 102ow 102Os,b
102Os,b 980m 102Os,b 950w 103Os,b
(S=O)
Table 3. Infrared spectra of disubstituted acetylene compounds and their complexes with dimethylsulphoxide and copper (I) compounds
81Om, 780w 72Os,650s 81Om, 780w 7OOs,650s 81Om, 77th~ 72Os,660s 81Om, 780w 72Os,650s 81Om, 790w 680%660s 81Om, 780w 72Os,680s 81Om, 790w 73os, 710s 81Om, 780w 72Qs,660 82Om, 790w 72Os,650 79om, 760w 71Os,660 81Om, 780w 73Os,650 81Om, 780m 720s
CHI and CHI rocking
A. C. UKWUEZE and S. R.
436
Table 4. The n.v. absorption
spectral
LANDOR
data of the prepared
copper
(I) complexes
Wavelength max. (nm) 275 274 273 275 274 275 275 274 273 215 274 213
(CuCN),.(DMSO),.(CH,),C(OH)CsC-Br (CUB~),.(DMSO),.(CH,)~C(OH)C=C~B~ (CuCl),.(DMSO),.(CH,),C(OH)C&-Br (CuCN),.(DMSO),.CZH5(CHX)C(OH)C=C-Br (CuBr),‘(DMSO),.C,H,(CH,)C(OH)C=C-Br (CUCI),.(DMSO),.C,H,(CH~)C(OH)C=C-Br (CUCN),~(DMSO)~~C~H,(CH~)C(OH)C=CCN (CuBr)L~(DMSO),~C,H,(CH~)C(OH)C=C~CN (CuCI),~(DMSO),~C,HS(CH,)C(OH)C=CCN (CUCN),~(DMSO)~C~H~(CH~)C(OH)C=CCI (CuBr)4.(DMSO),.C2H,(CH,)C(OH)C=C--CI (CuCI),.(DMSO),X,HS(CH,)C(OH)C-CCI
Table 5. The ‘H NMR spectral
data of the prepared
copper
(I) complexes
6 OH Protons
Molar absorptivity E Xl&X
208 194 201 205 195 198 206 195 198 208 197 198
(chemical
shifts in ppm relative to TMS)
6 Methyl and ethyl protons
0.90 0.95 0.90 0.95 0.95 0.90 0.95 0.90 0.95
ted. The highly deshielded O-H proton downfield in all the complexes prepared.
resonates
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