550
Inorg. Chem. 2001, 40, 550-553
Notes
the thallium salts of phenylcyanamide ligands (pcyd-) have been
previously described.6 Caution: Thallium is toxic.
Influence of the Inner Coordination Sphere on
the Ru(III)-Cyanamido Ligand-to-Metal Charge
Transfer Chromophore
Complex preparations were very similar, and so only one example
1
is shown below. Experimental details, elemental analyses, IR, and H
NMR data for the other complexes are in the Supporting Information.
Preparation of [Ru(bpy)(trpy)(4-Mepcyd)][PF6]‚DMF. [Ru(bpy)-
(trpy)Cl][PF6] (0.34 g, 0.51 mmol) was dissolved in 25 mL of N,N′
dimethylformamide (DMF) in a 50 mL round-bottom flask. Tl+[4-
Mepcyd]- (0.17 g, 0.51 mmol) was added, and the deep-red solution
was refluxed for 18 h. The reaction mixture was then chilled to -20
°C and filtered to remove a fine white TlCl precipitate. The crude
product precipitated as a deep-red-brown solid with the addition of
500 mL of ether to the filtrate and was collected by suction filtration.
Recrystallization was achieved by the slow diffusion of ether into a
saturated solution of the crude complex in DMF. Yield: 0.29 g (76%).
Peter J. Mosher,† Glenn P. A. Yap,‡ and
Robert J. Crutchley*,†
Ottawa-Carleton Chemistry Institute, Carleton University,
1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada,
and University of Ottawa, Ottawa,
Ontario K1N 6N5, Canada
ReceiVed July 18, 2000
1
ν(NCN): 2156 cm-1. H NMR (400 MHz, DMSO-d6): 9.63(d, 1H),
8.87(d, 1H), 8.80(d, 2H), 8.68(d, 2H), 8.61(d, 1H), 8.35(t, 1H), 8.23(t,
1H), 8.03(m, 3H), 7.80(t, 1H), 7.68(d, 2H), 7.41(m, 3H), 7.11(t, 1H),
6.58(d, 2H), 5.82(d, 2H). Anal. Calcd for [Ru(bpy)(trpy)(4-Mepcyd)]-
[PF6]‚DMF (C36H33N8OPF6Ru): C, 51.49; H, 3.96; N, 13.34. Found:
C, 51.03; H, 3.95; N, 13.22.
Introduction
The extensive π conjugation between the cyanamide group
and the phenyl ring provides an energetically favorable means
by which a metal ion can couple into a conjugated organic π
system. This has been experimentally demonstrated by the
extraordinary ability of 1,4-dicyanamidobenzene to mediate
metal-metal coupling in dinuclear ruthenium mixed-valence
complexes,1 and the wealth of data provided by the study of
these systems has permitted a quantitative evaluation of metal-
metal coupling within the context of Marcus-Hush theory.2 The
recent interest in the field of inorganic chemistry to develop
novel hybrid materials that combine coordination and organic
chemistry provides further impetus to this research.
In this study, we have synthesized and characterized the
complexes [Ru(bpy)(trpy)L]+ where trpy is 2,2′:6′,2′′-terpyri-
dine, bpy is 2,2′-bipyridine, and L is 4-methyl-, 3-chloro-, 2,4-
dichloro-, 2,4,5-trichloro-, 2,4,6-trichloro-, 2,3,4,5-tetrachloro-
2,3,5,6-tetrachloro-, or pentachlorophenylcyanamido anion ligand.
Spectroelectrochemical oxidation to the Ru(III) complexes
permitted an analysis of their Ru(III)-cyanamide ligand-to-
metal charge transfer (LMCT) spectral properties and metal-
ligand coupling elements in comparison to their pentaammineru-
thenium(III) analogues.3
Oscillator Strength Calculation. The approach used for non-
Gaussian band shapes has been previously described.7 A figure showing
the fitting procedure on the low-energy LMCT band of [Ru(bpy)(trpy)-
(2,3,4,5-Cl4pcyd)]2+ has been placed in the Supporting Information.
Crystallography. Crystals of [Ru(bpy)(trpy)(2,4-Cl2pcyd)]PF6‚DMF
were grown by ether diffusion into a DMF solution of the complex.
The data were collected on a 1K Siemens Smart CCD using Mo KR
radiation (λ ) 0.710 73 Å) at 238(2) K using an ω-scan technique and
corrected for absorptions using equivalent reflections.8 No symmetry
higher than triclinic was observed, and solution in the centric space
group option yielded chemically reasonable and computationally stable
results of refinement. The structure was solved by direct methods and
refined with full-matrix least-squares procedures. Anisotropic refinement
was performed on all non-hydrogen atoms. All hydrogen atoms were
calculated. Scattering factors are contained in the SHELXTL 5.1
program library.
Results
The Ru(II) complexes were synthesized in generally good
yields according to the following metathesis reaction in refluxing
DMF.
Experimental Section
[Ru(bpy)(trpy)Cl]+ + Tl+L- f [Ru(bpy)(trpy)L]+ + TlClV
Equipment. UV-vis spectroscopy was perfomed on a CARY 5
UV-vis-NIR spectrophotometer. IR spectra were taken with a
BOMEM Michelson-100 FT-IR spectrophotometer as KBr disks. The
instrumentation used to perform cyclic voltammetry and spectroelec-
trochemistry has been described previously.4
Materials. All reagents and solvents used were reagent grade or
better. Tetrabutylammonium hexafluorophosphate (TBAH) was pur-
chased from Aldrich and recrystallized twice from ethanol/water and
then vacuum-dried at 110 °C. Syntheses of [Ru(bpy)(trpy)Cl][PF6]5 and
Under these conditions, the cyanamide group preferentially binds
to Ru(II) through the nitrile nitrogen instead of the amide
nitrogen as shown by the crystal structure discussed below. A
previous H NMR study of the reaction of phenylcyanamide
ligands with Ru(II) 2,6-bis(1-methylbenzimidazol-2-yl)pyridine
complexes indicated that the amide bound linkage isomer
1
† Carleton University.
‡ University of Ottawa.
(1) Evans, C. E. B.; Naklicki, M. L.; Rezvani, A. R.; White, C. A.;
Kondratiev, V. V.; Crutchley, R. J. J. Am. Chem. Soc. 1998, 120,
13096.
(2) Hush, N. S. Prog. Inorg. Chem. 1967, 8, 391.
(3) Crutchley, R. J.; McCaw, K.; Lee, F. L.; Gabe, E. J. Inorg. Chem.
1990, 29, 2576.
(5) Takeuchi, K. J.; Thompson, M. S.; Pipes, D. W.; Meyer, T. J. Inorg.
Chem. 1984, 23, 1845.
(6) Crutchley, R. J.; Naklicki, M. L. Inorg. Chem. 1989, 28, 1955.
(7) Evans, C. E. B.; Ducharme, D.; Naklicki, M. L.; Crutchley, R. J. Inorg.
Chem. 1995, 34, 1350.
(4) Desjardins, P.; Yap, G. P. A.; Crutchley, R. J. Inorg. Chem. 1999,
38, 5901.
(8) Blessing, R. Acta Crystallogr. 1995, A51, 33.
10.1021/ic0008159 CCC: $20.00 © 2001 American Chemical Society
Published on Web 12/07/2000
Mosher
