The trans influence in mer-tri­chloro­nitridobis­(tri­phenyl­arsine)­ruthenium(VI)

The title compound, mer-[RuCl₃N(C₁₈H₁₅As)₂], is the first structurally characterized example of a nitride complex in which ruthenium is six-coordinated to monodentate ligands only. The Ru[triple bond]N bond length [1.6161 (15) Å] is relatively long, and the trans influence of the nitride ligand is reflected by the difference between the Ru—Cl_trans and Ru—Cl_cis bond lengths [0.1234 (4) Å]. The N—Ru—Cl_trans axis is sited on a twofold axis.

S1. Comment

Ruthenium nitrido complexes have been well known since 1972 (Griffith & Pawson, 1972). However, all of the structurally characterized Ru≡N complexes with monodentate auxiliary ligands are square pyramidal and five-coordinate (Phillips & Skapski, 1975; Collison et al., 1981; Sharpley et al., 1988; Liang & Sharpley, 1996), which fact provides a qualitative indication of the strong trans-influence of the nitrido ligand. In order to obtain a good quantitative measure of the trans-influence unperturbed by the steric requirements of polydentate ligands, we have undertaken a study of mer-[RuNCl₃(AsPh₃)₂] (I).

The structure of (I) consists of discrete monomers, and the coordination geometry (Fig. 1 and Table 1) of is distorted octahedral. The three chloride ligands are arranged in a meridional configuration in which one chloride ligand is trans to the nitride, as proposed by Pawson & Griffith (1975).

The Ru≡N bond length of 1.6161 (15) Å is relatively long compared with other ruthenium nitrido compounds and is only exceeded in bis(1,2-bezenedithiolate)nitridoruthenate(VI) [1.613 (5) and 1.621 (5) Å in two independent molecules; Sellmann et al., 1997] and µ-oxo-tetrakis(2,5-dimethyl-2,5-hexanediamine-N,N')nitridodiruthenium(VI) [1.66 (1) Å; Chiu et al., 1996].

The Ru—As bond length of 2.5533 (3) Å is the longest reported Ru—As bond length in ruthenium compounds with AsPh₃ and related ligands. Note that arsine ligands support ruthenium in oxidation states varying from Ru⁰ in [Ru(AsPh₃)(CO)₄] (Martin et al., 1983) to Ru^VI in ruthenium nitride complexes such as the title compound.

In five- and six-coordinate complexes with strong π-donor ligands, such as oxide and nitride ligands, the central metal is invariably displaced out of the plane of the equatorial ligands, towards the multiply bonded ligand. This phenomenon is much less pronounced in the six-coordinate compounds, probably as a result of steric interactions. Given the N—Ru—Cl1 and N—Ru—As angles of 93.325 (7) and 93.59 (1)° in (I), the Ru atom lies 0.1483 (2) Å above the equatorial plane defined by? the two Cl and two As atoms. This deviation is less than half the out-of-plane distances seen in five-coordinate nitrido compounds, where the deviations range from 0.34 Å in [MoN(N₃)₄]^- (Dehnicke et al., 1980) to 0.768 Å in [TcN(Se₂C═C(CN)₂)]^2- (Abram et al., 1991). In (I), the Ru—Cl_trans bond length [2.5020 (4) Å] is longer than the Ru—Cl_cis bond length [2.3786 (3) Å]. This trans influence is relatively small compared with that observed for other six-coordinate nitrido complexes (cf. Table 2), possibly because of the small out-of-plane displacement of the Ru atom in (I), which reflects the steric bulk of the AsPh₃ ligands and the concomitant strain involved in closing all angles involving the arsine ligands.

The closely related compound mer-[Ru(NO)Cl₃(AsPh₃)₂] (Souza et al., 1995) is isostructual with (I). The geometric parameters of these two complexes are almost identical (Table 3), but the nitrosyl ligand does not exert any trans influence. This result is parallelled for first-row transition metals by the strong trans influence found in [Mn(N)(CN)₅]^3- [0.253 (7) Å; Bendix et al., 2000] and the absence of any trans influence in [Mn(NO)(CN)₅]^3- [0.03 (1) Å; Tullberg and Vannerberg, 1967). These findings reflect the general rule that, while strong π-donor ligands exert a trans influence, π-acceptors do not (Lyne & Mingos, 1995).

Importantly, the steric demands of the AsPh₃ ligand shield the nitrido ligand in (I) from intermolecular interactions. Accordingly, the packing (Fig. 2) is governed by the arrangement of the phenyl groups of the AsPh₃ ligands, with several relatively short intermolecular C···C distances [3.696–3.9 Å]. The rhombicity of the molecules is mirrored in the packing; all Ru≡N directions are parallel (or antiparallel) and all As—As vectors are parallel. The packing thus explains the strong dichroism of the solid compound and makes it a good candidate for polarized single-crystal absorption and luminescence spectroscopy (Cowman et al., 1976; Lamet et al., 1993) on an unperturbed Ru≡N moiety.

S2. Experimental

Compound (I) was prepared according to the method described by Pawson & Griffith (1975). Crystals were grown by adding a solution of [Bu₄N][RuNCl₄] in methanol to a solution of excess AsPh₃ in acetone at room temperature and allowing slow evaporation of the solvent. The crystals are pronouncedly dichroic, namely red and yellow.

S3. Refinement

H atoms were found in a difference Fourier map and were included in the refinement at idealized positions, riding on their parent atom, with C—H bond lengths of 0.93 Å.

Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: DIRAX (Duisenberg, 1992); data reduction: EVALCCD (Duisenberg, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997) and SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976).

Figures

	Fig. 1. A view of the molecular structure of [RuNCl3(AsPh3)2], with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The crystal packing, showing the parallel and antiparallel Ru≡ N directions parallel to the b axis. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity.

mer-trichloronitridobis(triphenylarsine)ruthenium(VI)

Crystal data

[RuCl3N(AsC18H15)2]	F(000) = 1656
Mr = 833.87	Dx = 1.713 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 34589 reflections
a = 12.0020 (4) Å	θ = 2.2–35.0°
b = 14.5630 (9) Å	µ = 2.79 mm^−1
c = 18.526 (2) Å	T = 122 K
β = 92.882 (5)°	Prism, red and yellow
V = 3234.0 (4) Å^3	0.27 × 0.18 × 0.14 mm
Z = 4

Data collection

Nonius KappaCCD area-detector diffractometer	7120 independent reflections
Radiation source: fine-focus sealed tube	6361 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
ω and φ scans	θmax = 35.0°, θmin = 2.2°
Absorption correction: integration Gaussian integration (Coppens, 1970)	h = −19→19
Tmin = 0.462, Tmax = 0.877	k = −23→23
55021 measured reflections	l = −29→29

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.052	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0173P)^2 + 4.8314P] where P = (Fo^2 + 2Fc^2)/3
7120 reflections	(Δ/σ)max = 0.001
196 parameters	Δρmax = 0.62 e Å^−3
0 restraints	Δρmin = −0.93 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

- 0.0706 (0.0010) x + 14.5627 (0.0017) y + 0.0370 (0.0005) z = 3.8768 (0.0005)

* 0.0000 (0.0000) As1 * 0.0000 (0.0000) Cl1 * 0.0000 (0.0000) As1 * 0.0000 (0.0000) Cl1 - 0.1483 (0.0002) Ru1

Rms deviation of fitted atoms = 0.0000

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ru1	0.0000	0.255394 (8)	0.2500	0.00929 (3)
N1	0.0000	0.14442 (10)	0.2500	0.0153 (3)
Cl1	−0.17848 (2)	0.26487 (2)	0.188570 (16)	0.01445 (5)
Cl2	0.0000	0.42720 (3)	0.2500	0.01609 (7)
As1	0.106252 (9)	0.266385 (8)	0.134322 (6)	0.00948 (3)
C1	0.15328 (9)	0.14305 (8)	0.11152 (6)	0.01168 (18)
C2	0.21054 (10)	0.09280 (8)	0.16602 (7)	0.0142 (2)
H2	0.2264	0.1193	0.2110	0.017*
C3	0.24374 (11)	0.00301 (8)	0.15278 (7)	0.0164 (2)
H3	0.2830	−0.0302	0.1886	0.020*
C4	0.21818 (11)	−0.03692 (9)	0.08593 (7)	0.0183 (2)
H4	0.2406	−0.0968	0.0771	0.022*
C5	0.15925 (12)	0.01222 (9)	0.03225 (7)	0.0182 (2)
H5	0.1410	−0.0154	−0.0120	0.022*
C6	0.12729 (11)	0.10298 (8)	0.04445 (7)	0.0149 (2)
H6	0.0891	0.1363	0.0082	0.018*
C7	0.02819 (9)	0.30835 (8)	0.04667 (6)	0.01176 (18)
C8	−0.07042 (10)	0.26370 (8)	0.02368 (7)	0.0146 (2)
H8	−0.0995	0.2174	0.0518	0.017*
C9	−0.12484 (10)	0.28882 (9)	−0.04138 (7)	0.0166 (2)
H9	−0.1902	0.2590	−0.0569	0.020*
C10	−0.08192 (11)	0.35828 (9)	−0.08324 (7)	0.0177 (2)
H10	−0.1185	0.3747	−0.1268	0.021*
C11	0.01552 (11)	0.40321 (9)	−0.06015 (7)	0.0179 (2)
H11	0.0437	0.4501	−0.0880	0.021*
C12	0.07109 (10)	0.37821 (8)	0.00478 (7)	0.0148 (2)
H12	0.1366	0.4081	0.0201	0.018*
C13	0.24129 (9)	0.33844 (8)	0.14375 (6)	0.01186 (18)
C14	0.34570 (10)	0.29664 (8)	0.14436 (7)	0.0156 (2)
H14	0.3514	0.2334	0.1386	0.019*
C15	0.44156 (11)	0.35006 (10)	0.15365 (8)	0.0192 (2)
H15	0.5114	0.3222	0.1546	0.023*
C16	0.43369 (11)	0.44470 (9)	0.16155 (7)	0.0181 (2)
H16	0.4980	0.4801	0.1675	0.022*
C17	0.32932 (11)	0.48636 (9)	0.16057 (7)	0.0163 (2)
H17	0.3239	0.5497	0.1656	0.020*
C18	0.23283 (10)	0.43345 (8)	0.15209 (7)	0.0144 (2)
H18	0.1631	0.4613	0.1520	0.017*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ru1	0.00894 (5)	0.00864 (5)	0.01011 (5)	0.000	−0.00124 (4)	0.000
N1	0.0158 (6)	0.0132 (6)	0.0170 (7)	0.000	0.0000 (5)	0.000
Cl1	0.01121 (11)	0.01749 (12)	0.01422 (12)	−0.00021 (8)	−0.00373 (9)	0.00074 (9)
Cl2	0.01383 (16)	0.01050 (15)	0.0239 (2)	0.000	0.00106 (14)	0.000
As1	0.00927 (5)	0.00871 (5)	0.01031 (5)	−0.00031 (3)	−0.00109 (4)	0.00038 (3)
C1	0.0116 (4)	0.0106 (4)	0.0128 (5)	0.0003 (3)	0.0001 (4)	0.0003 (3)
C2	0.0154 (5)	0.0130 (5)	0.0138 (5)	0.0018 (4)	−0.0017 (4)	0.0001 (4)
C3	0.0170 (5)	0.0135 (5)	0.0185 (5)	0.0037 (4)	−0.0005 (4)	0.0015 (4)
C4	0.0224 (6)	0.0121 (5)	0.0205 (6)	0.0024 (4)	0.0035 (5)	−0.0008 (4)
C5	0.0260 (6)	0.0141 (5)	0.0146 (5)	0.0011 (4)	0.0014 (5)	−0.0034 (4)
C6	0.0190 (5)	0.0132 (5)	0.0124 (5)	0.0009 (4)	0.0000 (4)	−0.0003 (4)
C7	0.0112 (4)	0.0121 (4)	0.0118 (5)	0.0010 (3)	−0.0011 (4)	0.0003 (3)
C8	0.0129 (5)	0.0156 (5)	0.0151 (5)	−0.0018 (4)	−0.0014 (4)	0.0006 (4)
C9	0.0141 (5)	0.0189 (5)	0.0164 (5)	0.0005 (4)	−0.0038 (4)	−0.0019 (4)
C10	0.0194 (6)	0.0181 (5)	0.0151 (5)	0.0045 (4)	−0.0040 (4)	0.0010 (4)
C11	0.0209 (6)	0.0158 (5)	0.0167 (5)	0.0012 (4)	−0.0011 (4)	0.0043 (4)
C12	0.0142 (5)	0.0145 (5)	0.0156 (5)	−0.0008 (4)	−0.0016 (4)	0.0019 (4)
C13	0.0111 (4)	0.0126 (4)	0.0118 (5)	−0.0024 (3)	−0.0007 (4)	−0.0005 (4)
C14	0.0123 (5)	0.0150 (5)	0.0194 (5)	−0.0002 (4)	0.0005 (4)	−0.0022 (4)
C15	0.0107 (5)	0.0231 (6)	0.0237 (6)	−0.0013 (4)	0.0000 (4)	−0.0036 (5)
C16	0.0152 (5)	0.0215 (6)	0.0175 (5)	−0.0063 (4)	0.0010 (4)	−0.0043 (4)
C17	0.0180 (5)	0.0144 (5)	0.0165 (5)	−0.0045 (4)	0.0017 (4)	−0.0027 (4)
C18	0.0135 (5)	0.0135 (5)	0.0162 (5)	−0.0012 (4)	0.0009 (4)	−0.0005 (4)

Geometric parameters (Å, º)

Ru1—N1	1.6161 (15)	C7—C8	1.3979 (16)
Ru1—As1	2.5533 (3)	C8—C9	1.3906 (17)
Ru1—Cl1	2.3786 (3)	C8—H8	0.9300
Ru1—Cl1^i	2.3786 (3)	C9—C10	1.3893 (19)
Ru1—Cl2	2.5020 (4)	C9—H9	0.9300
Ru1—As1^i	2.5533 (3)	C10—C11	1.3887 (19)
As1—C13	1.9313 (11)	C10—H10	0.9300
As1—C7	1.9327 (11)	C11—C12	1.3942 (18)
As1—C1	1.9357 (11)	C11—H11	0.9300
C1—C6	1.3938 (17)	C12—H12	0.9300
C1—C2	1.3991 (16)	C13—C14	1.3927 (17)
C2—C3	1.3924 (17)	C13—C18	1.3965 (16)
C2—H2	0.9300	C14—C15	1.3924 (18)
C3—C4	1.3884 (19)	C14—H14	0.9300
C3—H3	0.9300	C15—C16	1.3898 (19)
C4—C5	1.3896 (19)	C15—H15	0.9300
C4—H4	0.9300	C16—C17	1.3911 (19)
C5—C6	1.3979 (17)	C16—H16	0.9300
C5—H5	0.9300	C17—C18	1.3932 (17)
C6—H6	0.9300	C17—H17	0.9300
C7—C12	1.3937 (17)	C18—H18	0.9300
N1—Ru1—Cl1	93.325 (7)	C5—C6—H6	120.4
N1—Ru1—Cl1^i	93.324 (7)	C12—C7—C8	120.04 (11)
Cl1—Ru1—Cl1^i	173.350 (15)	C12—C7—As1	121.44 (9)
N1—Ru1—Cl2	180.0	C8—C7—As1	118.44 (9)
Cl1—Ru1—Cl2	86.675 (7)	C9—C8—C7	119.69 (11)
Cl1^i—Ru1—Cl2	86.676 (7)	C9—C8—H8	120.2
N1—Ru1—As1	93.59 (1)	C7—C8—H8	120.2
Cl1—Ru1—As1	94.047 (8)	C10—C9—C8	120.28 (12)
Cl1^i—Ru1—As1	85.537 (8)	C10—C9—H9	119.9
Cl2—Ru1—As1	86.41 (1)	C8—C9—H9	119.9
N1—Ru1—As1^i	93.59 (1)	C11—C10—C9	120.07 (12)
Cl1—Ru1—As1^i	85.535 (8)	C11—C10—H10	120.0
Cl1^i—Ru1—As1^i	94.046 (8)	C9—C10—H10	120.0
Cl2—Ru1—As1^i	86.41 (1)	C10—C11—C12	120.12 (12)
As1—Ru1—As1^i	172.812 (7)	C10—C11—H11	119.9
C13—As1—C7	105.86 (5)	C12—C11—H11	119.9
C13—As1—C1	105.74 (5)	C7—C12—C11	119.79 (11)
C7—As1—C1	104.15 (5)	C7—C12—H12	120.1
C13—As1—Ru1	114.23 (3)	C11—C12—H12	120.1
C7—As1—Ru1	118.92 (3)	C14—C13—C18	120.17 (11)
C1—As1—Ru1	106.76 (4)	C14—C13—As1	120.92 (9)
C6—C1—C2	120.28 (11)	C18—C13—As1	118.88 (9)
C6—C1—As1	121.90 (9)	C15—C14—C13	119.63 (11)
C2—C1—As1	117.76 (9)	C15—C14—H14	120.2
C3—C2—C1	119.91 (11)	C13—C14—H14	120.2
C3—C2—H2	120.0	C16—C15—C14	120.46 (12)
C1—C2—H2	120.0	C16—C15—H15	119.8
C4—C3—C2	119.87 (12)	C14—C15—H15	119.8
C4—C3—H3	120.1	C15—C16—C17	119.80 (12)
C2—C3—H3	120.1	C15—C16—H16	120.1
C3—C4—C5	120.30 (11)	C17—C16—H16	120.1
C3—C4—H4	119.9	C16—C17—C18	120.21 (12)
C5—C4—H4	119.9	C16—C17—H17	119.9
C4—C5—C6	120.33 (12)	C18—C17—H17	119.9
C4—C5—H5	119.8	C17—C18—C13	119.72 (11)
C6—C5—H5	119.8	C17—C18—H18	120.1
C1—C6—C5	119.29 (11)	C13—C18—H18	120.1
C1—C6—H6	120.4

Symmetry code: (i) −x, y, −z+1/2.