Bis(N,N-diethyl-1,1-di­seleno­carbam­ato-Se)­selenium, [(Se₂CNEt₂)₂Se]

The poly­seleno title compound, bis(N,N-diethyl­seleno­carbamoyl) tri­selenide, [(Se₂CNEt₂)₂Se] or C₁₀H₂₀N₂Se₅, is obtained from the disproportion of sodium N,N-diethyl-1,1-di­seleno­carbamate. An Se atom connects two N,N-diethyl-1,1-di­seleno­carbamate groups with Se-Se distances in the range 2.4500 (11)-2.8601 (12) Å

S1. Comment

In sharp contrast to many studies on the chemistry of metal complexes with 1,1-dithiolate ligands, the chemistry of metal complexes with 1,1-diselenolate ligands has received scant attention. Although the 2,2-dicyanoethylence-1,1-diselenolate and N,N-diethyl-1,1-diselenocarbamate ligands were prepared many years ago (Jensen & Henriksen, 1970; Barnard et al., 1961), to our surprise, there are very few papers referring to such diselenolate ligands, among which the investigation was focused on the spectroscopic properties (Jensen & Krishnan, 1970), and very few crystal structures, such as bis(tetra-n-butylammonium) bis(2,2-dicyanoethylene-1,1-diselenolato)selenium(II) (Hummel et al., 1992) and selenium bis(1-pyrrolidinecarbodiselenoate) (Esperas et al., 1975), have been determined.

One of our current research interests is directed towards the understanding of transition metal complexes with seleno ligands (Hong et al., 1998; Cao et al., 1994). In an attempt to prepare organic ligands with polyselenide, we ran the oxidation of sodium N,N-diethyl-1,1-diselenocarbamate in MeOH and isolated an organic polyseleno compound ligand [{Se₂CN(Et)₂} ₂Se], (I). The compound contains two N,N-diethyl-1,1-diselenocarbamate groups connected by an inorganic Se atom. If C1—Se1 and C6—Se3 are considered as double bonds, Se—Se—Se can be regarded as as a polyseleno center with an angle of 89.56 (4)°. The Se—Se distances in the range 2.4500 (11)–2.8601 (12) Å are comparible to those found in polyseleno compounds (Hummel et al., 1992; Esperas et al., 1975).

S2. Experimental

The title compound was obtained from the disproportion of sodium N,N-diethyl-1,1-diselenocarbamate in CH₃OH. NaSe₂CN(Et)₂ (0.20 g, 0.75 mmol) was disolved in 30 ml of CH₃OH in air. The reaction solution turned red gradually. After stirring for 5 h, the red solution was filtered. The filtrate was kept in an icebox for one day to yield crystalline product of the title complex. Red prism crystals suitable for X-ray diffraction analysis were obtained by recrystallization from THF/CH₃OH at room temperature.

Computing details

Data collection: SMART CCD Software (Siemens, 1994); cell refinement: SMART CCD Software; data reduction: SMART CCD Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

Bis(N,N-diethyl-1,1-diselenocarbamate)selenium

Crystal data

C10H20N2Se5	F(000) = 1056
Mr = 563.08	Dx = 2.167 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.719 (1) Å	Cell parameters from 456 reflections
b = 10.029 (2) Å	θ = 8.3–19.6°
c = 25.615 (5) Å	µ = 10.60 mm^−1
β = 90.65 (3)°	T = 293 K
V = 1726.0 (5) Å^3	Prism, red
Z = 4	0.28 × 0.24 × 0.22 mm

Data collection

Smart CCD diffractometer	2901 independent reflections
Radiation source: fine-focus sealed tube	2205 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.040
ω scans	θmax = 25.0°, θmin = 1.6°
Absorption correction: empirical (using intensity measurements) empirical (using intensity measurements) from equivalent reflections (XEMP in SHELXTL; Siemens, 1994)	h = −7→7
Tmin = 0.065, Tmax = 0.097	k = −11→11
5262 measured reflections	l = −21→30

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.048	H-atom parameters constrained
wR(F^2) = 0.113	w = 1/[σ^2(Fo^2) + (0.0564P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max < 0.001
2901 reflections	Δρmax = 0.74 e Å^−3
155 parameters	Δρmin = −0.99 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0076 (5)

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.

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. The structure was solved by direct methods. All non-H atoms were refined with anisotropic displacement parameters. The positions of all hydrogen atoms were generated geometrically (C—H bond fixed at 0.96 Å), assigned isotropic thermal parameters, and allowed to ride on their respective parent C atoms before the final cycle of least-squares refinement. All calculations

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

	x	y	z	Uiso*/Ueq
Se1	0.39112 (12)	0.59694 (8)	0.34056 (3)	0.0526 (3)
Se2	−0.06586 (11)	0.68677 (7)	0.34203 (3)	0.0477 (2)
Se3	0.40455 (13)	1.03773 (8)	0.42985 (3)	0.0591 (3)
Se4	−0.05674 (12)	0.98294 (7)	0.41251 (3)	0.0511 (3)
Se5	0.19784 (11)	0.82449 (7)	0.38426 (3)	0.0430 (2)
N1	0.0761 (9)	0.4639 (5)	0.2893 (2)	0.0409 (14)
N2	0.0992 (10)	1.2146 (6)	0.4548 (3)	0.0568 (17)
C1	0.1316 (10)	0.5650 (7)	0.3194 (2)	0.0393 (16)
C2	0.2204 (12)	0.3667 (7)	0.2699 (3)	0.053 (2)
H2A	0.3480	0.4094	0.2681	0.080*
H2B	0.1834	0.3379	0.2353	0.080*
C3	0.2416 (16)	0.2487 (9)	0.3055 (4)	0.089 (3)
H3A	0.3387	0.1871	0.2927	0.080*
H3B	0.2801	0.2777	0.3399	0.080*
H3C	0.1142	0.2056	0.3069	0.080*
C4	−0.1336 (12)	0.4394 (7)	0.2738 (3)	0.0520 (19)
H4A	−0.2186	0.4746	0.3003	0.080*
H4B	−0.1572	0.3452	0.2714	0.080*
C5	−0.1878 (13)	0.5021 (9)	0.2221 (3)	0.073 (3)
H5A	−0.3248	0.4849	0.2136	0.080*
H5B	−0.1666	0.5966	0.2246	0.080*
H5C	−0.1046	0.4659	0.1954	0.080*
C6	0.1471 (11)	1.0978 (7)	0.4360 (2)	0.0420 (17)
C7	−0.1105 (12)	1.2566 (8)	0.4609 (3)	0.061 (2)
H7A	−0.1227	1.3136	0.4908	0.080*
H7B	−0.1909	1.1788	0.4664	0.080*
C8	−0.1869 (14)	1.3315 (9)	0.4129 (4)	0.086 (3)
H8A	−0.3234	1.3573	0.4169	0.080*
H8B	−0.1066	1.4095	0.4078	0.080*
H8C	−0.1753	1.2737	0.3832	0.080*
C9	0.2550 (15)	1.3239 (10)	0.4647 (4)	0.086 (3)
H9A	0.2002	1.4107	0.4580	0.080*
H9B	0.3660	1.3102	0.4421	0.080*
C10	0.3226 (19)	1.3166 (11)	0.5191 (5)	0.112 (4)
H10A	0.4223	1.3826	0.5267	0.080*
H10B	0.2101	1.3303	0.5413	0.080*
H10C	0.3767	1.2293	0.5252	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Se1	0.0444 (5)	0.0572 (5)	0.0562 (5)	0.0075 (4)	−0.0019 (4)	−0.0103 (4)
Se2	0.0450 (5)	0.0411 (4)	0.0572 (5)	0.0040 (3)	0.0070 (4)	−0.0145 (3)
Se3	0.0515 (5)	0.0583 (5)	0.0672 (6)	0.0038 (4)	−0.0123 (4)	−0.0153 (4)
Se4	0.0493 (5)	0.0461 (5)	0.0580 (5)	−0.0032 (4)	0.0042 (4)	−0.0146 (4)
Se5	0.0524 (5)	0.0415 (4)	0.0351 (4)	0.0004 (3)	0.0027 (3)	−0.0052 (3)
N1	0.047 (4)	0.043 (3)	0.033 (3)	0.001 (3)	0.005 (3)	−0.007 (3)
N2	0.054 (4)	0.049 (4)	0.067 (4)	−0.005 (3)	0.004 (3)	−0.019 (3)
C1	0.047 (4)	0.040 (4)	0.031 (3)	0.003 (3)	0.009 (3)	0.002 (3)
C2	0.067 (5)	0.047 (4)	0.044 (4)	0.017 (4)	0.016 (4)	−0.010 (3)
C3	0.135 (10)	0.063 (6)	0.071 (6)	0.044 (6)	0.019 (6)	−0.011 (5)
C4	0.061 (5)	0.045 (4)	0.050 (4)	−0.007 (4)	0.004 (4)	−0.006 (3)
C5	0.082 (7)	0.076 (6)	0.061 (6)	−0.010 (5)	−0.018 (5)	−0.002 (5)
C6	0.057 (5)	0.038 (4)	0.031 (3)	0.000 (4)	0.004 (3)	0.002 (3)
C7	0.068 (6)	0.049 (5)	0.066 (6)	0.009 (4)	0.018 (5)	−0.014 (4)
C8	0.071 (7)	0.075 (7)	0.114 (9)	0.020 (5)	0.021 (6)	0.023 (6)
C9	0.086 (8)	0.095 (8)	0.076 (7)	0.007 (6)	0.003 (6)	−0.020 (6)
C10	0.123 (10)	0.111 (10)	0.101 (9)	−0.014 (8)	0.026 (8)	−0.023 (7)

Geometric parameters (Å, º)

Se1—Se5	2.8601 (12)	N1—C2	1.467 (8)
Se1—C1	1.848 (7)	N1—C4	1.480 (9)
Se2—C1	1.898 (7)	N2—C6	1.308 (9)
Se2—Se5	2.4847 (12)	N2—C7	1.480 (10)
Se3—Se5	2.7981 (12)	N2—C9	1.535 (11)
Se3—C6	1.840 (7)	C2—C3	1.501 (11)
Se4—C6	1.883 (7)	C4—C5	1.506 (10)
Se4—Se5	2.4500 (11)	C7—C8	1.525 (12)
N1—C1	1.325 (8)	C9—C10	1.462 (14)
C1—Se2—Se5	89.6 (2)	N1—C1—Se2	118.5 (5)
C6—Se4—Se5	89.1 (2)	Se1—C1—Se2	117.4 (4)
Se4—Se5—Se2	89.56 (4)	N1—C2—C3	112.1 (6)
C1—N1—C2	121.6 (6)	N1—C4—C5	112.8 (7)
C1—N1—C4	123.0 (6)	N2—C6—Se3	124.1 (6)
C2—N1—C4	115.4 (6)	N2—C6—Se4	119.0 (6)
C6—N2—C7	122.1 (7)	Se3—C6—Se4	116.9 (4)
C6—N2—C9	122.0 (7)	N2—C7—C8	111.5 (7)
C7—N2—C9	115.3 (6)	C10—C9—N2	109.0 (8)
N1—C1—Se1	124.2 (5)