Bis(diethoxyselenophosphinoyl) triselenide and bis(diisopropoxyselenophosphinoyl) diselenide

The title compounds, bis(diethoxyselenophosphinoyl) triselenide, [P(OEt)₂Se]Se₃[P(OEt)₂Se], and bis­(diisopropoxy­selenophosphinoyl) diselenide, [P(OⁱPr)₂Se]Se₂[P(OⁱPr)₂Se], comprise an Se₃ chain or an Se₂ chain bridging two (RO)₂PSe groups.

S1. Comment

As part of our investigation of selenometalate complexes, we have recently reported the preparation, structure and spectroscopy of [Mo₃(µ₃-S)(µ₂-S₂)₃(Se₂P(OEt)₂)₃]Br (Béreau & Ibers, 1999). Although the H⁺ salt (Jørgensen, 1962) and K⁺ salt (Kudchadker et al., 1968) of the Se₂P(OEt)₂ ligand have been known for some time, metal complexes of the ligand are rare; only three compounds containing [Se₂P(OEt)₂] have been structurally characterized (Liu et al., 1998, 1999; Béreau & Ibers, 1999). As an extension of these studies we reacted K[Se₂P(OEt)₂] with VCl₃ in ethanol. Compound (I) was obtained as a byproduct. This synthesis is very different from the literature preparation (Kudchadker et al., 1968), which involves refluxing a stoichiometric mixture of P₂Se₅ and ethanol in cyclohexane for 4 h. Compound (II) was obtained according to this same procedure, from P₂Se₅, 2-propanol and n-heptane. \scheme

Fig. 1 and Fig. 2 are the displacement ellipsoid diagrams of (I) and (II), respectively. Compound (II) has a crystallographically imposed center of symmetry, but it possesses non-crystallographic symmetry very close to 2/m. The least-squares plane through atoms Se1, Se1A, Se2, Se2A, P1 and P1A has the equation in crystal coordinates of -2.830x + 5.713y + 5.419z = 1.441. The coefficients do not have rational ratios and hence the molecular symmetry does not correspond to undetected crystallographic symmetry. Within the Se₃ bridge of (I), the Se—Se bond distances are equivalent with Se1—Se2 = 2.3448 (6) and Se1—Se3 = 2.3439 (6) Å. In the Se₂ bridge of (II), the Se—Se bond distance is Se1—Se2 = 2.3951 (6) Å. These distances are normal for Se—Se single bonds (Tattershall et al., 1997). The two P atoms have tetrahedral environments in both (I) and (II), being bonded to two Se atoms and two O atoms. The P—Se bond distances involving Se atoms of the Se₃ and Se₂ chains are 2.2412 (11) and 2.2378 (10) Å for (I) and 2.2223 (8) Å for (II); these correspond to single bonds. Those P—Se bonds involving terminal Se atoms, at 2.0652 (9) and 2.0721 (9) Å for (I) and 2.0733 (7) Å for (II), correspond to double bonds. The P—O bond distances range from 1.569 (2) to 1.581 (2) Å for (I) and are 1.567 (2) and 1.567 (2) Å for (II).

There appears to be no literature on the metal coordination chemistry of compounds (I) and (II). Yet, given the extensive literature on chalcogen ligands, we believe that (I) and (II) could act as potential ligands, exhibiting an Se,Se-chelation mode through the two terminal Se atoms to form an eight-membered ring for (I) and a seven-membered ring for (II). For (I), the µ₂-Se ligand could act as as an additional coordination site and the ligand could exhibit η³– coordination through the two terminal Se atoms and the bridging Se atom.

S2. Experimental

Compound (I) was prepared from a mixture of VCl₃ (50 mg, 0.3 mmol) and K[Se₂P(OEt)₂] (280 mg, 0.9 mmol) in previously degassed absolute ethanol (10 ml). The deep purple solution was stirred at room temperature for 2 h. The solvent was removed under vacuum. The residue was disolved in diethyl ether (10 ml) and the resulting solution was stored at 277 K. Yellow crystals grew in 35% yield over two weeks. Spectroscopic analysis: ¹H NMR (CD₃OD, p.p.m.): 4.16 (m, CH₂), 1.80 (t, CH₃); ³¹P NMR (CD₃OD, p.p.m., ¹J_PSe in Hz): 69.5 (901, 570). Some pink crystals of unknown composition were also obtained. Compound (II) was prepared according to the synthesis reported by Kudchadker et al. (1968). Orange crystals were grown directly from the reaction mixture in 55% yield. Spectroscopic analysis: ¹H NMR (CD₃OD, p.p.m.): 5.11 (m, CH), 1.56 (d, CH3); ³¹P NMR (CD₃OD, p.p.m., ¹J_PSe in Hz): 63.3 (884, 532).

S3. Refinement

H atoms were generated in calculated positions and constrained with the use of a riding model·The isotropic displacement parameter for each H atom was set 20% larger than that of the parent atom.

Computing details

For both compounds, data collection: SMART (Bruker, 1999); cell refinement: SMART (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: SHELXTL97 (Sheldrick, 1997a); software used to prepare material for publication: SHELXTL97.

Figures

	Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level and H atoms are drawn as spheres of arbitrary radii.
	Fig. 2. The molecular structure of (II). Displacement ellipsoids are drawn at the 50% probability level and H atoms are drawn as spheres of arbitrary radii.

(I) bis(diethoxyselenophosphinoyl) triselenide

Crystal data

[(C2H5O)4P2Se5]	Z = 2
Mr = 636.98	F(000) = 600
Triclinic, P1	Dx = 2.161 Mg m^−3
a = 8.320 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 11.222 (3) Å	Cell parameters from 8192 reflections
c = 12.409 (3) Å	θ = 2.1–25.0°
α = 115.317 (4)°	µ = 9.52 mm^−1
β = 107.351 (4)°	T = 153 K
γ = 92.688 (4)°	Needle, yellow
V = 979.0 (5) Å^3	0.31 × 0.07 × 0.03 mm

Data collection

Bruker SMART 1000 CCD diffractometer	3398 independent reflections
Radiation source: standard-focus sealed tube	2893 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
ω scans	θmax = 25°, θmin = 2.1°
Absorption correction: numerical face-indexed (SHELXTL; Sheldrick, 1997a)	h = −9→9
Tmin = 0.434, Tmax = 0.921	k = −13→13
6938 measured reflections	l = −14→14

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)] = 0.021	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.054	H-atom parameters constrained
S = 0.90	w = 1/[σ^2(Fo^2) + (0.04Fo^2)^2]
3398 reflections	(Δ/σ)max = 0.001
172 parameters	Δρmax = 0.54 e Å^−3
0 restraints	Δρmin = −0.46 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.

Refinement. Hydrogen atoms were generated in calculated positions and constrained with the use of a riding model·The isotropic displacement parameter for each hydrogen atom was set 20% larger than the atom to which it is attached. The final models were restricted to anisotropic displacement parameters for all non-hydrogen atoms.

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

	x	y	z	Uiso*/Ueq
Se1	0.25242 (4)	0.05311 (3)	0.49913 (3)	0.02567 (9)
Se2	0.05647 (4)	0.19214 (3)	0.54976 (3)	0.02582 (9)
Se3	0.48764 (4)	0.19252 (3)	0.51663 (3)	0.02733 (9)
Se4	0.62316 (4)	0.26035 (4)	0.30999 (4)	0.04279 (11)
Se5	−0.01517 (5)	0.37428 (4)	0.83322 (4)	0.04576 (11)
P1	0.15677 (10)	0.26861 (8)	0.76130 (8)	0.02794 (18)
P2	0.40586 (10)	0.17483 (8)	0.32058 (8)	0.02652 (17)
O1	0.3479 (3)	0.3455 (2)	0.80858 (19)	0.0303 (5)
O2	0.2037 (3)	0.1489 (2)	0.7901 (2)	0.0387 (5)
O3	0.3155 (2)	0.0257 (2)	0.21968 (19)	0.0298 (5)
O4	0.2399 (3)	0.2371 (2)	0.3001 (2)	0.0325 (5)
C1	0.3815 (4)	0.4689 (3)	0.7984 (3)	0.0371 (8)
H1A	0.3262	0.5363	0.8455	0.045*
H1B	0.3371	0.4505	0.7099	0.045*
C2	0.5721 (4)	0.5181 (4)	0.8526 (3)	0.0447 (9)
H2A	0.5989	0.5997	0.8482	0.067*
H2B	0.6252	0.4510	0.8046	0.067*
H2C	0.6146	0.5353	0.9399	0.067*
C3	0.0941 (4)	0.0686 (4)	0.8169 (4)	0.0461 (9)
H3A	−0.0170	0.0946	0.8061	0.055*
H3B	0.0759	−0.0258	0.7571	0.055*
C4	0.1718 (6)	0.0878 (6)	0.9452 (5)	0.0873 (18)
H4A	0.0974	0.0349	0.9616	0.131*
H4B	0.1892	0.1812	1.0042	0.131*
H4C	0.2804	0.0601	0.9551	0.131*
C5	0.4089 (4)	−0.0845 (3)	0.1960 (3)	0.0431 (9)
H5A	0.3994	−0.1271	0.2479	0.052*
H5B	0.5297	−0.0495	0.2192	0.052*
C6	0.3381 (5)	−0.1834 (4)	0.0613 (3)	0.0519 (10)
H6A	0.4012	−0.2548	0.0461	0.078*
H6B	0.3471	−0.1408	0.0102	0.078*
H6C	0.2194	−0.2197	0.0393	0.078*
C7	0.2477 (4)	0.3807 (3)	0.3734 (4)	0.0406 (8)
H7A	0.3152	0.4322	0.3501	0.049*
H7B	0.3012	0.4090	0.4637	0.049*
C8	0.0699 (5)	0.4035 (4)	0.3446 (4)	0.0591 (11)
H8A	0.0715	0.4977	0.3910	0.089*
H8B	0.0048	0.3533	0.3691	0.089*
H8C	0.0179	0.3745	0.2549	0.089*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Se1	0.02814 (16)	0.02575 (16)	0.02378 (16)	0.00686 (12)	0.01256 (12)	0.00965 (13)
Se2	0.02637 (16)	0.02703 (17)	0.02482 (16)	0.00786 (12)	0.00974 (12)	0.01196 (13)
Se3	0.02533 (16)	0.02883 (17)	0.02313 (16)	0.00381 (12)	0.00845 (12)	0.00813 (13)
Se4	0.03507 (19)	0.0523 (2)	0.0535 (2)	0.00681 (15)	0.02461 (17)	0.02969 (19)
Se5	0.0414 (2)	0.0587 (2)	0.0402 (2)	0.02487 (17)	0.02564 (17)	0.01663 (18)
P1	0.0287 (4)	0.0352 (4)	0.0243 (4)	0.0119 (3)	0.0143 (3)	0.0138 (4)
P2	0.0247 (4)	0.0308 (4)	0.0261 (4)	0.0068 (3)	0.0117 (3)	0.0131 (3)
O1	0.0298 (11)	0.0329 (12)	0.0264 (11)	0.0082 (9)	0.0098 (9)	0.0122 (10)
O2	0.0427 (13)	0.0507 (14)	0.0471 (14)	0.0184 (11)	0.0267 (11)	0.0361 (12)
O3	0.0274 (11)	0.0305 (12)	0.0263 (11)	0.0089 (9)	0.0096 (9)	0.0082 (9)
O4	0.0304 (11)	0.0312 (12)	0.0364 (12)	0.0099 (9)	0.0128 (10)	0.0151 (10)
C1	0.0385 (18)	0.0281 (17)	0.0378 (19)	0.0072 (14)	0.0126 (15)	0.0096 (15)
C2	0.039 (2)	0.048 (2)	0.037 (2)	−0.0002 (16)	0.0075 (16)	0.0156 (17)
C3	0.0378 (19)	0.058 (2)	0.049 (2)	−0.0033 (16)	0.0107 (17)	0.035 (2)
C4	0.062 (3)	0.148 (5)	0.073 (3)	−0.015 (3)	0.006 (3)	0.085 (4)
C5	0.045 (2)	0.040 (2)	0.036 (2)	0.0204 (16)	0.0101 (16)	0.0116 (16)
C6	0.059 (2)	0.041 (2)	0.037 (2)	0.0197 (18)	0.0123 (18)	0.0035 (17)
C7	0.047 (2)	0.0330 (19)	0.050 (2)	0.0161 (15)	0.0267 (17)	0.0189 (17)
C8	0.053 (2)	0.050 (2)	0.084 (3)	0.0283 (19)	0.027 (2)	0.035 (2)

Geometric parameters (Å, º)

Se1—Se3	2.3439 (6)	P2—O4	1.578 (2)
Se1—Se2	2.3448 (6)	O1—C1	1.465 (4)
Se2—P1	2.2412 (11)	O2—C3	1.454 (4)
Se3—P2	2.2378 (10)	O3—C5	1.461 (4)
Se4—P2	2.0721 (9)	O4—C7	1.460 (4)
Se5—P1	2.0652 (9)	C1—C2	1.495 (5)
P1—O2	1.569 (2)	C3—C4	1.442 (5)
P1—O1	1.581 (2)	C5—C6	1.462 (5)
P2—O3	1.569 (2)	C7—C8	1.477 (5)
Se3—Se1—Se2	105.44 (3)	O3—P2—Se3	109.68 (9)
P1—Se2—Se1	98.43 (3)	O4—P2—Se3	107.83 (9)
P2—Se3—Se1	101.07 (2)	Se4—P2—Se3	105.24 (4)
O2—P1—O1	96.40 (12)	C1—O1—P1	120.07 (19)
O2—P1—Se5	118.86 (9)	C3—O2—P1	125.3 (2)
O1—P1—Se5	118.51 (9)	C5—O3—P2	122.22 (19)
O2—P1—Se2	108.76 (10)	C7—O4—P2	121.1 (2)
O1—P1—Se2	105.30 (8)	O1—C1—C2	107.2 (3)
Se5—P1—Se2	107.83 (4)	C4—C3—O2	110.5 (3)
O3—P2—O4	96.42 (11)	O3—C5—C6	109.8 (3)
O3—P2—Se4	118.67 (9)	O4—C7—C8	107.8 (3)
O4—P2—Se4	118.52 (9)
P1—Se2—Se1—Se3	−87.84 (3)	Se2—Se1—Se3—P2	−87.75 (3)

(II) bis(diisopropoxyselenophosphinoyl) diselenide

Crystal data

[(C3H7O)4P2Se4]	Z = 1
Mr = 614.12	F(000) = 298
Triclinic, P1	Dx = 1.831 Mg m^−3
a = 8.3796 (10) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.5314 (10) Å	Cell parameters from 8192 reflections
c = 8.5577 (10) Å	θ = 2.4–25.0°
α = 98.668 (2)°	µ = 6.74 mm^−1
β = 111.851 (2)°	T = 153 K
γ = 93.459 (2)°	Block, orange
V = 556.81 (11) Å^3	0.13 × 0.09 × 0.04 mm

Data collection

Bruker SMART 1000 CCD diffractometer	1933 independent reflections
Radiation source: standard-focus sealed tube	1745 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.018
ω scans	θmax = 25.0°, θmin = 2.4°
Absorption correction: numerical face-indexed (SHELXTL; Sheldrick, 1997a)	h = −9→9
Tmin = 0.425, Tmax = 0.877	k = −10→10
4701 measured reflections	l = −10→10

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)] = 0.026	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.071	H-atom parameters constrained
S = 1.33	w = 1/[σ^2(Fo^2) + (0.04Fo^2)^2]
1933 reflections	(Δ/σ)max = 0.001
100 parameters	Δρmax = 1.16 e Å^−3
0 restraints	Δρmin = −0.45 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.

Refinement. Hydrogen atoms were generated in calculated positions and constrained with the use of a riding model·The isotropic displacement parameter for each hydrogen atom was set 20% larger than the atom to which it is attached. The final models were restricted to anisotropic displacement parameters for all non-hydrogen atoms.

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

	x	y	z	Uiso*/Ueq
P1	0.32173 (9)	0.30607 (8)	0.11244 (8)	0.02269 (17)
Se1	0.40785 (4)	0.16835 (3)	0.30048 (3)	0.03273 (12)
Se2	0.56404 (3)	0.42694 (4)	0.11210 (4)	0.03466 (13)
O1	0.2052 (2)	0.2225 (2)	−0.0758 (2)	0.0288 (4)
O2	0.2007 (2)	0.4351 (2)	0.1291 (2)	0.0272 (4)
C1	0.2520 (4)	0.0823 (3)	−0.1653 (4)	0.0331 (7)
H1A	0.3753	0.0681	−0.1002	0.040*
C2	0.1341 (5)	−0.0624 (4)	−0.1754 (4)	0.0484 (8)
H2A	0.1544	−0.0804	−0.0595	0.073*
H2B	0.1580	−0.1562	−0.2408	0.073*
H2C	0.0131	−0.0450	−0.2326	0.073*
C3	0.2312 (5)	0.1195 (4)	−0.3391 (4)	0.0434 (8)
H3A	0.3111	0.2147	−0.3236	0.065*
H3B	0.1118	0.1394	−0.3997	0.065*
H3C	0.2575	0.0286	−0.4062	0.065*
C4	0.2473 (4)	0.5548 (3)	0.2891 (3)	0.0284 (6)
H4A	0.3671	0.5464	0.3702	0.034*
C5	0.1185 (5)	0.5168 (4)	0.3666 (4)	0.0455 (8)
H5A	0.1295	0.4104	0.3966	0.068*
H5B	0.0009	0.5186	0.2836	0.068*
H5C	0.1414	0.5966	0.4701	0.068*
C6	0.2402 (4)	0.7174 (4)	0.2393 (4)	0.0372 (7)
H6A	0.3278	0.7360	0.1915	0.056*
H6B	0.2633	0.7998	0.3408	0.056*
H6C	0.1249	0.7220	0.1533	0.056*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P1	0.0222 (3)	0.0238 (4)	0.0219 (3)	0.0017 (3)	0.0083 (3)	0.0047 (3)
Se1	0.0383 (2)	0.03172 (19)	0.02818 (18)	0.00304 (13)	0.01040 (14)	0.01274 (13)
Se2	0.02215 (18)	0.0449 (2)	0.0406 (2)	0.00306 (13)	0.01094 (14)	0.02222 (15)
O1	0.0277 (10)	0.0316 (10)	0.0220 (9)	0.0089 (8)	0.0049 (8)	0.0001 (8)
O2	0.0240 (10)	0.0304 (10)	0.0236 (9)	0.0053 (8)	0.0066 (8)	0.0008 (8)
C1	0.0362 (16)	0.0338 (16)	0.0258 (13)	0.0146 (13)	0.0082 (12)	0.0010 (12)
C2	0.065 (2)	0.0345 (18)	0.0406 (18)	0.0081 (16)	0.0157 (17)	0.0038 (15)
C3	0.055 (2)	0.0468 (19)	0.0273 (15)	0.0105 (16)	0.0172 (15)	−0.0019 (14)
C4	0.0298 (15)	0.0270 (15)	0.0243 (13)	0.0049 (11)	0.0078 (12)	−0.0005 (11)
C5	0.057 (2)	0.046 (2)	0.0415 (18)	0.0025 (16)	0.0308 (17)	0.0032 (15)
C6	0.0375 (17)	0.0315 (16)	0.0380 (16)	0.0046 (13)	0.0111 (14)	0.0027 (13)

Geometric parameters (Å, º)

P1—O2	1.5670 (18)	O2—C4	1.484 (3)
P1—O1	1.5673 (19)	C1—C2	1.505 (5)
P1—Se1	2.0733 (7)	C1—C3	1.516 (4)
P1—Se2	2.2223 (8)	C4—C5	1.505 (4)
Se2—Se2^i	2.3951 (6)	C4—C6	1.510 (4)
O1—C1	1.475 (3)
O2—P1—O1	96.46 (10)	C4—O2—P1	121.26 (16)
O2—P1—Se1	119.29 (8)	O1—C1—C2	108.0 (2)
O1—P1—Se1	119.34 (8)	O1—C1—C3	105.7 (2)
O2—P1—Se2	108.85 (8)	C2—C1—C3	113.5 (3)
O1—P1—Se2	108.40 (8)	O2—C4—C5	106.9 (2)
Se1—P1—Se2	104.04 (3)	O2—C4—C6	106.9 (2)
P1—Se2—Se2^i	98.35 (2)	C5—C4—C6	113.2 (3)
C1—O1—P1	122.28 (17)
P1—Se2—Se2^i—P1^i	180.0

Symmetry code: (i) −x+1, −y+1, −z.