Three sulfur-containing diborane(4) compounds

The preparation and structures of three diborane(4) compounds are described. The compound B₂(3,4-S₂C₄H₂-1-S)₂ [2,2′-bi(1,3,5,2-tri­thia­borapentalene), C₈H₄B₂S₆] is planar and lies at a crystallographic inversion centre. The amine adducts [B₂(C₃S₅)₂(NHMe₂)₂] [2,2′-bis­(di­methyl­amino)-2,2′-bi(1,3,4,6,2-tetra­thia­borapentalene-5-thione), C₁₀H₁₄B₂N₂S₁₀] and [B₂(1,2-S₂C₂H₄)₂(NHMe₂)₂]·0.33CH₂Cl₂ [1,2-bis­(di-methylamino)-1,1:2,2-bis(dimethylenedithioxy)diborane(4) di­chloro­methane solvate, C₈H₂₂B₂N₂S₄·0.33CH₂Cl₂] contain di­methyl­amine ligands bound to each boron in an anti conformation about the B—B bond, with tetrahedral geometry at the B atoms. The crystal structures display a number of S...S interactions, which appear to dictate the packing arrangements.

S1. Comment

The number of diborane(4) compounds containing the B₂E₄ (E = O or S) central core that have been structurally characterized continues to grow (Clegg et al., 1998), especially for E = O, largely as a result of interest in these compounds as reagents in metal catalysed diboration reactions (Marder & Norman, 1998). Here, we report some novel sulfur-containing diborane(4) compounds, 2,2'-bi(1,3,5,2-trithiaborapentalene), (I), 2,2'-bis(dimethylamino)-2,2'-bi(1,3,4,6,2-tetrathiaborapentalene-S-thione), (IV) and 1,2-bis(dimethylamino)-1,1:2,2-bis(dimethylenedithioxy)diborane(4) dichloromethane solvate, (V). \scheme

Molecules of (I) (Fig. 1) lie at an inversion centre and have approximate D_{2 h} symmetry. The B—B bond length in (I) is 1.672 (12) Å, cf. 1.675 (5) Å in B₂(1,2-S₂C₆H₄)₂, (II) and 1.680 (4) Å in B₂(1,2-S₂-4-MeC₆H₃)₂ (III) (Clegg et al., 1998). Molecules of (II) and (III), like (I), are planar in the solid state, presumably to allow closer packing. The two independent B—S bonds in (I) are 1.800 (6) and 1.807 (6) Å, cf. 1.788 (2) and 1.796 (2) Å in (II), and 1.790 (2) and 1.788 (2) Å in (III). Angles around the boron centre range from 114.1 (3)–123.0 (5)°, as expected for an sp² hybridized boron centre, with the smaller angle caused by the chelating ring.

Compounds (IV) (Fig. 2) and (V) (Fig. 3) are Lewis base adducts of diborane(4) compounds, in which the amines bind to the Lewis acidic boron centres. The amines are arranged in an anti conformation relative to the B—B bond [N1—B2—B1—N2 = -155.69 (18) and 161.91 (17)° for (IV) and (V), respectively]. The molecules are staggered, rather than eclipsed, about the B—B bond [S2—B1—B2—S6 = -157.83 (12), S1—B1—B2—S6 = -40.3 (2), S2—B1—B2—S7 = 83.79 (18) and S1—B1—B2—S7 = -158.66 (13)° in (IV), and S3—B2—B1—S1 = 167.64 (12), S3—B2—B1—S2 = 48.1 (2), S4—B2—B1—S1 = -73.49 (17) and S4—B2—B1—S2 = 166.93 (13)° in (V)]. A number of similar adducts of diborane(4) compounds have been structurally characterized (Clegg et al., 1997). The B—B lengths in (IV) and (V) are 1.746 (4) and 1.758 (5) Å, respectively, markedly longer than in the Bsp²—Bsp² cases highlighted above and consistent with a change in hybridization and a higher coordination number at the boron. The B—B bond lengths in [B₂(1,2-S₂C₆H₄)₂(4-pic)₂] (4-pic = 4-picoline) and [B₂(1,2-S₂C₆H₄)₂(PMe₂Ph)₂] are 1.715 (1) and 1.750 (4) Å, whilst in the mono-adducts [B₂(1,2-S₂C₆H₄)₂(4-pic)] and [B₂(1,2-S₂C₆H₄)₂(PEt₃)] the B—B bond lengths are 1.701 (7) and 1.707 (3) Å, respectively (Clegg et al., 1997?), intermediate between Bsp²—Bsp² and Bsp³—Bsp³ bonds. Interestingly, molecules of (VI) (C₂(S₃C₃H₂)₂; Rovira et al., 1994?) and (VII) (please define) lie over an inversion centre and a C₂ axis respectively; whilst similar symmetries are possible for (IV) and (V), neither exhibit exact symmetry in the solid state.

Angles around the B atoms [105.29 (13)–113.5 (2)° in (IV) and 104.30 (15)–119.9 (2)° in (V)] are consistent with tetrahedral geometry. The B—S bonds in (IV) [1.933 (3)–1.954 (3) Å] and (V) [1.913 (3)–1.943 (3) Å] are longer by ca 0.1 Å than those in (I)-(III), for similar reasons as referred to above, together with the fact that any B—S π-bonding present in (II) is likely to be reduced in (IV) and (V). The BS₂C₂ rings in (IV) display an envelope conformation, with B1 and B2 lying 0.14 and 0.17 Å, respectively, out of the mean plane of their respective five-membered rings. Similar deviations are observed in (VI) and (VII). In (V), the BS₂C₂ rings are puckered, with the S—C—C—S torsion angles being -45.0 (3) and 44.4 (4)° for S1—C1—C2—S2 and S3—C3—C4—S4, respectively.

A packing diagram of the molecules of (I) is shown in Fig. 4. The molecules adopt a modified herring-bone packing motif where there is no ring-ring overlap between molecules in the `stacks', such that the distance between planes of molecules in the stacks is 2.44 Å. The angle between the direction of different stacks in the c direction is 51.6°. The packing in (II) differs from that of (I) in that molecules of (II) form planar sheets utilizing inter- and intrastack S···S interactions. In (I), exocyclic S···S interactions are present [S3···S3^v = 3.621 (4) Å; symmetry code: (v) 1 - x, 1 - y, -z] (van der Waals radius of S = 1.8 Å), approximately parallel to the crystallographic a axis. There are also interactions between adjacent molecules in stacks [S2···S1ⁱⁱⁱ = 3.618 (3) Å; symmetry code: (iii) x, y, 1 + z]. π-stacking appears to have been precluded by the formation of S···S interactions, since these interactions are formed in the direction of the S lone pairs, resulting in a herring-bone arrangement of molecules with no π interactions and short intra-stack distances. There are also possible S···S interactions between molecules in stacks in different directions [S2···S2^iv = 3.799 (2) and S1···S1ⁱⁱ = 3.857 (2) Å; symmetry codes: (iv) x, 1/2 - y, 1/2 + z; (ii) x, 3/2 - y, 1/2 + z].

The carbon analogue of (I), C₂(S₃C₃H₂)₂, (VI), has been structurally characterized (Rovira et al., 1994) in space group P2₁/a with molecules of (VI) also lying at inversion centres, and whilst there are no striking structural differences in the molecular structure other than those expected, the packing arrangement is slightly different. Although the classic herring-bone packing is observed, the exact arrangement of molecules is different to that of (I), due to the different S···S interactions (Fig. 5). The angle between the direction of non-parallel stacks in (VI) is 65.6° and there are no short intrastack S···S interactions (the shortest S···S contacts are 3.991 Å), but there are reasonable ring-ring interactions: the π-stacking distance is 3.62 Å. There are, however, two unique sets of S···S contacts between adjacent molecules in differently directed stacks [S2···S1ⁱ = 3.546 and S2···S1ⁱⁱ = 3.606 Å; symmetry codes: (i) x - 1/2, -1/2 - y, z; (ii) x - 1/2, 1/2 - y, z]. Again, there are interactions between the terminal S atoms of adjacent molecules [3.531 (1) Å].

The crystal structures of (I) and (VI) demonstrate that with a minimal number of hydrogen atoms, S···S interactions efficiently mimic hydrogen bonds in playing an important role in the association of molecules.

Fig. 6 shows the packing of molecules of (IV) in the crystal structure, with the NHMe₂ groups omitted. The packing of the molecules of is best described as ruffled chains propagating in the a direction [S10ⁱ···S10ⁱⁱⁱ = 3.393 (2) and S5···S5ⁱⁱ = 3.552 (1) Å; symmetry codes: (i) 1 - x, 1 - y, -z; (ii) 3 - x, 2 - y, 1 - z; (iii) 2 + x, 1 + y, z], and interactions of S atoms in adjacent chains [S4ⁱⁱⁱ···S9ⁱⁱ = 3.787 (1), S4ⁱⁱⁱ···S7ⁱⁱ 3.437 (1), S2ⁱⁱ···S2ⁱⁱⁱ = 3.417 (1), S2ⁱⁱ···S7ⁱⁱⁱ = 3.438 (1), S3···S8ⁱ = 3.607 (1), S1···S8ⁱ = 3.410 (1), S1···S6ⁱ = 3.626 (1) and S6ⁱ···S6 = 3.877 (1) Å.] create an infinite ruffled sheet. Sheets are stacked in the b direction with one close contact [S3···S7^iv 3.531 (1) Å; symmetry code: (iv) x + 1, y, z].

In addition to the S···S interactions in the crystal structures of (I?) and (IV), there are a number of S···H hydrogen bonds, though these are long and at the sum of the van der Waals radii of S and H atoms (3.0 Å). In (V), in the absence of S···S contacts, there are a number of (long) S···H hydrogen bonds. Please check ALL symmetry codes in the preceding paragraphs.

S2. Experimental

For (I), a solution of n-BuLi (2.8 ml of a 1.6 M solution in hexanes) was added to a cooled solution (195 K) of 3,4-dibromothiophene (1.0 g, 4.5 mmol) in Et₂O (10 ml) and the reaction was stirred for 30 min, after which time elemental S (0.144 g, 4.5 mmol) was added. The reaction was then stirred at 195 K for 1 h, after which time the addition of n-BuLi and elemental S was repeated. The reaction was then allowed to warm to room temperature and was stirred for a further 30 min. After this time the reaction was recooled to 195 K and HCl (10 ml of a 1.0 M solution in Et₂O) was added. Upon warming to room temperature a precipitate formed and the solution became yellow. Filtration afforded a yellow solution which was reduced in volume to ca 10 ml, which also removed any unreacted HCl. The filtrate was then cooled to 273 K and B₂(NMe₂)₄ (0.5 ml, 2.5 mmol; Brotherton et al., 1960) was added, resulting in the immediate formation of a yellow precipitate. The reaction was stirred for 12 h, after which time the Et₂O was removed by syringe and the solid washed with hexane (5 × 5 ml) to give the crude bis-amine adduct [B₂(3,4-S₂C₄H₂-1-S)₂(NHMe₂)₂]. To a suspension of [B₂(3,4-S₂C₄H₂-1-S)₂(NHMe₂)₂] (0.15 g, 0.37 mmol) in Et₂O (5 ml) HCl (1 ml of a 1.0 M solution in Et₂O) was added and the reaction stirred for 3 h. After this time the solid was removed by filtration and washed with Et₂O (2 × 5 ml). Combination and evaporation of the Et₂O fractions gave compound (I) as a yellow solid, and this was recrystallized by dissolving in toluene and layering with hexane (yield: 0.8 g, 69%). ¹H NMR (CDCl₃) δ 7.37p.p.m.; ¹¹B {¹H} NMR (CDCl₃) δ 62.7p.p.m. For (IV), B₂(NMe₂)₄ (0.3 ml, 1.5 mmol) was added to a solution of 1,2-ethanedithiol (0.28 g, 3.0 mmol) in hexane (20 ml) and the solution refluxed for 5 h, after which it was allowed to cool to room temperature and then refrigerated at 243 K overnight. The solvent was then removed by syringe, affording (IV) as a white crystalline solid (yield: 0.36 g, 81%). ¹¹B {¹H} NMR (CDCl₃) δ 5.8p.p.m. Addition of HCl affords B₂(1,2-S₂C₂H₄)₂ in solution; ¹¹B{¹H} NMR (CDCl₃) δ 65.8p.p.m. For (V), a solution of [B₂Cl₄(NHMe₂)₂] (0.26 g, 1.0 mmol; Lawlor et al., 1998) in tetrahydrofuran (2 ml) was added to a stirred suspension of [NEt₄]₂[Zn(C₃S₅)₂] (0.50 g, 21 mmol) in tetrahydrofuran (10 ml), resulting in a colour change from dark red to light yellow. Crystals of (V) were isolated by layering this solution with toluene (2 ml), CH₂Cl₂ (volume?) and hexane (10 ml). ¹¹B {¹H} NMR (CDCl₃) δ 41.8p.p.m.

S3. Refinement

H atoms were constrained to idealized geometries and assigned isotropic displacement parameters 1.2 times the U_iso value of their attached C (1.5 U_iso for methyl groups), with the exception of H1 and H2 in (IV) which were located from the electron density difference map. During refinement of (I), high residual electron density, poor agreement factors (R1 = 0.240 and wR2 = 0.586), a β angle close to 90° and unusual shapes of the diffraction peaks all suggested non-merohedral twinning. Addition of the pseudo-orthorhombic twin law (100, 010, 001) improved convergence and greatly reduced the agreement factors and the features in the final difference map. The volume fraction of one of the twin components was found to be 0.383 (3). The twinning is presumably responsible for the rather high electron density residuals (highest peak 1.12 e ų, 0.81 Å from S2; deepest trough -0.71 e ų, 0.85 Å from S1). The good agreement between the chemcially equivalent bond lengths and angles and the reasonable ellipsoids suggests that the model is satisfactory. In (V), the Cl atoms of the dichloromethane molecule were located on a threefold axis with the C atom disordered over two sets of three sites, each with an occupancy of about 1/6. The atoms C9 [occupancy factor 3*0.178 (8)] and C9' were refined isotropically. Attached H atoms were not included.

Computing details

For all compounds, data collection: SMART (Siemens, 1995a); cell refinement: SAINT (Siemens, 1995a); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Siemens, 1995b); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The molecular structure of (I). Ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii [symmetry code: (i) 2 - x, 1 - y, 1 - z]. Please check symmetry code.
	Fig. 2. The molecular structure of (IV). Ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
	Fig. 3. The molecular structure of (V). Ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii. The dichloromethane solvate is omitted.
	Fig. 4. Packing diagram for (I) viewed down the b axis [symmetry codes: (i) 2 - x, 1 - y, 1 - z; (ii) x, 3/2 - y, 1/2 + z; (iii) x, y, 1 + z; (iv) x, 1/2 - y, 1/2 + z; (v) 1 - x, 1 - y, -z].
	Fig. 5. Packing diagram for (VI) viewed along [101] [symmetry codes: (i) 1? - 1/2, -1/2 - y, z; (ii) 1? - 1/2, 1/2 - y, z]. Please clarify x - 1/2 or ?
	Fig. 6. Packing diagram for (IV) viewed down the b axis, with the amine groups omitted for clarity [symmetry codes: (i) 1 - x, 1 - y, -z; (ii) 3 - x, 2 - y, 1 - z; (iii) 2 + x, 1 + y, z; (iv) x + 1, y, z].

(I) 2,2'-bi(1,3,5,2-trithiaborapentalene)

Crystal data

C8H4B2S6	F(000) = 316
Mr = 314.10	Dx = 1.737 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 13.549 (2) Å	Cell parameters from 62 reflections
b = 7.525 (2) Å	θ = 5–50°
c = 5.891 (4) Å	µ = 1.10 mm^−1
β = 90.04 (3)°	T = 173 K
V = 600.6 (4) Å^3	Plate, colourless
Z = 2	0.55 × 0.40 × 0.01 mm

Data collection

Siemens SMART CCD area detector diffractometer	1383 independent reflections
Radiation source: fine-focus sealed tube	1150 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
Detector resolution: 60 pixels mm^-1	θmax = 27.5°, θmin = 2.7°
ω rotation with narrow frame scans	h = −13→17
Absorption correction: SADABS (sheldrick, 1996) ?	k = −9→9
Tmin = 0.37, Tmax = 0.88	l = −7→7
3856 measured reflections

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)] = 0.055	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.135	H-atom parameters constrained
S = 0.98	Calculated w = 1/[σ^2(Fo^2) + (0.0882P)^2] where P = [max(Fo^2,0) + 2Fc^2]/3
1382 reflections	(Δ/σ)max = 0.001
74 parameters	Δρmax = 1.12 e Å^−3
0 restraints	Δρmin = −0.71 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. Refinement on F² for ALL reflections except for 1 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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.

Unit-cell dimensions were determined from reflections taken from three sets of 30 frames (at 0.3° steps in ω), typically at 10–30 s. A full hemisphere of reciprocal space was scanned by 0.3° ω steps at ϕ 0, 90 and 180° with the area detector held at 2θ = -29° for (I) and (V); for (IV) a full sphere of reciprocal space was scanned. The crystal-to-detector distance was 4.974 cm. Crystal decay was monitored by repeating the initial 50 frames at the end of data collection and analysing the duplicate reflections. No decay was observed in any data set.

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

	x	y	z	Uiso*/Ueq
B1	0.9409 (5)	0.4994 (7)	0.4593 (10)	0.0167 (11)
S1	0.90031 (10)	0.5845 (2)	0.1893 (2)	0.0184 (3)
S2	0.84291 (11)	0.4094 (2)	0.6327 (2)	0.0196 (3)
S3	0.58766 (11)	0.5154 (2)	0.2313 (3)	0.0287 (4)
C1	0.7475 (4)	0.4611 (7)	0.4425 (9)	0.0200 (11)
C2	0.7746 (4)	0.5453 (7)	0.2345 (9)	0.0194 (11)
C3	0.6950 (4)	0.5837 (7)	0.1018 (10)	0.0239 (12)
H3	0.6983	0.6403	−0.0422	0.029*
C4	0.6481 (4)	0.4350 (7)	0.4660 (9)	0.0242 (12)
H4	0.6172	0.3807	0.5930	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
B1	0.028 (3)	0.005 (2)	0.017 (2)	0.000 (2)	−0.001 (2)	0.002 (2)
S1	0.0223 (6)	0.0135 (6)	0.0195 (6)	−0.0002 (5)	0.0011 (5)	0.0022 (4)
S2	0.0249 (7)	0.0140 (6)	0.0200 (6)	−0.0006 (5)	0.0012 (6)	0.0026 (4)
S3	0.0226 (6)	0.0281 (8)	0.0353 (7)	0.0037 (6)	0.0002 (7)	−0.0014 (6)
C1	0.026 (3)	0.010 (3)	0.023 (3)	0.003 (2)	0.002 (2)	−0.001 (2)
C2	0.025 (3)	0.014 (2)	0.020 (3)	0.003 (2)	0.000 (2)	−0.005 (2)
C3	0.029 (3)	0.018 (3)	0.025 (3)	0.000 (2)	−0.001 (2)	0.000 (2)
C4	0.026 (3)	0.023 (3)	0.024 (3)	0.001 (2)	0.005 (3)	−0.001 (2)

Geometric parameters (Å, º)

B1—B1^i	1.672 (12)	S3—C4	1.717 (6)
B1—S1	1.800 (6)	S3—C3	1.722 (6)
B1—S2	1.807 (6)	S3—S3^iv	3.621 (4)
S1—C2	1.749 (5)	C1—C4	1.368 (8)
S2—C1	1.753 (6)	C1—C2	1.428 (8)
S2—S1^ii	3.618 (3)	C2—C3	1.362 (7)
S2—S2^iii	3.799 (2)
B1^i—B1—S1	122.9 (5)	C4—S3—C3	93.4 (3)
B1^i—B1—S2	123.0 (5)	C4—S3—S3^iv	153.7 (2)
S1—B1—S2	114.1 (3)	C3—S3—S3^iv	103.9 (2)
C2—S1—B1	95.9 (3)	C4—C1—C2	113.8 (5)
C2—S1—S1^v	89.6 (2)	C4—C1—S2	129.0 (4)
B1—S1—S1^v	63.6 (2)	C2—C1—S2	117.2 (4)
C1—S2—B1	95.6 (3)	C3—C2—C1	112.5 (5)
C1—S2—S1^ii	131.0 (2)	C3—C2—S1	130.3 (4)
B1—S2—S1^ii	102.6 (2)	C1—C2—S1	117.1 (4)
C1—S2—S2^iii	129.4 (2)	C2—C3—S3	110.5 (4)
B1—S2—S2^iii	132.5 (2)	C1—C4—S3	109.7 (4)
S1^ii—S2—S2^iii	61.80 (4)

Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+1/2, z+1/2; (iv) −x+1, −y+1, −z; (v) x, −y+3/2, z+1/2.

(IV) 2,2'-bis(dimethylamino)-2,2'-bi(1,3,4,6,2-tetrathiaborapentalene-S-thione

Crystal data

C10H14B2N2S10	Z = 2
Mr = 504.45	F(000) = 516
Triclinic, P1	Dx = 1.629 Mg m^−3
a = 9.578 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.686 (2) Å	Cell parameters from 132 reflections
c = 12.172 (3) Å	θ = 5–50°
α = 95.56 (2)°	µ = 1.07 mm^−1
β = 91.99 (2)°	T = 123 K
γ = 113.349 (12)°	Needle, orange
V = 1028.5 (4) Å^3	0.5 × 0.1 × 0.1 mm

Data collection

Siemens SMART CCD area detector diffractometer	4654 independent reflections
Radiation source: fine-focus sealed tube	3579 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
Detector resolution: 60 pixels mm^-1	θmax = 27.5°, θmin = 1.7°
ω rotation with narrow frame scans	h = −12→12
Absorption correction: SADABS (sheldrick, 1996) ?	k = −12→12
Tmin = 0.70, Tmax = 0.92	l = −15→15
10786 measured reflections

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)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.072	H atoms treated by a mixture of independent and constrained refinement
S = 0.97	Calculated w = 1/[σ^2(Fo^2) + (0.0385P)^2] where P = [max(Fo^2,0) + 2Fc^2]/3
4654 reflections	(Δ/σ)max = 0.001
224 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.41 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. Refinement on F² for ALL reflections except for 0 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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
B1	0.5772 (3)	0.5840 (3)	0.2826 (2)	0.0125 (5)
B2	0.4094 (3)	0.4217 (3)	0.2492 (2)	0.0118 (5)
S1	0.73855 (6)	0.59055 (7)	0.18881 (5)	0.01337 (13)
S2	0.65921 (6)	0.58975 (7)	0.43303 (5)	0.01503 (14)
S3	1.07636 (6)	0.72149 (7)	0.27398 (5)	0.01448 (13)
S4	1.00500 (7)	0.72002 (7)	0.50245 (5)	0.01757 (14)
S5	1.33093 (7)	0.83799 (7)	0.45365 (5)	0.01808 (14)
S6	0.36083 (7)	0.36325 (7)	0.09138 (5)	0.01564 (14)
S7	0.23644 (6)	0.45438 (6)	0.30383 (5)	0.01306 (13)
S8	0.02887 (7)	0.19494 (7)	−0.00892 (5)	0.01986 (15)
S9	−0.08678 (7)	0.28016 (7)	0.19093 (5)	0.02042 (15)
S10	−0.30664 (8)	0.07809 (8)	0.00505 (6)	0.0291 (2)
N1	0.4151 (2)	0.2758 (2)	0.3029 (2)	0.0150 (4)
H1	0.424 (4)	0.298 (4)	0.365 (3)	0.050*
N2	0.5539 (2)	0.7410 (2)	0.2777 (2)	0.0152 (4)
H2	0.489 (4)	0.737 (4)	0.324 (3)	0.050*
C1	0.8838 (3)	0.6555 (3)	0.2962 (2)	0.0138 (5)
C2	0.8498 (3)	0.6543 (3)	0.4032 (2)	0.0149 (5)
C3	1.1456 (3)	0.7627 (3)	0.4116 (2)	0.0149 (5)
C4	0.1651 (3)	0.3081 (3)	0.0972 (2)	0.0165 (5)
C5	0.1105 (3)	0.3478 (3)	0.1900 (2)	0.0164 (5)
C6	−0.1313 (3)	0.1788 (3)	0.0592 (2)	0.0204 (5)
C7	0.5408 (3)	0.2327 (3)	0.2667 (2)	0.0210 (5)
H7A	0.6369	0.3230	0.2747	0.032*
H7B	0.5183	0.1882	0.1889	0.032*
H7C	0.5500	0.1585	0.3126	0.032*
C8	0.2700 (3)	0.1360 (3)	0.2898 (2)	0.0213 (6)
H8A	0.1859	0.1623	0.3132	0.032*
H8B	0.2804	0.0623	0.3355	0.032*
H8C	0.2488	0.0920	0.2119	0.032*
C9	0.6915 (3)	0.8832 (3)	0.3116 (2)	0.0233 (6)
H9A	0.7377	0.8766	0.3830	0.035*
H9B	0.6619	0.9694	0.3187	0.035*
H9C	0.7653	0.8971	0.2555	0.035*
C10	0.4849 (3)	0.7528 (3)	0.1689 (2)	0.0212 (6)
H10A	0.3941	0.6597	0.1458	0.032*
H10B	0.5593	0.7670	0.1133	0.032*
H10C	0.4559	0.8394	0.1764	0.032*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
B1	0.0100 (13)	0.0162 (13)	0.0115 (12)	0.0060 (11)	0.0002 (10)	−0.0012 (10)
B2	0.0072 (12)	0.0154 (13)	0.0118 (12)	0.0044 (10)	−0.0003 (9)	−0.0014 (10)
S1	0.0079 (3)	0.0201 (3)	0.0105 (3)	0.0046 (2)	−0.0005 (2)	−0.0006 (2)
S2	0.0071 (3)	0.0236 (3)	0.0105 (3)	0.0025 (2)	−0.0003 (2)	−0.0002 (2)
S3	0.0075 (3)	0.0195 (3)	0.0140 (3)	0.0034 (2)	0.0003 (2)	0.0001 (2)
S4	0.0085 (3)	0.0257 (3)	0.0136 (3)	0.0026 (2)	−0.0015 (2)	−0.0007 (2)
S5	0.0076 (3)	0.0225 (3)	0.0198 (3)	0.0035 (2)	−0.0026 (2)	−0.0048 (2)
S6	0.0100 (3)	0.0228 (3)	0.0114 (3)	0.0047 (2)	−0.0007 (2)	−0.0017 (2)
S7	0.0073 (3)	0.0167 (3)	0.0132 (3)	0.0038 (2)	−0.0008 (2)	−0.0022 (2)
S8	0.0144 (3)	0.0234 (3)	0.0149 (3)	0.0015 (3)	−0.0026 (2)	−0.0016 (2)
S9	0.0096 (3)	0.0263 (3)	0.0211 (3)	0.0040 (3)	−0.0014 (2)	−0.0017 (3)
S10	0.0135 (3)	0.0354 (4)	0.0258 (4)	−0.0017 (3)	−0.0055 (3)	−0.0011 (3)
N1	0.0126 (10)	0.0155 (10)	0.0150 (10)	0.0044 (8)	0.0001 (8)	−0.0009 (8)
N2	0.0112 (10)	0.0161 (10)	0.0169 (10)	0.0044 (8)	0.0030 (8)	−0.0003 (8)
C1	0.0082 (11)	0.0158 (11)	0.0159 (11)	0.0039 (9)	−0.0017 (9)	−0.0006 (9)
C2	0.0086 (11)	0.0182 (12)	0.0155 (12)	0.0036 (9)	−0.0016 (9)	−0.0010 (10)
C3	0.0102 (12)	0.0153 (11)	0.0174 (12)	0.0040 (9)	−0.0012 (9)	−0.0011 (9)
C4	0.0118 (12)	0.0186 (12)	0.0154 (12)	0.0027 (10)	−0.0026 (9)	0.0003 (10)
C5	0.0093 (12)	0.0182 (12)	0.0193 (12)	0.0039 (10)	−0.0026 (9)	0.0000 (10)
C6	0.0149 (13)	0.0205 (13)	0.0206 (13)	0.0017 (10)	−0.0011 (10)	0.0033 (10)
C7	0.0199 (13)	0.0218 (13)	0.0275 (14)	0.0148 (11)	0.0015 (11)	0.0034 (11)
C8	0.0176 (13)	0.0137 (12)	0.0283 (14)	0.0017 (10)	0.0008 (11)	0.0026 (10)
C9	0.0162 (13)	0.0131 (12)	0.036 (2)	0.0025 (10)	0.0000 (11)	−0.0021 (11)
C10	0.0247 (14)	0.0232 (13)	0.0198 (13)	0.0129 (11)	0.0035 (11)	0.0070 (11)

Geometric parameters (Å, º)

B1—N2	1.628 (3)	S5—S5^iv	3.5518 (14)
B1—B2	1.746 (4)	S5—S5^iv	3.5518 (14)
B1—S1	1.938 (3)	S6—C4	1.739 (2)
B1—S2	1.954 (3)	S6—S1^i	3.6257 (11)
B2—N1	1.632 (3)	S6—S6^i	3.8768 (15)
B2—S7	1.933 (3)	S7—C5	1.749 (2)
B2—S6	1.935 (3)	S7—S4^ii	3.4373 (11)
S1—C1	1.749 (2)	S8—C6	1.729 (3)
S1—S8^i	3.4095 (11)	S8—C4	1.745 (2)
S1—S6^i	3.6257 (11)	S8—S1^i	3.4095 (11)
S2—C2	1.744 (2)	S8—S3^i	3.6067 (11)
S2—S2^ii	3.4165 (14)	S9—C5	1.739 (2)
S2—S7^ii	3.4383 (11)	S9—C6	1.741 (3)
S3—C3	1.728 (2)	S10—C6	1.645 (2)
S3—C1	1.737 (2)	S10—S10^v	3.393 (2)
S3—S7^iii	3.5305 (10)	N1—C7	1.489 (3)
S4—C3	1.720 (2)	N1—C8	1.497 (3)
S4—C2	1.746 (2)	N2—C9	1.489 (3)
S4—S7^ii	3.4373 (11)	N2—C10	1.494 (3)
S4—S9^ii	3.7871 (12)	C1—C2	1.354 (3)
S4—S6^ii	6.091 (2)	C4—C5	1.347 (3)
S5—C3	1.668 (2)
N2—B1—B2	113.5 (2)	C4—S6—S1^i	80.54 (8)
N2—B1—S1	107.4 (2)	B2—S6—S1^i	155.55 (8)
B2—B1—S1	113.1 (2)	C4—S6—S6^i	129.84 (9)
N2—B1—S2	106.84 (15)	B2—S6—S6^i	114.69 (8)
B2—B1—S2	110.2 (2)	S1^i—S6—S6^i	55.43 (2)
S1—B1—S2	105.29 (13)	C5—S7—B2	94.74 (11)
N1—B2—B1	112.3 (2)	C5—S7—S4^ii	94.69 (9)
N1—B2—S7	107.2 (2)	B2—S7—S4^ii	129.99 (8)
B1—B2—S7	110.7 (2)	C6—S8—C4	97.48 (12)
N1—B2—S6	107.35 (15)	C6—S8—S1^i	140.34 (9)
B1—B2—S6	113.4 (2)	C4—S8—S1^i	87.24 (8)
S7—B2—S6	105.57 (12)	C6—S8—S3^i	100.01 (9)
C1—S1—B1	95.48 (11)	C4—S8—S3^i	131.16 (9)
C1—S1—S8^i	92.71 (8)	S1^i—S8—S3^i	51.76 (2)
B1—S1—S8^i	141.84 (8)	C5—S9—C6	97.19 (12)
C1—S1—S6^i	144.30 (8)	C6—S10—S10^v	156.98 (10)
B1—S1—S6^i	110.12 (8)	C7—N1—C8	108.3 (2)
S8^i—S1—S6^i	51.83 (2)	C7—N1—B2	114.1 (2)
C2—S2—B1	95.99 (11)	C8—N1—B2	116.2 (2)
C2—S2—S2^ii	158.25 (9)	C9—N2—C10	108.8 (2)
B1—S2—S2^ii	103.42 (8)	C9—N2—B1	115.8 (2)
C2—S2—S7^ii	89.44 (8)	C10—N2—B1	114.1 (2)
B1—S2—S7^ii	171.47 (8)	C2—C1—S3	116.1 (2)
S2^ii—S2—S7^ii	70.20 (3)	C2—C1—S1	120.6 (2)
C3—S3—C1	97.13 (11)	S3—C1—S1	123.28 (14)
C3—S3—S7^iii	77.32 (8)	C1—C2—S2	119.1 (2)
C1—S3—S7^iii	113.85 (8)	C1—C2—S4	116.1 (2)
C3—S4—C2	97.00 (11)	S2—C2—S4	124.76 (14)
C3—S4—S7^ii	161.74 (9)	S5—C3—S4	122.63 (14)
C2—S4—S7^ii	89.44 (8)	S5—C3—S3	123.72 (14)
C3—S4—S9^ii	122.45 (8)	S4—C3—S3	113.65 (13)
C2—S4—S9^ii	139.36 (8)	C5—C4—S6	119.7 (2)
S7^ii—S4—S9^ii	50.03 (2)	C5—C4—S8	116.0 (2)
C3—S4—S6^ii	165.99 (8)	S6—C4—S8	124.29 (14)
C2—S4—S6^ii	96.97 (8)	C4—C5—S9	116.6 (2)
S7^ii—S4—S6^ii	19.683 (13)	C4—C5—S7	119.9 (2)
S9^ii—S4—S6^ii	44.09 (2)	S9—C5—S7	123.44 (14)
C3—S5—S5^iv	149.56 (9)	S10—C6—S8	123.42 (15)
C3—S5—S5^iv	149.56 (9)	S10—C6—S9	123.8 (2)
S5^iv—S5—S5^iv	0.00 (4)	S8—C6—S9	112.74 (14)
C4—S6—B2	95.13 (11)

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+1, −y+1, −z+1; (iii) x+1, y, z; (iv) −x+3, −y+2, −z+1; (v) −x−1, −y, −z.

(V) 1,2-bis(dimethylamino)-1,1:2,2-bis(dimethylenedithioxy)diborane(4) dichloromethane solvate

Crystal data

C8H22B2N2S4·0.33CH2Cl2	Dx = 1.351 Mg m^−3
Mr = 324.53	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3	Cell parameters from 273 reflections
a = 29.629 (3) Å	θ = 5–50°
c = 9.438 (2) Å	µ = 0.69 mm^−1
V = 7175.6 (17) Å^3	T = 173 K
Z = 18	Needle, colourless
F(000) = 3006	0.4 × 0.1 × 0.1 mm

Data collection

Siemens SMART CCD area detector diffractometer	2888 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.038
Graphite monochromator	θmax = 27.5°, θmin = 1.4°
Detector resolution: 60 pixels mm^-1	h = −34→38
ω rotation with narrow frame scans	k = −38→35
15138 measured reflections	l = −12→11
3658 independent reflections

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.129	H-atom parameters constrained
S = 1.30	w = 1/[σ^2(Fo^2) + (0.044P)^2 + 20.867P] where P = [max(Fo^2,0) + 2Fc^2]/3
3658 reflections	(Δ/σ)max = 0.001
157 parameters	Δρmax = 1.27 e Å^−3
0 restraints	Δρmin = −0.66 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. Refinement on F² for ALL reflections except for 0 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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	Occ. (<1)
B1	0.20685 (12)	−0.02069 (12)	0.4514 (3)	0.0192 (6)
B2	0.20020 (12)	−0.01816 (12)	0.2670 (3)	0.0197 (6)
S1	0.27421 (3)	−0.01263 (3)	0.49095 (8)	0.02416 (18)
S2	0.15851 (3)	−0.08274 (3)	0.55607 (8)	0.02427 (18)
S3	0.13218 (3)	−0.03911 (3)	0.19478 (8)	0.02757 (19)
S4	0.24342 (3)	0.05338 (3)	0.20414 (8)	0.0285 (2)
N1	0.20302 (10)	0.02798 (9)	0.5250 (3)	0.0228 (5)
H1C	0.2234	0.0571	0.4694	0.027*
N2	0.22223 (9)	−0.05292 (9)	0.1847 (3)	0.0231 (5)
H2C	0.2566	−0.0395	0.2138	0.028*
C1	0.25751 (13)	−0.04940 (13)	0.6567 (4)	0.0321 (7)
H1A	0.2842	−0.0592	0.6792	0.039*
H1B	0.2566	−0.0277	0.7351	0.039*
C2	0.20473 (13)	−0.09792 (12)	0.6409 (4)	0.0331 (7)
H2A	0.1914	−0.1133	0.7354	0.040*
H2B	0.2082	−0.1239	0.5832	0.040*
C3	0.15038 (16)	0.01010 (15)	0.0581 (4)	0.0438 (9)
H3A	0.1621	−0.0004	−0.0277	0.053*
H3B	0.1199	0.0136	0.0323	0.053*
C4	0.19386 (17)	0.06166 (15)	0.1125 (4)	0.0481 (10)
H4A	0.1793	0.0771	0.1782	0.058*
H4B	0.2100	0.0859	0.0320	0.058*
C5	0.19398 (13)	−0.10876 (12)	0.2266 (4)	0.0321 (7)
H5A	0.1928	−0.1114	0.3302	0.048*
H5B	0.2121	−0.1261	0.1882	0.048*
H5C	0.1584	−0.1256	0.1891	0.048*
C6	0.22322 (13)	−0.05051 (14)	0.0267 (3)	0.0314 (7)
H6A	0.2416	−0.0140	−0.0038	0.047*
H6B	0.1874	−0.0678	−0.0095	0.047*
H6C	0.2413	−0.0682	−0.0103	0.047*
C7	0.22376 (14)	0.04256 (13)	0.6722 (3)	0.0316 (7)
H7A	0.2589	0.0473	0.6764	0.047*
H7B	0.2009	0.0148	0.7378	0.047*
H7C	0.2251	0.0751	0.6990	0.047*
C8	0.14942 (13)	0.02106 (14)	0.5234 (4)	0.0334 (7)
H8A	0.1348	0.0114	0.4277	0.050*
H8B	0.1512	0.0538	0.5513	0.050*
H8C	0.1271	−0.0066	0.5900	0.050*
C9	0.0424	0.0509	0.7322	0.062 (4)*	0.156 (8)
Cl1	0	0	0.6474	1.00 (2)*	0.47 (2)
Cl2	0	0	0.8258	1.00 (2)*	0.47 (2)
C9'	0.0525	0.0085	0.7668	0.084 (3)*	0.178 (8)
Cl1'	0	0	0.6474	1.00 (2)*	0.53 (2)
Cl2'	0	0	0.8258	1.00 (2)*	0.53 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
B1	0.0201 (15)	0.0169 (14)	0.0193 (16)	0.0082 (12)	0.0014 (12)	−0.0010 (12)
B2	0.0198 (15)	0.0185 (15)	0.0180 (15)	0.0075 (13)	0.0019 (12)	0.0002 (12)
S1	0.0210 (4)	0.0267 (4)	0.0232 (4)	0.0107 (3)	−0.0012 (3)	−0.0022 (3)
S2	0.0235 (4)	0.0199 (4)	0.0245 (4)	0.0071 (3)	0.0022 (3)	0.0041 (3)
S3	0.0242 (4)	0.0343 (4)	0.0231 (4)	0.0138 (3)	−0.0018 (3)	−0.0003 (3)
S4	0.0329 (4)	0.0209 (4)	0.0253 (4)	0.0087 (3)	0.0069 (3)	0.0042 (3)
N1	0.0280 (13)	0.0200 (12)	0.0204 (12)	0.0119 (10)	0.0023 (10)	−0.0004 (9)
N2	0.0222 (12)	0.0234 (12)	0.0215 (13)	0.0097 (10)	−0.0002 (10)	−0.0044 (10)
C1	0.0337 (17)	0.0316 (17)	0.0312 (17)	0.0164 (15)	−0.0077 (14)	0.0021 (13)
C2	0.0389 (19)	0.0261 (16)	0.0312 (18)	0.0140 (14)	−0.0083 (14)	0.0051 (13)
C3	0.050 (2)	0.054 (2)	0.0322 (19)	0.030 (2)	−0.0050 (16)	0.0078 (17)
C4	0.064 (3)	0.039 (2)	0.042 (2)	0.027 (2)	−0.0070 (19)	0.0127 (17)
C5	0.0394 (18)	0.0240 (16)	0.0321 (18)	0.0153 (14)	0.0035 (14)	−0.0046 (13)
C6	0.0328 (17)	0.0415 (19)	0.0184 (15)	0.0175 (15)	0.0017 (13)	−0.0070 (13)
C7	0.0436 (19)	0.0300 (17)	0.0209 (16)	0.0182 (15)	−0.0023 (14)	−0.0076 (13)
C8	0.0340 (18)	0.0354 (18)	0.0366 (19)	0.0218 (15)	0.0004 (14)	−0.0059 (14)

Geometric parameters (Å, º)

B1—N1	1.655 (4)	N1—C8	1.496 (4)
B1—B2	1.758 (5)	N2—C5	1.487 (4)
B1—S1	1.924 (3)	N2—C6	1.492 (4)
B1—S2	1.943 (3)	C1—C2	1.512 (4)
B2—N2	1.662 (4)	C3—C4	1.513 (6)
B2—S3	1.913 (3)	C9—Cl1	1.6120 (2)
B2—S4	1.942 (3)	C9—Cl2	1.6548 (2)
S1—C1	1.827 (3)	Cl1—C9^i	1.6120 (2)
S2—C2	1.826 (3)	Cl1—C9^ii	1.6120 (2)
S3—C3	1.815 (4)	Cl2—C9^i	1.6548 (2)
S4—C4	1.823 (4)	Cl2—C9^ii	1.6548 (2)
N1—C7	1.492 (4)
N1—B1—B2	108.7 (2)	C7—N1—B1	116.4 (2)
N1—B1—S1	109.22 (19)	C8—N1—B1	114.0 (2)
B2—B1—S1	108.56 (19)	C5—N2—C6	107.8 (2)
N1—B1—S2	105.77 (18)	C5—N2—B2	112.8 (2)
B2—B1—S2	119.9 (2)	C6—N2—B2	116.2 (2)
S1—B1—S2	104.30 (15)	C2—C1—S1	109.0 (2)
N2—B2—B1	110.4 (2)	C1—C2—S2	110.8 (2)
N2—B2—S3	107.99 (19)	C4—C3—S3	109.3 (2)
B1—B2—S3	117.5 (2)	C3—C4—S4	111.2 (3)
N2—B2—S4	106.54 (18)	Cl1—C9—Cl2	62.012 (12)
B1—B2—S4	108.80 (19)	C9—Cl1—C9^i	97.487 (8)
S3—B2—S4	104.97 (16)	C9—Cl1—C9^ii	97.487 (7)
C1—S1—B1	97.89 (14)	C9^i—Cl1—C9^ii	97.489 (7)
C2—S2—B1	99.62 (14)	C9—Cl2—C9^i	94.185 (9)
C3—S3—B2	98.67 (16)	C9—Cl2—C9^ii	94.185 (8)
C4—S4—B2	98.96 (16)	C9^i—Cl2—C9^ii	94.188 (8)
C7—N1—C8	107.7 (2)

Symmetry codes: (i) −x+y, −x, z; (ii) −y, x−y, z.