Tetra-chlorido-[N (2),N (2')-(di-methyl-silanedi-yl)bis-(N-tert-butyl-3-methyl-benzimid-amid-ato)-κ(2) N (2),N (2')]hafnium(IV).

The symmetric title mol-ecule, [Hf(C26H40N4Si)Cl4], lies about a twofold rotation axis. The Hf(IV) and Si atoms lie on the rotation axis with all other atoms being in general positions. The Hf(IV) atom is six-coordinated by two N atoms from the N (2),N (2')-(di-methyl-silanedi-yl)bis-(N-tert-butyl-3-methyl-benz-imid-amidate) ligand and four Cl(-) ions in a slightly distorted octa-hedral geometry. The two amidinate moieties are connected through the central Si atom with Si-N bond length of 1.762 (3) Å, generating the characteristic N-C-N-Si-N-C-N skeleton of a silyl-linked ansa-bis-(amidine) species.

Related literature

For reviews of related amidinate ligands and their applications, see: Edelmann (2012 ▶); n class="Gene">Lei et al. (2011 ▶); Münch et al. (2008 ▶). For a review of the modification of the steric and electronic properties of amidinate ligands by varying their substitution patterns, see: Liu et al. (2013 ▶); Qian et al. (2010 ▶). For related silyl-linked bis(amidinate) ligands and the synthesis of their metal complexes, including a closely related Hf complex, see: Bai et al. (2013 ▶).

Experimental

Crystal data

[Hfn class="Chemical">(C26H40N4Si)Cl4]

M = 757

Monoclinic,

a = 9.4373 (14) Å

b = 17.992 (3) Å

c = 19.966 (3) Å

β = 103.276 (3)°

V = 3299.5 (8) Å3

Z = 4

Mo Kα radiation

μ = 3.54 mm−1

T = 296 K

0.08 × 0.05 × 0.05 mm

Data collection

Bruker SMART area-detector diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T min = 0.765, T max = 0.843

7121 measured reflections

2920 independent reflections

2446 reflections with I > 2σ(I)

R int = 0.035

Refinement

R[F 2 > 2σ(F 2)] = 0.028

wR(F 2) = 0.061

S = 1.02

2920 reflections

169 parameters

H-atom parameters constrained

Δρmax = 0.53 e Å−3

Δρmin = −0.29 e Å−3

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL/PC (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813030328/sj5366sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813030328/sj5366Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

[Hf(C26H40N4Si)Cl4]	F(000) = 1512
Mr = 757	Dx = 1.524 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2487 reflections
a = 9.4373 (14) Å	θ = 2.5–22.1°
b = 17.992 (3) Å	µ = 3.54 mm−1
c = 19.966 (3) Å	T = 296 K
β = 103.276 (3)°	Block, colorless
V = 3299.5 (8) Å3	0.08 × 0.05 × 0.05 mm
Z = 4

Bruker SMART area-detector diffractometer	2920 independent reflections
Radiation source: fine-focus sealed tube	2446 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
φ and ω scans	θmax = 25.1°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −11→7
Tmin = 0.765, Tmax = 0.843	k = −21→19
7121 measured reflections	l = −23→23

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.061	H-atom parameters constrained
S = 1.02	w = 1/[σ2(Fo2) + (0.0266P)2] where P = (Fo2 + 2Fc2)/3
2920 reflections	(Δ/σ)max = 0.001
169 parameters	Δρmax = 0.53 e Å−3
0 restraints	Δρmin = −0.29 e Å−3

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.

	x	y	z	Uiso*/Ueq
Hf1	0.5000	0.540155 (12)	0.2500	0.03621 (10)
Cl1	0.63951 (14)	0.53649 (6)	0.36889 (6)	0.0584 (3)
Cl2	0.33063 (15)	0.63063 (6)	0.27686 (7)	0.0666 (4)
Si1	0.5000	0.37014 (8)	0.2500	0.0430 (4)
N1	0.2205 (4)	0.47999 (19)	0.33427 (18)	0.0510 (10)
H1	0.2186	0.5176	0.3074	0.061*
N2	0.3964 (3)	0.43808 (16)	0.28086 (16)	0.0363 (8)
C1	0.1179 (5)	0.4877 (3)	0.3814 (2)	0.0589 (13)
C2	0.2003 (7)	0.4884 (4)	0.4547 (3)	0.120 (3)
H2A	0.2335	0.4390	0.4683	0.180*
H2B	0.1379	0.5055	0.4833	0.180*
H2C	0.2825	0.5210	0.4596	0.180*
C3	0.0055 (7)	0.4271 (3)	0.3680 (4)	0.112 (3)
H3A	−0.0378	0.4246	0.3196	0.168*
H3B	−0.0685	0.4375	0.3926	0.168*
H3C	0.0509	0.3804	0.3832	0.168*
C4	0.0435 (7)	0.5621 (3)	0.3634 (3)	0.0891 (19)
H4A	0.1146	0.6012	0.3732	0.134*
H4B	−0.0279	0.5693	0.3901	0.134*
H4C	−0.0033	0.5630	0.3153	0.134*
C5	0.3128 (4)	0.4280 (2)	0.32526 (19)	0.0337 (9)
C6	0.3272 (5)	0.3587 (2)	0.3673 (2)	0.0415 (10)
C7	0.4307 (5)	0.3561 (2)	0.4283 (2)	0.0510 (11)
H7	0.4860	0.3984	0.4429	0.061*
C8	0.4556 (7)	0.2921 (3)	0.4691 (3)	0.0682 (15)
C9	0.3727 (8)	0.2312 (3)	0.4451 (3)	0.089 (2)
H9	0.3867	0.1879	0.4712	0.107*
C10	0.2714 (8)	0.2312 (3)	0.3850 (3)	0.088 (2)
H10	0.2182	0.1883	0.3706	0.105*
C11	0.2455 (6)	0.2957 (2)	0.3440 (3)	0.0652 (14)
H11	0.1760	0.2960	0.3026	0.078*
C12	0.5689 (8)	0.2921 (4)	0.5360 (3)	0.112 (2)
H12A	0.5769	0.2430	0.5554	0.167*
H12B	0.5408	0.3264	0.5674	0.167*
H12C	0.6611	0.3068	0.5276	0.167*
C13	0.6240 (6)	0.3125 (3)	0.3154 (2)	0.0676 (15)
H13A	0.6920	0.2872	0.2943	0.101*
H13B	0.5681	0.2768	0.3340	0.101*
H13C	0.6761	0.3439	0.3517	0.101*

	U11	U22	U33	U12	U13	U23
Hf1	0.04771 (16)	0.03029 (14)	0.03166 (14)	0.000	0.01126 (11)	0.000
Cl1	0.0724 (8)	0.0574 (7)	0.0391 (6)	−0.0115 (6)	−0.0002 (5)	0.0005 (5)
Cl2	0.0921 (10)	0.0479 (7)	0.0683 (8)	0.0238 (7)	0.0361 (8)	0.0044 (6)
Si1	0.0556 (11)	0.0302 (8)	0.0490 (11)	0.000	0.0241 (9)	0.000
N1	0.056 (2)	0.056 (2)	0.048 (2)	0.0136 (19)	0.0266 (19)	0.0120 (17)
N2	0.0409 (19)	0.0351 (17)	0.0345 (18)	−0.0027 (15)	0.0123 (16)	0.0020 (14)
C1	0.054 (3)	0.080 (3)	0.049 (3)	0.014 (3)	0.025 (2)	0.000 (2)
C2	0.109 (5)	0.207 (7)	0.044 (4)	0.072 (5)	0.018 (4)	−0.010 (4)
C3	0.096 (5)	0.095 (4)	0.174 (8)	−0.010 (4)	0.093 (5)	−0.014 (5)
C4	0.091 (4)	0.092 (4)	0.100 (5)	0.042 (4)	0.055 (4)	0.014 (3)
C5	0.035 (2)	0.037 (2)	0.028 (2)	−0.0086 (19)	0.0047 (18)	−0.0062 (16)
C6	0.058 (3)	0.036 (2)	0.039 (3)	−0.004 (2)	0.028 (2)	−0.0045 (18)
C7	0.061 (3)	0.047 (3)	0.048 (3)	0.000 (2)	0.020 (2)	0.005 (2)
C8	0.097 (4)	0.062 (3)	0.054 (3)	0.020 (3)	0.035 (3)	0.015 (3)
C9	0.174 (7)	0.041 (3)	0.076 (4)	0.008 (4)	0.076 (5)	0.011 (3)
C10	0.160 (7)	0.041 (3)	0.080 (4)	−0.033 (3)	0.062 (5)	−0.015 (3)
C11	0.085 (4)	0.058 (3)	0.061 (3)	−0.023 (3)	0.032 (3)	−0.013 (3)
C12	0.134 (6)	0.123 (5)	0.072 (5)	0.036 (5)	0.013 (4)	0.039 (4)
C13	0.084 (4)	0.062 (3)	0.071 (4)	0.030 (3)	0.045 (3)	0.025 (3)

Hf1—N2	2.233 (3)	C3—H3C	0.9600
Hf1—N2i	2.233 (3)	C4—H4A	0.9600
Hf1—Cl2i	2.4261 (11)	C4—H4B	0.9600
Hf1—Cl2	2.4261 (11)	C4—H4C	0.9600
Hf1—Cl1i	2.4366 (11)	C5—C6	1.491 (5)
Hf1—Cl1	2.4366 (11)	C6—C7	1.377 (6)
Hf1—Si1	3.0588 (16)	C6—C11	1.390 (6)
Si1—N2i	1.762 (3)	C7—C8	1.399 (6)
Si1—N2	1.762 (3)	C7—H7	0.9300
Si1—C13i	1.857 (5)	C8—C9	1.368 (8)
Si1—C13	1.857 (5)	C8—C12	1.507 (8)
N1—C5	1.318 (5)	C9—C10	1.351 (8)
N1—C1	1.504 (5)	C9—H9	0.9300
N1—H1	0.8600	C10—C11	1.409 (7)
N2—C5	1.327 (5)	C10—H10	0.9300
C1—C2	1.491 (7)	C11—H11	0.9300
C1—C3	1.502 (7)	C12—H12A	0.9600
C1—C4	1.516 (7)	C12—H12B	0.9600
C2—H2A	0.9600	C12—H12C	0.9600
C2—H2B	0.9600	C13—H13A	0.9600
C2—H2C	0.9600	C13—H13B	0.9600
C3—H3A	0.9600	C13—H13C	0.9600
C3—H3B	0.9600
N2—Hf1—N2i	69.32 (16)	H2A—C2—H2C	109.5
N2—Hf1—Cl2i	164.88 (9)	H2B—C2—H2C	109.5
N2i—Hf1—Cl2i	97.96 (9)	C1—C3—H3A	109.5
N2—Hf1—Cl2	97.96 (9)	C1—C3—H3B	109.5
N2i—Hf1—Cl2	164.88 (9)	H3A—C3—H3B	109.5
Cl2i—Hf1—Cl2	95.71 (6)	C1—C3—H3C	109.5
N2—Hf1—Cl1i	94.22 (9)	H3A—C3—H3C	109.5
N2i—Hf1—Cl1i	83.21 (9)	H3B—C3—H3C	109.5
Cl2i—Hf1—Cl1i	92.23 (4)	C1—C4—H4A	109.5
Cl2—Hf1—Cl1i	89.86 (4)	C1—C4—H4B	109.5
N2—Hf1—Cl1	83.21 (9)	H4A—C4—H4B	109.5
N2i—Hf1—Cl1	94.22 (9)	C1—C4—H4C	109.5
Cl2i—Hf1—Cl1	89.86 (4)	H4A—C4—H4C	109.5
Cl2—Hf1—Cl1	92.23 (4)	H4B—C4—H4C	109.5
Cl1i—Hf1—Cl1	176.89 (5)	N1—C5—N2	120.5 (3)
N2—Hf1—Si1	34.66 (8)	N1—C5—C6	119.6 (3)
N2i—Hf1—Si1	34.66 (8)	N2—C5—C6	119.9 (3)
Cl2i—Hf1—Si1	132.14 (3)	C7—C6—C11	119.6 (4)
Cl2—Hf1—Si1	132.14 (3)	C7—C6—C5	118.7 (4)
Cl1i—Hf1—Si1	88.45 (3)	C11—C6—C5	121.5 (4)
Cl1—Hf1—Si1	88.45 (3)	C6—C7—C8	122.2 (5)
N2i—Si1—N2	92.2 (2)	C6—C7—H7	118.9
N2i—Si1—C13i	116.87 (18)	C8—C7—H7	118.9
N2—Si1—C13i	108.80 (19)	C9—C8—C7	116.7 (5)
N2i—Si1—C13	108.80 (19)	C9—C8—C12	122.9 (5)
N2—Si1—C13	116.87 (18)	C7—C8—C12	120.4 (5)
C13i—Si1—C13	112.1 (3)	C10—C9—C8	122.8 (5)
N2i—Si1—Hf1	46.09 (10)	C10—C9—H9	118.6
N2—Si1—Hf1	46.09 (10)	C8—C9—H9	118.6
C13i—Si1—Hf1	123.93 (17)	C9—C10—C11	120.6 (5)
C13—Si1—Hf1	123.93 (17)	C9—C10—H10	119.7
C5—N1—C1	133.8 (4)	C11—C10—H10	119.7
C5—N1—H1	113.1	C6—C11—C10	117.9 (5)
C1—N1—H1	113.1	C6—C11—H11	121.0
C5—N2—Si1	127.0 (3)	C10—C11—H11	121.0
C5—N2—Hf1	131.4 (2)	C8—C12—H12A	109.5
Si1—N2—Hf1	99.25 (14)	C8—C12—H12B	109.5
C2—C1—C3	111.6 (5)	H12A—C12—H12B	109.5
C2—C1—N1	110.4 (4)	C8—C12—H12C	109.5
C3—C1—N1	110.6 (4)	H12A—C12—H12C	109.5
C2—C1—C4	109.5 (5)	H12B—C12—H12C	109.5
C3—C1—C4	109.2 (5)	Si1—C13—H13A	109.5
N1—C1—C4	105.2 (4)	Si1—C13—H13B	109.5
C1—C2—H2A	109.5	H13A—C13—H13B	109.5
C1—C2—H2B	109.5	Si1—C13—H13C	109.5
H2A—C2—H2B	109.5	H13A—C13—H13C	109.5
C1—C2—H2C	109.5	H13B—C13—H13C	109.5

Table 1

Selected bond lengths (Å)

Hf1—N2	2.233 (3)
Hf1—Cl2	2.4261 (11)
Hf1—Cl1	2.4366 (11)
Hf1—Si1	3.0588 (16)
Si1—N2	1.762 (3)
Si1—C13	1.857 (5)
N1—C5	1.318 (5)
N1—C1	1.504 (5)
N1—H1	0.8600