A copper(I) coordination polymer containing an adamantane P–N cage ligand

The tetra­dentate non-chelating ligand 2,4,6,8,9,10-hexa­methyl-2,4,6,8,9,10-hexa­aza-1,3,5,7-tetra­phosphaadamantane, P₄(NCH₃)₆, reacts with one equivalent of cuprous iodide to yield the title coordination polymer, catena-poly[[iodo­copper(I)]-μ-2,4,6,8,9,10-hexa­methyl-2,4,6,8,9,10-hexa­aza-1,3,5,7-tetra­phosphaadamantane-κ²P¹:P³], [CuI(C₆H₁₈N₆P₄)]_n. The polymer is linked through P—Cu coordination at two vertices of the cage. The Cu^I ions have a trigonal–planar geometry, coordinated by P atoms from two different ligands and the iodide. This structure represents the first crystallographically characterized coordination compound of this cage ligand.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• R factor = 0.027
• wR factor = 0.069
• Data-to-parameter ratio = 21.3

checkCIF/PLATON results

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Alert level C
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       3.15 Ratio
PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       3.17 Ratio
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.20

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Spectroscopic studies have shown that the cage compound P₄(NCH₃)₆ can coordinate up to four Lewis acids [Ni(CO)₃, or BH₃], one at each P vertex (Riess or Reiss & Van Wazer, 1967, 1968). Crystallographic studies of chalcogenide derivatives P₄(NCH₃)₆X_n (X = O or S, n = 1–4) have also been reported (Casabianca et al., 1978; Cotton et al., 1982, 1983). To date, no crystallographic characterization has been carried out on the coordiation complexes of P₄(NCH₃)₆. We have found this ligand to be effective at coordinating soft metal ions and here report the crystal structure of the coordination polymer [P₄(NCH₃)₆CuI]_n, (I). The Cu—P bond lengths are consistent with other known structures of Cu^I with P—N ligands at 2.2434 (8) and 2.2390 (8) Å for Cu1—P1 and Cu1—P4ⁱ, respectively. IR spectroscopy of solid (I) as a KBr pellet indicated a shift in νP—N from 825 cm⁻¹ for the uncomplexed ligand to 853 cm⁻¹ with shoulders at 871 and 880 cm⁻¹ for the complexed ligand. This shift is consistent with previous studies of the chalcogenide derivatives of the ligand. (Casabianca et al., 1977)

It is interesting to compare this structure with the CuI complex formed by hexamethylphosphorustriamide (HMPT), the monomeric analog of P₄(NCH₃)₆. The HMPT complex of Cu^I forms a cube-shaped Cu₄I₄ core with the P ligands bound peripherally to the four Cu vertices (Arkhireeva et al., 1990) The crystallographic cone angle for the cage ligand is estimated to be 140°, roughly 10° larger than that of HMPT (Mueller & Mingos, 1995).

The internal structure of the cage shows minor distortions to the P—N bond lengths typical of this family of compounds (Cotton et al., 1978, 1982, 1983). The P—N bonds lengths for P bonded to Cu (P1 and P4) are consistently shorter than those for non-coordinated P atoms. The geometry around the N atoms in the cage is roughly planar. The sum of angles around N atoms ranges from 356 to 346°. The least planar N atoms are at positions where this distortion relieves crowding between methyl groups of neighboring cages. The P—P distances within the cage range from 2.975 to 3.037 Å.

S2. Experimental

Manipulations were carried out using standard Schlenck technique. The title compound was prepared by cannula addition of cuprous iodide (0.050 g) in freshly distilled acetonitrile (20 ml) to a similarly prepared solution of P₄(NCH₃)₆ (0.105 g). Some precipitation occurred immediately. The reaction flask was sealed under nitrogen and refrigerated at 277 K. Crystal formation was observed after two days. The white blocks are air stable over a period of one week.

S3. Refinement

Hydrogen atoms were placed at appropriate positions (C—H = 0.98 Å) and refined with a riding isotropic displacement parameter 1.2 times that of the parent atom. The largest peak of residual electron density is 1.02 Å from C4. The position of atoms C2 and C4 in a relatively open region of space in the crystal allows greater vibrational motion resulting in elongated thermal ellipsoids for these atoms. Modeling of C4 as a disordered methyl group using a refined free variable for the relative occupancy gave no improvement in structure refinement.

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and POV-RAY (Persistence of Vision Pty. Ltd, 2004); software used to prepare material for publication: WinGX (Version 1.70; Farrugia, 1999).

Figures

	Fig. 1. Displacement ellipsoid plot of monomer unit. Displacement ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.
	Fig. 2. Displacement ellipsoid plot of [P4(NCH3)6CuI]n (n = 3). Displacement ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.
	Fig. 3. View along the b axis of P4(NCH3)6CuIn. Displacment ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.

catena-poly[[iodocopper(I)]-µ-2,4,6,8,9,10-hexamethyl-2,4,6,8,9,10-hexaaza- 1,3,5,7-tetraphosphaadamantane-κ²P¹:P³]

Crystal data

[CuI(C6H18N6P4)]	F(000) = 952
Mr = 488.58	Dx = 2.05 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.4321 (5) Å	Cell parameters from 6312 reflections
b = 11.6068 (7) Å	θ = 2.4–27.5°
c = 16.2351 (10) Å	µ = 3.73 mm^−1
β = 94.863 (1)°	T = 100 K
V = 1583.20 (17) Å^3	Block, colorless
Z = 4	0.19 × 0.16 × 0.14 mm

Data collection

Bruker SMART CCD area-detector diffractometer	3605 independent reflections
Radiation source: fine-focus sealed tube	3234 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ϕ and ω scans	θmax = 27.5°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→8
Tmin = 0.474, Tmax = 0.594	k = −14→15
9801 measured reflections	l = −21→20

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.027	w = 1/[σ^2(Fo^2) + (0.0262P)^2 + 1.8652P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.069	(Δ/σ)max = 0.001
S = 1.03	Δρmax = 1.23 e Å^−3
3602 reflections	Δρmin = −0.71 e Å^−3
169 parameters

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.

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

	x	y	z	Uiso*/Ueq
I1	0.72936 (2)	0.579312 (15)	0.069568 (12)	0.02046 (6)
Cu1	0.87384 (4)	0.71572 (3)	0.17027 (2)	0.01346 (8)
P1	1.04422 (8)	0.63047 (6)	0.26493 (4)	0.01229 (14)
P2	1.18719 (9)	0.62129 (6)	0.43828 (5)	0.01779 (15)
P3	1.39471 (8)	0.58751 (6)	0.29620 (5)	0.01705 (15)
P4	1.16248 (8)	0.40671 (6)	0.33530 (4)	0.01180 (14)
N1	1.0492 (3)	0.67457 (19)	0.36375 (14)	0.0160 (5)
N2	1.3636 (3)	0.63634 (19)	0.39244 (15)	0.0181 (5)
N3	1.2322 (3)	0.64358 (19)	0.23728 (14)	0.0156 (5)
N4	1.3376 (3)	0.44569 (19)	0.30059 (15)	0.0158 (5)
N5	1.1578 (3)	0.47475 (19)	0.42786 (14)	0.0151 (5)
N6	1.0262 (2)	0.48477 (18)	0.27578 (13)	0.0120 (4)
C1	0.9770 (4)	0.7866 (2)	0.38322 (18)	0.0205 (6)
H1A	1.0461	0.8494	0.3675	0.031*
H1B	0.9649	0.7909	0.4426	0.031*
H1C	0.8724	0.7938	0.3524	0.031*
C2	1.4423 (4)	0.7485 (3)	0.4131 (2)	0.0286 (7)
H2A	1.5502	0.7479	0.395	0.043*
H2B	1.4477	0.7608	0.473	0.043*
H2C	1.3809	0.8109	0.385	0.043*
C3	1.2445 (4)	0.6293 (3)	0.14700 (18)	0.0231 (6)
H3A	1.2028	0.5535	0.1295	0.035*
H3B	1.3562	0.6352	0.1352	0.035*
H3C	1.1824	0.6896	0.1169	0.035*
C4	1.4647 (4)	0.3604 (3)	0.3021 (3)	0.0486 (11)
H4A	1.5276	0.3634	0.3557	0.073*
H4B	1.5334	0.377	0.2579	0.073*
H4C	1.4183	0.2834	0.2939	0.073*
C5	1.2448 (4)	0.4127 (2)	0.49809 (18)	0.0216 (6)
H5A	1.234	0.3294	0.4894	0.032*
H5B	1.1999	0.4339	0.5497	0.032*
H5C	1.3576	0.434	0.5014	0.032*
C6	0.8605 (3)	0.4478 (2)	0.28647 (18)	0.0154 (5)
H6A	0.8445	0.3689	0.2659	0.023*
H6B	0.7857	0.4996	0.2553	0.023*
H6C	0.8419	0.4506	0.3452	0.023*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.02546 (11)	0.01183 (10)	0.02227 (11)	−0.00239 (7)	−0.00864 (7)	−0.00094 (7)
Cu1	0.01347 (16)	0.00879 (16)	0.01740 (17)	0.00064 (12)	−0.00299 (12)	0.00017 (12)
P1	0.0122 (3)	0.0086 (3)	0.0155 (3)	0.0002 (2)	−0.0019 (2)	−0.0004 (2)
P2	0.0240 (4)	0.0112 (3)	0.0168 (4)	0.0015 (3)	−0.0061 (3)	−0.0028 (3)
P3	0.0119 (3)	0.0109 (3)	0.0277 (4)	−0.0014 (2)	−0.0024 (3)	0.0019 (3)
P4	0.0115 (3)	0.0088 (3)	0.0146 (3)	−0.0001 (2)	−0.0019 (2)	−0.0005 (2)
N1	0.0195 (12)	0.0114 (11)	0.0165 (12)	0.0032 (9)	−0.0024 (9)	−0.0027 (9)
N2	0.0172 (11)	0.0102 (11)	0.0250 (13)	−0.0022 (9)	−0.0091 (9)	−0.0009 (9)
N3	0.0136 (11)	0.0141 (11)	0.0184 (12)	0.0000 (8)	−0.0016 (9)	0.0010 (9)
N4	0.0124 (11)	0.0084 (10)	0.0263 (13)	0.0000 (8)	0.0007 (9)	0.0008 (9)
N5	0.0205 (12)	0.0115 (11)	0.0127 (11)	0.0011 (9)	−0.0032 (9)	−0.0001 (8)
N6	0.0105 (10)	0.0089 (10)	0.0161 (11)	−0.0003 (8)	−0.0015 (8)	0.0002 (8)
C1	0.0289 (16)	0.0109 (13)	0.0219 (15)	0.0061 (11)	0.0029 (12)	−0.0008 (11)
C2	0.0264 (17)	0.0123 (14)	0.044 (2)	−0.0054 (12)	−0.0125 (14)	−0.0048 (13)
C3	0.0217 (15)	0.0255 (16)	0.0225 (15)	0.0013 (12)	0.0042 (12)	0.0030 (12)
C4	0.0276 (19)	0.0192 (18)	0.102 (4)	0.0005 (14)	0.025 (2)	−0.0033 (19)
C5	0.0313 (16)	0.0172 (14)	0.0150 (14)	0.0008 (12)	−0.0059 (12)	0.0015 (11)
C6	0.0122 (12)	0.0122 (13)	0.0217 (14)	−0.0007 (10)	0.0009 (10)	−0.0007 (10)

Geometric parameters (Å, º)

I1—Cu1	2.5151 (4)	N5—C5	1.488 (3)
Cu1—P4^i	2.2387 (7)	N6—C6	1.486 (3)
Cu1—P1	2.2430 (7)	C1—H1A	0.98
P1—N1	1.681 (2)	C1—H1B	0.98
P1—N3	1.691 (2)	C1—H1C	0.98
P1—N6	1.708 (2)	C2—H2A	0.98
P2—N1	1.721 (2)	C2—H2B	0.98
P2—N5	1.725 (2)	C2—H2C	0.98
P2—N2	1.728 (3)	C3—H3A	0.98
P3—N2	1.703 (3)	C3—H3B	0.98
P3—N4	1.718 (2)	C3—H3C	0.98
P3—N3	1.730 (2)	C4—H4A	0.98
P4—N4	1.686 (2)	C4—H4B	0.98
P4—N6	1.699 (2)	C4—H4C	0.98
P4—N5	1.701 (2)	C5—H5A	0.98
P4—Cu1^ii	2.2387 (7)	C5—H5B	0.98
N1—C1	1.481 (3)	C5—H5C	0.98
N2—C2	1.487 (3)	C6—H6A	0.98
N3—C3	1.487 (4)	C6—H6B	0.98
N4—C4	1.458 (4)	C6—H6C	0.98
P4^i—Cu1—P1	122.82 (3)	P4—N6—P1	121.66 (13)
P4^i—Cu1—I1	122.69 (2)	N1—C1—H1A	109.5
P1—Cu1—I1	114.49 (2)	N1—C1—H1B	109.5
N1—P1—N3	106.14 (12)	H1A—C1—H1B	109.5
N1—P1—N6	101.44 (11)	N1—C1—H1C	109.5
N3—P1—N6	102.12 (11)	H1A—C1—H1C	109.5
N1—P1—Cu1	118.83 (8)	H1B—C1—H1C	109.5
N3—P1—Cu1	109.81 (8)	N2—C2—H2A	109.5
N6—P1—Cu1	116.74 (8)	N2—C2—H2B	109.5
N1—P2—N5	101.67 (11)	H2A—C2—H2B	109.5
N1—P2—N2	102.50 (12)	N2—C2—H2C	109.5
N5—P2—N2	100.33 (11)	H2A—C2—H2C	109.5
N2—P3—N4	102.43 (12)	H2B—C2—H2C	109.5
N2—P3—N3	101.87 (11)	N3—C3—H3A	109.5
N4—P3—N3	99.89 (11)	N3—C3—H3B	109.5
N4—P4—N6	103.64 (11)	H3A—C3—H3B	109.5
N4—P4—N5	104.91 (12)	N3—C3—H3C	109.5
N6—P4—N5	100.93 (11)	H3A—C3—H3C	109.5
N4—P4—Cu1^ii	111.89 (8)	H3B—C3—H3C	109.5
N6—P4—Cu1^ii	114.93 (8)	N4—C4—H4A	109.5
N5—P4—Cu1^ii	118.82 (8)	N4—C4—H4B	109.5
C1—N1—P1	119.58 (18)	H4A—C4—H4B	109.5
C1—N1—P2	115.53 (18)	N4—C4—H4C	109.5
P1—N1—P2	121.47 (14)	H4A—C4—H4C	109.5
C2—N2—P3	113.5 (2)	H4B—C4—H4C	109.5
C2—N2—P2	112.0 (2)	N5—C5—H5A	109.5
P3—N2—P2	124.52 (13)	N5—C5—H5B	109.5
C3—N3—P1	113.37 (18)	H5A—C5—H5B	109.5
C3—N3—P3	112.63 (18)	N5—C5—H5C	109.5
P1—N3—P3	122.39 (14)	H5A—C5—H5C	109.5
C4—N4—P4	118.4 (2)	H5B—C5—H5C	109.5
C4—N4—P3	116.3 (2)	N6—C6—H6A	109.5
P4—N4—P3	121.83 (13)	N6—C6—H6B	109.5
C5—N5—P4	113.91 (18)	H6A—C6—H6B	109.5
C5—N5—P2	110.15 (17)	N6—C6—H6C	109.5
P4—N5—P2	122.04 (14)	H6A—C6—H6C	109.5
C6—N6—P4	112.14 (17)	H6B—C6—H6C	109.5
C6—N6—P1	112.98 (16)

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