Crystal structure of the layered arsenide Rb₃Cu₃As₂

The crystal structure of a new arsenide, Rb₃Cu₃As₂ (trirubidium tricopper diarsenide), has been established from single-crystal X-ray diffraction data. This compound crystallizes in the K₃Cu₃P₂ type, with layers of inter­linked CuAs₂ units. The partitioning of the available valence electrons yields the charge-balanced composition (Rb⁺)₃(Cu⁺)₃(As^3–)₂, placing this phase in a broad field of transition-metal-containing Zintl phases. First-principles calculations confirm a semiconducting ground state, in accordance with electron-counting considerations. Chemical bonding analysis reveals strong covalent Cu—As bonds and ionic Rb...As inter­actions. In addition, a weak attraction is found between the Cu atoms, possibly pointing toward cuprophilic inter­actions.

Computing details

Data collection: SMART (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 2014); software used to prepare material for publication: publCIF (Westrip, 2010) and STRUCTURE TIDY (Gelato & Parthé, 1987).

Trirubidium tricopper diarsenide

Crystal data

Rb3Cu3As2	Dx = 4.586 Mg m^−3
Mr = 596.87	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3m	Cell parameters from 508 reflections
a = 6.020 (4) Å	θ = 3.0–27.3°
c = 20.663 (12) Å	µ = 31.59 mm^−1
V = 648.4 (9) Å^3	T = 200 K
Z = 3	Block, red
F(000) = 792	0.06 × 0.06 × 0.04 mm

Data collection

Bruker SMART APEXII DUO CCD diffractometer	229 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.055
phi and ω scans	θmax = 29.5°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −8→8
Tmin = 0.129, Tmax = 0.264	k = −8→8
2941 measured reflections	l = −28→28
261 independent reflections

Refinement

Refinement on F^2	13 parameters
Least-squares matrix: full	0 restraints
R[F^2 > 2σ(F^2)] = 0.025	w = 1/[σ^2(Fo^2) + (0.0268P)^2 + 1.0297P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.056	(Δ/σ)max < 0.001
S = 1.10	Δρmax = 1.05 e Å^−3
261 reflections	Δρmin = −0.74 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

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

	x	y	z	Uiso*/Ueq
Rb1	0.0000	0.0000	0.09011 (4)	0.0189 (2)
Rb2	0.0000	0.0000	0.5000	0.0296 (4)
Cu	0.5000	0.0000	0.0000	0.0200 (3)
As	0.0000	0.0000	0.25740 (4)	0.0175 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Rb1	0.0185 (3)	0.0185 (3)	0.0198 (5)	0.00927 (16)	0.000	0.000
Rb2	0.0275 (5)	0.0275 (5)	0.0336 (8)	0.0138 (3)	0.000	0.000
Cu	0.0199 (4)	0.0229 (5)	0.0183 (5)	0.0115 (3)	−0.00161 (19)	−0.0032 (4)
As	0.0182 (3)	0.0182 (3)	0.0161 (5)	0.00909 (17)	0.000	0.000

Geometric parameters (Å, º)

Rb1—As	3.457 (2)	Rb2—Cu^xv	3.8574 (18)
Rb1—As^i	3.4877 (1)	Rb2—Cu^xxi	3.8574 (18)
Rb1—As^ii	3.488 (2)	Cu—As^ii	2.3413 (9)
Rb1—As^iii	3.4877 (10)	Cu—As^xxii	2.3413 (9)
Rb1—Cu^iv	3.5392 (11)	Cu—Cu^xxiii	3.0098 (9)
Rb1—Cu^v	3.5392 (7)	Cu—Cu^v	3.0098 (9)
Rb1—Cu^vi	3.5392 (17)	Cu—Cu^vii	3.0098
Rb1—Cu^vii	3.5392 (11)	Cu—Cu^xxiv	3.0098
Rb1—Cu	3.5392 (17)	Cu—Rb1^xxv	3.5392 (17)
Rb1—Cu^viii	3.5392 (7)	Cu—Rb1^ix	3.5392 (17)
Rb1—Rb1^ix	3.724 (3)	Cu—Rb1^xxvi	3.5392 (17)
Rb1—Rb2^x	3.8184 (5)	Cu—Rb2^xxvii	3.8574 (18)
Rb2—Rb1^xi	3.8184 (5)	Cu—Rb2^xxii	3.8574 (18)
Rb2—Rb1^xii	3.8184 (5)	As—Cu^xviii	2.3413 (10)
Rb2—Rb1^xiii	3.818 (2)	As—Cu^xv	2.3413 (9)
Rb2—Rb1^xiv	3.818 (2)	As—Cu^xx	2.3413 (12)
Rb2—Rb1^xv	3.8185 (11)	As—Rb1^i	3.4877 (1)
Rb2—Rb1^xvi	3.8185 (11)	As—Rb1^ii	3.488 (2)
Rb2—Cu^xvii	3.8574 (18)	As—Rb1^iii	3.4877 (10)
Rb2—Cu^xviii	3.8574 (18)	As—Rb2^xxviii	3.949 (2)
Rb2—Cu^xix	3.8574 (19)	As—Rb2^x	3.9489 (7)
Rb2—Cu^xx	3.8574 (19)	As—Rb2^xxii	3.9489 (11)
As—Rb1—As^i	94.82 (2)	Rb1^xii—Rb2—Cu^xxi	87.70 (3)
As—Rb1—As^ii	94.82 (2)	Rb1^xiii—Rb2—Cu^xxi	54.910 (17)
As^i—Rb1—As^ii	119.303 (7)	Rb1^xiv—Rb2—Cu^xxi	125.090 (17)
As—Rb1—As^iii	94.82 (2)	Rb1^xv—Rb2—Cu^xxi	125.09 (2)
As^i—Rb1—As^iii	119.30 (3)	Rb1^xvi—Rb2—Cu^xxi	54.91 (2)
As^ii—Rb1—As^iii	119.30 (3)	Cu^xvii—Rb2—Cu^xxi	45.92 (2)
As—Rb1—Cu^iv	121.74 (2)	Cu^xviii—Rb2—Cu^xxi	134.08 (2)
As^i—Rb1—Cu^iv	38.916 (14)	Cu^xix—Rb2—Cu^xxi	45.92 (3)
As^ii—Rb1—Cu^iv	133.61 (3)	Cu^xx—Rb2—Cu^xxi	134.08 (3)
As^iii—Rb1—Cu^iv	87.47 (3)	Cu^xv—Rb2—Cu^xxi	180.0
As—Rb1—Cu^v	121.744 (19)	As^ii—Cu—As^xxii	180.00 (3)
As^i—Rb1—Cu^v	38.917 (19)	As^ii—Cu—Cu^xxiii	50.002 (19)
As^ii—Rb1—Cu^v	87.468 (19)	As^xxii—Cu—Cu^xxiii	129.998 (19)
As^iii—Rb1—Cu^v	133.60 (3)	As^ii—Cu—Cu^v	129.998 (19)
Cu^iv—Rb1—Cu^v	50.33 (3)	As^xxii—Cu—Cu^v	50.002 (19)
As—Rb1—Cu^vi	121.74 (2)	Cu^xxiii—Cu—Cu^v	180.0
As^i—Rb1—Cu^vi	87.47 (2)	As^ii—Cu—Cu^vii	50.00 (2)
As^ii—Rb1—Cu^vi	133.60 (4)	As^xxii—Cu—Cu^vii	130.00 (2)
As^iii—Rb1—Cu^vi	38.92 (2)	Cu^xxiii—Cu—Cu^vii	60.00 (3)
Cu^iv—Rb1—Cu^vi	50.33 (2)	Cu^v—Cu—Cu^vii	120.00 (3)
Cu^v—Rb1—Cu^vi	94.86 (3)	As^ii—Cu—Cu^xxiv	130.00 (2)
As—Rb1—Cu^vii	121.74 (2)	As^xxii—Cu—Cu^xxiv	50.00 (2)
As^i—Rb1—Cu^vii	133.61 (3)	Cu^xxiii—Cu—Cu^xxiv	120.00 (3)
As^ii—Rb1—Cu^vii	38.916 (17)	Cu^v—Cu—Cu^xxiv	60.00 (3)
As^iii—Rb1—Cu^vii	87.47 (4)	Cu^vii—Cu—Cu^xxiv	180.0
Cu^iv—Rb1—Cu^vii	116.51 (4)	As^ii—Cu—Rb1^xxv	69.355 (19)
Cu^v—Rb1—Cu^vii	94.86 (3)	As^xxii—Cu—Rb1^xxv	110.645 (19)
Cu^vi—Rb1—Cu^vii	94.86 (4)	Cu^xxiii—Cu—Rb1^xxv	64.84 (3)
As—Rb1—Cu	121.74 (2)	Cu^v—Cu—Rb1^xxv	115.16 (3)
As^i—Rb1—Cu	87.47 (2)	Cu^vii—Cu—Rb1^xxv	115.164 (7)
As^ii—Rb1—Cu	38.92 (2)	Cu^xxiv—Cu—Rb1^xxv	64.836 (7)
As^iii—Rb1—Cu	133.60 (3)	As^ii—Cu—Rb1^ix	110.645 (19)
Cu^iv—Rb1—Cu	94.86 (4)	As^xxii—Cu—Rb1^ix	69.355 (19)
Cu^v—Rb1—Cu	50.327 (12)	Cu^xxiii—Cu—Rb1^ix	115.16 (3)
Cu^vi—Rb1—Cu	116.51 (5)	Cu^v—Cu—Rb1^ix	64.84 (3)
Cu^vii—Rb1—Cu	50.33 (2)	Cu^vii—Cu—Rb1^ix	64.836 (7)
As—Rb1—Cu^viii	121.74 (2)	Cu^xxiv—Cu—Rb1^ix	115.164 (7)
As^i—Rb1—Cu^viii	133.60 (3)	Rb1^xxv—Cu—Rb1^ix	180.00 (2)
As^ii—Rb1—Cu^viii	87.47 (2)	As^ii—Cu—Rb1^xxvi	110.65 (3)
As^iii—Rb1—Cu^viii	38.916 (16)	As^xxii—Cu—Rb1^xxvi	69.35 (3)
Cu^iv—Rb1—Cu^viii	94.86 (3)	Cu^xxiii—Cu—Rb1^xxvi	64.84 (3)
Cu^v—Rb1—Cu^viii	116.51 (4)	Cu^v—Cu—Rb1^xxvi	115.16 (3)
Cu^vi—Rb1—Cu^viii	50.327 (12)	Cu^vii—Cu—Rb1^xxvi	115.164 (7)
Cu^vii—Rb1—Cu^viii	50.33 (3)	Cu^xxiv—Cu—Rb1^xxvi	64.836 (7)
Cu—Rb1—Cu^viii	94.86 (3)	Rb1^xxv—Cu—Rb1^xxvi	63.49 (5)
As—Rb1—Rb1^ix	180.0	Rb1^ix—Cu—Rb1^xxvi	116.51 (5)
As^i—Rb1—Rb1^ix	85.18 (2)	As^ii—Cu—Rb1	69.35 (3)
As^ii—Rb1—Rb1^ix	85.18 (2)	As^xxii—Cu—Rb1	110.65 (3)
As^iii—Rb1—Rb1^ix	85.18 (2)	Cu^xxiii—Cu—Rb1	115.16 (3)
Cu^iv—Rb1—Rb1^ix	58.26 (2)	Cu^v—Cu—Rb1	64.84 (3)
Cu^v—Rb1—Rb1^ix	58.256 (19)	Cu^vii—Cu—Rb1	64.836 (7)
Cu^vi—Rb1—Rb1^ix	58.26 (2)	Cu^xxiv—Cu—Rb1	115.164 (7)
Cu^vii—Rb1—Rb1^ix	58.26 (2)	Rb1^xxv—Cu—Rb1	116.51 (5)
Cu—Rb1—Rb1^ix	58.26 (2)	Rb1^ix—Cu—Rb1	63.49 (5)
Cu^viii—Rb1—Rb1^ix	58.26 (2)	Rb1^xxvi—Cu—Rb1	180.0
As—Rb1—Rb2^x	65.527 (18)	As^ii—Cu—Rb2^xxvii	105.31 (3)
As^i—Rb1—Rb2^x	160.35 (3)	As^xxii—Cu—Rb2^xxvii	74.69 (3)
As^ii—Rb1—Rb2^x	65.248 (10)	Cu^xxiii—Cu—Rb2^xxvii	67.038 (11)
As^iii—Rb1—Rb2^x	65.25 (3)	Cu^v—Cu—Rb2^xxvii	112.962 (11)
Cu^iv—Rb1—Rb2^x	152.656 (10)	Cu^vii—Cu—Rb2^xxvii	67.037 (13)
Cu^v—Rb1—Rb2^x	152.655 (18)	Cu^xxiv—Cu—Rb2^xxvii	112.963 (13)
Cu^vi—Rb1—Rb2^x	102.589 (15)	Rb1^xxv—Cu—Rb2^xxvii	118.02 (3)
Cu^vii—Rb1—Rb2^x	63.10 (2)	Rb1^ix—Cu—Rb2^xxvii	61.98 (3)
Cu—Rb1—Rb2^x	102.59 (2)	Rb1^xxvi—Cu—Rb2^xxvii	61.985 (19)
Cu^viii—Rb1—Rb2^x	63.11 (3)	Rb1—Cu—Rb2^xxvii	118.02 (2)
Rb1^ix—Rb1—Rb2^x	114.473 (18)	As^ii—Cu—Rb2^xxii	74.69 (3)
Rb1^xi—Rb2—Rb1^xii	180.0	As^xxii—Cu—Rb2^xxii	105.31 (3)
Rb1^xi—Rb2—Rb1^xiii	104.04 (2)	Cu^xxiii—Cu—Rb2^xxii	112.962 (11)
Rb1^xii—Rb2—Rb1^xiii	75.96 (2)	Cu^v—Cu—Rb2^xxii	67.038 (11)
Rb1^xi—Rb2—Rb1^xiv	75.96 (2)	Cu^vii—Cu—Rb2^xxii	112.963 (13)
Rb1^xii—Rb2—Rb1^xiv	104.04 (2)	Cu^xxiv—Cu—Rb2^xxii	67.037 (13)
Rb1^xiii—Rb2—Rb1^xiv	180.0	Rb1^xxv—Cu—Rb2^xxii	61.98 (3)
Rb1^xi—Rb2—Rb1^xv	75.96 (3)	Rb1^ix—Cu—Rb2^xxii	118.02 (3)
Rb1^xii—Rb2—Rb1^xv	104.04 (3)	Rb1^xxvi—Cu—Rb2^xxii	118.015 (19)
Rb1^xiii—Rb2—Rb1^xv	75.96 (4)	Rb1—Cu—Rb2^xxii	61.98 (2)
Rb1^xiv—Rb2—Rb1^xv	104.04 (4)	Rb2^xxvii—Cu—Rb2^xxii	180.0
Rb1^xi—Rb2—Rb1^xvi	104.04 (3)	Cu^xviii—As—Cu^xv	80.00 (4)
Rb1^xii—Rb2—Rb1^xvi	75.96 (3)	Cu^xviii—As—Cu^xx	80.00 (5)
Rb1^xiii—Rb2—Rb1^xvi	104.04 (4)	Cu^xv—As—Cu^xx	80.00 (4)
Rb1^xiv—Rb2—Rb1^xvi	75.96 (4)	Cu^xviii—As—Rb1	132.08 (2)
Rb1^xv—Rb2—Rb1^xvi	180.00 (2)	Cu^xv—As—Rb1	132.08 (2)
Rb1^xi—Rb2—Cu^xvii	54.910 (17)	Cu^xx—As—Rb1	132.08 (3)
Rb1^xii—Rb2—Cu^xvii	125.090 (17)	Cu^xviii—As—Rb1^i	71.73 (2)
Rb1^xiii—Rb2—Cu^xvii	54.910 (13)	Cu^xv—As—Rb1^i	142.74 (4)
Rb1^xiv—Rb2—Cu^xvii	125.090 (14)	Cu^xx—As—Rb1^i	71.730 (17)
Rb1^xv—Rb2—Cu^xvii	87.70 (3)	Rb1—As—Rb1^i	85.18 (2)
Rb1^xvi—Rb2—Cu^xvii	92.30 (3)	Cu^xviii—As—Rb1^ii	71.73 (3)
Rb1^xi—Rb2—Cu^xviii	125.090 (17)	Cu^xv—As—Rb1^ii	71.730 (15)
Rb1^xii—Rb2—Cu^xviii	54.910 (17)	Cu^xx—As—Rb1^ii	142.74 (4)
Rb1^xiii—Rb2—Cu^xviii	125.090 (13)	Rb1—As—Rb1^ii	85.18 (2)
Rb1^xiv—Rb2—Cu^xviii	54.910 (14)	Rb1^i—As—Rb1^ii	119.303 (7)
Rb1^xv—Rb2—Cu^xviii	92.30 (3)	Cu^xviii—As—Rb1^iii	142.74 (4)
Rb1^xvi—Rb2—Cu^xviii	87.70 (3)	Cu^xv—As—Rb1^iii	71.73 (2)
Cu^xvii—Rb2—Cu^xviii	180.0	Cu^xx—As—Rb1^iii	71.73 (3)
Rb1^xi—Rb2—Cu^xix	54.910 (14)	Rb1—As—Rb1^iii	85.18 (2)
Rb1^xii—Rb2—Cu^xix	125.090 (14)	Rb1^i—As—Rb1^iii	119.30 (3)
Rb1^xiii—Rb2—Cu^xix	92.30 (4)	Rb1^ii—As—Rb1^iii	119.30 (3)
Rb1^xiv—Rb2—Cu^xix	87.70 (4)	Cu^xviii—As—Rb2^xxviii	130.151 (17)
Rb1^xv—Rb2—Cu^xix	125.090 (18)	Cu^xv—As—Rb2^xxviii	130.151 (13)
Rb1^xvi—Rb2—Cu^xix	54.910 (17)	Cu^xx—As—Rb2^xxviii	70.43 (4)
Cu^xvii—Rb2—Cu^xix	45.92 (3)	Rb1—As—Rb2^xxviii	61.65 (2)
Cu^xviii—Rb2—Cu^xix	134.08 (3)	Rb1^i—As—Rb2^xxviii	61.421 (10)
Rb1^xi—Rb2—Cu^xx	125.090 (14)	Rb1^ii—As—Rb2^xxviii	146.84 (4)
Rb1^xii—Rb2—Cu^xx	54.910 (14)	Rb1^iii—As—Rb2^xxviii	61.42 (3)
Rb1^xiii—Rb2—Cu^xx	87.70 (4)	Cu^xviii—As—Rb2^x	130.15 (2)
Rb1^xiv—Rb2—Cu^xx	92.30 (4)	Cu^xv—As—Rb2^x	70.43 (3)
Rb1^xv—Rb2—Cu^xx	54.910 (17)	Cu^xx—As—Rb2^x	130.151 (10)
Rb1^xvi—Rb2—Cu^xx	125.090 (17)	Rb1—As—Rb2^x	61.653 (18)
Cu^xvii—Rb2—Cu^xx	134.08 (3)	Rb1^i—As—Rb2^x	146.84 (4)
Cu^xviii—Rb2—Cu^xx	45.92 (3)	Rb1^ii—As—Rb2^x	61.421 (10)
Cu^xix—Rb2—Cu^xx	180.0	Rb1^iii—As—Rb2^x	61.42 (3)
Rb1^xi—Rb2—Cu^xv	87.70 (3)	Rb2^xxviii—As—Rb2^x	99.31 (3)
Rb1^xii—Rb2—Cu^xv	92.30 (3)	Cu^xviii—As—Rb2^xxii	70.43 (3)
Rb1^xiii—Rb2—Cu^xv	125.090 (17)	Cu^xv—As—Rb2^xxii	130.15 (3)
Rb1^xiv—Rb2—Cu^xv	54.910 (17)	Cu^xx—As—Rb2^xxii	130.152 (19)
Rb1^xv—Rb2—Cu^xv	54.91 (2)	Rb1—As—Rb2^xxii	61.65 (2)
Rb1^xvi—Rb2—Cu^xv	125.09 (2)	Rb1^i—As—Rb2^xxii	61.42 (3)
Cu^xvii—Rb2—Cu^xv	134.08 (2)	Rb1^ii—As—Rb2^xxii	61.42 (3)
Cu^xviii—Rb2—Cu^xv	45.92 (2)	Rb1^iii—As—Rb2^xxii	146.84 (4)
Cu^xix—Rb2—Cu^xv	134.08 (3)	Rb2^xxviii—As—Rb2^xxii	99.31 (4)
Cu^xx—Rb2—Cu^xv	45.92 (3)	Rb2^x—As—Rb2^xxii	99.31 (3)
Rb1^xi—Rb2—Cu^xxi	92.30 (3)

Symmetry codes: (i) −x−1/3, −y−2/3, −z+1/3; (ii) −x+2/3, −y+1/3, −z+1/3; (iii) −x−1/3, −y+1/3, −z+1/3; (iv) −x+y, −x, z; (v) −y, x−y−1, z; (vi) x−1, y, z; (vii) −x+y+1, −x+1, z; (viii) −y, x−y, z; (ix) −x, −y, −z; (x) x+1/3, y+2/3, z−1/3; (xi) −x+1/3, −y+2/3, −z+2/3; (xii) x−1/3, y−2/3, z+1/3; (xiii) −x−2/3, −y−1/3, −z+2/3; (xiv) x+2/3, y+1/3, z+1/3; (xv) x−1/3, y+1/3, z+1/3; (xvi) −x+1/3, −y−1/3, −z+2/3; (xvii) −x+y+1/3, −x+2/3, z+2/3; (xviii) −x+y+2/3, −x+1/3, z+1/3; (xix) −y+1/3, x−y−1/3, z+2/3; (xx) −y−1/3, x−y−2/3, z+1/3; (xxi) x−2/3, y−1/3, z+2/3; (xxii) x+1/3, y−1/3, z−1/3; (xxiii) −y+1, x−y, z; (xxiv) −x+y+1, −x, z; (xxv) x+1, y, z; (xxvi) −x+1, −y, −z; (xxvii) x+2/3, y+1/3, z−2/3; (xxviii) x−2/3, y−1/3, z−1/3.