Arsenic(III) Halide Complexes with Acyclic and Macrocyclic Thio- and Selenoether Coligands: Synthesis and Structural Properties
dataset
posted on 2002-03-22, 00:00 authored by Nicholas J. Hill, William Levason, Gillian ReidThe preparations of the new complexes [AsBr<sub>3</sub>{MeS(CH<sub>2</sub>)<sub>2</sub>SMe}], [AsX<sub>3</sub>([9]aneS<sub>3</sub>)] (X = Cl, Br or I; [9]aneS<sub>3</sub> =
1,4,7-trithiacyclononane), [AsCl<sub>3</sub>([14]aneS<sub>4</sub>)] ([14]aneS<sub>4</sub> = 1,4,8,11-tetrathiacyclotetradecane), [AsX<sub>3</sub>([8]aneSe<sub>2</sub>)] ([8]aneSe<sub>2</sub> = 1,5-diselenacyclooctane), [(AsX<sub>3</sub>)<sub>2</sub>([16]aneSe<sub>4</sub>)] ([16]aneSe<sub>4</sub> = 1,5,9,13-tetraselenacyclohexadecane),
and [(AsBr<sub>3</sub>)<sub>2</sub>([24]aneSe<sub>6</sub>)] ([24]aneSe<sub>6</sub> = 1,5,9,13,17,21-hexaselenacyclotetracosane) are described. These are
obtained from direct reaction of the appropriate AsX<sub>3</sub> and 1 mol equiv of the thio- or selenoether ligand in anhydrous
CH<sub>2</sub>Cl<sub>2</sub> (or thf for X = I) solution. The products have been characterized by microanalysis and IR and <sup>1</sup>H NMR
spectroscopy. In solution they are extensively dissociated, reflecting the weak Lewis acidity of AsX<sub>3</sub>. Reaction of
AsX<sub>3</sub> with MeSe(CH<sub>2</sub>)<sub>2</sub>SeMe or MeC(CH<sub>2</sub>EMe)<sub>3</sub> (E = S or Se) gave only oils. Treatment of PCl<sub>3</sub> or PBr<sub>3</sub> with
Me<sub>2</sub>S, MeE(CH<sub>2</sub>)<sub>2</sub>EMe, or [9]aneS<sub>3</sub> failed to give solid complexes, and there was no evidence from NMR spectroscopy
for any adduct formation in solution. The crystal structures of the first series of thioether and selenoether complexes
of As(III) are described: [AsBr<sub>3</sub>{MeS(CH<sub>2</sub>)<sub>2</sub>SMe}], C<sub>4</sub>H<sub>10</sub>AsBr<sub>3</sub>S<sub>2</sub>, <i>a</i> = 10.2818(6) Å, <i>b</i> = 7.8014(5) Å, <i>c</i> = 14.503(1) Å, β = 102.9330(2)°, monoclinic, <i>P</i>2<sub>1</sub>/<i>c</i>, <i>Z</i> = 4; [AsI<sub>3</sub>{MeS(CH<sub>2</sub>)<sub>2</sub>SMe}], C<sub>4</sub>H<sub>10</sub>AsI<sub>3</sub>S<sub>2</sub>, <i>a</i> = 9.1528(1) Å, <i>b</i> =
11.5622(2) Å, <i>c</i> = 12.0939(2) Å, β = 93.863(1)°, monoclinic, <i>P2</i><i><sub>1</sub></i>/<i>n</i>, <i>Z</i> = 4; [AsCl<sub>3</sub>([9]aneS<sub>3</sub>)], C<sub>6</sub>H<sub>12</sub>AsCl<sub>3</sub>S<sub>3</sub>, <i>a</i> =
17.520(4) Å, <i>b</i> = 17.520(4) Å, <i>c</i> = 16.790(7) Å, tetragonal, <i>I</i>4<sub>1</sub><i>cd</i>, <i>Z</i> = 16; [AsCl<sub>3</sub>([14]aneS<sub>4</sub>)], C<sub>10</sub>H<sub>20</sub>AsCl<sub>3</sub>S<sub>4</sub>, <i>a</i>
= 13.5942(2) Å, <i>b</i> = 7.7007(1) Å, <i>c</i> = 18.1270(3) Å, β = 111.1662(5)°, monoclinic, <i>P2</i><i><sub>1</sub></i>/<i>n</i>, <i>Z</i> = 4; [(AsCl<sub>3</sub>)<sub>2</sub>([16]aneSe<sub>4</sub>)], C<sub>12</sub>H<sub>24</sub>As<sub>2</sub>Cl<sub>6</sub>Se<sub>4</sub>, <i>a</i> = 9.764(3) Å, <i>b</i> = 13.164(1) Å, <i>c</i> = 10.627(2) Å, β = 114.90(1)°, monoclinic, <i>P2</i><i><sub>1</sub></i>/<i>n</i>,
<i>Z</i> = 2; [(AsBr<sub>3</sub>)<sub>2</sub>([16]aneSe<sub>4</sub>)], C<sub>12</sub>H<sub>24</sub>As<sub>2</sub>Br<sub>6</sub>Se<sub>4</sub>, <i>a</i> = 10.1220(1) Å, <i>b</i> = 13.4494(2) Å, <i>c</i> = 10.5125(2) Å, β =
113.49(2)°, monoclinic, <i>P2</i><i><sub>1</sub></i>/<i>n</i>, <i>Z</i> = 2. [AsBr<sub>3</sub>{MeS(CH<sub>2</sub>)<sub>2</sub>SMe}] and [AsI<sub>3</sub>{MeS(CH<sub>2</sub>)<sub>2</sub>SMe}] reveal discrete μ<sup>2</sup>-halo As<sub>2</sub>X<sub>6</sub> dimeric structures involving distorted octahedral As(III), with the dithioether ligand chelating. [AsCl<sub>3</sub>([9]aneS<sub>3</sub>)] adopts a discrete molecular distorted octahedral geometry with the thioether behaving as a weakly coordinated
<i>fac</i>-capping ligand. [AsCl<sub>3</sub>([14]aneS<sub>4</sub>)] forms an infinite sheet involving two μ<sup>2</sup>-chloro ligands on each As but bridging
to two distinct As centers. Each macrocycle coordinates to two adjacent As centers via one S atom, giving a
<i>cis</i>-octahedral Cl<sub>4</sub>S<sub>2</sub> donor set at As(III). The structures of [(AsCl<sub>3</sub>)<sub>2</sub>([16]aneSe<sub>4</sub>)] and [(AsBr<sub>3</sub>)<sub>2</sub>([16]aneSe<sub>4</sub>)] adopt
2-dimensional sheet structures with μ<sup>2</sup>-dihalo As<sub>2</sub>X<sub>6</sub> dimers cross-linked by μ<sup>4</sup>-tetraselenoether macrocycles, giving
a disorted <i>cis</i>-X<sub>4</sub>Se<sub>2</sub> donor set at each As center. These species are compared with their antimony(III) and bismuth(III) analogues where appropriate.
