Remarkable Differences in the Coordination Chemistry of Structurally Related 1,2,4‐Triphosphaferrocenes with Copper(I) Halides and Silver(I) Salts

Abstract

The coordination behavior of 1,2,4‐triphosphaferrocenes [FeCpR(η5‐P3C2tBu2)] [CpR = Cp (1), Cp″′ = η5‐C5H2tBu3 (3)] towards CuI halides is significantly influenced by the substitution pattern of the cyclopentadienyl ring attached to the iron atom. The reaction of the Cp derivative 1 with CuBr in a 1:1 stoichiometry leads to the dimeric complex [{FeCp(η5:η1:η1‐P3C2tBu2)}{μ‐CuBr(MeCN)}]2 (5b), in which two 1,2,4‐triphosphaferrocenes are linked by two CuBr units. By using a 1:2 stoichiometry, the 1D polymeric compound [{FeCp(η5:η1:η1:η1‐P3C2tBu2)}μ‐{(CuBr)3(MeCN)2}]n (6) is formed in which the triphosphaferrocenes are bridged by (CuBr)2{CuBr(MeCN)2} units. Starting from CuI, independent of the stoichiometry, the cage compound [{FeCp(η5:η1:η1‐P3C2tBu2)}3{Cu(μ‐I)}3{Cu(μ3‐I)}3{Cu(NCMe)}(μ6‐I)](7) is formed. However, if the bulky Cp″′ derivative 3 is used already in a 1:1 stoichiometry with CuBr, a transformation of the initially five‐membered 1,2,4‐triphospholyl ring into a four‐membered 1,2‐diphosphete ligand is observed, which is linked by CuBr moieties forming the dimeric paramagnetic complex [{FeCp″′(η4:η1:η1‐P2C2tBu2)}(μ‐CuBr)]2 (9). Furthermore, applying a 1:2 stoichiometry between 3 and CuX (X = Br, I) the complete fragmentation of the 1,2,4‐triphospholyl ring under mild conditions into a tetraphosphabutadiene ligand is observed. In the formed 1D polymeric complexes [{(FeCp″′)2(μ,η4:η1:η1‐P4)}{(μ‐CuX)2(MeCN)}]n [X = Br (10a), I (10b)] this ligand represents now the middle deck of the triple‐decker sandwich complexes linked by four‐membered [(CuX)2(CH3CN)] moieties. Moreover, the reaction of the Cp derivative 1 with the Ag salt of the weakly coordinating anion [Al{OC(CF3)3}]4– leads to the dimeric Ag(CH3CN)‐bridged dicationic product [{FeCp(η5‐P3C2tBu2)}Ag(MeCN)]2[Al{OC(CF3)3}4]2 (11).

Formation of 1,3‐Diphosphacyclobutadiene Complexes from Phosphaalkynes and Their Coordination Behavior

“…Deuterated solvents were degassed, dried, and distilled prior to use. The crystals were washed with n-hexane and dried in vacuo (crystalline yield: 4a: 7 mg, 36%; 4b: 10 mg, 45 %; 4c: (2) [CpЈЈЈ 3 Co 3 (C 2 tBu 2 P 2 ) 3 Cu 3 Cl 2 ] + , 1345.4 (2) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 - Cu 4 Cl 3 ] + , 1245.5 (5) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 Cu 3 Cl 2 ] + , 11.47.5 (9) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 Cu 2 Cl] + , 1047.6 (9) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 -Cu] + , 794.0 (8) [CpЈЈЈCo(C 2 tBu 2 P 2 )Cu 3 Cl 2 + CH 3 CN] + , 753 (7) [CpЈЈЈCo(C 2 tBu 2 P 2 )Cu 3 Cl 2 ] + , 696.1 (26) [CpЈЈЈCo(C 2 tBu 2 P 2 )Cu 2 Cl + CH 3 1) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 Cu 4 I 3 ] + , 1429.2 (4) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 Cu 3 I 2 ] + , 1239.3 (1) [CpЈЈЈ 2 Co 2 (C 2 tBu 2 P 2 ) 2 -Cu 2 I] + , 936.8 (3) [CpЈЈЈCo(C 2 tBu 2 P 2 )Cu 3 I 2 ] + , 786.0 (17) [CpЈЈЈCo(C 2 tBu 2 P 2 )Cu 2 I + CH 3 CN] + , 596.1 (100) [CpЈЈЈCo(C 2 tBu 2 P 2 )Cu + CH 3 CN] + . The chemical shifts are reported in ppm relative to internal tetramethylsilane (TMS) or external phosphoric acid.…”

An Approach to Mixed PnAsm Ligand Complexes

“…The analogous all‐phosphorus polymer [{Cp′′′Fe} 2 (μ,η 4:4:1:1 ‐P 4 ){Cu(μ‐Cl)} 2 (MeCN)] ∞ ( 5 )4b, 20 exhibits a similar undulated chain motif as observed in 4 with slightly longer EE bond lengths (2.136(2), 2.149(2), and 2.382(2) Å) than the PP distances in 5 (2.096(2), 2.102(2), and 2.372(2) Å), because of the partial arsenic population in 4 . The Cu1P4 and Cu2P1 distances of 2.214(2) and 2.151(2) Å are slightly shorter than the corresponding distances in 5 (2.229(1) and 2.163(1) Å).…”

Isomerization, Ring Expansion, and Ring Contraction of 1,3‐Diphosphete Complexes

“…After further dilution, a second fraction of crystals of 4 can be obtained together with green block‐shaped crystals of 5 (Figure ). The bond lengths of the five‐membered 6π‐electron aromatic ring in 4 are comparable to those of other triphospholyl complexes –…”