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. The bis(hexatriynyl) complexes (R2C(CH2PPh2)2)2Pt((CΞC)3H)2 (14; R = c, n‐Bu; e, p‐tolCH2) con­dense with the diiodide complexes R2C(CH2PPh2)2PtI2 (9a,c) in the presence of CuI (cat.) and excess HNEt2 to give the title macrocycles [(R2C(CH2PPh2)2)Pt(CΞC)3]4 (16c,e). The bis(triethylsilylpolyynyl) complexes (n‐Bu2C(CH2PPh2)2)Pt((CΞC)nSiEt3)2 (n = 2, 3) react with I2 at rt to give mainly the diiodide complex 9c and the coupling product Et3Si(CΞCCΞC)nSiEt3. Analogous reactions of the Pt4C24 macrocycle 16c also give 9c, but no sp 13C NMR signals or mass spectrometric Cxz+ ions (x = 24‐100) could be detected. It is proposed that some cyclo[24]car­bon is generated, but then rapidly converts to other forms of elemental carbon. 

Reactions of trans‐(C6F5)(p‐tol3P)2Pt(C≡C)nSiEt3 (PtC2nSi; n = 5, 7, 9) and ex­cess PtCl in the presence of wet n‐Bu4N+ F– under Sonogashira‐type conditions (CuCl, base, other additives) afford the title compounds PtC10Pt, PtC14Pt, and PtC18­Pt in 42‐32% yields. A four‐fold substitution of the phosphine ligands in PtC10Pt by PEt3 affords Pt'C10Pt' (78%), and a Sonogashira reaction of Pt'C2H and Pt'Cl affords Pt'C2Pt' (68%). Certain sp chain extension reactions that lead to or employ the precursors PtC10Si, PtC12Si, PtC14Si, and PtC18Si sometimes give byproducts derived from C2 loss, and possible origins are discussed. 

In a seminal 1972 study, TESCxTES with x = 8, 12, 16, and 24 (TES = SiEt3) were presented as unisolable and thus only characterized by UV-visible spectroscopy. We find that TESC24TES is obtained from the reaction of trans-(C6F5)(p-tol3P)2Pt(C≡C)5SiEt3 and crude HC8TES under Hay oxidative cross coupling conditions. Hay oxidative homocouplings of HC4TES and crude HC8TES afford TESC8TES (83%) and TESC16TES (5%). A Cadiot-Chodkiewicz reaction of BrC4Br and HC4TES (2 equiv) yields TESC12TES (11%). All of these compounds are crystalline, and the crystal structures of TESC8TES and TESC16TES are determined. 

Photolyses of trans-Fe(CO)3(As((CH2)n)3As) (n =a, 10; b, 12; c, 14) in the presence of PMe3, or reactions of trans-[Fe(CO)2(NO)(As((CH2)n)3As)]+ BF4− and n-Bu4N+ Cl−, affordthe air stable title complexes As((CH2)n)3As (8a−c) in 79−34%yields. With 8a, the in, in and out, out isomers are separable andeach is crystallographically characterized. With 8b,c, the isomersrapidly interconvert by homeomorphic isomerization, but eachcrystallizes (contrathermodynamically) as an out, out isomer.Reactions of 8c with H2O2 or 8b with BH3 give 8c·2O or 8b·2BH3,respectively (85−94%). Reactions of 8c with MCl2 (M = Pt, Pd,Ni), Rh(CO)(Cl), and Fe(CO)3 sources afford the correspondingcage-like complexes trans-MLn(As((CH2)14)3As) (86−51%). Thecrystal structures of 8c·2O and the PtCl2 and PdCl2 adducts are determined and compared to those of 8a−c and diphosphorusanalogs. The corresponding distibine Sb((CH2)14)3Sb is analogously prepared, but precursors necessary for the bismuth analogcould not be accessed due to the diminished BiR3 Lewis basicity 

UV irradiation of yellow CH2Cl2 solutions of trans-Fe(CO)3(P-((CH2)10)3P) (2a) and PMe3 (10 equiv) gives, in addition to the previously reported dibridgehead diphosphine P((CH2)10)3P (46%), a green paramagnetic complex that crystallography shows to be the trigonal-bipyramidal iron(I) radical trans-[Fe(CO)2(Cl)(P((CH2)10)3P)]• (1a•; 31% after workup). This is a rare example of an isolable species of the formula [Fe(CO)4−n(L)n(X)]• (n = 0−3, L =two-electron-donor ligand; X = one-electron-donor ligand). Analogous precursors with longer P(CH2)nP segments (n = 12, 14, 16, 18) give only the demetalated diphosphines, and a rationale is proposed. The magnetic susceptibility of 1a•,assayed by Evans’ method and SQUID measurements, indicates a spin (S) of 1/2. Cyclic voltammetry shows that 1a• undergoes a partially reversible one-electron oxidation, but no facile reduction. The UV−visible, EPR, and 57Fe Mössbauer spectra are analyzed in detail. Complex 2a is similarly studied, and, despite the extra valence electron, exhibits a comparable oxidation potential (ΔE1/2 ≤0.04 V). The crystal structure shows a cage conformation, solvation level, disorder motif, and unit cell parameters essentially identical to those of 1a•. DFT calculations provide much insight regarding the structural, redox, and spectroscopic properties. 

Photolyses of trans- Fe(CO)3(P((CH2)n)3P (n = 10 (a), 12 (b), 14 (c),16 (d), 18 (e)) in the presence of PMe3 provide the first economical and scalable route to macrobicyclic dibridgehead diphosphines P((CH2)n)3P (1). These are isolated as mixtures of in,in/out,out isomers that equilibrate with degenerate in,out/out,in isomers at 150 °C via pyramidal inversion at phosphorus. For the entire series, VT 31P NMR data establish or bound Keq rates, and activation parameters for a variety of phenomena, many of which involve homeomorphic isomerizations, topological processes by which certain molecules can turn themselve sinside out. This provides the first detailed mapping of such trends in homologous series of aliphatic bicyclic compounds XE((CH2)n)3EX with any type of bridgehead. Isomeric diborane adducts 1 a,d·2BH3 are also characterized. Crystal structures of out,out-1 a and in,in-1 a·2BH3 aid isomer assignments and reveal unusual cage conformations. 

CuI catalyzes reactions of cis -(R 2 C(CH 2 PPh 2 ) 2 )Pt(CCCCH) 2 and cis -(R 2 C(CH 2 PPh 2 ) 2 )PtI 2 in secondary amine solvents HNR’ 2 to give the title adducts [(R 2 C(CH 2 PPh 2 ) 2 )Pt(CCCC)] 4 ·(H 2 NR’ 2 + I − ) n (R/R’/ n = Me/Et/1, Me/((CH 2 CH 2 ) 2 O) 0.5 /3, Et/Et/1, Et/CH 2 CHCH 2 /1; 92–42%). Crystal structures of these or closely related species establish folded Pt 4 cores containing ammonium cation guests, with NH/ and NCH/CC hydrogen bonding. DOSY NMR experiments show that the host/guest relationship can be maintained in solution.