The Palamas Archaeological Project: A preliminary report of the 2022 fieldwork conducted by the ongoing Greek–Swedish archaeological field programme in Palamas, region of Karditsa, Thessaly

This paper presents the preliminary results from the 2022 fieldwork of the Palamas Archaeological Project, an ongoing Greek–Swedish collaboration in the region of Karditsa, Thessaly. Working over the course of two separate field seasons, the project team conducted aerial, architectural, fieldwalking, and geophysical surveys at a number of sites within the survey area, including at the important multi-phase fortified settlements at Metamorfosi and Vlochos. Limited excavations were also conducted at the latter site, producing new evidence for the Hellenistic and Early Byzantine phases of the ancient city, including a probable cemetery. The work continues to add to the knowledge of the archaeology of the region, highlighting the long and dynamic history of human habitation in western Thessaly

The Vlochos Archaeological Project: Report on the 2016– 2018 seasons of Greek-Swedish archaeological work at Vlochos, Thessaly

The Vlochos Archaeological Project (2016–2018) was a Greek-Swedish archaeological investigation of the remains of the ancient urban site at Vlochos in western Thessaly, Greece. Employing a wide array of noninvasive methods, the project succeeded in completely mapping the visible remains, which had previously not been systematically investigated. The extensive remains of multi-period urban fortifications, a ClassicalHellenistic city, a Roman town, and a Late Antique fortress were identified, evidence of the long history of habitation on this site. Since comparatively little fieldwork has been conducted in the region, the results significantly increase our knowledge of the history and archaeology of Thessaly

Synthesis, structure, and properties of {(Me₃Si)₂CH}₂SnH(OH)

The Lappert stannylene SnR2, R = CH(SiMe3)2, adds water and methanol to yield the low-melting-point, crystalline hydroxy- and methoxydiorganostannanes R2SnH(OH) (1) and R2SnH(OMe) (2). The corresponding deuterated derivatives R2SnD(OD) (1-d2) and R2SnD(OCD3) (2-d4) have also been prepared. Compounds 1 and 2 react with D2O with retention of the Sn−H bond to give R2SnH(OD) (1-d(SnOD)). The reaction is thought to proceed by an SN2 type mechanism via a [R2SnH(OR‘)2]- (R‘ = H, D, or Me) intermediate or transition state. Consistent with this, 2-d4 is hydrolyzed to R2SnD(OH) (1-d(SnD)). A single-crystal X-ray structure analysis of 1 reveals that individual molecules form Ci-symmetrical dimers in the solid with short O−H···O* hydrogen bridges (O···O* = 2.854(2) Å). Reaction of 1 with (iPr2PC2H4PiPr2)Pd(C2H4) results in oxidative addition of the Sn−H bond to Pd0 to give the known (iPr2PC2H4PiPr2)Pd(H)−SnR2(OH) (3)

cis-(R‘₂PC₂H₄PR‘₂)PdH(SnR₃) Complexes: Trapped Intermediates in the Palladium-Catalyzed Hydrostannation of Alkynes

The complexes (R'2PC2H4PR'2)Pd(C2H4) (R' = iPr, tBu) react with R3SnH (R = Me, nBu) by displacement of the ethene ligand and oxidative addition of the Sn−H bond to generate the chelating phosphane stabilized cis PdII hydrido stannyl complexes (R'2PC2H4PR'2)PdH(SnR2) (R' = iPr (1), tBu (2)). Complex 1a (R' = iPr, R = Me), containing the smallest substituents, is only transiently formed but has been detected at −80 °C by NMR spectroscopy. It reacts further with Me3SnH, even at −120 °C, by eliminating hydrogen to give (dippe)Pd(SnMe3)2 (3). In contrast, the isolated (dippe)PdH(SnnBu3) (1b) is briefly stable at ambient temperature, whereas the sterically encumbered species (dtbpe)PdH(SnR3) (R = Me (2a), nBu (2b)) are stable well above 100 °C. The molecular structure of 2a has been determined by X-ray crystallography. Complex 2a reacts with 2 equiv of C2R''2 (R'' = CO2Me) to give (dtbpe)Pd(C2R''2) (4) and predominantly the corresponding (E)-vinylstannane (E)-(R'')(H)CC(SnMe3)(R'') (E-5). Since 2a also catalyzes the hydrostannation of the alkyne, the cis PdII hydrido stannyl complexes 1a,b and 2a,b represent trapped intermediates in the Pd-catalyzed hydrostannation of alkynes. The existence of the complexes also sheds light on the mechanism of the Pd-catalyzed degradation of R3SnH into Sn2R6 and H2

Novel (R₂PC₂H₄PR₂)M⁰−COT Complexes (M = Pd, Pt) Having Semiaromatic η²-COT or Dianionic η²(1,4)-COT Ligands

The complexes (R2PC2H4PR2)Pd(C2H4) (R = iPr, tBu) react with COT by displacement of the ethene ligand to afford the novel mononuclear complexes (R2PC2H4PR2)Pd(η2-C8H8) (R = iPr (1a), tBu (1b)). The COT ligand of 1a,b is semiaromatic; i.e., it is planar with alternating C-C and C=C bonds as expected for the monoanion [C8H8]-. Treatment of 1a,b with (R2PC2H4PR2)Pd-alkene complexes generates the dinuclear derivatives {(R2PC2H4PR2)Pd}2(μ-η2,η2-C8H8) (R = iPr (2a), tBu(2b)). The complexes 2a,b are labile; elimination of the COT ligand from 2a gives rise to homoleptic Pd2(μ-dippe)2. Reaction of (dippe)PtCl2 with (tmeda)2Li2COT or displacement of the alkene ligands in {(dippe)Pt}2(µ-η2,η2-C8H12) (4) or (dippe)Pt(C2H4) (5) by COT produces (dippe)Pt(η2-C8H8) (6a), which in the solid state also has a semiaromatic COT ligand. In solution, complex 6a is in equilibrium with the novel isomeric form (dippe)PtII{η2(1,4)-C8H8} (6b). The complexes are characterized by IR, MS, and solution and solid-state NMR

Reversible Water and Methanol Activation at the PdSn Bond¹

Water, alkanol, and amine activation reactions of transition metals may lead to complexes in which a hydro substituent is paired with an hydroxy, alkoxy, or amide substituent, all of which are potential reactive sites. 2 Well-studied examples are the d6 Ir(III) cis hydro hydroxy complexes [(Me3P)4Ir(H)OH]+PF6- 3a (ionic; stable at 100 °C) and (R3P)3Ir(H)OH(Cl) (R = Me, Et; neutral; reversible water elimination at 20 °C). 3b Of the d10 metal complexes, {(c-C6H11)3P}2Pt oxidatively adds phenols (ArOH; Ar = C6H5, C6F5) at 20 °C to afford stable trans-{(c-C6H11)3P}2Pt(H)OAr. 4 Similarly, (iPr3P)2Pt reacts with H2O to give thermally unstable trans-(iPr3P)2Pt(H)OH. 5a,b In contrast, (iPr3P)2Pd does not react with water at 20 °C. 5c Furthermore, the stannylene SnR2 (R = CH(SiMe3)2) 6a is reported to decompose in water and alkanol. 6b,c As we have recently discovered, the adducts L2Pd(0)=SnR2 (L2 = chelating bidentate phosphane) 7 undergo reversible oxidative additions of water and methanol.

(R₂PC₂H₄PR₂)Pd⁰−1-Alkyne Complexes

Displacement of the ethene ligand in (dippe)Pd(C2H4) (dippe = iPr2PC2H4PiPr2) by 1-alkynes RC⋮CH affords the mononuclear complexes (dippe)Pd(RC⋮CH) (R = Me (2a), Ph (3a), CO2Me (4), SiMe3 (5)). The molecular structure of 3a has been determined by X-ray crystallography. Mononuclear 2a and 3a have been reacted with stoichiometric amounts of (dippe)Pd(η1-C3H5)2 as a source for [(dippe)Pd0] to yield the dinuclear derivatives {(dippe)Pd}2(μ-RC⋮CH) (R = Me (2b), Ph (3b)). By the reaction of (dippe)Pd(C2H4) with difunctional vinylacetylene the mononuclear complex (dippe)Pd{(1,2-η2)-RC⋮CH} (R = CHCH2 (6a)) is formed, which is in equilibrium with isomeric (dippe)Pd{(3,4-η2)-H2CCHC⋮CH} (6b). Addition of [(dippe)Pd0] to 6a,b yields dinuclear {(dippe)Pd}2(μ-RC⋮CH) (R = CHCH2 (6c)). Reaction of (dippe)Pd(C2H4) with butadiyne affords (dippe)Pd(η2-HC⋮CC⋮CH) (7c). From dippe, Pt(cod)2, and C4H2 the Pt homologue has also been synthesized and thus, together with the already known Ni derivative, the series (dippe)M(η2-HC⋮CC⋮CH) (M = Ni (7a), Pd (7c), Pt (7f)) is now complete. When 7c and [(dippe)Pd0] are combined, the dinuclear complex {(dippe)Pd}2(μ-RC⋮CH) (R = C⋮CH (7e)) is formed in solution, whereas isomeric {(dippe)Pd}2{μ-(1,2-η2):(3,4-η2)-HC⋮CC⋮CH} (7d) is present in the solid state. The preparation of the Pd0−1-alkyne complexes refutes the conventional wisdom that this type of compound is inherently unstable. By reaction of (dippe)Pd(C2H4) with internal alkynes C2R2 the complexes (dippe)Pd(RC⋮CR) (R = Me (8a), Ph (9), CO2Me (10), SiMe3 (11)) have also been prepared. Combining 8a with [(dippe)Pd0] affords dinuclear {(dippe)Pd}2(μ-MeC⋮CMe) (8b). Finally, solution thermolysis of 2b and 8b gives rise to dinuclear alkyne-free Pd2(dippe)2 (12)