Subvalent Group 4B Metal Alkyls and Amides. Part I. The Synthesis and Physical Properties of Kinetically Stable Bis[bis(trimethysilyl)methyl]germanium(ii), -tin(ii), and -lead(ii) t
B X l SQ J) Suinmarjj Photolysis of R,Sn [R = (RSe3Si),CH] with ambient temperatures in solvents such as hesane or benzenc, visible light in benzene a t ambient temperature yields the stable radical R,Sn+, which has an e.s.r. solution spectrum possibly by reactions (1) and (2).showing coupling with the methine protons and ll9Sn and 117Sn nuclei.) WE report the preparation and e.s.r. spectrum of a novel organotin radical R,Sn. [R = (Me,Si),CH]. This species is readily formed in high concentration (10-2 to 10-3 M) by the photolysis with visible light [R2Sn has Am,, at 495, 332, and 239 nm in n-C,HI4] of deoxygenated solutions of R,Sn,l a t The overall process is thus viewed as a novel photochemical disproportionation: 2MII + MI + MIII. The evidence rests on the unequivocal characterisation (see below) of R,Sn. and the failure to observe deposition of a tin mirror
Me,Si),CHLi and SnCl, in ether a t 0" give Sn [CH(SiMe,),],, which is diamagnetic at room temperature and behaves chemically as a singlet 'stannylene', yielding complexes such as R,SnM'(CO), (M' = Cr or Mo).
2275 Subvalent Group 4B Metal Alkyls and Amides. Part 1 1 2 The Chemistry and Properties of Bis[ bis(trimethylsilyl)methyl]tin (11) and its Lead Analogue?
Three species of closely related woodpeckers (sapsuckers; Sphyrapicus) hybridize where they come into contact, presenting a rare ‘λ‐shape’ meeting of hybrid zones. Two of the three arms of this hybrid zone are located on either side of the Interior Plateau of British Columbia, Canada bordering the foothills of the Coast Mountains and the Rocky Mountains. The third arm is located in the eastern foothills of the Rocky Mountains. The zones of hybridization present high variability of phenotypes and alleles in relatively small areas and provide an opportunity to examine levels of reproductive isolation between the taxa involved. We examined phenotypes (morphometric traits and plumage) and genotypes of 175 live birds across the two hybrid zones. We used the Genotyping By Sequencing (GBS) method to identify 180 partially diagnostic single nucleotide polymorphisms (SNPs) to generate a genetic hybrid index (GHI) for each bird. Phenotypically diverged S. ruber and S. nuchalis are genetically closely related, while S. nuchalis and S. varius have similar plumage but are well separated at the genetic markers studied. The width of both hybrid zones is narrower than expected under neutrality, and analyses of both genotypes and phenotypes indicate that hybrids are rare in the hybrid zone. Rarity of hybrids indicates assortative mating and/or some form of fitness reduction in hybrids, which might maintain the species complex despite close genetic distance and introgression. These findings further support the treatment of the three taxa as distinct species.
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