Xcode 4.5 Release was released on 19 Sep 2012 and requires macOS 10.7+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/xcode_4.5/xcode_4.5.dmg.
Release notes are located at https://developer.apple.com/library/content/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW643.
The SDKs it contains are:
- iOS 10A403
- macOS 11E52
- macOS 12C237
The compilers it contains are:
- clang 4.1 (Build 421.11.65)
- LLVM-GCC (Build 2336.11.00)